Performance of Au/Nafion/Pt electrodes in benzene–water electrochemical hydrogenation

Au/Nafion/Pt electrodes were used in the coupled reaction system of benzene hydrogenation and water electrolysis for hydrogen production and storage. Au/Nafion/Pt electrodes with the short electrode spacing reduce hydrogen evolution and increase current density and current efficiency. The morphology of metal layer surface of electrodes and electrochemistry hydrogenation reactions were studied. The results showed that the morphology and conductivity of metal layer surface of electrodes were related to the reduction reaction rate of metal complex in the electrode preparation process. The Au complex reduction reaction rate and Au deposition rate were lower than Pt complex reduction reaction rate, yielding a dense smooth Au surface which had low resistance and was not conducive to the diffusion of H+. Benzene hydrogenation reaction rate increased and current efficiency decreased with increased electrode potential. The effect of electrode potential on current efficiency was similar for all electrodes tested. Au/Nafion/Pt electrodes had the highest current efficiency and current density among the electrodes tested; the current density of benzene hydrogenation was higher than 100 mA/cm2 and 90% current efficiency.