Nickel catalysts for hydrogen evolution from CsH2PO4

Unsupported nickel was evaluated as an electrocatalyst material in an electrochemical hydrogen pump using the superprotonic solid acid CsH2PO4 as a proton exchange membrane. In humidified hydrogen at 250 °C, Ni-based electrodes display a stable proton reduction current of 207 mA cm−2 at a −0.2 V cell potential. Electrodes utilizing carbon-supported Pt catalysts evolved hydrogen at 558 mA cm−2 under identical conditions. Hydrogen evolution and oxidation are reversible on Pt, but hydrogen oxidation activity is virtually absent on Ni.