Sciencemadness Discussion Board

Tin Oxide + Antimony Oxide Anode

dann2 - 3-4-2007 at 16:36

Hello,

During a discussion regarding (Per)Chlroate Anode making someone here asked about a patent (and give a number) which described making a Ti substrate anode which involved Tin and Antimony Oxides only. No Lead Dioxide or anything else.
Can anyone here tell me where the post is, I cannot find it for the life of me.
Hope description is accurate.

TIA,
Dann2

12AX7 - 3-4-2007 at 20:15

For reference:
http://www.sciencemadness.org/talk/viewthread.php?tid=2465&a...

"...a semiconducting coat of Sb doped SnO2..."
"...Then a thin (about 0.1mm) layer of alpha PbO2..."
"...The final coat of beta PbO2 was then plated..."

The SnO2 sounds like a primer as it were, perhaps to improve conductivity (Ti is almost impossible to plate as it anodizes readily).

I wonder if the more popular indium tin oxide would work even better.

Tim

dann2 - 4-4-2007 at 15:15

Thanks for reply,

The thread was about two months ago. The anode the guy mentioned did not involve any lead dioxide, only (I think) tin and Antimony oxide. Perhaps I am mistaken.

Cheers,

Dann2

dann2 - 24-5-2007 at 17:44

Hello,

I found the patent (or one similar). It used a doped Tin oxide on its own an
an anode for brine electrolysis.

Part below.
_________________________________________________________

US Patent No. 3,627,669
Example 1 only. The electrode was used without any coating over the Doped Tin.
EXAMPLE 1

A composition suitable for coating on to an electrode support was prepared by boiling under a reflux condenser for 12 hours a mixture of 15 g. of stannic chloride, 0.4 g. of water and 55 g. of n-amyl alcohol and then stirring into 5.8 g. of the resultant mixture 0.125 g. of antimony trichloride. Twelve coats of this composition were painted on to a strip of titanium which had been immersed overnight in hot oxalic acid solution to etch the surface, then washed and dried. Each coating was dried in an oven at 200.degree. C. before the next coat was applied and after each third coat the structure was heated in air in a furnace at 450.degree. C. to convert the coating substantially to the oxides of antimony and tin. The total weight of the finished coating was 11.0 g./m squared of the titanium surface. The theoretical composition of the finished coating was SnO2 90 percent, oxides of antimony (calculated as Sb2O3) 10 percent by weight.

The coated titanium was operated successfully as an anode in chlorinated brine containing 21.5 percent w/w NaCl at pH 3 and 65.degree. C. with a current density of 8 kA/m squared. The chlorine overpotential was initially 470 mv. and had risen to 480 mv. after 5 days.
________________________________________________________-


Dann2

Here's another patent I just found.

jpsmith123 - 28-5-2007 at 14:48

In this patent, a layer of tin and antimony oxides is used as an intermediate layer between the titanium substrate and an outer coating of MnO2.

But there is also an example where the MnO2 is put on directly over the titanium without using any SnO2.

In some examples, the MnO2 is electroplated on from an aqueous MnSO4 solution (and then baked) and in other examples, it is formed by thermal decomposition of a manganese nitrate solution.

Since a 5 lb bag of manganese sulfate can be bought for under $10 from a garden store, and if the MnO2 can be easily electrodeposited onto titanium or graphite (as the literature implies) and if it can be easily converted to the beta form at kitchen stove temperatures, and being that it is relatively non-toxic and environmentally friendly...then it may be the ideal material for an anode for small scale perchlorate production.

It may be a little less efficient than PbO2 or platinum, but if the above advantages can be realized, that's a small price to pay, IMO.

And even if it only lasts a few hundred hours, so what? You can just make another one.

Attachment: 4028215.pdf (702kB)
This file has been downloaded 841 times


dann2 - 28-5-2007 at 16:29

Hello,

Sounds like a good find.

Manganese sulphate in the Garden store? is use as a trace metal supply for plants? or did you mean ceramic store.

Did not read the patent yet (downloading slow connection), but perhaps the anode with no Sn02 undercoat was/is a massive anode as such. The electrical connection NOT being made to the Ti but to the MnO2 directly. The Ti just being used a physical thing to hold the MnO2.
Seen a Lead Dioxide anode patent done that way.

Good find.

Cheers

Dann2

jpsmith123 - 28-5-2007 at 17:12

Here's a 5 lb. bag of manganese sulfate for sale on ebay. I guess you could call it "fertilizer".

http://cgi.ebay.com/Manganese-Sulfate-for-Palms-Trees-Shrubs...

BTW "Example 8" of the patent is the case without the intermediate layer. It seems the electrical connection was made to the titanium as they mention a somewhat higher voltage on the electrode compared to those with the intermediate layer.

hashashan - 28-5-2007 at 22:24

but what will you do whith an anode that cant go from chloride to perchlorate directly.
the removal of chloride from the chlorate is quite a mess

alancj - 28-5-2007 at 22:41

Well, there ARE other uses for good anodes... one could use it to produce a myriad of other products from electrolysis. Of course they're all boring except for the (per)chlorates ;)

I have MnO2, any ideas on turning that into the sulfate?

-Alan

edit: wait, I think there is a thread on that already...

[Edited on 28-5-2007 by alancj]

12AX7 - 29-5-2007 at 19:34

Quote:
Originally posted by hashashan
but what will you do whith an anode that cant go from chloride to perchlorate directly.
the removal of chloride from the chlorate is quite a mess


How do you figure? I find it quite simple. I don't have silver nitrate on hand, but I do have lead acetate on hand and I can quite easily wash potassium chlorate to that extent (less than 0.1% Cl, say).

Tim

dann2 - 29-5-2007 at 19:39

Quote:
Originally posted by alancj
Well, there ARE other uses for good anodes... one could use it to produce a myriad of other products from electrolysis. Of course they're all boring except for the (per)chlorates ;)



[Edited on 28-5-2007 by alancj]


Hello,

The Perchlorates seem to be where everyone is trying to get to.

All anode materials that can make Perchlorate will go from Chloride to Perchlorate without stopping as far as the chemistry is concerned (AFAIK).
It is the wear excessive wear rate that makes it not a great way to go. Perhaps I am too obsessed with wear rates but even graphite costs money and then there is the horrible mess........

There are three types of MnO2, Alpha, Beta and Gamma.
Alpha you do not want, Beta is best, Gamma is OK. (AFAIK)
Beta is what you get with thermal decomposition methods.
Gamma with electrodeposition methods.
There are other oxides you do not want which you get if you
heat too much.
Mn02 does not alloy into Ti oxide (like the way Ru Oxide does).
I pulled the following from a book.

