Recent progress on tungsten oxide-based materials for the hydrogen and oxygen evolution reactions

As a form of clean and renewable energy, hydrogen has received much attention recently. However, industrial hydrogen production is primarily via conversion of natural gas, which consumes a large amount of energy and emits large volumes of greenhouse gases. Electrochemical water electrolysis is a promising, pollution-free method for the production of hydrogen from water. Efficient, cost-effective, stable and abundant catalysts that can drive hydrogen production in water with minimal electrical bias are a major goal towards achieving electrolysis on a large scale. Recently, tungsten oxide-based materials have emerged as one of the most promising electrocatalytic compounds, due to their activity, low cost and durability in both acid and base conditions. There are often oxygen vacancies in metal oxides, whether intentional or not, which can potentially promote the water electrolysis. In this review, we provide an overview of tungsten oxide-based materials used for electrocatalytic water splitting. In addition, mechanisms to improve the electrocatalytic activities of oxygen vacant tungsten oxide are summarized and discussed, with proposals for future research. This review article will provide a valuable resource for scientists pursuing materials for electrochemical water splitting.