Synthesis And Photocatalytic Performance Of CdS/CoS₂ Nanomaterials

With the increase of population and the continuous development of industry and agriculture,the increase of organic pollutants in water sources has seriously threatened the ecological security of human beings.Most of the current water treatment methods are difficult and inefficient,and cannot completely solve the pollution problem.Photocatalytic technology has become a promising alternative to the degradation of many organic pollutants.CdS semiconductors are visible light-driven photocatalysts with narrow band gaps,which have attracted widespread interest.However,the low utilization of visible light,rapid charge recombination,and low photogenerated electrons and hole migration capabilities restrict its application.Therefore,combining CdS with cobalt disulfide frame st ructure with well-matched energy band structure can not only increase the reactive active sites and improve the aggregation state of CdS,but also inhibit the recombination of electron holes through heterostructure to enhance the photocatalytic degradation performance.In response to the above problems,the main research content of this paper is divided into the following two aspects:（1）The cobalt disulfide nanomaterials with layered double-shell hollow structure were successfully synthesized by hydrothermal synthesis using ZIF-67precursor.The cubic structure with uniform particle size of about 600 nm and regular morphology was obtained by adjusting reaction conditions.Subsequently,CdS/CoS₂ composite material was successfully synthesized by hydrothermal method.A series of characterization methods confirmed the successful synthesis of CdS/CoS₂,and then explored the influence of CoS₂on the properties of CdS.CdS/CoS₂showed enhanced light absorption and larger specific surface area.The results show that the CoS₂ frame structure can effectively improve the specific surface area of CdS,increase the light response capacity and slow down the composite of photoelectric charge and hole.（2）Furthermore,the catalytic and photoelectric properties of a series of CdS/CoS₂-2 were characterized.Using methyl orange as indicator,the photocatalytic degradation of CdS/CoS₂-2 was studied.The results showed that CdS/CoS₂-2 exhibited the best photocatalytic degradation efficiency.The degradation efficiency of CdS/CoS₂-2 was 94%under 60 min visible light irradiation,and the photocurrent response was the best with the photocurrent difference of 30μA.The rate constant K(0.04985 min^-1)is about three times that of CdS(0.01645 min^-1),and the degradation efficiency can still reach 87.8%after five cycles.Then the effect of p H on the photocatalytic activity is studied.It was found that CdS/CoS₂-2 could maintain a high degradation rate of Mo in the range of p H=5-11,and the degradation effect was better under acidic conditions than that under alkaline conditions.The degradation efficiency and degradation rate of 0.09734min^-1 could reach 99%at p H=5.The CdS/CoS₂-2 sample also showed strong catalytic performance for Rh B,MB and 4-NP,and the degradation effect on simulated wastewater indicated that CdS/CoS₂-2 had a good practical application prospect.