Rational Design of LDH/Zn2SnO4 Heterostructures for Efficient Mineralization of Toluene Through Boosted Interfacial Charge Separation

Abstract

It is crucial to efficiently separate and transport photo-induced charge carriers for the effective implementation of photocatalysis toward environmental remediation. A rational design strategy is proposed to validate such proposition through the construction of an interfacial structure in the form of LDH/Zn2SnO4 heterostructures in this research. The interfacial charge transfer on LDH/Zn2SnO4 is greatly promoted via the unique charge transfer pathway, as characterized by transient photocurrent responses, X-ray photoelectron spectroscopy, electron paramagnetic resonance spectrum, and photoluminescence analysis. As such, it contributes to the generation of reactive oxygen species (ROS) and the activation of reactants for the mineralization of toluene. According to the in situ DRIFTS spectra analysis, the accumulation of benzoic acid takes place possibly through the partial oxidation of the methyl group on toluene at the interface of the LDH/Zn2SnO4 heterostructure. This process can greatly promote the photocatalytic oxidation of toluene with the enhanced ring-opening efficiency. The LDH/Zn2SnO4 is thus demonstrated as superior photocatalyst against toluene (removal efficiency of 89.5%; mineralization of 83.1%; and quantum efficiency of 4.55 x 10(-6) molecules/photon). As such, the performance of this composite far exceeds that of their individual components (e.g., P25, pure Mg-Al LDH, or Zn2SnO4). This study is expected to offer a new path to the interfacial charge transfer mechanism based on the design of highly efficient photocatalysts for air purification.