Crystalline/Amorphous-Ru/VOx Phase Engineering Expedites The Alkaline Hydrogen Evolution Kinetics

Abstract

Active and durable catalysts for hydrogen evolution reaction (HER) are of great significance for developing renewable hydrogen energy. Herein, crystalline/amorphous-Ru/VO_x (c/a-Ru/VO_x) heterogeneous catalysts are conceived, in which the amorphous VO_x exposes more active sites and enhances charge transport compared with the counterpart with a crystal phase structure, strengthening the electronic interaction between metal-support. As expected, c/a-Ru/VO_x-500 with heat treatment at 500 °C exhibits excellent HER performance under alkaline conditions, with an overpotential of only 33 mV at 10 mA cm⁻² and small Tafel slope (27 mV dec⁻¹), superior to commercial platinum/carbon (Pt/C) catalysts. Particularly, its mass activity (0.335 A mg_Ru⁻¹) is 1.5 times greater than that of Pt/C (0.224 A mg_Pt⁻¹) at an overpotential of 50 mV. Also, it shows good industrial application prospects through tests under high temperature, high alkalinity, and large current conditions. Theoretical calculations unveil that there exists a charge redistribution at c/a-Ru/VO_x heterointerfaces, which makes the surface of Ru takes on an electron-deficient state, resulting in optimization of adsorption and desorption for different reaction intermediates. This optimized behavior effectively reduces the thermodynamic energy barrier, allowing the catalyst with greatly enhanced HER performance. The exploration provides a promising strategy for designing efficient and durable catalysts for HER.