Defect-engineered plasmonic Z-scheme heterostructures for superior photoelectrochemical water oxidation

Abstract

The Z-scheme photoelectrochemical (PEC) catalytic system that mimics natural photosynthesis is considered an encouraging method to improve the catalytic activities of the catalysts and finally address the global energy crisis. Herein, a plasmon-enhanced Z-Scheme heterostructure is synthesized via interface-structure-designing and defect-engineering. The optimized TiO2/Au/ZnIn2S4OS exhibits an excellent PEC catalytic activity with a photocurrent density of 3.80 mA/cm2 at 1.23 V (vs RHE), which is 2.1 times higher than that of TiO2 nanorod arrays. The density functional theory (DFT) calculation results demonstrate that the synergy of O, S-defects can tailor the charge density distribution and electronic structure of ZnIn2S4, which effectively improves the electrical conductivity of the photocatalyst. The kinetic and thermodynamic behavior investigation, as well as theoretical simulations, indicate that the successful construction of the Z-scheme system can significantly improve the redox capacity and photo-excited electron-hole separation efficiency of the catalysts, thereby promoting the water oxidation activity. Furthermore, the Au nanodots sandwiched between TiO2 and ZnIn2S4OS are found to play multifunctional roles in boosting the PEC catalytic performance. This work provides a valuable approach to constructing defects-dominated Z-scheme systems at the atomic scale and sheds light on new insight into the LSPR effect for improving the catalytic performance in Z-scheme systems.