Electrochemical reduction of Hydrogen forms hydride?

  1. Would the electrochemical reduction of H2 form Hydrogen Anions of H-

    H2 + 2e- -> 2H-

    If this is the case, is the following true?

    H- + (1/2)H2 -> H2
  2. jcsd
  3. Borek

    Staff: Mentor

    Not sure about the "electrochemical" part (I feel like you will have problems finding a solvent), but in general to get hydrides (especially ionic ones) you need to reduce hydrogen, so the reaction looks correct.

    If it is intended as a full reaction, you won't be able to balance it. If it is intended as a half reaction, it is not different from the previous one.
  4. Thank you. Electrochemistry is an underexplored field in my opinion with a lot of potential. Can I ask why you said there will be a problem finding a solvent? I was thinking both a H2O solution or an alcohol solution could would as long as the electrolyte is largely dissolvable and nonreactive.

    Based on your expertise, would you say that these Hydride anions formed via the reduction of H2 would have a similar effect on reducing organic compounds as various metal hydrides? Theoretically they should react just the same. In metal hydrides the hydride ion breaks off and reacts with the organic molecule to reduce and hydrogenate it, leaving the metal part floating in the solution, so ideally a lone hydride ion should react with the organic molecule in the same fashion, yet, with no metal byproducts.
    Last edited: Jan 11, 2014
  5. Borek

    Staff: Mentor

    You will reduce the solvent before you will be able to reduce the hydrogen.
  6. Is this so?

    I remember reading that the electrical requirement to reduce H-H is not much higher than the electrical requirement to reduce a number of compounds that are very commonly reduced electrochemically, such as the bond between N-O2 bonds.

    I did come across this study, in the abstract, the claim the oxidation of hydrogen only occurs when hydrogen adheres to the surface of the cathode. http://link.springer.com/chapter/10.1007/978-1-84800-936-3_3#page-1 . Though, they are speaking in terms of using a catalyst. Perhaps a catalyst would be required for the reaction to occur.
  7. Borek

    Staff: Mentor

    So far you listed ethanol and water. As a rule of thumb - if something eagerly reacts with the hydride, it will react on the electrode before hydrogen gets reduced. That's redox potentials, GenChem101.

    In some cases that's not exactly true, as sometimes reactions require huge overpotentials due to being kinetically hampered.

    But, assuming your hydride gets produced on the electrode, to be able to react in the bulk of the solution it needs to be soluble. That means polar solvent, and these are rarely electrochemically inert.

    Hardly surprising, that's what happens in all electrochemical experiments - reaction takes place only on the electrode surface. Further reactions can take place in the bulk, but the only place the original reaction can go is the electrode, electrons don't freely float in the solution (with some remarkable exceptions).
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