Cu doping induced lattice distortion and oxygen vacancy formation in PbBiO₂Br:Band structure modulation enhances photocatalytic nitrogen fixation and pollutant degradation performance

Photocatalytic nitrogen fixation has emerged as a sustainable alternative for ammonia synthesis, playing a crucial role in alleviating energy shortages and environmental pollution. In this study, PbBiO₂Br was applied to photocatalytic nitrogen fixation for the first time, and its photocatalytic performance was effectively enhanced through Cu doping. The catalyst was synthesized via a simple reduction method, and its morphology, structure, and physicochemical properties were systematically investigated using various characterization techniques and density functional theory calculations. The results revealed that the incorporation of Cu²⁺ partially replaced Pb²⁺, inducing lattice distortion in PbBiO₂Br, promoting the formation of oxygen vacancies, and modifying its electronic band structure. Specifically, Cu doping led to a slight bandgap narrowing, a reduction in work function, and a significant upward shift in the conduction band position. These changes enhanced light absorption, facilitated charge carrier migration and separation, and improved the reduction ability of photogenerated electrons. Moreover, Cu doping promoted N₂ adsorption and activation. Consequently, the photocatalytic nitrogen fixation performance of Cu- doped PbBiO₂Br was significantly enhanced, achieving an optimal nitrogen fixation rate of 293 μmol L^-1 g^-1 h^-1, which is 3.6 times higher than that of pristine PbBiO₂Br. Additionally, Cu- PbBiO₂Br also showed good activity in the photocatalytic degradation of RhB, with a degradation rate 4.6 times higher than that of PbBiO₂Br. This work offers new insights into the application of PbBiO₂Br in photocatalytic nitrogen fixation and offers valuable guidance for the development of highly efficient nitrogen fixation materials in the future.