From Electrodes of Conductive Metallic Oxides (Book)

In the case of Mn(NO3)2 the decomposition takes place at relatively low temperatures, practically
already at 100C. The choice of the pyrolyzing temperature is very critical in this case in that at higher
temperatures (above 400C) MnO2 decomposes to Mn2O3. The closeness of the two temperature ranges is such that

mixed oxides or MnO2 with a surface layer of Mn2O3 are often obtained. Such a surface film strongly decreases

the conductivity of the entire layer.
The pyrolysis of Mn(NO3)2 gives the Beta form of MnO2 (but below
150C other varieties of MnO2 may be obtained), whereas the electrochemical deposition and chemical
methods give rise to Gamma MnO2 (at room temperature Alpha MnO2 may be obtained). The relationship
between Beta and Gamma is one of stoichiometry and lattice order. The transition from one form to
the other occures by simply heating. The Gamma form loses water progressively and becomes increasingly
stoichoimetric until the Beta form developes. Above 400C decomposition to Mn2O3 takes place and at
higher temperatures Mn3O4 is formed. Beta MnO2 losses water at 110C which is however not bound to
the lattice. As a matter of fact, electrodes are sometimes prepared with a pyrolythic layer covered
by electrolythic MnO2.
MnO2 has also been prepared from the Carbonate by pyrolysis.

Beta MnO2 has higher conductivity than Gamma MnO2
_______________________________________________________

Dann2

alancj - 29-5-2007 at 19:54

Quote:
Originally posted by 12AX7
Quote:
Originally posted by hashashan
but what will you do whith an anode that cant go from chloride to perchlorate directly.
the removal of chloride from the chlorate is quite a mess


How do you figure? I find it quite simple. I don't have silver nitrate on hand, but I do have lead acetate on hand and I can quite easily wash potassium chlorate to that extent (less than 0.1% Cl, say).

Tim


I think what hashashan meant was that it is hard to separate out sodium chlorate from the chloride present in a chlorate cell in order to prepare it for a perchlorate cell. This is an issue if your anode can't be used to go all the way from chloride to perchlorate non-stop. The potassium salt can’t be used to make perchlorate since both are not very soluble.

-Alan

hashashan - 30-5-2007 at 03:55

Of course you can purify the chlorade from the chloride. I did it once, but it is a reall mess.
Either you recristalyze several times(if you have about 3 liters it can take you all day to do so) or you can go to potassium, recrystalize once and then return to sodium using sodiumn sulfate (which is also not a very good method because you do have to wait quite a lot time before all the potassium sulfate settles.
Anyway i call a perfect anode an anode that i can just stick into a bucket and go to a trip for 2 weeks, come back and get perch.

if you have to purify it somewhere in the middle its not very good, too mesy for me.

jpsmith123 - 30-5-2007 at 18:33

Dann2, there are several MnO2 anode patents assigned to "Diamond Shamrock". They seem to be saying in all these that Mn(NO3)2 generally makes a better MnO2 anode than any other precursor compound such as MnSO4.

According to them, this is true whether the coating is put on by electroplating or by way of painted-on thermodecomposable salt solution.

They also claim that anode quality is dependant on baking temperature and impurities.

As I see it, a significant part of this effect must be mediated by changes in crystal size and/or structure.

And if this is the case, then who knows, maybe a MnSO4 solution with the right additive might be just as good a precursor as Mn(NO3)2.

I'm attaching a paper which discusses making MnO2 by electrodeposition from MnSO4, using a TiSO4 dopant. (Although this particular paper was concerned with making MnO2 for cathode material in an alkaline cell it is an interesting read).

(BTW I wonder if MnO2 anode subject matter shoud be under its own seperate heading?)

Attachment: Electrodeposition of Manganese Dioxide technical report.doc (102kB)
This file has been downloaded 1745 times


dann2 - 17-12-2007 at 22:04

Hello,

@Roscoe

Do you have any Anode patents involving DTO that have a low Sb content in the DTO coating that do not substitute something else (Nobels) for the Antimony.
You stated that they were posted to the board. I am unable to find any.

Dann2

Rosco Bodine - 18-12-2007 at 03:27

I'm trying to find it just for you :D

Here's one but I'm not sure it is the one I had in mind so I will add to the list as I can .

US3917518

US3865703

US3793164

The noble metals were for doping the TiO2 more than the SnO2 . As they would use thicker layers of SnO2 the Sb was substituted because it was cheaper , and did a fine job of
making the SnO2 conductive , even though it didn't do much for the TiO2 . As for the nobles being substituted for the
Sb , you have it backwards what they were doing .
You don't need to use more Sb to account for the lower
use of nobles . Because even at very low levels of Sb ,
a couple of percent to perhaps 5% , the job of making the SnO2 conductive is accomplished and then some , and the conductivity worsens from there with increasing Sb , while the physical integrity of the layer suffers also .



[Edited on 18-12-2007 by Rosco Bodine]

jpsmith123 - 18-12-2007 at 05:45

Just wondering, has anyone been able to use OTC 95/5 solder to make a suitable precursor for a pyrolytic DTO coating?

Xenoid - 18-12-2007 at 09:43

Quote:
Originally posted by jpsmith123
Just wondering, has anyone been able to use OTC 95/5 solder to make a suitable precursor for a pyrolytic DTO coating?


I thought that's what everyone was already using, there are plenty of references

http://www.sciencemadness.org/talk/viewthread.php?tid=8592&a...

better speak to Eclectic about it!

I gather Dann2 doesn't have access to 95/5 lead free solder, thats why he's working with the separate elements - AFAIK.....

Rosco Bodine - 18-12-2007 at 10:19

Sheesh it is beginning to look like a bismuth containing
solder alloy could be desirable as well ,
if indications this may be the case are confirmed .
It may take the Sb working together with the Bi ,
At this juncture though, both appear to possibly , probably , be needed together . Wish I could be more specific .

[Edited on 18-12-2007 by Rosco Bodine]

dann2 - 19-12-2007 at 10:37

Hello,



Quote:
Originally posted by jpsmith123
Just wondering, has anyone been able to use OTC 95/5 solder to make a suitable precursor for a pyrolytic DTO coating?


I have failed in all attempts. Perhaps someone more skilled in the art, eh. But on a serious note SnCl2 (<strike>the Stannate</strike> sorry Stannous Chloride!!!) has not been used in any patent that I have seen. I have been using ebay Tin and Sb metal at above 15% Sb. Also used SnCl2:2H20 (solid out of a jar) + SbClx (Sb metal dissolved with HCl + H2O2).
Then there is the 'upping the oxidation state to Stannic (SnCl4) thing'. I was not able to make any headway with that either.
One problem I had was when you added the Sb Trichloride to the SnCl2 + H2O2 mix, it ppt'ed as Sb Oxide (or is it Hydrated Oxide).
If some of you guys could come up with a plan for to get solid SnCl4:5H2O from the SnCl2 + H2O2 then it may be possible to proceed with the solid SnCl4:5H2O (as per the patents).
You should not need to go to the solid admittedly but when you have the solid you (sort of ) know where you stand.
(The SnCl2 coming originally from Tin + HCl, ie.OTC.)

I have since obtained a jar of SnCl4:H2O

Sorry for not posting for a whole day but the divorce papers arrived today and I had to look through them..... (OJ'ing :D)

Dann2

[Edited on 19-12-2007 by dann2]

jpsmith123 - 19-12-2007 at 14:04

Well Dann2 today I tried to buy some 95/5 solder locally, and I couldn't find any; Lowe's didn't have it, Home Depot didn't have it (and I know they used to carry it), and I didn't see it at Sears, either.

Maybe tomorrow if I get a chance I'll try some smaller hardware stores.

