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.