Synthesis of WO 3@ZnWO 4@ZnO-ZnO hierarchical nanocactus arrays for efficient photoelectrochemical water splitting

摘要

AbstractHierarchical heterostructures with large surface areas and multiple interfaces as photoanode materials, are holding great promise for photoelectrochemical (PEC) water splitting toward efficient solar energy utilization. In this work, the cactus-like WO3@ZnWO4@ZnO-ZnO (i.e.W@WZ@Z-Z) arrays compromising the first-order W@WZ@Z core-shell nanosheets and the second-order ZnO nanosheets, have been fabricated by combining atomic layer deposition (ALD) technique and hydrothermal process. The modification of ZnO nanosheets on the surface of WO3and the simultaneous formation of ZnWO4in-between buffer layer have endowed the photoanode a drastic enhancement in both ultraviolet light absorption and charge separationviathe favorable band alignment at the WO3-ZnWO4-ZnO interfaces. Particularly, the W@WZ@Z-Z nanocactus (NC) array photoanode with a 30nm ZnO layer on WO3precisely controlled by ALD, exhibited around 3.8 times higher photocurrent density (~ 1.57mA/cm2) at 1.23Vvs.RHE than pristine WO3photoanode (~ 0.41mA/cm2), with little loss after long-term continuous illumination as well. Overall, the novel combination of WO3with ZnO and the ZnWO4buffer layer, and construction of hierarchical heterostructures, along with the resulted improvement in light absorption and charge separation which have b