After all the work you've done in trying to use the metals...to no avail...well I don't think I'll even attempt to retrace your footsteps. What I'm curious about is whether or not the 95/5 solder can be anodically dissolved in NH4OH and deposited from that solution, as per the process described in the patent Rosco recently uploaded.

Quote:

Sorry for not posting for a whole day but the divorce papers arrived today and I had to look through them..... (OJ'ing )


Yes I've found that women for some reason don't like to play second fiddle to things like perchlorate anodes.

chloric1 - 19-12-2007 at 16:17

Quote:

Yes I've found that women for some reason don't like to play second fiddle to things like perchlorate anodes.


Well, AFAIK from my experience is that is situations such this, it shows the true intelligence and neediness of certain women. Some can be supportive, many not. There is the art of compromise( I call appeasement) if you are lucky enough to get a woman that even slightly submissive, then you can show them how you could make money or hep your fellow man. But then again some women are just not reasonable enough to let a man breathe a little.

[Edited on 12/19/2007 by chloric1]

jpsmith123 - 19-12-2007 at 16:38

Well being that Christmas is coming, I think Dann2 just needs to get her something special...like maybe some nice titanium jewelry...heck he could even coat it with DTO! How many women this year do you think will be getting earrings that can also make perchlorate?

Twospoons - 19-12-2007 at 17:16

The ones in the know will be demanding Pt earrings - none of this cheapskate DTO-Ti rubbish.

Xenoid - 19-12-2007 at 17:20

Quote:
Originally posted by jpsmith123
Well Dann2 today I tried to buy some 95/5 solder locally, and I couldn't find any; Lowe's didn't have it, Home Depot didn't have it (and I know they used to carry it), and I didn't see it at Sears, either.

Maybe tomorrow if I get a chance I'll try some smaller hardware stores.


@ jpsmith123

I've just been discussing the situation here in NZ with Twospoons. The only place we have found here is an online electronics parts company. I think this type of solder is mainly used in electronics, and will be the .8 - 1.0 mm dia. resin cored wire type!

jpsmith123 - 19-12-2007 at 17:33

I'm surprised an electronics place has it. Over here it's mainly used for plumbing applications. And it seems to be slowly being replaced by Sn/Ag.

Rosco Bodine - 19-12-2007 at 18:16

I've seen 95/5 solid wire in the hardware sections
of stores on carded 4 oz rolls , but it seems to be
getting replaced by other alloys .

It looks like the alloys that contain bismuth should
also be a priority . It is strongly suspected that bismuth is
the likely material which supplies a catalytic selectivty to
the anode coating for producing perchlorate , as opposed
to the anode dumping its energy early at too low a voltage by preferentially evolving oxygen and or chlorine , or becoming involved in some sort of unfavorable equilibrium where the reaction doesn't go to completion for perchlorate .

There is definitely a surface chemistry reaction on the anode surface which involves more than just the
voltage potential on inert spectator anodes . Absent
that selectivity about the anode , the cell could just
run forever happily making hydrogen and oxgen from
the water .

jpsmith123 - 19-12-2007 at 18:41

I wonder if the SnO2 - Sb2O3 - Bi2O3 - etc. film could be made from a gas-flame-oxidized metal film?

Maybe if someone has a relatively high temperature solder pot (I've seen some advertised as going over 500 C) they could try an experiment.

Suppose a piece of titanium is hydrided and then immersed in molten Sn/Sb/Bi. Then if the temp is made to rise further to the range of 400 - 450 C, maybe the hydride will decompose and the metal will wet the titanium.

Then the coated titanium could possibly be heated in air with a gas flame to 550 degrees C or more and the coating converted to oxide?

Although even if it works it may not be much less burdensome than repeated dipping and baking anyway.

Rosco Bodine - 19-12-2007 at 18:59

Ineteresting idea .

It would be a very easy solution if it worked .
Just have an anti-passivation tinning / DTO precursor
"instant anode alloy" , tin that sucker and then fire it up:D

This idea tracks parallel with something I was thinking about awhile back using an amalgam solder / flux mixture to defeat the passivation layer and then just cooking off the mercury in a furnace hot enough to do the job . It seems plausible .

That was basically an interface alternative idea though ,
and it wouldn't work except for the first coat . You
would still need the subsequent layers added thickness
for wear . A millimeter or so coating is probably needed
for a few thousand hours service , so the one coat would only work for and inconveniently short time although
unlike the plain spinel one coat , it probably would make perchlorate . Some lead might have to go into that alloy .

These may be of interest , just found them and it raised an eyebrow because it sort of fits what I have been thinking
http://dx.doi.org/10.1016/S0167-2738(98)00410-X

http://dx.doi.org/10.1016/0167-2738(94)90400-6

http://dx.doi.org/10.1016/j.jeurceramsoc.2007.02.106
These articles have been reviewed but appear to be using methods and temperatures which are not really pertinent
to the coatings application we are contemplating , but rather involve ground materials and compressed pellet sintering of materials for sensors . So I am not going to attach these here .

[Edited on 20-12-2007 by Rosco Bodine]

Rosco Bodine - 20-12-2007 at 17:25

Quote:
Originally posted by dann2
Hello,

@Roscoe

Do you have any Anode patents involving DTO that have a low Sb content in the DTO coating that do not substitute something else (Nobels) for the Antimony.
You stated that they were posted to the board. I am unable to find any.

Dann2


Here's a more interesting reference than the ones posted earlier , as the same source did some comparisons on
longevity of some of these doped SnO2 coating schemes , using accellerated wear " torture test " conditions .

Curiously also this is the *only* reference I have found
where cobalt doped SnO2 is referenced specifically in
regards to the intermediate layer anode coating application .
I had supposed this was possible , but until now had found
nothing specific .

This is a very interesting reference also with regards to
another idea involving doping of TiO2 . This suggests that indeed it is possible to use a controlled thickness TiO2 oxidation surface on titanium , as for example a brief anodizing in 50% KOH , followed by doping by diffusion
from a subsequent layer . A variation on the rectifier patent
US2711496 using for example a cobalt dopant , and perhaps
some others should result in a doped TiO2 interface that is
conductive and essentially non-rectifying baked interface ,
though no examples are given . The thickness and chemistry
of the TiO2 layer would likely have bearing on how well this may work for particular dopants .

[Edited on 20-12-2007 by Rosco Bodine]

Attachment: US4584084 Co2O3 v Sb2O3 and other DTO dopant comparison tests.pdf (272kB)
This file has been downloaded 1100 times


dann2 - 21-12-2007 at 16:19

Hello,

See US 4,839,007 for an SnO2 only anode. They claim that the SnO2 has a very high O2 Overpotential.
There for it shoud be OK for Perclorate? if it does not corrode I guess.

Dann2

Rosco Bodine - 21-12-2007 at 17:40

That's a good find .

