Construction of Defect-Rich RhCu Nanotubes with Highly Active Rh3Cu1 Alloy Phase for Overall Water Splitting in All pH Values

The combination of precious metals with non-noble metals is an effective way to develop highly efficient, stable, and low cost electrocatalysts for overall water splitting. Herein, RhCu nanotubes (NTs) with rich structural defects are successfully synthesized by a mixed-solvent strategy, which display superior activity and excellent stability for both the hydrogen evolution reaction (HER) and oxygen evolution reaction in all pH values. In particular, it only needs 8, 12, and 57 mV to deliver the current density of 10 mA cm(-2) for HER in alkaline, acidic, and neutral conditions, respectively. Experiments combined with density functional theory (DFT) calculations reveal that the exposure of a suitable composition of a highly active Rh3Cu1 alloy phase through acid etching is the key to improve electrocatalytic performance, since it weakens the adsorption free energy of atomic oxygen and hydrogen, as well as facilitating the dissociation of water molecules. In addition, the structural defects can also boost the catalytic performance because the adsorption of reactants can be largely enhanced. The results provide a simple method to prepare alloy NTs as highly efficient electrocatalysts for overall water splitting in all pH values.