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

Abstract

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.

Few-Layered WS2 Anchored on Co, N-Doped Carbon Hollow Polyhedron for Oxygen Evolution and Hydrogen Evolution

“…TMDs have been widely studied in cutting-edge electrolytic applications. Theoretical and experimental studies have shown that TMDs, such as molybdenum disulfide (MoS 2 ) and tungsten disulfide (WS 2 ), possess excellent hydrogen evolution activity due to their unique structure and electronic structure. , However, WS 2 is semiconductor with low electrical conductivity hampering electron transfer and low edge active sites greatly limiting its electrocatalytic performances . Semiconductors require additional potential to drive electrons to the active site, and this additional driving force can be minimized by reducing the size, adding conductive materials, and being in close contact with conductive substrates.…”

Multifunctional materials for photo-electrochemical water splitting

“…The disadvantage of this material is that it has a high recombination rate of photogenerated electron and hole pairs and low charge transfer efficiency. [192][193][194][195] A WS 2 nanosheet doped with Ti and Mo was prepared at a relatively low temperature through the CVD process. The WS 2 nanosheet doped with both Ti and Mo showed increased PEC performance, while the Tidoped WS 2 nanosheet exhibited the highest photocurrent density of 10.44 mA cm À2 .…”

2D material based heterostructures for solar light driven photocatalytic H2production

“…WS 2 based Z-scheme heterojunctions offered excellent H 2 production from photocatalytic water splitting by optimization of pristine WS 2 , including the recombination of charge pairs, active centres and photostability. 188 Xue et al 189 constructed a direct Z-scheme WO 3 /WS 2 /CdS tandem heterojunction with a high photocatalytic H 2 evolution rate of 14.34 mmol h −1 g −1 and an outstanding apparent quantum efficiency (AQE) of 22.96% at 435 nm as shown in Fig. 9c and d. The electrons transfer from the CB of CdS to the CB of adjacent WO 3 and WS 2 , forming a dual built-in IEF at the heterointerfaces of the WS 2 /CdS and WO 3 /CdS.…”