If it is accurate information , yeah it should work but different and lower figures are given US4208450 .
There is also a catalytic material involved for perchlorate
anodes . The coating needs to be chemically favorable
for the formation of the pechlorate .

dann2 - 22-12-2007 at 10:15

Hello,

DTO makes Perchlorate. I have run a jam jar cell making Na Perchlorate untill the Li came along.....:(

I have uploaded some papers sent to me from RongPeng.
They related to SnO2, +++++
Available here:


http://mihd.net/lqk84u



Dann2

[Edited on 22-12-2007 by dann2]

[Edited on 22-12-2007 by dann2]

Rosco Bodine - 22-12-2007 at 13:23

Quote:
Originally posted by dann2
Hello,

DTO makes Perchlorate. I have run a jam jar cell making Na Perchlorate untill the Li came along.....:(

It may not have been the Li , it may have just
been the DTO reaching the end of its numbered days
which would have occurred in any electrolyte .
Quote:

I have uploaded some papers sent to me from RongPeng.
They related to SnO2, +++++
Available here:
http://mihd.net/lqk84u
Dann2


Read with interest .

The adhesion problems that were encountered for the
ATO-Ti interface may be cured by a Co spinel interface , which by diffusion into a subsequent ATO layer results in a more dense and conductive layer which should have lower oxygen permeability as well . And lower temperatures are required for the process variation .

dann2 - 24-12-2007 at 07:15

Hello,

Just to sum up how my DTO 'Anode' test turned out. I started it on 29 Nov. It had been running untill about 2 days ago (The Li put an end to it's gallop). Subtracting 3 days from this to allow for times when I was using the power supply for other things this means that it lasted approx. 450 hours, most of this time in a Perchlroate cell.
Good enoug for a coat between LD and Ti? I will be hopeing so.
Regarding Tin compound for getting DTO coating on Ti, the only show in town (as far as I can see anyways) is SnCl4:5H2O . Not OTC stuff unfortunately.
How does industry manufcature SnCl4:5H2O?
It is not impossible to make SnCl4(anhydrous) at home via Tin metal + Cl gas. This has been used in one patent for an undercoat and also for a DTO only anode.

Seasons Greetings, BTW, hic hic.
Thank goodness my stock of real wine (Absolute Ethahol) is still large :D

Dann2

Rosco Bodine - 24-12-2007 at 16:20

Quote:
Originally posted by dann2
Regarding Tin compound for getting DTO coating on Ti, the only show in town (as far as I can see anyways) is SnCl4:5H2O .


You must be kidding .

pH critical for adhesion of ATO

Rosco Bodine - 1-1-2008 at 06:12

Here is an article which supports something I have postulated , maybe "guessed":P would help explain
some of the uncertainties and varying adhesion problems
which dann2 has reported concerning the ATO on Ti experiments . The article supports my idea that the
chlorides presursor mixtures are an unstable reaction mixture , the composition of which is variable with time and pH , and there is a *narrow* window condition where
they adhere and develop on baking to produce the desired film . Miss that target composition , which changes minute by minute for the *reaction mixture* of precursors prepared according to the abbreviated instructions supplied by the patents .......and the mixture won't stick to the substrate .

The test substrate was not Ti , but glass . But it is probable that the applicable film chemistry would not be improved on a less inert substrate . Whatever condition variables would prevent the desired film formation and adhesion on the more inert substrate , would more likely be aggravated rather than remedied by a more reactive substrate .

[Edited on 1-1-2008 by Rosco Bodine]

Attachment: TSF99.pdf (511kB)
This file has been downloaded 1382 times


more concerning pH and substrates

Rosco Bodine - 1-1-2008 at 07:39

The attached reference gives some more information concerning the instability of the (+IV) SnCl4 chloride precursor and pH range found to be useful for producing adherent coatings , and this study was done
using Si wafers as the substrate .

Also described is the benefit of using a hydrophyllic material
at the interface to facilitate the deposition of the SnO2 and to enhance the quality and thickness of the film .

This precisely parallels my suggested use for the mixed valency inorganic polymers of the Pytlewski patent
US3890429 , as a wetting agent ...the first thing applied
to the Ti substrate ...regardless of whatever goes on next .

Attachment: TSF2000.pdf (382kB)
This file has been downloaded 1101 times


dann2 - 6-1-2008 at 15:00

Hello,

(Repete post from somewhere else) but I though I would stick this in here for the record.

ly got around to titrating the product from a Perchlorate cell which had the DTO anode running in it.
This cell had been run for much much more than the run time of the cell (going from Chlorate to Perchlorate).
The cell product contains 79% Chlorate.
You also get ignition when the product is mixed with sugar and a drop of Sulphuric applied.

DTO is a hopeless anode for Perchlorate making.

Dann2

Rosco Bodine - 6-1-2008 at 15:49

Just to be clear you mean not DTO in general ,
but specifically ATO ( Sb doped SnO2 ) that is not
efficient enough as a working coating for a perchlorate
anode , though it does seem to have fair conductivity
and physical endurance in the electrolyte , when it can be gotten to stick well to the substrate . Adhesion difficulties
could make alternative dopants for SnO2 more attractive
than Sb , for intermediate layer DTO schemes .

It shouldn't be any sad farewell for the difficultly soluble
antimony dopant precursors , when readily soluble nitrates
of cobalt and perhaps other soluble nitrates as well can
produce DTO compositions which are superior in their
properties , and easier to implement .

DTO is a generic term for all doped tin oxide regardless
of the dopant(s) . DTO="doped tin oxide"

Bi doped SnO2 is looking more interesting for a working coating .

Iron doped SnO2 , or Manganese doped SnO2 are also
likely cadidates .

Did you successfully make the zirconyl nitrate ?
It could have usefulness in the same way as the TiO2
has in those tertiary SnO2 compositions .

chloric1 - 6-1-2008 at 18:16

A little off topic but related: I downloaded a doc or a patent talking about doping Manganese dioxide with Vanadium in a 9:1 ratio? All that is needed is to have manganese nitrate hexahydrate melted and add the prerequisent amount of vanadium pentoxide at around 100°C. This would be brushed on substrate and baked very simular to what is being done in the cobalt oxide anode thread. I am intrigued to know how vanadium pentoxide acts as an oxidation catalytist in electrochemical solution. I know with the contact process V2O5 is probably momentarily reduced to tetravalent V only to be reoxidized by the excess oxygen needed for the reaction. I wonder if this would aid oxidizing hypochlorite generated into the chlorate or it would just fill in crystaline gaps in the beta MnO2???

@Rosco-Vanadium Pentoxide is obviously pentavalent so it would be a good SnO2 dopant. Maybe this is helpfull or not.

Rosco Bodine - 6-1-2008 at 18:58

That sounds very familiar . I have looked at so many references I am unsure which one you are talking about .
IIRC , Lead nitrate and vanadium pentoxide can also be used as a baked coating .

That's interesting about the vanadium doping or perhaps it is a mixed oxide or spinel . There are huge numbers of combinations of these things , but the ones we are interested in is focused on the ones that are reasonably
conductive and form at relatively low temperatures ,
and adhere well and hopefully are catalytically active while having a high oxygen overvoltage .

I have an idea that any of the metal oxides which
tend to form transiently stable peroxy compounds might
function as catalytically active materials for perchlorate anodes .....permanganic , pervanadic , perchromic
"nascent acid molecules" could form on the surface of the anode and oxidize the chlorate ion to perchlorate ion ,
being reduced back to their lower energy manganic ,
vanadic , or chromic states and getting "recharged"
oxidized once again by nascent anodic oxygen .
It would seem that such materials would also tend
to present the highest oxygen overvoltage , which
is needed to kick the chlorate up to perchlorate .

