Tailoring the acidity of WO3/ZrO2 to regulate the energy barrier of water dissociation in alkaline hydrogen evolution

Abstract

Alkaline water electrolysis (AWE) is an important technique to produce hydrogen of high purity. The efficiency of alkaline water electrolysis is limited by the sluggish kinetics of hydrogen evolution reaction (HER). The root cause for the sluggish kinetics of alkaline HER is the high energy barrier for the water dissociation process. Here, we demonstrate the regulation of the energy barrier for water dissociation in HER by optimizing the acidity of the electrocatalyst. WO3/ZrO2 solid acid electrocatalyst is developed and the acidity of the electrocatalyst is controlled by the amount of WO3 loaded on ZrO2. Experimental analysis proves that the HER performance of WO3/ZrO2 is well correlated with its acidity and such a correlation is rationalized with theoretical calculations. The optimal WO3/ZrO2 electrocatalyst exhibited a low overpotential of 249 mV at a current density of 100 mA cm−2 and excellent stability under working conditions. The novel low-cost solid acid electrocatalyst developed in this work is promising for AWE applications. In addition, the strategy of lowering the water dissociation barrier by acidity regulation of the electrocatalyst may shed light on the future design of advanced electrocatalysts.