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> - Cathode material: Prussian white Ferrocyanides — not the cheapest compound to synthesize

• ajross 5y ago
  That's what I'm interested in. And yes, it does seem that the use of the artist's pigment name seems intended to obscure the fact that this is a complicated material. Any solid state chemists here who can enlighten us?
  • philipkglass 5y ago
    Ferrocyanide anion has a complicated looking structure but it is easy to synthesize. The input materials are hydrogen cyanide (cheaply produced from methane and ammonia via the Andrussow process), calcium hydroxide, and iron(II) chloride. Combined, they form ferrocyanide. Despite the toxic hydrogen cyanide used in production, ferrocyanides are nontoxic because the cyanide is so tightly bound to iron. Potassium ferrocyanide is used as an anticaking agent in table salt. I have made Prussian blue before by roasting dried blood (organic fertilizer) with sodium hydroxide, extracting with water, and letting it partially oxidize in air. Blood provides both iron and nitrogen. This was an industrial process, historically, before artificial nitrogen fixation.
    • baybal2 5y ago
      Indeed, I instantly recalled the same "blood and sodium hydroxide" stuff from high school chemistry class, and thought of it still being a thing. It doesn't seem to be too expensive, nor too cheap: https://www.alibaba.com/products/sodium_ferrocyanide/CID8020399.html?IndexArea=product_en&pid=PID605_0000_0101 https://www.alibaba.com/products/sodium_ferrocyanide/CID8020...