White Yeti
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Electrochemical anode materials.
**update**
The fact that boron phosphide decomposes in water changes everything.
I still think that the theory is relatively promising, I just chose the wrong material -.-
This is the idea/ theory:
A chemically inert semiconducting network solid of some kind that is resistant to attack by acids and bases is doped with so much impurity that it
becomes a degenerate semiconductor. It would have a low enough resistivity and a high enough level of chemical resistance to be used as an anode for
electrochemical reactions without showing any signs of corrosion or degradation.
Since boron phosphide won't work well as an anode, here is a list of substances that I considered using before settling for boron phosphide:
SiC
BN
TiO2
PbS
CuO
Most promising on top, least promising on bottom.
I have not checked the chemical inertnesses of all these materials thoroughly enough to conclude that they can be used in aqueous solutions of acids
and bases, but must of these should be fairly chemically inert to withstand the corrosive effects of HCl, H2SO4, NaOH etc... Also, there might be some
substances that could be used as anodes that I might have missed. So please feel free to comment.
So, what do you guys think? Which material would be best suited for use as an anode once it has been turned into a degenerate semiconductor?
Thank you for your patience.
[Edited on 7-21-2011 by White Yeti]
[Edited on 7-21-2011 by White Yeti]
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Rogeryermaw
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that's a tough question since boron and phosphorus are two of the elements used to dope silicon. i wonder that using these elements on a substrate
made of the same elements might have undesirable properties? arsenic and gallium are two other commonly used elements.
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IrC
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I am a little confused with this one. You want to use this as an electrode in a basic or acidic solution? I assume this is so from :
"I was thinking about using this material to make an anode that would not degrade when used."
Correct me if I am wrong but would not either contain some amount of H2O? This chemical is even worse than the metal phosphides, even the slightest
trace of water in the air has it sitting there producing PH3 with the resulting dead fish/garlic smell, the limit being 0.3 ppm in air. Meaning you
cant even let it sit around in open air let alone use it for an electrode in some kind of solution. I have to wonder at both your questions and
statements, the MSDS being very prevalent online. Makes me think you have absolutely zero idea what you are doing let alone what you are saying. Not
to mention you have not even done minimal research on this chemical. How are you going to make an electrode out of a gritty powder which decays in
open air. Your electrode would disintegrate just sitting on the shelf. Also, the resulting phosphine will kill you. Do not mess with this chemical it
is clear you are playing with danger far beyond your knowledge and experience.
http://www.espi-metals.com/msds%27s/Boron%20Phosphide.htm
"Solubility in H2O: Decomposes in H20 with evolution of PH3.
Appearance and Odor: Maroon powder, fishy or garlic-like odor in moist air."
Appears you did not even read the MSDS.
You stated: "it is not attacked by strong acids and bases, and only attacked by molten alkali baths."
No worry, plain water will eat it up quickly. The resulting gas production is quite deadly.
http://en.wikipedia.org/wiki/Boron_phosphide
This is interesting, clearly you got your information from this page. Proof of concept about the danger of believing something anyone can write and
edit. Trust ESPI Metals long before you trust wiki.
IX. SPECIAL PRECAUTIONS
Precautions to Be Taken in Handling and Storage: Handle under dry protective gas. Wash thoroughly after handling. Do not get in eyes, on skin or
clothing. Do not breathe dust, vapor, mist, or gas. Keep away from heat, sparks and open flames. Store in tightly sealed containers. Empty
container may contain hazardous residues. Flammable solid, dangerous when wet.
This from: http://www.espimetals.com/index.php/msds/112-boron-phosphide
BP is not attacked by acids or boiling aqueous alkali water solutions. It is only attacked by molten alkalis.[4].
What bothers me about the above line from wiki is they cite a reference. I know however ESPI actually deals with these chemicals so I am unsure the
source of conflict in the statement. Hopefully Woelen can come in and clear this one up.
[Edited on 7-21-2011 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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Rogeryermaw
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i was under the impression he wanted to use this as a substrate for semiconductor construction. the term anode in that context could mean the positive
side of many electronic devices, diodes for example. i think the OP needs to expand on the information contained in his question.
