Research On The Solvent Selection Mechanism Of Copper Sulfide Phase And Its Application In Photoelectric Catalysis

As an important component in the field of semiconductor materials,metal sulfide has attracted more and more researchers'attention and research due to its diverse structure and excellent physical and chemical properties.Among many metal sulfides,copper sulfide(Cu_2-xS)crystals contain a large number of holes,which is a typical P-type semiconductor material.Because of its distinctive properties in macro-magnetism,optics,electricity,thermodynamics,and biology,it has become a very popular research material in many cutting-edge applications.These properties are closely related to its crystal structure and morphology.As we all know,Cu_2-xS,as a copper-sulfur compound containing stoichiometry and non-stoichiometry,has a variety of crystal structures and morphologies.However,they are easily affected by environmental changes and transform each other.As a result,its suitable use also changes.Therefore,it is very meaningful to study the phase transition mechanism between them and the corresponding applications.This paper is based on a two-step heating method with ethylene glycol and triethylenetetramine as solvents,copper chloride dihydrate?CuCl₂.2H₂O? as the copper source,and thiourea?CH₄N₂S? as the sulfur source.The transformation from petal-like CuS to near-spherical Cu₂S to regular hexagonal Cu₇S₄ nanosheets was achieved only by adjusting the solvent ratio.The influence of crystal morphology and size on its photoelectric properties was discussed,and its phase transition mechanism was analyzed in depth.In addition,due to the excellent photoelectric performance of copper sulfide,the application research of photocatalytic degradation of organic dyes and the counter electrode of dye-sensitized solar cells?DSSC? is expanded in this paper.Secondly,the degradation of methylene blue,rhodamine B and methyl orange by three different copper sulfide materials?CuS,Cu₂S,Cu₇S₄? was studied,and their degradation performance on different organic dyes was investigated.The results show that the degradation effect of three kinds of copper sulfide on methylene blue is relatively better.With the addition of 50 mg copper sulfide,the degradation rates reached 100%,93%,and 98%,respectively,and the time spent was 60min,480 min,and 300 min,respectively.For rhodamine B,the 50mg copper sulfide additions were only CuS and Cu₇S₄ has a degradation effect on rhodamine B,reaching 100% and75%degradation rates,respectively,and the time is 150 min and 300 min.In the 50mg copper sulfide addition amount,the three materials did not degrade methyl orange.Among them,CuS has the largest specific surface area due to its special morphology and contains a large number of holes,so it has the best degradation effect among the three materials.In the application research of dye-sensitized solar cells,powders of the three materials were dissolved in glycerol solution to prepare semi-solid colloids.Different copper sulfide films were obtained by a simple knife coating process.Different copper sulfide film counter electrodes were obtained by annealing at 200?,250?,and 300?for 10 minutes.It is found that CuS and Cu₇S₄ have the best electrical performance at 250?,and the square resistance is the lowest among the three annealing temperatures,which are 3.39?/sq and 4.52?/sq,respectively,and reach the highest cell efficiency of 3.62%and 3.24%,respectively.The electrical performance of Cu₂S is relatively good at the annealing temperature of 300?.The sheet resistance is 7.69?/sq,the lowest value of the three temperatures,which achieves a cell efficiency of 2.72%.The Cu S thin film is relatively efficient as a counter-electrode of DSSC.This is mainly due to its large number of holes,which is equivalent to a large number of carriers,semi-metallicity,high conductivity,and low internal resistance of the cell.Secondly,its own flower-like structure allows it to have a larger specific surface area,which can provide more active sites,which is conducive to catalytic reduction of electrolytes and improve battery performance.