Defective ZrO2−x supported Ru nanoparticles as a Mott–Schottky photocatalyst for efficient ammonia synthesis under ambient conditions

Well-crafted semiconductors exhibiting favorable band structures and strong electron-donating properties can provide a viable pathway for solar-driven nitrogen activation under ambient conditions. In this study, we demonstrate that the nitrogen photo-fixation process can be enhanced by introducing oxygen vacancies and a Ru co-catalyst. The Ru-loaded ZrO2−x photocatalyst achieved an impressive NH3 production rate of 3256 μg g−1 h−1 under visible light irradiation (at 400 nm). Defective ZrO2−x with its enhanced reducing ability and narrow band gap possesses a low work function and excellent electron-donating capability, resulting in remarkable photocatalytic performance for ammonia synthesis under visible light. The supported Ru co-catalyst induces upward band bending in defective ZrO2−x, forming an interfacial Schottky barrier that facilitates the separation of photogenerated charge carriers and provides energetic electrons for nitrogen activation. Mott–Schottky photocatalysts with enhanced back donation ability establish a one-way channel for the transmission of photoexcited electrons, thereby further improving the photocatalytic performance of ammonia synthesis at room temperature.