Constructing the V_o‑TiO₂/Ag/TiO₂ Heterojunction for Efficient Photoelectrochemical\nNitrogen Reduction to Ammonia

Abstract

Photoelectrochemical\n(PEC) nitrogen (N₂) fixation technology\nprovides the possibility to produce ammonia (NH₃) under\nmild conditions, but the efficiency of N₂ reduction in\nthis process is greatly limited due to the high bond energy and ionic\npotential of N₂. Herein, the V_o-TiO₂/Ag/TiO₂ photoelectrode consisting of rutile TiO₂ nanorod arrays, Ag nanoparticles, and anatase TiO₂ nanosheets\nwith oxygen vacancies (V_o-TiO₂) was constructed\nfor accelerating the PEC reduction of N₂ into ammonia.\nThe separation of photogenerated carriers can be promoted by the heterojunction\namong TiO₂ nanorods, Ag nanoparticles, and V_o-TiO₂ nanosheets. Furthermore, the photogenerated electrons\nfrom the conduction band of TiO₂ and the hot electrons\nfrom Ag nanoparticles’ local surface plasmon resonance (LSPR)\neffect were injected into the conduction band of V_o-TiO₂, and they were further captured by V_o-TiO₂ oxygen vacancy and can reduce N₂ that adsorbed\non the catalyst to NH₃. Without any sacrificial agent,\nthe average NH₃ production rate can reach 51.2 μg\nh^–1 cm^–2. The catalyst exhibited\nexcellent stability even after multiple uses. The LSPR effect of Ag\nnanoparticles and heterojunction structure promote the better PEC\nperformance of TiO₂ nanorod arrays.