ABSTRACT Photocatalytic N 2 fixation offers a promising sustainable alternative to the energy‐intensive Haber–Bosch process. Since N 2 fixation involves the reduction and oxidation half‐reactions, understanding their synergistic relationship and achieving their cooperation is crucial for improving the overall efficiency of N 2 fixation. To fulfill this objective, we have designed a type of Ru‐WO 3− x /CoO x photocatalyst with respective reduction and oxidation active sites. In this type of photocatalyst, Ru doping not only provides reduction sites to facilitate N 2 adsorption and activation but also optimizes the band structure by widening the defect band and elevating the Fermi level. Meanwhile, the CoO x clusters serve as O 2 evolution sites that can accelerate hole utilization and improve electron–hole separation, thereby enhancing N 2 reduction. Consequently, the Ru‐WO 3− x /CoO x photocatalyst gives an impressive NH 3 production rate of 131.95 µmol g −1 h −1 in pure water, superior to the photocatalysts with a single type of active site. The optimized catalyst delivers a solar‐to‐chemical conversion efficiency of 0.22% under AM 1.5G light illumination and maintains an apparent quantum efficiency above 0.2% within the entire test range, including the near‐infrared region. This work underscores the mutual influence of the oxidation and reduction half‐reactions in photocatalysis and highlights the cooperation between redox‐active sites.
Wu et al. (Thu,) studied this question.