Janus transition metal dichalcogenides: a superior platform for photocatalytic water splitting

Janus two-dimensional (2D) materials, referring to the layers with different surfaces, have attracted intensive research interest due to the unique properties induced by symmetry breaking, and promising applications in energy conversion. Based on the successful experimental synthesis of Janus transition metal dichalcogenides (TMDC), here we present a review on their potential application in photocatalytic overall water splitting, from the perspectives of the latest theoretical and experimental progress. Four aspects which are related to photocatalytic reaction, including the adsorption of water molecules, utilization of sunlight, charge separation and transport, and surface chemical reactions have been discussed, and it is concluded that the Janus structures have better performances than symmetric TMDCs. At the end of this review, we raise further challenges and possible future research directions for Janus 2D materials as water-splitting photocatalysts.