There is some support for this idea I think in the pink
permanganate tinting that is being observed in Xenoids
test cell , as permanganate is certainly present from
"escaped particles" which have loosened from the anode surface and floated away into the electrolyte .
The corresponding colorations would I expect appear
for the other peracidic , peroxidic states for chromium
and vanadium .

dann2 - 6-1-2008 at 19:01

Quote:
Originally posted by Rosco Bodine
Just to be clear you mean not DTO in general ,
but specifically ATO ( Sb doped SnO2 ) that is not
efficient enough as a working coating for a perchlorate
anode , though it does seem to have fair conductivity
and physical endurance in the electrolyte , when it can be gotten to stick well to the substrate .DTO is a generic term for all doped tin oxide regardless
of the dopant(s) . DTO="doped tin oxide"
snip
, or Manganese doped SnO2 are also
likely cadidates .

Did you successfully make the zirconyl nitrate ?
It could have usefulness in the same way as the TiO2
has in those tertiary SnO2 compositions .


Hello,

The initials DTO when I use them, have ALWAYS been referring to Damm Tin Oxide. :P
(Your right, I should call it ATO)

The only reason I started to experiment with ATO was because I need it for the LD on Ti Anode. It lasted so long in a Perchlorate cell and seemed to make Perchlorate easily I thought it might do as an anode in it's own right.

The Zr Nitrate is (if it exists) still dissolved in a labeled jar. Since the Co anode came to nill I put it on the shelf.
Going to concentrate on the LD (on ATO or possilbe Magnetite). I need to get up off my butt.

Dann2

Rosco Bodine - 6-1-2008 at 20:46

Quote:
Originally posted by dann2
Hello,

The initials DTO when I use them, have ALWAYS been referring to Damm Tin Oxide. :P
(Your right, I should call it ATO)

Don't be discouraged , the Sb doping is from many indications is perhaps the most fickle of the candidate dopants for SnO2 in terms of getting good dispersion and good adhesion , at least as a binary composition in the absence of some third component . Added Co , Mn or Fe might improve it and make it more easily workable . I'd have to go back and check that , but it seems there is probably a few better alternatives to the binary ATO composition .
Quote:

The only reason I started to experiment with ATO was because I need it for the LD on Ti Anode.

Nada ! You don't need ATO , you just need a DTO
intermediate layer , and if there is a DTO which works
as good or better than ATO and serves the same purpose ,
then you are still in business .
Quote:

It lasted so long in a Perchlorate cell and seemed to make Perchlorate easily I thought it might do as an anode in it's own right.
That's what you get for thinking ;)
ATO just doesn't have the catalytic selectivity for making the perchlorate . Some other product(s) are being preferentially
evolved as the "work" done by the current passed .
Something else must be applied as a working coating .
Quote:

The Zr Nitrate is (if it exists) still dissolved in a labeled jar. Since the Co anode came to nill I put it on the shelf.
Going to concentrate on the LD (on ATO or possilbe Magnetite). I need to get up off my butt.
Dann2

The cobalt spinel solves the interface and adhesion problem
simultaneously , (which is no small problem) , and it is a useful dopant in mixture with SnO2 , and other materials .
It does what it does do very well , solving some problems , but it is only a component , not an anode coating complete
in itself anymore than is ATO . Anyway , trust what your experiments reveal and don't keep banging your head against that ATO "wall" ....but go around it to something probably better in a Co spinel interface / DTO sealing layer scheme . It is there that the usefulness of the Co will become
realized . ( hopefully ) :P

By request for R.P. Wang

Rosco Bodine - 13-3-2008 at 10:04

In response to U2U message for phase data concerning the
Sb doped SnO2 system , attached is one of several references which contain pertinent information . I will have to go back and look for the others but there are a few more .

IIRC there has been a range of figures reported for the
dopant saturation limit which seems to vary according to the method of preparation and precursors , the more complete
the dispersion of smaller particles in advance of sintering ,
the more complete is the diffusion after sintering , allowing
up to 8% Sb in the best conditions at saturation and threshold for lattice rupture .

IIRC the range seems to be from 3 to 8% and this article
putting saturation at 5% Sb is about the average of the
different sources , after *dismissing* as impossible some
patent references which suggest figures like 16% :D which
is simply at odds with every more extensive study results .

Attachment: Electroless deposition of SnO2 and Antimony doped SnO2 films .pdf (505kB)
This file has been downloaded 1006 times


dann2 - 13-3-2008 at 11:58

Hello,

What patents would they be now??
Obviously not the Diamond Shamrock one's, they are up at 25% :D:D

Are we talking about best % for bare ATO anodes or when using ATO AS an interface between Ti and LD.

Perhaps we are getting hung up on %. It may not be that important. Anywhere from 0% (residual Chloride being the dopant) to 26% SB is acceptable (for an interface coating anyways).

Least 'rupture %' may not corrospond to best anode material. It is a rather big assumption/extrapolation to make.
Quite frankly ((Madam :D), I must admit,) I don't have a clue!!

Cheers,

Dann2

[Edited on 13-3-2008 by dann2]

Rosco Bodine - 13-3-2008 at 12:33

Really I am not emotionally involved with any dopant in particular or any particular percentage as I know it's likely
that a mixture of two or three may turn out to be the best
scheme anyway . Antimony loads up SnO2 more quickly than does Manganese or Iron or Cobalt , and by implication from the little there is concerning Bismuth ,
Antimony works a lot the same way only the Bismuth
has a better catalytic effect for perchlorate . What the antimony seems to do best is in small amounts , even
fractions of 1% , it greatly reduces the grain structure
after sintering . So in that regard I see the Antimony
as being useful but for different reasons and in different
percentage , much lower percentage , where its value
is physical toughening , and better electrical conductivity , and raising oxygen overvoltage being more useful than as any catalyst . So Antimony hardens and densifies the SnO2 and does other good things , but only to a point ,
and since it can't do it all , it needs to be part of a larger scheme where other dopants add their contribution ,
like cobalt giving chlorine selectivity , and bismuth being catalytic for perchlorate , while manganese seems to
be almost a neutral O2 selective conductive SnO2 diluent and dopant which is basically aligning with the SnO2 as a cosolvent oxide , a trisolvent oxide effect actually with the cobalt spinel if all three are present .

Antimony seems to have a hardening effect on the mixed oxides similarly as it would for the metal alloys , like a
small percentage of silver added to tin , or a small percentage of antimony added to lead . A small amount is
very beneficial , but then above a limit it trashes the same grain as it greatly improved at a lesser percentage .
Antimony is like a strong spice , a little is good , but a
lot tends to overwhelm the recipe ....sort of like tarragon
in a stew .

R.P.Wang - 13-3-2008 at 19:32

Quote:
Originally posted by Rosco Bodine
In response to U2U message for phase data concerning the
Sb doped SnO2 system , attached is one of several references which contain pertinent information . I will have to go back and look for the others but there are a few more .

