Schottky junction with Bi/Bi2O3 core–shell nanoparticle modified g-C3N4 for boosting photocatalytic H2O2 evolution from pure water

Abstract

The Schottky junction at the metal/semiconductor interface is a promising and effective method for achieving efficient solar-driven H₂O₂ evolution in a green and sustainable reaction solution. Bearing the merits of non-precious metal bismuth (Bi) in mind, in this work, special metal Bi nanoparticles (NPs) that are wrapped with a layer of Bi₂O₃ membrane (Bi/Bi₂O₃) were coupled with layered g-C₃N₄via a facile hydrothermal route. The formed Bi/Bi₂O₃ core–shell structure as the integral-unit of the cocatalyst for constructing Schottky-junction photocatalysts towards photocatalytic H₂O₂ evolution is firstly reported. The introduction of metallic Bi/Bi₂O₃ not only boosts the interfacial unidirectional-transfer from excited g-C₃N₄ due to the built-in Schottky-junction, but also accelerates the critical rate-limiting-step of the second-step single-electron ˙O₂⁻ reduction to H₂O₂. Without adding any sacrificial reagents, the dual functionality of the Bi/Bi₂O₃@g-C₃N₄ composite contributes to continuous and sufficient supply of electrons for the multi-electron participated H₂O₂ production pathways, as well as the increased selectivity of the two-electron O₂ reduction process. Consequently, the Bi/Bi₂O₃@g-C₃N₄ composite creates a 70-times enhanced H₂O₂ production rate in comparison with pristine g-C₃N₄ using pure water as a reaction liquid. This work is expected to expand the applications of engineering Schottky junctions towards high-efficiency solar H₂O₂ production in a green reaction solution.