| The energy crisis and environmental issues are two major challenges facing human society today.Finding clean,renewable energy sources and efficient ways to convert and utilize energy is the key to solving this dilemma.The use of solar energy,as a nearly unlimited,environmentally friendly and easily accessible energy source,is one of the effective solutions to the energy dilemma.Semiconductor photocatalysis and photocatalytic technologies are driven by solar energy,and the redox effect of semiconductor materials to decompose H2O into H2 and O2,or reduce the greenhouse gas CO2 into CO,CH4 and C2H4 and other low-carbon alkanes,through the above process to achieve the direct conversion and storage of solar energy.At the same time,these technologies can also use solar energy to remove toxic and harmful pollutants from water and air,improving environmental quality.In the process of conversion,storage and utilization of solar energy,semiconductor catalysts with photo-responsive capability are the core to realize photoconversion,which is now the focus of research in the field of photocatalysis.In this paper,two applications of photocatalytic CO2 reduction and photocatalytic antibiotic pollutant wastewater treatment will be accomplished by using semiconductor materials around hollow multi-shell layer structure with material design,surface modification,and improved carrier transport as regulatory strategies,respectively.The main research results available are as follows:(1)A hollow multishell layer Z-Scheme heterostructure composite catalyst of ln2S3/3S-TiO2 was prepared for efficient CO2 reduction and selective generation of CH4.The selective modification of the hollow multistage structure was achieved by using the regulation of zero-point charge,and a photocatalytic CO2 reduction system and online detection system were constructed.In2S3/3S-TiO2 heterojunction extended the titanium dioxide light absorption range from the UV region to the visible region,and the hollow multi-shell lay er structure effectively realizes the cascade function in spatial order,and the sequential diffusion process that generates*CO inside the shell is limitedly utilized to achieve ultra-high selective generation of the 8e-product CH4.InS3(60%)@3S-TiO2 achieves 313.05μmol g-1 h-1 and 98.28%of methane yield and selectivity,respectively,under the reaction conditions of no sacrificial agent,no noble metal,and atmospheric temperature and pressure.The results of XPS analysis and related photoelectric characterization confirm the electron transfer pathway as Z-scheme,and the in situ infrared spectra and series of control tests prove that the improvement of performance and selectivity was attributed to the structural design of the catalyst.The above experiments were carried out by a combination of structural engineering and heterojunction design to achieve the modulation of catalytic efficiency and product selectivity.The catalytic mechanism to achieve the existence of cascade at the spatial interface was also explored.(2)The hollow multishell structure composite catalyst of CuInS2@3S-TiO2 was prepared for highly efficient photocatalytic.degradation of levofloxacin.Based on the selective modification of hollow multishell layer TiO2,a suitable binary metal sulfide and hollow multishell layer titanium dioxide were selected to form a CuInS2@3S-TiO2 multilevel structure composite catalyst to construct a photocatalytic combination system for the efficient degradation of levofloxacin,and the degradation mechanism of the system was explored by optimizing a series of degradation parameters.,This system was chosen to combine the catalytic ability of the electrochemical process itself and the photocatalytic ability of the semiconductor itself from the problems of limited energy utilization form the conventional degradation system and the tendency of the catalyst to particle agglomeration,etc.,so as to achieve the efficient degradation of the target pollutant in a synergistic manner by making full use of the energy input from the light source.The results show that the degradation efficiency of this system for LEV can re ach 93.7%within 40 min under the optimized conditions of 7.5 mA cm-2,natural pH(5.5),and 25℃ for CuInS2(5%)@3S-TiO2/NF.This experiment confirms that the transfer path of electrons is Z-scheme according to XPS,Tauc curve,and Mott-Schottky test,and the analysis of burst experiments concludes that the possible redox reactions on the electrode surface and the active species generated during degradation include holes(h+),hydroxyl radicals(-OH)and superoxide radicals(O2*),and h+ is the one that plays an important role part of the process. |
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