MOF-derived synthesis of MnS/InSp-n heterojunctions with hierarchical structures for efficient photocatalytic CO reduction.

Photoreduction of CO to valuable fuels with semiconductor photocatalysts is a good solution to the problems of global warming and energy crisis. Creation of hybrid nanomaterials with hierarchical and/or heterojunction structures is beneficial to develop efficient photocatalysts for CO reduction. Herein we present a convenient method to obtain a hybrid photocatalyst consisting of MnS and InS nanosheets with assembled hierarchical structures through using Mn-loaded MIL-68(In) submicro-rods as templates. Owing to the dispersive Mn and In ions in templates, numerous small p-n heterojunctions of MnS/InS could be simultaneously produced in each hierarchical particle. The p-type MnS and n-type InS with an original type II band alignment can create a stronger built-in electric field after the formation of p-n heterojunctions, which is favorable for charge separation and migration to catalyst surface. The prepared MnS/InS heterojunctions show an 4-fold higher photocatalytic activity toward CO reduction than pristine MnS and InS. The MnS/InS hierarchical structures were well characterized and their working mechanism was explored. This work demonstrates a facile strategy to create efficient hybrid photocatalysts with both hierarchical structures and p-n heterojunctions for photocatalytic applications.