MOFs-derived plum-blossom-like junction In/In2O3@C as an efficient nitrogen fixation photocatalyst: Insight into the active site of the In3+ around oxygen vacancy

Nitrogen activation with low-cost, visible-light-driven photocatalysts continues to be a major challenge. Since the discovery of biological nitrogen fixation, multi-component systems have achieved higher efficiency due to the synergistic effects, thus one of the challenges has been distinguishing the active sites in multi-component catalysts. In this study, we report the photocatalysts of In/In2O3@C with plume-blossom-like junction structure obtained by one-step roasting of MIL-68-In. The “branch” is carbon for supporting and protecting the structure, and the “blossom” is In/In2O3 for the activation and reduction of N2, which form an efficient photocatalyst for nitrogen fixation reaction with the performance of 51.83 μmol h−1 g−1. Experimental studies and DFT calculations revealed the active site of the catalyst for nitrogen fixation reaction is the In3+ around the oxygen vacancy in In2O3. More importantly, the elemental In forms the Schottky barrier with In2O3 in the catalyst, which can generate a built-in electric field to form charge transfer channels during the photocatalytic activity, not only broadens the light absorption range of the material, but also exhibits excellent metal conductivity.