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IrC
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I thought about that use of anode and you may be correct. Just so long as he realizes he must handle this chemical either in a vacuum or in an inert
gas atmosphere, as well as being sure he is very clear on the toxic nature of BP and possible PH3. Reading that wiki page leaves much to be desired.
No mention of how dangerous BP really is to handle. To state "it is not attacked by strong acids and bases, and only attacked by molten alkali baths."
with no mention of H2O contact just seems negligent of the writer of that wiki page.
He will likely think I was too harsh in my first post but I felt he needed to know what an unfriendly chemical this is.
"Science is the belief in the ignorance of the experts" Richard Feynman
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White Yeti
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BP doping
To IrC,
Ok, thanks a lot for the info.
As I said before, I had a very hard time finding information on this compound to start with. I guess my sources provided misleading information. I
suggest someone with wikipedia editing rights corrects the content. Nonetheless, it is easy to point out a problem, providing a solution is more
difficult. Do you know of any accurate sources that would provide information on the chemical/ semiconductor/ physical properties of such obscure
compounds as boron phosphide? I do not rely on wikipedia because it is trustworthy, I rely on it because I do not have any other information resources
and because I don't want to pay for a PDF that may or may not contain the information I seek.
On the heels of what Rogeryermaw said, I didn't realise that my post sounded like I was using boron phosphide as a semiconductor substrate. To
clarify, I was hoping to use this material to make an anode to run electrochemical reactions. Alas, since this cannot be done, I will have to find
another semiconductor material that is chemically inert and easily melted and doped. Any suggestions?
I thought I was off to a great start, the theory seems promising. A chemically inert semiconducting network solid of some kind that is resistant to
attack by acids and bases is doped with so much impurity that it becomes a degenerate semiconductor. It would have a low enough resistivity and a high
enough level of chemical resistance to be used as an anode for electrochemical reactions without showing any signs of corrosion or degradation.
I was considering silicon carbide before I settled with BP. However, I do not own an arc furnace or any other furnace that is capable of melting SiC
into the shape of an anode.
Boron nitride, zinc sulfide, copper monosulfide, lead sulfide, titanium IV oxide, copper II oxide, bismuth sulfide, nickel II oxide could also be used
as anodes, however I have not checked the chemical inertnesses of all these materials thoroughly enough to conclude that they can be used in aqueous
solutions of acids and bases.
"He will likely think I was too harsh in my first post but I felt he needed to know what an unfriendly chemical this is."
I don't mind you being harsh, on the contrary, it shows that you care, and I appreciate that.
Regards.
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hissingnoise
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| Quote: | It would have a low enough resistivity and a high enough level of chemical resistance to be used as an anode for electrochemical reactions without
showing any signs of corrosion or degradation.
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Start saving your pocket money now and in a few (short) years you'll be able to purchase enough Pt foil to satisfy all your electrochemical desires
 !
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Rogeryermaw
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damn hiss you beat me to the punch! platinum and gold are fairly non-reactive for this purpose. unfortunately, they are quite cost prohibitive.
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IrC
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"Do you know of any accurate sources that would provide information on the chemical/ semiconductor/ physical properties of such obscure compounds as
boron phosphide? I do not rely on wikipedia because it is trustworthy, I rely on it because I do not have any other information resources and because
I don't want to pay for a PDF that may or may not contain the information I seek."
No that is one of my complaints. MIT (not gore) invented the internet as a way for scientists to freely exchange scientific information. I thought it
was a good idea at the time but never realized until too late they would all be charging high prices for it. I have seen PDF's with $300 price tags.
Piratebay helps in this once in a while.
Forgot to add, start by searching this site. There has been much discussion on this subject here.
[Edited on 7-21-2011 by IrC]
"Science is the belief in the ignorance of the experts" Richard Feynman
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hissingnoise
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Quote: Originally posted by Rogeryermaw  | | damn hiss you beat me to the punch! platinum and gold are fairly non-reactive for this purpose. unfortunately, they are quite cost prohibitive.
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I tried gold in a chlorate cell many, many years ago and found it wanting.
On start-up a green coating of a gold chloride quickly formed . . .
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