Self-sacrificed BiOBr template-assisted synthesis of α-Bi2O3/Bi3O4Br heterojunctions with oxygen vacancies for enhanced photocatalytic nitrogen fixation.

The catalytic conversion of nitrogen to ammonia is one of the most significant processes in nature and the chemical industry. However, the traditional Haber-Bosch process of ammonia synthesis consumes substantial energy and emits a large amount of carbon dioxide. The efficiency of photocatalytic N2 activation is severely limited by the lack of N2 adsorption sites and poor carrier utilization. Herein, an efficient α-Bi2O3/Bi3O4Br heterojunction is proposed with a photocatalytic nitrogen fixation activity of 238.67 μmol·g-1·h-1. Compared with the BiOBr precursor, α-Bi2O3 and Bi3O4Br, the α-Bi2O3/Bi3O4Br heterojunction with oxygen vacancies can improve the adsorption and activation capacity of N2 and promote the separation efficiency of charge carrier pairs by accommodating photogenerated electrons under visible light through the mechanism of N-type semiconductors. Therefore, oxygen vacancies and heterojunction engineering of semiconductive nanomaterials provide a promising method for the rational design of photocatalysts to enhance the rate of ammonia synthesis under mild conditions.