Synthesis of CuInS2 Quantum Dots/In2S3/ZnO Nanowire Arrays with High Photoelectrochemical Activity

Decoration of CuInS2 (CIS) quantum dots (QDs) on ZnO nanowires (NWs) with an interlayer of In2S3 as photoelectrode has been successfully fabricated on FTO via the simple solution routes for photoelectrochemical (PEC) application. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction are utilized to systematically analyze the morphology and structure of the CIS QD/In2S3/ZnO NWs heterostructure. The composition of this multilayer heterostructure and the removal of QD ligands by a thermal process are confirmed by X-ray photoelectron spectra. In comparison with CIS QDs/ZnO NWs, the CIS QD/In2S3/ZnO heterostructural photoelectrode displays an efficient charge separation and carrier transport path for photocurrent up to 2.4 mA·cm–2 that is competitive with other Cd- and Pb-free QD-based materials. In addition, Mott–Schottky analysis demonstrates the negative shift of the flat band in the CIS QD/In2S3/ZnO, which benefits the early onset potential. Significantly, this hierarchical photoelectrode shows the improvement the absorption and conversion of solar light in the visible region obtained using a pristine ZnO structure. Our research paves the way for exploring lead-free and lead-free sulfide materials in the new category of solar applications.