TiO₂ Quantum Dots/Fe₃S₄ Heterojunction Nanocomposites for Efficient Ammonia Production through Nitrogen Fixation upon Simulated Sunlight

Using semiconductor photocatalysts instead of the traditional Haber-Bosch procedure to produce ammonia is a promising strategy to save energy and prevent environmental pollution. Therefore, finding a suitable photocatalyst with high efficiency and stability has become one of the big challenges of research communities in the field of heterogeneous photocatalysis. Herein, S-scheme TiO₂ quantum dots (QDs)/Fe₃S₄ heterojunction photocatalysts were synthesized through a hydrothermal route. The nitrogen photofixation measurements exhibited that the TiO₂ QDs/Fe₃S₄ photocatalysts have excellent activities, where the generation of NH₃ by the optimized nanocomposite reached 16,624 μmol L^-1 g^-1 upon simulated sunlight. This amount was almost 19.9, 6.30, and 2.85 times as high as those of TiO₂, TiO₂ QDs, and Fe₃S₄ photocatalysts, respectively. The promoted photocatalytic ability was devoted to outstanding visible-light absorption, accelerated segregation of photoinduced electron-hole pairs, and enhanced surface area. The key purpose of this research was the rational design of a photocatalyst based on TiO₂ QDs through a one-pot and facile fabrication procedure, which exhibits admirable performance in the field of photocatalytic nitrogen fixation. Considering the advantages of binary TiO₂ QDs/Fe₃S₄ photocatalysts, it is anticipated that this photocatalyst could be utilized in solar energy conversion processes.