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

Abstract

A hundred years on, the energy-intensive Haber–Bosch process continues to turn the N₂ 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 N₂ that is based on clean energy. Surface oxygen vacancies (surface O_vac) hold great potential for N₂ 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 TiO₂ layer on plasmon-enhanced rutile TiO₂/Au nanorods. Surface O_vac in the outer amorphous TiO₂ thin layer promote the adsorption and activation of N₂, which facilitates N₂ reduction to ammonia by excited electrons from ultraviolet-light-driven TiO₂ and visible-light-driven Au surface plasmons. The findings offer a new approach to N₂ photofixation under ambient conditions (that is, room temperature and atmospheric pressure).