Recent Advances in WS2 and Its Based Heterostructures for Water-Splitting Applications

The energy from fossil fuels has been recognized as a main factor of global warming and environmental pollution. Therefore, there is an urgent need to replace fossil fuels with clean, cost-effective, long-lasting, and environmentally friendly fuel to solve the future energy crisis of the world. Therefore, the development of clean, sustainable, and renewable energy sources is a prime concern. In this regard, solar energy-driven hydrogen production is considered as an overriding opening for renewable and green energy by virtue of its high energy efficiency, high energy density, and non-toxicity along with zero emissions. Water splitting is a promising technology for producing hydrogen, which represents a potentially and environmentally clean fuel. Water splitting is a widely known process for hydrogen production using different techniques and materials. Among different techniques of water splitting, electrocatalytic and photocatalytic water splitting using semiconductor materials have been considered as the most scalable and cost-effective approaches for the commercial production of sustainable hydrogen. In order to achieve a high yield of hydrogen from these processes, obtaining a suitable, efficient, and stable catalyst is a significant factor. Among the different types of semiconductor catalysts, tungsten disulfide (WS2) has been widely utilized as a catalytic active material for the water-splitting process, owing to its layered 2D structure and its interesting chemical, physical, and structural properties. However, WS2 suffers from some disadvantages that limit its performance in catalytic water splitting. Among the various techniques and strategies that have been constructed to overcome the limitations of WS2 is heterostructure construction. In this process, WS2 is coupled with another semiconducting material in order to facilitate the charge transfer and prevent the charge recombination, which will enhance the catalytic performance. This review aims to summarize the recent studies and findings on WS2 and its heterostructures as a catalyst in the electrocatalytic and photocatalytic water-splitting processes.