Investigation on the Photocatalytic Hydrogen Evolution Properties of Z-Scheme Au NPs/CuInS<sub>2</sub>/NCN-CN<i><sub>x</sub></i> Composite Photocatalysts
Rui Zhang, Haoyu Wang, YinYin Li, Dejun Wang, Yanhong Lin, Ziheng Li, Tengfeng Xie
Abstract
Aiming at precisely adjusting the interfacial electric field of the Z-scheme heterojunction to facilitate carrier transfer, we construct a new series of Au NPs/CuInS 2 /NCN-CN x composite photocatalysts for photosplitting water into hydrogen. By regulating the Cu vacancy via Cu/In ratios, the optimal band structure has been achieved for CuInS 2 /NCN-CN x samples. Au nanoparticles (NPs) are further in situ grown on CuInS 2 /NCN-CN x by photodeposition, which enable the light absorption range to expand to further improve light utilization due to its surface plasmon resonance (SPR) effect. With the aid of surface photovoltage (SPV), transient photovoltage (TPV), and Kevin probe force microscopy (KPFM) techniques, the carrier transfer mechanism of Au NPs/CuInS 2 /NCN-CN x is investigated, which can well meet the Z-scheme transfer system, and Cu deficiency regulation can slightly change the interfacial electric field from the CuInS 2 /NCN-CN x heterojunction. Besides, the deposition location of Au NPs is also suggested by the comparison of Au NPs photodeposited on the composite photocatalyst under full-spectrum or 550 nm irradiation, which also confirms that our CuInS 2 /NCN-CN x photocatalysts meet the Z-scheme mechanism. The cooperative effect of the Z-scheme transfer mechanism and the SPR effect present a H 2 evolution rate of 10.72 mmol h –1 g –1 when the Pt is adopted as a cocatalyst and triethanolamine as a sacrificial reagent, about 21 times as high as that of pure NCN-CN x . Our work attempts a new way to improve the photocatalytic properties of Au NPs/CuInS 2 /NCN-CN x composite Z-scheme photocatalysts, which is also beneficial for designing more efficient photocatalysts for photosplitting water into hydrogen.