Enhanced Photocatalytic Production of H2O2 through Regulation of Spatial Charge Transfer and Light Absorption over a MnIn2S4/WO3 (Yb, Tm) Z-Scheme System

Abstract

The photocatalytic production of hydrogen peroxide (H2O2) from H2O and O2 is a promising approach, owing to its advantage of utilization of green solar energy without addition of organic sacrificial agents. However, the H2O2 productivity is still far from satisfactory, due to inefficient sunlight absorption and the low photogenerated charge mobility of photocatalysts. Herein, a Z-scheme photocatalytic system is constructed by combining MnIn2S4 with Yb3+ and Tm3+ WO3 (WO3 (Yb, Tm)) semiconductors. The Z-scheme interface heterojunction can inhibit the recombination of photogenerated carriers and retain photogenerated electrons and holes with high redox potentials. Particularly, the co-doped Yb3+ and Tm3+ can harvest near-infrared (NIR) excitation energy and then generate fluorescence emission with shorter wavelengths, which is beneficial to expand the optical response range of the photocatalytic system. With the synergy of the promoted photogenerated charge separation and enhanced optical absorption, the proposed photocatalytic system of MnIn2S4/WO3 (Yb, Tm) exhibits a H2O2 production rate of 1188 μmol h–1 g–1 in pure water, which is 37.2 and 8.8 times that of WO3 and MnIn2S4, respectively. This work offers a new avenue for the design and improvement of photocatalytic systems for H2O2 production.