Surficial charge state tuning of tungsten carbide for catalyzing alkaline hydrogen evolution reaction

Rational tuning the surface charge state for catalysts is an attractive strategy to promote their catalytic activity toward catalyzing diverse chemical and electrochemical reactions. In this work, we modified the surface of a pure tungsten carbide (WC) material with an ultra-thin nitrogen doped carbon (NC) layer (WC@NC) for catalyzing alkaline hydrogen evolution reaction (HER). The XPS studies revealed an increased electron density on WC when the NC layer was introduced on its surface. Thus, a significant decrease of 282 mV in overpotential at 10 mA cm-2 was observed on WC@NC electrode in comparison with the pristine WC electrode. The higher electrochemical active surface area, lower activation energy barrier, and excellent durability were identified by various electrochemical measurements. The three-dimensional charge density difference was also calculated and the results indicated that an electron-transfer process occurred from the NC layer (donor) to the WC layer (acceptor) through the interface of WC@NC composite material. The analysis explained the underlying mechanism for the promotion of the HER activity. Such a comprehensive study is expected to provide useful guidance for promoting the catalytic performance of diverse catalysts toward different reactions. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.