Growth of Highly Active Amorphous RuCu Nanosheets on Cu Nanotubes for the Hydrogen Evolution Reaction in Wide pH Values

Abstract Rational design of low‐cost, highly efficient, and stable electrocatalysts for the hydrogen evolution reaction (HER) has attracted wide attention. Herein, 3D RuCu nanocrystals (NCs) are successfully synthesized by a facile wet chemistry method, in which amorphous RuCu nanosheets are directly grown on crystalline Cu nanotubes (NTs). Importantly, the obtained 3D RuCu NCs only need 18 and 73 mV to deliver the current density of 10 mA cm −2 for HER in alkaline and neutral media, respectively. Density functional theory calculations and experiments reveal that the Ru sites on the surface of amorphous nanosheets are the highly active centers for HER. Moreover, this catalyst can expose more surface area for water splitting compared to pure nanosheets because the unique 3D structure can effectively prevent the aggregation of nanosheets. Meanwhile, the interface between amorphous nanosheets and crystalline NTs is essential to boost the HER performance because the amorphous phase with many unsaturated bonds can facilitate adsorption of reactants and crystalline Cu with superior conductivity can promote the transfer of electrons. This work provides a facile method to prepare an original 3D Ru‐based electrocatalyst with highly active HER performance in wide pH values.