Study On The Photocatalytic Performance Of CuInS₂ Quantum Dots Doped And Its Composites Assembled

In recent years,quantum dots of ternary sulfides（e.g CuInS₂,AgInS₂,ZnIn₂S₄）have attracted a lot of attention because they usually have an optical band gap that closely matches the solar spectrum,valuable photoluminescence properties and promising photocatalytic activity.In addition,these sulfides are considered environmentally safe and do not cause toxicity problems without the risk of releasing harmful Cd²⁺or Pb²⁺ions as in the case of Cd S or Pb S.Copper indium disulfide（CuInS₂,CIS）is a typical I-III-VI₂ semiconductor that absorbs in almost the entire visible region,allowing efficient use of solar energy.The photoinduced properties of CIS become particularly prominent in the quantum dot form,and CIS quantum dots（QDs）have been mostly studied for applications in solar energy conversion,light-emitting diodes,and bioimaging,although it still represents a limited part of CIS QDs research.Indeed,the photocatalytic potential of CIS-based nanomaterials is still to be fully understood and exploited.In this paper,aiming at the problems in the research and development of CIS QDs,the photocatalytic performance of CIS QDs was improved from the aspects of metal ion doping alloying,shell-core structure synthesis and heterostructure construction.The main contents are as follows:（1）CIS QDs were synthesized in water by reverse thermal implantation,which is the first report of CIS with definite exciton absorption.Cu-Al-In-S alloying QDs catalysts with 2D mesogenic structure were prepared by aluminum ion doping.The CIS QDs prepared by reverse thermal implantation have good water solubility.By doping Al³⁺,the 2D mesomorphic structure of aluminum-doped CIS QDs（Al-CIS）can be obtained.By analyzing and comparing the effect of aluminum ion doping amount on the degradation of tetracycline hydrochloride by CIS,combined with morphological structure characterization and photoelectrochemical performance test,The photocurrent density of Al-CIS is 6.4 times higher than that of CIS QDs,and the carrier concentration is 2.45 times higher than that of CIS QDs.Within half an hour,Al-CIS increased the removal rate of TC from 57.5%of the original CIS to 95.1%,and the degradation rate was increased by 2.5 times.the photocatalytic degradation of tetracycline hydrochloride by Al-CIS 2D mesogenic structure and CIS QDs was studied.Based on the study of degradation kinetics and carrier kinetics,the mechanism of 2D mesomorphic structure to enhance photocatalytic performance was revealed.This is expected to provide new insights into the hierarchical structure of ternary quantum dots designed to enhance photocatalysis.（2）CIS QDs were synthesized in aqueous solution at 180℃,surface defects were improved by ligand-assisted zinc alloying,or these defects were passivated or wrapped by depositing ZnS.ZCIS QDs and their core-shell CIS-ZnS and ZCIS-ZnS QDs were customized.The photocatalytic degradation properties of CIS QDs,ZCIS QDs,core-shell CIS-ZnS and ZCIS-ZnS were tested.The rate constant of degradation kinetics of CIS-ZnS is 0.06742min^-1,which is 3.6 times of that of CIS(0.01885 min^-1).Based on the crystal structure,photoelectrochemical properties and energy band analysis,the role of surface defects of CIS QDs in photocatalysis was studied.（3）CIS QDs were synthesized by hydrothermal method and Ti O₂ nanowire array electrodes were synthesized by hydrothermal and calcination methods.CIS QDs were grown into Ti O₂nanowire array electrodes to form p-n heterostructures.The optoelectronic properties of Ti O₂nanowire array electrodes were improved by the high light absorption system of CIS in the visible region,the carrier transport capacity of heterostructures and the inhibition of photogenerated electron-hole recombination.Thus,the possibility of using it as a photocatalytic electrode is discussed.