IIRC there has been a range of figures reported for the
dopant saturation limit which seems to vary according to the method of preparation and precursors , the more complete
the dispersion of smaller particles in advance of sintering ,
the more complete is the diffusion after sintering , allowing
up to 8% Sb in the best conditions at saturation and threshold for lattice rupture .

IIRC the range seems to be from 3 to 8% and this article
putting saturation at 5% Sb is about the average of the
different sources , after *dismissing* as impossible some
patent references which suggest figures like 16% :D which
is simply at odds with every more extensive study results .


About the optimum doping content of Sb, different methods have different data, most are ranges from 1%To 10%, this ratio are most based on the best conductivity and structure stability! If you use Sb-SnO2 anode in electrochemistry, the service life of anode is not only related to the Sb content. I will attach this file, see the conclution of this file.

Attachment: Preparation and Characterization of Antimony-Doped Tin Dioxide Electrodes. Part 1. Electrochemical Characterization.pdf (313kB)
This file has been downloaded 1283 times


dann2 - 9-2-2009 at 13:05

Hello Folks,

See attached:
Performance Comparison of Tin Oxide Anodes to Commercially Available Dimensionally Stable Anodes.

The study is in relation to treating waste water and pollutants.
Dann2

Attachment: Comparison of Tin Oxide to MMO.pdf (526kB)
This file has been downloaded 718 times


dann2 - 30-7-2010 at 12:54

Bump,

Paper here on an SnO2 Anode using SnCl2 (as opposed to using SnCl4



Attachment: 2008704+++++++++++++.pdf (502kB)
This file has been downloaded 748 times


dann2 - 8-9-2010 at 04:18

Hello,

I have had success using the procedure described in the above paper to obtain a coating of Tin Oxide using SnCl2.
I used Sb as opposed to Ce as the dopant.
Anode has ran in a Chlorate cell for 30 hours or so. It's good to go as an undercoat between LD and Ti.
The procedure eliminates the need for SnCl4:xH2O which can be difficult to obtain.

Dann2

[Edited on 8-9-2010 by dann2]

dann2 - 21-9-2010 at 12:39

Hello,

I thought someone might be interesed in the exact procedure I used to obtain Tin Oxide coating VIA SnCl2

Conductive Tin Oxide coating via Stannous Chloride (SnCl2)
Most Tin Oxide coatings on Ti have been achieved via SnCl4 (Stannic Chloride) which is somewhat difficult to obtain and not very easy to make.
The following scheme works well and uses Stannous Chloride which can easily be made from Tin metal and HCl or purchased.
It is taken from J. Material Sci. Technol., 2010, 26(2), 187-192.
"Active Stainless Steel/SnO2-CeO2 Anodes for Pollutants Oxidation Prepared by Thermal Decomposition."
(The paper is two posts above)
The procedure requires a reflux apparatus which need not be very elaborate. The prodedure from the article is as follows:

The precursor solution of SnO2-CeO2 was prepared by dissolving 4.52g SnCl2:2H2O and
0.09g CeCl3:7H2O in 50ml Ethyl alcohol. Firstly, the solution was stirred at room temperature
for 30 min. Secondly, the solution was heated and refuxed at 80C for 5 h. And then, after
sealing at room temperature for 24 h, the precursor solution was finally formed, which was
light yellow and transparent.


Antimony or other compounds can be substituted for the Ce dopant.

Detailed description
2.5 grams SnCl2:2H20 was dissolved in 15ml Distilled Methylated spirits.
0.52g of a liquid containing 31.8% Sb was added. (The Sb liquid was made from Antimony metal + HCl + H202.)
The solution turned slightly milkey due to the presence of water. (It went clear when reflux started.)
The solution was then stirred for approx. half an hour at room temperature and then refluxed for 5 hours. At the end of reflux the solution was slightly cloudy.
The solution was put into a stoppered bottle and let sit 24 hours. At this stage it was very slightly yellow and slightly cloudy.

A piece of Grade 1 Ti that had been etched for approx. 2 hours in 12% HCl at 90°C was washed in clean water and dried with a heat gun. The Ti was then liberaly brushed with the solution and let drip dry for 5 minutes.
The Ti was then shaken to remove excess solution and dried using the heat gun. The Ti was kept moving while the drying was taking place so that puddles of solution did not form on any areas of the Ti.
This solution application and drying procedure was carried out twice more and the Ti was then baked in an oven at 480°C for approx. 7 minutes.
The Ti received three more coats of solution + bake and then three more coats of solution + bake (9 coats and three bakes total).
The Titanium was a deep blue colour when finished.
It was placed into a Chlorate cell and was still running OK after a week with 4.2 Volts accross the cell at an Anode current density of approx. 70mA per square cm.

Distilled Vodka (90% Ethanol + 10% water) was also used as the solvent instead of distilled Methylated spirits. When the Antimony liquid was added the solution went very cloudy with a large precipitation of white Antimony Oxide. The solution was refluxed and most of the cloudyness disappeared. This solution was also successful at forming conductive ATO coatings on Ti. Anhydrous Ethanol is probably best if you can obtain it.


Would F do as a dopant?

Dann2

bbartlog - 22-9-2010 at 06:54

Nice, detailed description. Might try this some time. One question: is the baking temperature of 480°C necessary? My regular household oven obviously doesn't reach such temperatures and while I can easily get it that hot in a vessel heated by other means the temperature control I can get at higher temps is not currently that great.

dann2 - 22-9-2010 at 12:35

Hello bbartlog,

AFAIK you need to go to these temperatures when working with Tin Oxide. All Tin Oxide coatings on Anodes (however they are achieved) seem to be always given a final bake at close to 500C.

I think it's fair to assume that you can substitute Tin/Antimony solder dissolved in HCl + H2O2 for the solid (ebay) SnCl2 + Antimony liquid (metal + HCl + H2O2) that I used. That make the whole thing OTC.

The Anode made above using the distilled Vodka (6% water 94% Ethanol) has failed after a few hours testing so I am guessing that water is a no no.

Dann2

ATO from OTC solder

dann2 - 3-10-2010 at 16:25

Hello,

I attempted the procedure above using Tin/Antimony (95/5) solder and had success. I do not have any solder so I had to actually make some from Tin and Antimony. I had spend some time trying to achieve this approx. 2 years ago without success. The procedure I used is below. It's the same as the procedure above except that you just make the Chlorides from the solder.
________________________________________

Tin/Antimony solder can be had OTC in some places so it was decided to attempt an ATO coating using 95% Tin + 5% Antimony solder. First a small amount of the solder was made from Sn and Sb. If purchasing solder the contained flux (if present) may have to be removed by heating the solder and burning it off.
3.25 grams Tin and 0.17 grams Antimony were melted together and mixed in an Iron timble. The still molten contents were emptied out onto a piece of glass so as to form a thin sheet. This was cut into a number of small pieces and added to 30 ml (about half this amount would probably suffice) of 20% HCl and refluxed in a round bottomed flask with stirring. After approx. 45 minutes all the Tin had dissolved leaving the Sb as a fine powder. Two ml of 35% Hydrogen Peroxide was added dropwise (careful) and the Antimony reacted within a few seconds. A clear solution (very small amount of cloudyness) resulted. The solution was heated on an oil bath at 150°c with stirring untill there was just a very small pool of liquid (approx. 2 cc) left at the bottom of the flask. As HCl was coming off ventilation was needed. Some solid Chlorides deposited on the sides of the round bottom flask. It may be helpful to attach some vaccuum to the flask to speed things up. The small amount of liquid solidified when the flask cooled down and when dissolved in 30ml of solvent it was found that the weigh of the Chlorides was 6.8 grams. A further 38ml of distilled Methylated spirits (68ml total) was added to the Chlorides in the flask and stirred at room temperature for half an hour. The solution was then refluxed for 5 hours and then let stand for 24 hours in a stoppered bottle (ie. same procedure as above using purchased SnCl2 and Antimony Chloride).
An attempt to use 12% HCl for reacting with the solder was first made but a large amount of Oxides formed. The water content was probably too high. 20% HCl or greater is needed. Anhydrous Ethanol would probably be better than the distilled Methylated spirits of you can get it. 190% proof Ethanol is NOT OK. The Methylated spirits was distilled using a fractionating column. The first 10% of distillate and the last 5% (still in boiling flask) was discarded.

