Promoted Fixation of Molecular Nitrogen with Surface Oxygen Vacancies on Plasmon‐Enhanced TiO₂ Photoelectrodes

A hundred years on, the energy‐intensive Haber–Bosch process continues to turn the N 2 in air into fertilizer, nourishing billions of people while causing pollution and greenhouse gas emissions. The urgency of mitigating climate change motivates society to progress toward a more sustainable method for fixing N 2 that is based on clean energy. Surface oxygen vacancies (surface O vac ) hold great potential for N 2 adsorption and activation, but introducing O vac on the very surface without affecting bulk properties remains a great challenge. Fine tuning of the surface O vac by atomic layer deposition is described, forming a thin amorphous TiO 2 layer on plasmon‐enhanced rutile TiO 2 /Au nanorods. Surface O vac in the outer amorphous TiO 2 thin layer promote the adsorption and activation of N 2 , which facilitates N 2 reduction to ammonia by excited electrons from ultraviolet‐light‐driven TiO 2 and visible‐light‐driven Au surface plasmons. The findings offer a new approach to N 2 photofixation under ambient conditions (that is, room temperature and atmospheric pressure).