Synthesis Of CuInZnS Based Composites And Their Photocatalytic Degradation Of NO Gas Under Visible Light Irradiation

The problem of environmental pollution has become increasingly serious today,environmental problems caused by organic pollutants and harmful gases has attracted more and more attention,the atmospheric pollutants of nitric oxide?NO?component will cause the formation of acid rain and photochemical smog,serious damage to the environment and harm to human health,so people need to find a convenient and efficient method of effective non-toxic the control and removal of nitric oxide?NO?in the air of harmful gases.The photocatalytic technology of converting solar energy to solve practical problems has been a concern.Photocatalytic technology is considered as an environmentally friendly technology for the removal of nitric oxide?NO?because of its poor reaction conditions,low energy consumption,and two environmental pollution and high catalytic efficiency.CuInS₂-ZnS?CIZS?as a new type I-III-VI₂ semiconductor nanomaterials,because the band gap adjustable structure,stable chemical properties,and does not contain toxic heavy elements,has gradually become a hot research,but the mechanism of material elements in the proportion for the photocatalytic performance is not clear well,how to further improve the catalytic activity of the problems will be solved.The following work has been carried out in this paper for the two scientific problems:?The first part of this thesis is the preparation of CIZS nanomaterials.CIZS nanomaterials with different Cu ratios?0.01,0.02,0.04,0.08?were prepared by aqueous solution method at different temperatures at 60,70,80,90,and by changing the amount of CuCl.Finally,through transmission electron microscopy of CIZS nano material preparation?TEM?,energy dispersive analysis?EDS?,N2-adsorption?BET?and UV Vis absorption spectroscopy?UV-abs?and a series of tests to analyze the temperature and Cu ion ratio on CIZS morphology,spectral absorption range,photocatalysis the influence of performance.?Through the analysis found that the characterization of CIZS nanomaterials morphology,particle size and Cu ion ratio and temperature are closely related,on the one hand when Cu ion ratio is low,CIZS is not a good crystal morphology,the shape of the floc,not forming,but with the increase of CIZS ratio of Cu ion particles gradually as the internal micro sphere,and the surface more smooth,more uniform size,in addition with the increase in the size of Cu crystal ion ratio increased gradually.On the other hand,the CIZS synthesized under heating conditions has less impurity,more pure crystal material and better crystal spherical structure.The Cu ion ratio and reaction temperature also affect the visible spectral response range of CIZS material.When the Cu ion ratio increases and the reaction temperature rises,the UV-abs absorption curve of CIZS has corresponding red shift,and the band gap decreases,and the visible spectrum response range expands.In order to confirm this result,we use the special quasi random structure?SQS?in four 64-atoms supercells with different CuInS₂ and ZnS mixing ratios?The simulation results show that the larger Cu/Zn ratio will lead to the increase of the absorption coefficient of visible light.The results of XRD and spectral changes described above are all in accordance with the theoretical simulation results.In this paper,nitric oxide?NO?was used as the target degradation product.The results showed that the photocatalytic efficiency of CIZS nanoparticles was the best,reaching 47.71%when the reaction temperature was 90 C and the ratio of Cu was 0.04.When the ratio of Cu continues to increase,the photocatalytic activity of the material decreases.?Because the phase CIZS of photogenerated electron hole composite easily,in order to further enhance its photocatalytic performance,we introduce the reduced graphene oxide?rGO?,were successfully prepared CIZS/rGO composite photocatalytic materials,the crystal structure of prepared samples were analyzed by characterization,particle size and optical properties.It is found that the addition of rGO and CIZS formed heterojunction close enough,not only increases the surface area of the material,increase the activity of adsorption contact point,and effectively improve the electron transfer capability in the interface,so that the electron hole separation,thereby enhancing the efficiency of photocatalytic degradation of materials.The degradation efficiency of the CIZS/rGO complex with relative mass ratio of 30wt%to NO was the best,reaching 59.79%,and increased by 47%compared with the simple CIZS.This paper provides a new way to improve the photocatalytic activity of CIZS,the theoretical calculation and the experimental data are strong evidence that the different proportion of elements has a significant impact on the photocatalytic activity,and provide a new method for removing nitrogen oxides and other harmful gases?...