Tuning Electronic Structure of 2D In2S3 via P Doping and Size Controlling Toward Efficient Photoelectrochemical Water Oxidation

Two‐dimensional (2D) lamellar materials possess the advantages of strong light–matter interactions and tunable band structure, rendering possible high conversion efficiency of solar to fuel. Herein, the controlled fabrication of small‐sized P doped 2D In 2 S 3 arrays (P‐In 2 S 3 ) via preseeding method is demonstrated, which is a feasible approach to regulate the bandgap and attain large specific surface area with more active sites. A fraction of S sites is substituted by P atoms to form InP bonds, the substitutional doping introduces a hybridized state near the valance band of In 2 S 3 through the integration of P 3s, P 3p, and S 3p orbitals. By P doping, the electronic structure is tuned, the charge recombination is suppressed, and the surface reaction kinetics are improved, addressing all three major problems at once for water oxidation. With the synergistic effect of size and impurity states, more than fivefold enhancement is achieved in photocurrent, and high oxidation kinetics efficiency (79%). Therefore, the combination of size controlling synthesis of a 2D lamellar structure and doping strategies can be further developed in solar energy conversion devices.