S-scheme OV–TiO2@Cu7S4 heterojunction on copper mesh for boosting visible-light nitrogen fixation

Abstract

In the field of photocatalysis, the loaded photocatalyst possesses the advantages of controllable morphology, uniform preparation, low cost, and easy recovery. It can effectively avoid the secondary pollution caused by the powder catalyst and is considered a potential substitute for the powder photocatalyst. In this work, TiO2 and Cu7S4 hybrid materials with oxygen vacancies (OV) grown in situ on copper mesh (CM) were prepared by anion exchange and hydrothermal reaction. The characterization results showed that the concentration of oxygen vacancies in TiO2 increased significantly after calcination. Under the simulated visible light, the liquid film reaction was adopted. The yield of NH3 synthesized by OV–TiO2@Cu7S4/CM photocatalyst was 133.42 μmol cm−2 h−1, 5.2 and 2.2 times that of pure TiO2 and Cu7S4, respectively. The enhanced photocatalytic performance is attributed to the synergistic effect between the interfacial electric field of the S-scheme heterostructure and the abundant oxygen vacancies, which induces the efficient separation and migration of carriers. The cycle experiment showed that OV–TiO2@Cu7S4/CM heterojunction has excellent stability in photocatalytic nitrogen fixation. This work provides insight into the design of S-scheme photocatalysts with rich surface defects for green and efficient reduction of N2.