g-C3N4-wrapped nickel doped zinc oxide/carbon core-double shell microspheres for high-performance photocatalytic hydrogen production.

ABSTRACT

The development of efficient heterojunctions with enhanced photocatalytic properties is considered a promising approach for photocatalytic hydrogen production. In this study, graphitic carbon nitride (g-C3N4)-wrapped nickel-doped zinc oxide/carbon (Ni-ZnO@C/g-C3N4) core-double shell heterojunctions with unique core-double shell structures were employed as efficient photocatalysts through an innovative approach. Ni doping can enhance the intensity and range of visible light absorption in ZnO, and the carbon core coupled with the hollow double-shell structure can accelerate the charge transfer rate and improve the photon utilization efficiency. Meanwhile, the construction of the Z-scheme heterojunction extended the electron-hole pair transport path. In addition, the Z-scheme charge-transfer mechanism of Ni-ZnO@C/g-C3N4 under simulated sunlight was verified by photoluminescence (PL) and electron spin resonance (ESR) experiments. As a result, the obtained photocatalyst acquired a high hydrogen evolution rate of 336.08 µmol g-1h-1, which is 36.49 times higher than that of pristine ZnO. Overall, this work may provide a pathway for the construction of highly efficient photocatalysts with unique core-double shell structures.