Mesoporous RhRu Nanosponges with Enhanced Water Dissociation toward Efficient Alkaline Hydrogen Evolution

Lowering the energy barrier of water dissociation is critical to achieving highly efficient hydrogen evolution in alkaline conditions. Herein, we reported mesoporous RhRu nanosponges with enhanced water dissociation behavior as a new class of high-performance electrocatalysts for alkaline hydrogen evolution reaction (HER). The obtained nanosponges have a binary alloy structure (fcc) and a highly porous structure with high surface area. Our RhRu catalyst displayed an outstanding HER activity with an overpotential of 25 mV at 10 mA cm^-2 and a Tafel slope of 47.5 mV dec^-1 in 1.0 M KOH, which significantly outperformed that of commercial Pt/C catalyst and was even comparable to the classic Pt/metal (hydro)oxide catalysts. Density functional theory (DFT) calculations disclosed that charge redistribution on the RhRu alloy surface enabled tuning of the Ru d-band center and then promoted the adsorption and dissociation of water molecules. Based on the experimental results and theoretical modeling, a bifunctional mechanism contributed to the remarkable alkaline HER activity on the RhRu catalyst surface.