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

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 TiO 2 /Au/ZnIn 2 S 4 O S exhibits an excellent PEC catalytic activity with a photocurrent density of 3.80 mA/cm 2 at 1.23 V (vs RHE), which is 2.1 times higher than that of TiO 2 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 ZnIn 2 S 4 , 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 TiO 2 and ZnIn 2 S 4 O S 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.