BiOCl-Fe₂O₃@TiO₂ Mesoporous Composite for Photoelectrochemical Synthesis of Ammonia

Abstract

Nitrogen reduction reaction is an indispensable part of chemical production, and traditional Haber-Bosch process has the problems of high energy consumption and serious CO 2 emission.Solar-driven photoelectrochemical synthesis of ammonia has received much attention because it can be carried out under mild conditions.However, the yield of ammonia and conversion efficiency are too low to be practical due to the high dissociation energy of the triply bonded nitrogen molecule.The development of non-precious metal oxide catalysts for ammonia synthesis has the advantages of low commercial cost, high selectivity, and strong operability, which may provide the possibility for commercialization in green ammonia synthesis.In this work, we reported the synthesis of BiOCl-Fe 2 O 3 @TiO 2 mesoporous composite through a sol-gel method followed by in-situ decomposition approach.The obtained composites were systematically characterized and utilized for photoelectrochemical synthesis of ammonia.The results show that Fe 2 O 3 is strongly coupled with TiO 2 to produce a metal oxide-semiconductor heterojunction, while BiOCl nanoparticles are uniformly distributed on the surfaces.Compared to pure TiO 2 , the band gap of composite becomes remarkably narrowed.As a result, the visible light absorption is enhanced and the utilization of photogenerated carriers is increased.In addition, BiOCl-Fe 2 O 3 @TiO 2 composite has plenty of Ti 3+ for improving the photoelectric migration efficiency.With the presence of BiOCl, the yield of ammonia is significantly increased.Compared with pure TiO 2 , the ammonia yield of BiOCl-Fe 2 O 3 @TiO 2 is increased by 7 times, and its ammonia production rate remains stable over 10 h test.Our work offers a new route for photoelectrocatalytic synthesis of green ammonia.