| The rapid development of economy and industrialization has caused two major problems:environmental pollution and energy shortage.Common methods of wastewater treatment and wastewater detection usually suffer from low efficiency,narrow scope and high cost.Currently,photocatalysis using solar energy to degrade water pollutants and construct fluorescent and photoelectric sensors to detect environmental pollutants have become the frontier of research,and highly efficient photocatalytic materials are the key for photocatalytic applications.Cu In S2is considered to be the most promising semiconductor material because of its low synthesis cost,non-toxic and non-polluting nature,stable physical and chemical properties and unique electronic band structure.However,Cu In S2 has drawbacks such as easy recombination of photogenerated electrons and holes,as well as susceptibility to photo-corrosion.In this paper,ZnS was introduced to prepare CuInS2/ZnS nanocomposites.The visible light catalytic degradation of tetracycline hydrochloride（TCH）and the construction of fluorescence/electrochemical detection methods were explored.The work includes four parts:1.A n-n type CuInS2/ZnS composite semiconductor（CIS/ZnS）was successfully prepared via a solvothermal method.CIS/ZnS was characterized using various analysis techniques,including XRD,XPS,HRTEM,BET,UV-vis-DRS,and PL.The results showed that the composite of ZnS and CIS changed the morphology of CIS,increased its specific surface area,enhanced its absorption of visible light,and reduced the recombination efficiency of photogenerated electrons and holes in CIS.2.TCH was used as a model pollutant.The photocatalytic activity tests of CIS/ZnS with different composite ratios showed that CIS/ZnS（molar ratio 1:2）exhibited the best photocatalytic activity,and the degradation efficiency of 20 mg photocatalyst for TCH（40mg/L,100 m L）reached 86%with 3 h.The improved photocatalytic activity of CIS/ZnS（1:2）was attributed to the expanded absorption range of light and the promotion of charge separation after the composite.Five active species including·O2-,·OH,e-,h+and 1O2 were involved in the reaction during the photocatalytic degradation.In addition,CuInS2/ZnS（1:2）exhibited high stability after five consecutive cycles.3.Water-soluble CIS/ZnS was prepared using cysteine and serine as stabilizers via a low-temperature liquid-phase method.XRD,XPS,and HRTEM were used to characterize CIS/ZnS,which showed that the prepared CIS/ZnS was approximately spherical,with the oxidation states of Cu,In,S,and Zn in the sample being+1,+3,-2,and+2,respectively.By utilizing the fluorescence quenching effect of TCH on CIS/ZnS,a quantitative analysis method for TCH detection was established.The linear range of the method was determined to be 1.0×10-4～6.4×10-9mol/L,with a detection limit of 4.32×10-9 mol/L.The average recovery rate of TCH added to tap water ranged from 99.4%to 105.7%.4.A working electrode for the detection of TCH in water using a photoelectrochemical method was prepared by coating water-soluble CIS/ZnS（4.0 mg/m L）onto ITO（30.00μL）.By optimizing experimental conditions,a linear relationship between the relative decrease in photocurrentΔI/I0and the logarithm of TCH concentration（mol/L）was observed at an applied voltage of 0.25 V.The linear equation was determined to beΔI/I0=0.0946 log C+1.0480,with R2=0.9951.The linear range for TCH detection was 6.4×10-9～1.0×10-4 mol/L,with a detection limit of 1.4×10-9 mol/L.The average recovery of TCH added to water ranged from 102.50%to105.90%.This method has the advantages of simplicity and low detection limit,making it suitable for the determination of TCH content in water. |
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