MOFs-derived plum-blossom-like junction In/In 2 O 3 @C as an efficient nitrogen fixation photocatalyst: Insight into the active site of the In 3+ 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/InO@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/InO for the activation and reduction of N, which form an efficient photocatalyst for nitrogen fixation reaction with the performance of 51.83 μmol h g. Experimental studies and DFT calculations revealed the active site of the catalyst for nitrogen fixation reaction is the In around the oxygen vacancy in InO. More importantly, the elemental In forms the Schottky barrier with InO 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.