Electron repulsion tuned electronic structure of TiO2 by fluorination for efficient and selective photocatalytic ammonia generation

Abstract

The photocatalytic conversion of nitrogen into high-value ammonia products holds tremendous potential in the global nitrogen cycle. However, the activation of N₂ and competition of hydrogen evolution limit the improvement of nitrogen fixation performance. In this study, we developed a fluorinated TiO₂ (F-TiO₂) using a hydrothermal-annealing method. The incorporation of F dopants not only enhances the adsorption and activation of N₂ through electronic structure regulation, but also facilitates an in situ increase in active sites via the electron repulsion effect between F and Ti atoms. In addition, the presence of F on the surface effectively improved the nitrogen supply problem and optimized the nitrogen fixation selectivity for its hydrophobic modulation. The NH₃ yield of the F-TiO₂ photocatalyst reached 63.8 μmol h⁻¹ g⁻¹, which was 8.5 times higher than that of pure TiO₂. And the selectivity experiment showed that the electronic ratio of NH₃ to H₂ production reached 0.890. This research offers valuable insights for the design of highly efficient and selective nitrogen-fixing photocatalysts.