Interfacial effects in hierarchically porous α-MnO2/Mn3O4 heterostructures promote photocatalytic oxidation activity

Abstract

Constructing hybrid nanocatalysts with more active surfaces/interfaces is crucial for promoting catalytic activities for oxidative removal of volatile organic compounds (VOCs). Herein, we have successfully designed and synthesized a hierarchically porous α-MnO2/Mn3O4 nanostructure with numerous interfaces using a simple topotactic transformation synthesis strategy. The real time observation of the growth dynamics from δ-MnO2 to α-MnO2/Mn3O4 is achieved by in-situ transmission electron microscopy. The in-situ formed α-MnO2/Mn3O4 hybrid supplies not only numerous intimate interfaces but also a direct Z-scheme junction, greatly promoting the generation of superoxide radicals. It also forms more oxygen vacancies that brings about absorption of more O2 molecules on the surface, thus generating more superoxide radicals in unit time. As a result, the hybrid shows much better catalytic oxidation activity for eliminating VOCs as compared to pure α-MnO2 and Mn3O4. The results demonstrate a feasible way to construct hierarchically porous heterostructures with improved photocatalytic activity for eliminating VOCs.