Ag nanoparticles modified hollow tubular In2O3 for enhanced photocatalytic nitrogen reduction to ammonia†

The photocatalytic nitrogen reduction reaction provides an alternative process for nitrogen cycling and ammonia (NH₃) production under mild conditions. Herein, we have synthesized Ag-loaded In₂O₃ (Ag@In₂O₃-X) by solvothermal and photoreduction methods. The introduction of Ag significantly alters the band structure of In₂O₃, resulting in a slight reduction in the band gap and a more negative conduction band position, thereby facilitating the generation of reductive electrons in In₂O₃. Moreover, the synergistic interaction between loaded Ag nanoparticles and In₂O₃ forms a Schottky barrier, which widens the light absorption range and promotes charge separation. Under simulated sunlight, the photocatalytic nitrogen fixation performance of Ag@In₂O₃-5 reaches 35.56 μmol h⁻¹ g_cat⁻¹, which is higher than other composites and 3.58 times that of pure In₂O₃. At the same time, the catalyst has good structural stability and cycle life. Density functional theory (DFT) calculations demonstrate that Ag exhibits a stronger interaction with N₂ and lowers the potential barrier of the N₂ hydrogenation reaction. The synergistic effect between precious metals and semiconductors offers novel insights and presents challenges for the photocatalytic N₂ fixation process. This work provides new insights and challenges for designing and synthesizing nanomaterials for photocatalytic nitrogen fixation.