Separated redox site strategies for engineering highly efficient photocatalysts: a pagoda-like In2O3/CuO heteroepitaxial structure coated with a N-doped C layer

Abstract

In order to prepare efficient photocatalysts, it is necessary to consider not only the generation, separation and migration of photo-generated carriers, but also the effective activation of reactants and the reasonable distribution of redox sites. In this article, we utilized a MOF-on-MOF heterostructure with epitaxial relationship as the precursor to synthesize N-doped C encapsulated pagoda-like CuO–In₂O₃ (In₂O₃/CuO@N-C) heteroepitaxial micro-rods. In the obtained In₂O₃/CuO@N-C hierarchical pagoda-like micro-rods, the loose lamellar structure enhanced the light-harvesting capability, the formed CuO–In₂O₃ p–n heterojunction improved the separation efficiency of photo-generated carriers, and the coated N-doped carbon layer facilitated the transfer of photo-generated carriers and the activation of reactants. More importantly, the directional separation of CuO (external nanosheets) and In₂O₃ (central axis) acted as oxidation and reduction sites to react with 2-phenyl-1,2,3,4-tetrahydroisoquinoline and indole, respectively, which effectively avoided the inverse reaction of cross-dehydrogenative coupling (CDC). Therefore, the obtained pagoda-like In₂O₃/CuO@N-C heteroepitaxial micro-rods exhibited excellent photocatalytic activity for the CDC reaction. The present work provides a new design strategy for the comprehensive construction of a high efficiency photocatalytic material system.