Heterogeneous Synergetic Effect of Metal-Oxide Interfaces for Efficient Hydrogen Evolution in Alkaline Solutions

Water dissociation in alkaline solutions is one of the biggest challenges in hydrogen evolution reactions (HERs). The key is to obtain a catalyst with optimal and balanced OH adsorption energy and H adsorption/H₂ desorption energy. Herein, we synthesized a Ni₁₇W₃/WO₂ catalyst on the Ni foam that optimized the coverage and size of Ni₁₇W₃ alloys decorated on the NiWO₄/WO₂ substrate. Our experiments showed that Ni₁₇W₃-NiWO₄ interfaces could accelerate water dissociation, and Ni₁₇W₃-WO₂ interfaces facilitate adsorbed H atoms spillover and H₂ desorption. In addition, we applied a suite of characterization techniques to analyze surface evolution processes in catalysts under various cathodic potentials so as to illustrate the competition between chemical oxidation and electrochemical reduction reactions. The results demonstrated that high coverage of large Ni₁₇W₃ nanoparticles resulted in a greater stable interface. The two efficient interfaces synergetically promote the Volmer-Tafel reaction. Ni₁₇W₃/WO₂ catalysts exhibited extraordinary HER activity with a low overpotential of 48 mV at a 10 mA cm^-2 current density and a Tafel slope of 33 mV dec^-1. This work has shown that low-cost catalysts with proper hierarchical interfaces can be engineered and can be optimized into a tandem system, which will significantly promote HER activity in alkaline electrolytes.