The ATO precursor solution now had a very slightly yellow colour.
A piece of Ti was etched in 12% HCl for approx. one hour at 90°C , washed in water and dried using a heat gun. The Ti was painted liberally with the solution and let drip dry for 5 (this may be important) minutes. The Anode was then given a good shake and dried using the heat gun. The Ti was kept moving when drying so that no puddles of precursor were formed on the Ti. This was repeated twice more and the Anode then baked at 480°C for about 8 minutes. The Anode then received two more bakes with 3 coats per bake. (Total of 9 coats and 3 bakes).

The Anode did not passivate when used to electrolyze NaCl solution. The Voltage accross the cell when the Anode was placed into the cell for the first time was low at 3 Volts. This is always a good sign of a successful ATO coat on Ti.

______________________________________

Dann2

Eclectic - 3-10-2010 at 17:16

FINALLY! YAY! Almost verbatim what I suggested 2 years ago...

:P

(Well, to be fair, you DID cleverly use the alcohol bit after prepping the aqueous chlorides mixture.)

[Edited on 10-4-2010 by Eclectic]

dann2 - 4-10-2010 at 10:23

Quote: Originally posted by Eclectic  
FINALLY! YAY! Almost verbatim what I suggested 2 years ago...

:P

(Well, to be fair, you DID cleverly use the alcohol bit after prepping the aqueous chlorides mixture.)

[Edited on 10-4-2010 by Eclectic]


Huh!!!
That would have been the ShakeAndBake&reg; :cool:
The H202 was to get the Sb to react with HCl.

What happens when the Tin and Antimony Chlorides are refluxed in the Alcohol for the 5 hours?
Does some sort of Tin/Antimony Alkoxy compound form?
________________________________________
Eg. from US 3627669
A solution of an alkoxy-tin compound was prepared by boiling under reflux for 24 hours a mixture of 15 g. of stannic chloride and 55 g. of n-amyl alcohol. Into the resultant solution were dissolved 2.13 g. of antimony trichloride.........
____________________________________________

Cheers

Dann2

[Edited on 4-10-2010 by dann2]

Aqua_Fortis_100% - 24-1-2012 at 18:36

Quote: Originally posted by dann2  
Hello,

I have had success using the procedure described in the above paper to obtain a coating of Tin Oxide using SnCl2.
I used Sb as opposed to Ce as the dopant.
Anode has ran in a Chlorate cell for 30 hours or so. It's good to go as an undercoat between LD and Ti.
The procedure eliminates the need for SnCl4:xH2O which can be difficult to obtain.

Dann2

[Edited on 8-9-2010 by dann2]


Hello Dann2, I think you will like that article, it was made in 2005, but I found it ocasionally today:

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S... (pdf format: http://www.scielo.br/pdf/qn/v27n6/22271.pdf )

Here, they use both SnCl2-SbCl3 and SnSO4-Sb2(SO4)3 to compare with regular SnCl4*5H2O method.

As spected, SnSO4 baked anode was hopeless and will not be good (MEV pics very diverging with SnCl2 anode).

Its an interesting read, since they found that even with less coats/bake cycles, you can achieve a thicker ATO film than with SnCl4 method. The SnO2 from SnSO4 method only showed somewhat good on platinized Ti.

"HOW TO":

Quote:

EXPERIMENTAL PART

Pretreatment of the substrate

The pretreatment of the substrate (Ti) is one of the most important factors to control the quality of the coating of SnO2. However, there are a variety of methods of pretreatment, and significant differences are observed in their results. We chose to use the procedure reported by Lipp and Pletcher [4], who had electrodes with good reproducibility. Thus, the working electrodes (strips of titanium - 0.25 mm x 1 cm x 4 cm - from Aldrich ®, 99.7% purity) were subjected to the following pre-treatment:

a) Blasting the surface of Ti using glass microspheres with grain size from 60 to 70 micrometres followed by ultrasonic cleaning bath for 20 min, immersed in 2-propanol;

b) Before preparation of the oxide film, etching of Ti in boiling concentrated HCl for 1 min, followed by profuse rinsing with water and air drying.

In some cases, the substrate so pretreated was platinized through a galvanostatic electrodeposition (250 mA cm -2), using a solution of H2PtCl6 (20 g L -1) + HCl (300 g L -1) at 65 ° C for 10 min; a cylindrical platinum net was used as counter electrode.

Preparation of SnO2 films

After all the pre-treatment steps have been completed, the oxide films were prepared as follows:

a) Application, with a soft brush, a thin layer of an alcoholic (2-propanol) solution of SnCl2*2H2O 13% w/v 3 + SbCl3 0.2% w/v or SnSO4 12.3% w/v + Sb2(SO4)3 0.15%, evaporating the excess alcohol in air oven at 90°C for 10 min;

b) After two applications, formation of oxide layer thermally in an oven at 500°C for 20 min with a slow, continuous flow of oxygen;

c) Repetition of steps a) and b) by 10 times;

d) Annealing the film in the oven at 500°C for 60 min with a slow, continuous flow of oxygen.

The thickness of obtained films was estimated from their mass, taking into account the density of the oxide and its coverage area (see below).



.....

Now, see this:

Quote:
Thickness estimative of the SnO2 films

...

In the case of films using the precursor salts SnCl2*2H2O and SbCl3, the mass of films and their thicknesses varied in the range from 22.2 to 33.5 g*m-2 and 3.2 to 4.8 micrometres respectively, for a total of 10 applications, so the average value of the estimated thickness (and standard deviation) for these films is (3.8 ± 0.6) micrometers. Lipp and Pletcher, using a precursor salt of Sn[+4] doped with Sb[+3], reported mass and thickness in the range of 16-25 g*m-2 and 2.2 to 3.4 micrometres, respectively, for a total of 24 applications.This shows that the precursor Sn[+2] studied in this work, even with fewer applications, features SnO2 films thicker than those reported by Lipp and Pletcher. It should be noted that in all cases the content of Sn[+2] in the solution used was the same as that of Sn[+4] used by Lipp and Pletcher.


If you folks wants the full translation I can make it in few days.

