Catalyzing the Nitrogen Fixation under Ambient Environment: Progress and Prospects in TiO₂-Based Nanomaterials for...

TiO₂-based nanomaterials have attracted considerable attention for their ability to produce ammonia (NH₃) through photocatalysis, offering a sustainable method for nitrogen (N₂) fixation under ambient conditions. TiO₂, being a stable and benchmark semiconductor, shows great promise as a photocatalyst for utilizing light energy to show the pathway for efficient reduction of N₂ to NH₃. This review provides relevant information about the fundamental mechanisms of photocatalytic N₂ adsorption and reduction pathways, besides providing the insights essential for the development of efficient TiO₂-based photocatalysts. Various strategies, such as doping with metals and nonmetals, have been developed to modify the electronic structure of TiO₂, enabling it to absorb visible light more effectively. Furthermore, advanced strategies such as defect engineering, crystal facet modulation, and plasmonic hybrids have been extensively elucidated, demonstrating their critical role in enhancing charge carrier separation and boosting the efficiency of photocatalytic NH₃ synthesis. Moreover, the development of TiO₂-based composites by combining TiO₂ with other materials has provided promising outcomes, aiming to achieve more efficient and sustainable NH₃ production. Finally, the paper discusses the current limitations, challenges, and future perspectives in the development of high-efficiency TiO₂-based photocatalysts, experimental protocols for correct NH₃ quantification and further necessary advancements for scalable photocatalytic NH₃ production.