Construction Of MoO₃ Based Catalyst And Its Photo （Eletro） Catalytic Performance For Nitrogen Fixation

The traditional industrial nitrogen fixation method accelerates the nitrogen cycle in nature,but consumes a lot of fossil energy.Photocatalysis has attracted much attention because of its green and sustainable characteristics,but its efficiency is still low and there is still a certain distance from industrial production.MoO₃ is selected as the main material in this project.It is combined with other materials and used in the field of photocatalysis or photocatalysis to explore its nitrogen-fixing performance and mechanism.（1）Study on the construction of MoO₃/MIL-101（Fe）composite catalyst and its photocatalytic nitrogen fixation performance.One-dimensional nanofibrous MoO₃ and MIL-101（Fe）materials were synthesized by a simple hydrothermal method.The optical display range of the composite materials reached 600nm,which greatly expanded the response band of MoO₃ to light.The nitrogen fixation experiment showed that the composite sample had higher nitrogen fixation performance,in which 0.15MoFe had the highest nitrogen fixation efficiency of about 152 umol g^-1 h^-1,2.1 times that of MIL-101（Fe）.Meanwhile,the yield of hydrazine in the reaction was tested,which proved that the composite had strong product selectivity,and the possible reaction path of ammonia nitrogen was determined.（2）The construction of 2D/1D heterojunction of SnS₂@MoO₃ and its photocathode catalytic synthesis of ammonia.SnS₂@MoO₃ composites were prepared under different conditions by simple water bath and calcination.Scanning electron microscopy（SEM）showed that SnS₂ was uniformly grown on one-dimensional MoO₃nanofibers,forming a homogeneous core-shell structure catalyst.The UV-Vis spectrum shows the heterojunction structure of SnS₂ and MoO₃,and a narrower band gap is obtained.Electrochemical tests show that the composite has higher nitrogen fixing activity and a larger electrochemical active area.The results show that the NRR yield and Faraday efficiency obtained by SnMo-3 composite are 30.04ug mg^-1h^-1 and 13.41%,respectively.Compared with pure MoO₃ and SnS₂,the nitrogen fixing performance is improved by 2.3 and 4.6 times,and the Faraday efficiency is improved by 2.0 and 3.5times,respectively.（3）Construction of MoO₃-CuO/CF photocathode and its photocatalytic performance for ammonia synthesis.Copper foam was selected as the base material,on which a nanowire array was grown,and the composite material was combined with MoO₃ two-dimensional sheet.The photocurrent electrochemical impedance test showed that the composite material has a better effect of electron hole separation.Electrochemical LSV test shows that it has photoelectric coordination effect and higher nitrogen fixing activity.The photocatalytic nitrogen fixing test showed that the best photocatalytic nitrogen fixing efficiency and Faraday efficiency of the composite were10.2 mmol h^-1 m^-2 and 10.5%,respectively.Compared with pure CuO/CF,the nitrogen fixing performance and Faraday efficiency of the composite were 1.8 times and 2.2times higher,respectively.