Cheers

[Edited on 25-1-2012 by Aqua_Fortis_100%]

dann2 - 25-1-2012 at 08:46


They could get SnCl2 to work by a simple 'paint & baking' process. I could never get it to work. I always had to use SnCl4:5H2O.

Just wondering who are Lipp and Pletcher?



Dann2

[Edited on 25-1-2012 by dann2]

Aqua_Fortis_100% - 25-1-2012 at 10:20

I dont understand, there are minor diferences in your procedure that give it to work properly. Of these the major difference is applying 3 coats + bake whereas they bake after every coat and give the final annealing after 10 applications/bake cycles. I dont know what could be wrong in your process to apply/bake/apply/bake/etc, but they apparently did succeed in obtaining stable SnO2 coating from SnCl2 baking. Note air is always present, they used (slow) air flowing when at baking stage.

Lipp and Pletcher are authors of the article using SnCl4 procedure referenced in abovementioned study:

Quote:

"The preparation and characterization of tin dioxide coated titanium electrodes"

Abstract

The selection of an appropriate pretreatment of the substrate as well as coating procedure allows the preparation of stable SnO2 coated titanium electrodes. Such electrodes have been operated in O2 evolution for > 1000 h without unacceptable loss of activity and may be used as anodes for the oxidation of redox couples and organic molecules.


http://www.sciencedirect.com/science/article/pii/S0013468696...


Unfortunately I can get the full document on my hands, this seems to go for references board.

SnO2 + CeO2 Over Stainless Steel

jpsmith123 - 28-1-2012 at 10:34

Here's an interesting paper about anodes made using a precursor solution of SnCl2.2H2O and CeCl3.7H2O in ethyl alcohol. The substrate was stainless steel. Although the anodes in this case were intended for wastewater treatment, it might be worth testing for ClO3 and ClO4 as well.

Attachment: Active+Stainless+Steel_SnO_sub_2__sub_-CeO_sub_2__sub_+Anodes+for+Pollutants+Oxidation+Prepared+by+Thermal+Decomposition (473kB)
This file has been downloaded 738 times

[Edited on 28-1-2012 by jpsmith123]

jpsmith123 - 29-1-2012 at 13:22

I see that Dann2 already posted that paper a while ago. I don't know how that escaped me.

Anyway, hopefully this coming week I'll be doing my first experiments trying to electro-co-deposit SnO2 & Bi2O3.

I'll report on it when I do it.

dann2 - 30-1-2012 at 14:07

Quote: Originally posted by Aqua_Fortis_100%  

Lipp and Pletcher are authors of the article using SnCl4 procedure referenced in abovementioned study:

Quote:

"The preparation and characterization of tin dioxide coated titanium electrodes"

Lipp and Pletches is attached. They used SnCl4:5H20

@ AF 100% Can you post the one that uses SnCl2?

Cheers,
Dann2




Attachment: The preparation and Char of Tin Dioxide Titanium Electordes.pdf (459kB)
This file has been downloaded 1030 times


mogana100 - 9-2-2012 at 12:26

Hi

I have few questions about the SnO2 coating.

1. is it possible, or has anyone tried to use stainless steel as the substrate, as mentioned in the patent (for a chlorate cell, of course)?

2. @dann2: why did you use Sb as a dopant instead of Ce? CeO2-powder is aviable as high grade polishing paste for optics.

3. why refluxing the solution? are the chlorides reacting with the alcohol, or is it just for stirring (like when dissolving NaCl in water)?

[Edited on 9-2-2012 by mogana100]

dann2 - 9-2-2012 at 12:57


Hello,

Some reading here:
http://www.oxidizing.110mb.com/chlorate/semi.html

I spent alot of time trying to obtain SnO2 coatings (doped with Sb) using SnCl2. The process is simple. You dissolve the SnCl2 + some Antimony Chloride in alcohol, paint onto (clean and etched) Ti metal and bake in an oven to obtain the SnO2 (doped with Sb) coating.
I could never get it to work.

I had to use SnCl4:5H2O instead of the SnCl2 in the simple bake and paint process.
I seen the paper that describe the procedure whereby SnCl2 is refluxed with Alcohol (+ dopent, Ce is used in the article) and decided to try it with Sb.
It worked fine. When SnCl2 is refluxed with alcohol a Tin Alkoxy (also called Tin Alcoholate) (spelling may be off) compound is formed which works well to create coatings via the simple paint and bake process.

The only disadvantage with using SnCl4:5H2O is that it is difficult to obtain. SnCl2 can be made (or purchased) easily.

Tin Oxide Anodes, doped with Antimony, are not much use at making Chlorate or Perchlorate BTW.
Perhaps doped with Bismuth they may be good for Perchlorate. I don't know myself. I have never been able to make a Tin Oxide Anode doped with Bismuth. I just end up with pieces of passivated Ti metal after I bake the Anode.

What are you ultimately trying to do with the Tin Oxide (doped with whatever) Anode?

I mainly use the Tin Oxide, doped with Antimony coatings as an coating between Lead Dioxide and Ti metal (ie. in a Lead Dioxide Anode). It is much simpler to use MMO for this job (if you can get MMO).
Dann2

mogana100 - 10-2-2012 at 07:13

Hi

I want to use it as an precoat between the substrate and a lead dioxide coating.

I want to use stainless steel, because here in Germany, Titanium is pretty damn expensive: a sheet of Ti, 10cm*10cm 3,2mm thick costs 104€ (104€ ~= 140$ ). The price for an ingot of the same weight would be 2,8€ , ~= 4-5$.

This is the reason why I want to use a SS/CeO2:SnO2 anode as a kind of fault tolerant substrate instead of Titanium, because I can't get it cheaply.

dann2 - 10-2-2012 at 13:03


Stainless steel will be hopeless IMO.
Grade 5 Ti will be much much much better if you cannot get Grade one or two.

http://www.ebay.de/itm/3-x-Titanblech-Titan-Blech-1-5-mm-3-7...

Try bicycle shops and they might give you some scrap from an expensive bike.

Dann2

mogana100 - 10-2-2012 at 14:34

Thank you for the link.

But I don't understand why it shouln't work for making Chlorate, can you explain please? What is the chemical difference (at the anode of course) between this application (making chlorates) and the original application (oxidizing organic compounds in aqueous solutions), and why is the stainless steel not passivating like the titanium does? I'm just wondering because in both cases hydroxide ions are formed, so i can't see major differences.

(sorry for the noob-style questions, but I'm not experienced at this stuff, but I want to understand)

dann2 - 10-2-2012 at 17:38


I don't know much about oxidizing organic compounds but a Chlorate or Perchlorate cell will rapidly corrode any Stainless Steel that is exposed.
Tin Oxide coating (or any Oxide coating) will not protect something that is going to corrode as these coating have 'cracked mud morphology'. They look like cracked mud when viewed under a microscope. They do not 'seal' anything. You are depending on the nature of Valve metals (Ti, Nb, Ta) to form their own very tough coating to protect themselves anywhere the Tin oxide (or Ru Oxide if MMO) coating is not alloyed to the metal or anywhere the Tin Oxide coat wears away.
Read up on Valve metals. Stainless steel will not passivate in a Chlorate or Perchlorate cell.

Dann2