Accelerating Ru0/Ru4+ Adjacent Dual Sites Construction by Copper Switch for Efficient Alkaline Hydrogen Evolution

Abstract

The alkaline hydrogen evolution reaction (HER) always needs the nearby dual sites of water adsorption and H2 generation, and Ruthenium-based electrocatalysts are promising alternatives to platinum-based materials. However, achieving both high efficiency and long-term stability in the construction of the dual sites is still challenging. Herein, Cu-doped RuO2 (Cu-RuO2) is reported and undergoes instant activation for Ru0 production at the low potential state preceding the HER. The Cu2+ ions are demonstrated to work as the switch for obtaining the activated sample of Cu-RuO2-AC, which possesses the Ru-RuO2 structure. The sample of Cu-RuO2-AC gives an overpotential of only 19 mV at the current density of 10 mA cm−2 with a Tafel slope of 32.8 mV dec−1. Moreover, at the mass activity of 1 A mgRu−1, it only needs 88 mV, which is lower than the 343 mV of commercial 40% Ru/C, or the 154 mV of activated bare RuO2 (RuO2-AC). Density functional theory (DFT) calculations reveal that Cu2+ doping activates the nearby Ru4+. A two-electrode H-cell device of Cu-RuO2-AC||Cu-RuO2 needs only 1.66 and 1.78 V versus RHE to achieve a current density of 100 and 200 mA cm−2 of overall water splitting. This research can help design more efficient dual-site HER electrocatalysts.