Exploring the Polarization Photocatalysis of ZnIn₂S₄ Material toward Hydrogen Evolution by Integrating Cascade Electric Fields with Hole Transfer Vehicle

Abstract

Abstract Sluggish charge kinetics in photocatalysts and slow hole transfer in oxidation half‐reaction severely limit the photocatalytic activity of hydrogen evolution. ZnIn 2 S 4 with an asymmetrical layered structure of [S–In]–[S–In–S]–[Zn–S] unit cell is a promising material offering asymmetrical crystal polarization to overcome the limitation; however, the polarization‐induced internal electric field by this material remains largely unexplored. Herein, the polarization‐induced internal electric field of ZnIn 2 S 4 by engineering the polarity intensity in microscopic units is demonstrated for the first time. Specifically, ultrathin ZnIn 2 S 4 nanosheets are employed to establish a Ni 12 P 5 /ZnIn 2 S 4 ‐O (NP/ZIS‐O) system with powerful bulk and interface cascade electric field by the oxygen doping and ohmic junction. Enabled by such a design, the photogenerated electrons can rapidly migrate to NP active sites, suppressing the photogenerated electron‐hole pair recombination on ZIS‐O. To further overcome the inefficient hole transfer in oxidation half‐reaction, the preferential dehydrogenation of the α‐CH bond in benzyl alcohol is utilized as a vehicle to facilitate hole transfer. As a result, a remarkably enhanced H 2 generation of 15.79 mmol g –1 h –1 is achieved on NP/ZIS‐O, which is 8.16‐fold higher than that of pristine ZnIn 2 S 4 . Meanwhile, as a value‐added oxidation product, benzaldehyde can be produced at the rate of 17.63 mmol g –1 h –1 . This work presents a collaborative strategy for engineering charge behavior in photocatalysts with polarization features, and provides insights into materials design toward photocatalytic hydrogen production and organic synthesis from the angle of charge kinetics.