Abstract
Developing strategies for producing hydrogen economically and in greener ways is still an unaccomplished goal. Photoelectrochemical (PEC) water splitting using photoelectrodes under neutral electrolyte conditions provides possibly one of the greenest routes to produce hydrogen. Here, we demonstrate that chlorophyll extracts can be used as an efficient exfoliant to exfoliate bulk MoS(2) and WS(2) to form a thin layer of a MoS(2)/WS(2) heterostructure. Thin films of solution-processed MoS(2) and WS(2) nanosheets display photocurrent densities of -1 and -5 mA/cm(2), respectively, and hydrogen evolution under simulated solar irradiation. The exfoliated WS(2) is significantly more efficient than the exfoliated MoS(2); however, the MoS(2)/WS(2) heterostructure results in a 2500% increase in photocurrent densities compared to the individual constituents and over 12 h of PEC durability under a neutral electrolyte. Surprisingly, in real seawater, the MoS(2)/WS(2) heterostructure exhibits stable hydrogen production after solar illumination for 12 h. The synthesis method showed, for the first time, how the MoS(2)/WS(2) heterostructure can be used to produce hydrogen effectively. Our findings highlight the prospects for this heterostructure, which could be coupled with various processes towards improving PEC efficiency and applications.