Improved Photo-Excited Carriers Transportation of WS2 -O-Doped-Graphene Heterostructures for Solar Steam Generation.

Abstract

Two-dimensional (2D) transition metal dichalcogenides and graphene have revealed promising applications in optoelectronic and energy storage and conversion. However, there are rare reports of modifying the light-to-heat transformation via preparing their heterostructures for solar steam generation. In this work, commercial WS2 and sucrose are utilized as precursors to produce 2D WS2 -O-doped-graphene heterostructures (WS2 -O-graphene) for solar water evaporation. The WS2 -O-graphene evaporators demonstrate excellent average water evaporation rate (2.11kgm-2 h-1 ) and energy efficiency (82.2%), which are 1.3- and 1.2-fold higher than WS2 and O-doped graphene-based evaporators, respectively. Furthermore, for the real seawater with different pH values (pH 1 and 12) and rhodamine B pollutants, the WS2 -O-graphene evaporators show great average evaporation rates (≈2.08 and 2.09kgm-2 h-1 , respectively) for producing freshwater with an extremely low-grade of dye residual and nearly neutral pH values. More interestingly, due to the self-storage water ability of WS2 -O-graphene evaporators, water evaporation can be implemented without the presence of bulk water. As a result, the evaporation rate reaches 3.23kgm-2 h-1 , which is ≈1.5 times higher than the regular solar water evaporation system. This work provides a new approach for preparing 2D transition metal dichalcogenides and graphene heterostructures for efficient solar water evaporation.