Research On The Application Of Metal Organic Framework Derivatives Co/N-C And Lead-Free Halide Perovskite In Environmental Catalysis

The reduction of greenhouse gases in the atmosphere and the degradation and removal of organic dyes in water are the two major problems in environmental governance.Based on the characteristics of two new materials Metal Organic Frameworks(MOFs)derivative Co/N-C and lead-free halide perovskite Cs2AgxNa1-xInCl6(x=0,0.6,1),this paper takes CH4/CO2 reforming reaction and photocatalytic degradation of organic dyes as an example to study the application possibility of these two kinds of new materials in environmental catalysis,so as to further develop new high-performance catalysts suitable for environmental catalysis provide reference.The main research contents are as follows:(1)Based on the poor activity caused by the agglomeration of active components of traditional catalysts,a strategy of using cobalt based MOFs(Co-MOFs)derivatives as catalysts in CH4/CO2 reforming process was proposed.The Co-MOFs derivative Co/N-C material was synthesized by one-step method at room temperature,and annealed at high temperature.In view of the problem that the stability of the lead-free halide perovskite visible photocatalyst is poor in the water system,a new type of photocatalyst,Cs2AgxNa1-xInCl6,was prepared.The Cs2AgxNa1-xInCl6 with adjustable composition was synthesized by hydrothermal method-The inherent characteristics of the material,such as morphology,structure and crystallinity,were studied in detail by SEM,TEM and XRD.It provides a basis for the further study of photocatalytic properties.(2)The Co-MOFs derivative Co/N-C was used as catalyst for reforming greenhouse gas CH4/CO2 to synthesis Co/H2.The effect of different annealing temperature on the catalytic performance of Co-MOFs derivative was studied by X-ray photoelectron spectroscopy(XPS),Fourier infrared spectroscopy(FTIR),BET and BJH.The results shows the Co/N-C material that prepared at different annealing temperature has a significant effect on the catalytic performance.As the annealing temperature is 800℃,the reduction degree of the active component Metal Co nanoparticles in Co/N-C is higher,and they are uniformly distributed on the N-doped Carbon substrate,with the smallest average particle size and higher activity degree,so they present good catalytic activity and stability.The conversion ratio of CH4 and CO2 was 57.07%and 33.18%respectively.The ratio of H2/CO was kept at 0.95.The catalyst was stable at 2 h and kept good activity.(3)A new type of lead-free halide perovskite Cs2AgxNa1-xInCl6 was used as photocatalyst to study the degradation of organic dyes in water under light.UV-Vis,PL,time resolved PL and photocurrent measurements were used to characterize the generation,separation and recombination of photo-generated carriers.The effects of different Na content in the catalyst on the carrier lifetime,absorption and photocurrent were compared.It is found that the fluorescence intensity of Cs2AgInCl6 and Cs2NaInCl6 are relatively low,while the fluorescence intensity of Cs2Ag0.60Na0.40InCl6 is the highest,indicating that doping improves the radiation recombination efficiency.Moreover,after Na doping,the average lifetime of photo-generated carrier increases to 204 ns,while,after Na element is completely replaced,the average lifetime of Cs2NaInCl6 decreases to 174 ns,so appropriate Na doping can improve the lifetime of photo-generated carriers.It also can be seen from the catalytic performance that appropriate Na doping can improve the catalytic performance.However,as Na completely replaces Ag,the degradation activity will be significantly reduced.Cs2Ag0.60Na0.40InCl6 photocatalyst showed the best photocatalytic activity.In 120 minutes,the degradation efficiency of Rhodamine 6G and methyl orange reached 94.94%and 93.41%,respectively.Furthermore,after five cycles,the degradation efficiency remained above 90%,indicating it had good stability.In this paper,the strategy of using Co-MOFs derivatives as catalyst in CH4/CO2 reforming process and lead-free halide perovskite as photocatalyst to degrade organic dyes in water are proposed,respectively.This work provides reference for the research and development of new high-performance environmental catalysts.It is of great significance for greenhouse gas emission reduction and organic dye degradation.