3D ordered porous CdS/AgI/ZnO nanostructures for high performance photoelectrochemical water splitting.

Three-dimensional (3D) ordered porous CdS/AgI/ZnO nanostructures were designed to perform as high-performance photoelectrodes for photoelectrochemical water splitting applications relying on the advantages of extremely large active surface area, high absorption capacity in the visible light region, fast carrier separation and transportation caused by the intrinsic ladder-like band arrangement. These nanostructures were fabricated by employing a three-stage experiment in a sequence of hard mold assisted electrochemical deposition, wet chemical method and deposition-precipitation. Firstly, 3D ordered ZnO nanostructures were electrochemically deposited using a polystyrene (PS) film as the sacrificed template. AgI nanoparticles (NPs) were then decorated on the interfacial ZnO nanostructures by deposition-precipitation. Finally, these binary AgI/ZnO nanoporous networks were thoroughly wet-chemically coated with a CdS film to form a so-called "ternary interfacial CdS/AgI/ZnO nanostructures". The photoelectrochemical water splitting properties of the fabricated 3D nanostructures were studied and compared systematically. As a result, the highest efficiency of the fabricated 3D-ordered porous CdS/AgI/ZnO measured under the irradiation of solar simulation, is about 5.2 %, which is relatively 1.5, 3.5 and 11.3 times greater than that of the corresponding CdS/ZnO (3,4%), AgI/ZnO (1.5%) and pristine porous ZnO (0.46%) photoelectrodes, respectively. The significant improvement in the photoelectrochemcial activity is assigned to the enhanced charge separation and transport of ternary photoelectrodes caused by an inconventional ladder-like band arrangement formed between interfacial CdS-AgI-ZnO. Our work provides a promising strategy for developing such ternary photoelectrode generations possessing higher stability and efficiency towards water splitting processes.