Construction Of Bismuth Molybdate Based Photocatalyst And Nitrogen Fixation Performance

Ammonia（NH₃）is an important industrial raw material for chemical fertilizer industry and basic organic chemical industry.In addition,ammonia is a hydrogen rich substance（17.6 wt%）,low liquefaction pressure（～8 atm）and safe transportation.It can be used as an ideal zero carbon fuel and hydrogen energy carrier.At present,industrial synthetic ammonia adopts the traditional Haber Bosch process,which takes high-purity hydrogen（H₂）and nitrogen（N₂）as raw materials.It needs to be carried out under high temperature and high pressure.The reaction conditions are harsh,consumes a lot of energy and emits a lot of carbon dioxide（CO₂）.Therefore,it is of great theoretical and practical significance to explore a green synthetic ammonia process with low energy consumption and low emission.Photocatalysis can realize ammonia synthesis with water（H₂O）and N₂ as raw materials at room temperature,using solar driven semiconductor catalysis to activate N≡N bond,which provides a new way to develop a new green ammonia synthesis process.Based on this,this paper takes Bi₂MoO₆as the main catalyst,and effectively widens the light response range of Bi₂MoO₆ and regulates the carrier separation/transmission performance through the control strategies of surface defects,semiconductor coupling and transition metal doping,so as to realize the efficient activation of N₂.The main conclusions are as follows:Firstly,OVs-Bi₂MoO₆ was synthesized by solvothermal method,and then Bi₂S₃/OVs-Bi₂MoO₆ heterojunction was constructed by in-situ ion exchange method with L-Cysteine as sulfur source.OVs improves the carrier separation efficiency of Bi₂MoO₆ and broadens the photoresponse range.The cocatalyst Bi₂S₃ loading realizes the spatial separation and synchronous activation of N₂ reduction half reaction（NRR）and water oxidation half reaction（OER）,which significantly improves the photocatalytic nitrogen fixation performance of Bi₂MoO₆.Secondly,the transition metal Co was introduced into Bi₂MoO₆by secondary hydrothermal method to dope and regulate the d-band electronic structure of Bi₂MoO₆to form the doping energy level.At the same time,the OV_S formed can promote the chemical adsorption and activation of N₂ molecules.After doped,it has excellent photocatalytic nitrogen fixation performance.Thirdly,In₂O₃/Bi₂MoO₆ heterostructure was constructed by electrostatic self-assembly method,and In-O-Bi/Mobond was formed at the interface,which provided a channel for rapid carrier transfer at the interface.Combined with N₂-TPD and EPR testing technology,the charge transfer law between N₂ and H₂O molecules and the catalyst was deeply analyzed,and the synergistic strengthening mechanism of Bi₂MoO₆and In₂O₃for OER and NRR semi reaction was revealed.