Synergistic Regulation of Hydrophobicity and Carrier Transport Based on Bipyridine Derivatives to Enhance the Photocatalytic Performance of Defective TiO2 for Ammonia Synthesis

The efficient adsorption and activation of nitrogen by photocatalysts, as well as the rapid transport and separation of charge carriers, are key factors affecting the efficiency of photocatalytic ammonia synthesis. This article achieves simultaneous regulation of surface hydrophobicity and carrier transport of defective TiO2 (Vo-TiO2) based on seven bipyridine derivatives with different substituent types and positions. Among the seven prepared composite photocatalysts, Vo-TiO2 modified with 2,2-bipyridyl-6,6-dicarboxylic acid (6-dcbpy-Vo-TiO2) has a photocatalytic activity of 768 μmol g–1 h–1 for ammonia synthesis. By examining the hydrophobicity, absorbance, structural characteristics, defect changes, photoelectrochemical characteristics, etc. of the seven composite photocatalysts obtained and combining theoretical calculations, the influence mechanism of different substituent types and positions of bipyridine derivatives on the photocatalytic performance of Vo-TiO2 for synthetic ammonia was revealed. This work provides an effective reference for the application of bipyridine derivatives on the photocatalytic nitrogen fixation for ammonia synthesis.