Coupling Methanol Oxidation with Hydrogen Evolution on Bifunctional Co-Doped Rh Electrocatalyst for Efficient Hydrogen Generation

Efficient hydrogen production from electrochemical overall water splitting requires high-performance electrocatalysts for hydrogen evolution reaction (HER) and a fast oxidation reaction to replace sluggish oxygen evolution reaction. Herein, Co-doped Rh nanoparticles are thus grown on carbon black using Co nanosheets as the bridge. These nanoparticles with a size of approximate to 1.94 nm exhibit the overpotential of as low as 2 mV at 10 mA cm(-2) for the HER, and a mass activity of as high as 889 mA mg(-1) for the methanol oxidation reaction (MOR) in alkaline media. As confirmed by density functional theory simulations, such excellent activity originates from Co-doping, which reduces reaction energy barriers for both the rate-determining step of a Volmer process during the HER and the conversion of *CO to COOH* during the MOR (namely the enhanced adsorption of H2O and COOH*). Coupling boosted HER on the cathode with accelerated MOR on the anode, efficient H-2 generation is achieved. This two-electrode cell only requires a cell voltage of 1.545 V at 10 mA cm(-2) with impressive long-life cycling stability. Such performance even outperforms that of commercial Pt/C || IrO2 cell. This study offers a new strategy to achieve efficient HER from overall water splitting.

Automated summary

In this study, efficient hydrogen production from water splitting is achieved using Co-doped Rh nanoparticles as electrocatalysts. The results show that Co-doping reduces reaction barriers and enhances the adsorption capacity of reactants, resulting in excellent activity. In a two-electrode cell, the combination of fast oxidation reaction on the anode and efficient hydrogen evolution reaction on the cathode enables efficient water splitting for hydrogen production.