Metal-Free Phosphorus-Doped ZnIn₂S₄ Nanosheets\nfor Enhanced Photocatalytic CO₂ Reduction

Abstract

ZnIn₂S₄ (ZIS)\nhas shown great potential in photocatalytic solar-energy conversion.\nHowever, it is still suffering from severe charge recombination and\npoor surface area. Nonmetal heteroatom doping is considered as an\neffective strategy for improving its photocatalytic performance. Herein,\nphosphorus-doped ZIS (P-ZIS) nanosheets were prepared by a simple\nhydrothermal treatment of ZIS using NaH₂PO₄ as\na precursor. The effect of P doping on the crystal structure, band\nstructure, and the photocatalytic CO₂ reduction activity\nof ZIS under visible light were investigated. It was found that P\ndoping in the lattice of ZIS plays a key role in tuning its electronic\nproperties. The ratio of ZIS to NaH₂PO₄ influences\nthe photocatalytic performance of P-ZIS, and the optimum ratio is\n1:15. Optimized P-ZIS exhibits a remarkable visible-light photocatalytic\nCO production rate of 18.8 μmol/30 min, 2.5-folds higher than\nthat of the pure ZIS. The ultrathin nanosheets feature and an upward\nshift of CB edge result in the enhancement of CO₂ photoreduction\nefficiency of P-ZIS. This work demonstrates a simple route for P doping\nin ZIS and provides guidance for the controllable design and synthesis\nof high-efficient photocatalysts by nonmetal heteroatom doping.