Exploring the Polarization Photocatalysis of ZnIn_2S_4 Material toward Hydrogen Evolution by Integrating Cascade Electric Fields with Hole Transfer Vehicle

摘要

Sluggish charge kinetics in photocatalysts and slow hole transfer in oxidationhalf-reaction severely limit the photocatalytic activity of hydrogen evolution.ZnIn_2S_4 with an asymmetrical layered structure of [S–In]–[S–In–S]–[Zn–S] unitcell is a promising material offering asymmetrical crystal polarization to overcomethe limitation; however, the polarization-induced internal electric fieldby this material remains largely unexplored. Herein, the polarization-inducedinternal electric field of ZnIn_2S_4 by engineering the polarity intensity in microscopicunits is demonstrated for the first time. Specifically, ultrathin ZnIn_2S_4nanosheets are employed to establish a Ni_(12)P_5/ZnIn_2S_4-O (NP/ZIS-O)system with powerful bulk and interface cascade electric field by the oxygendoping and ohmic junction. Enabled by such a design, the photogeneratedelectrons can rapidly migrate to NP active sites, suppressing the photogeneratedelectron-hole pair recombination on ZIS-O. To further overcomethe inefficient hole transfer in oxidation half-reaction, the preferential dehydrogenationof the α-C-H bond in benzyl alcohol is utilized as a vehicle tofacilitate hole transfer. As a result, a remarkably enhanced H_2 generation of15.79 mmol g~(–1) h~(–1) is achieved on NP/ZIS-O, which is 8.16-fold higher than that of pristine ZnIn_2S_4. Meanwhile, as a value-added oxidation product,benzaldehyde can be produced at the rate of 17.63 mmol g~(–1) h~(–1). This workpresents a collaborative strategy for engineering charge behavior in photocatalystswith polarization features, and provides insights into materials designtoward photocatalytic hydrogen production and organic synthesis from theangle of charge kinetics.