Hydrogen production from the electrooxidation of methanol and potassium formate in alkaline media on carbon supported Rh and Pd nanoparticles

Small organic molecules such as alcohols and formate salts can be readily transformed into hydrogen and carbon dioxide through electrochemical reforming at low energy cost. In this article methanol and potassium formate are studied for hydrogen production in alkaline anion exchange membrane electroreformers using two anode electrocatalysts, nanoparticle Pd and Rh supported on carbon (5 wt%). Firstly, we report a study of the electrochemical activity of both catalysts in electrochemical test cells at 80 °C. Formate oxidation kinetics are found to be fast on both catalysts. Rh/C shows the best performance for methanol electrooxidation with an onset potential 200 mV lower than Pd/C and a specific activity almost double reaching the value of 2600 A/g(Rh). The energy cost and conversion efficiency for hydrogen production was determined in complete electrochemical reforming cells at 80 °C using both anode catalysts. The energy costs are low for both substrates (<14 KWh/kg(H2)) with Pd/C producing hydrogen from potassium formate at an energy cost of 5 KWh/kg(H2). Considering both the energy consumption and conversion efficiency (substrate to hydrogen), it is shown that the Rh/C catalyst performs best with methanol as substrate.