Controllable Preparation And Visible Light Photocatalytic Performance Of MxS(M=Ag,Cu,Zn)/CA Composites

With the environmental pollution problem and the global energy crisis becoming increasingly severe,how to use solar energy efficiently and develop a photocatalyst with low-cost visible light response has become a research hotspot in the field of photocatalysis.Metal sulfide photocatalyst materials have narrow band gaps,moderate energy band positions,and good visible light response,which have attracted wide attention of researchers.However,single-component metal sulfides still have some drawbacks,including well-known photo-etching,low charge-separation efficiency,and the tendency for the particles to aggregate during the synthesis process.Biomass-based aerogels have a three-dimensional network porous structure that can disperse sulfide semiconductor photocatalysts and form good interface contact,which is beneficial to charge transfer and separation.In this paper,biomass carbon aerogels were used as the carrier materials to construct the biomass carbon-based metal sulfide aerogel composite material by loading three kinds of metal sulfide.The photocatalytic activity was studied,and the possible photocatalytic mechanism was further discussed.1.A novel high-performance Ag₂S/CA photocatalytic composite material which was synthesized via a facile hydrothermal treatment,and in situ growth method,followed by a vacuum freeze-drying process.The structural properties,morphologies,optical,surface chemistry,electronic properties and photocatalytic performance of the composite materials were investigated through varying the different amount of Ag₂S.Then Ag₂S/CA composites were applied for the photodegradation of the methylene blue?MB?and ciprofloxacin?CIP?wastewater.As a result,the optimum photocatalytic performance of 55%Ag₂S/CA exhibited excellent photocatalytic efficiency for MB degradation,which was about 2.8 times higher than that of pure Ag₂S.This improved photocatalytic performance could be mainly attributed by unique 3D catenulate carbon networks,which can be highly favorable to disperse of Ag₂S on the surface of CA.According to the ESR analysis,it can be inferred that the·OH and·O₂^-radicals are the main active species for the photodegradation process.2.Carbon-based wet gels were synthesized by low-temperature carbonization,and then Cu S/CA composite photocatalysts were prepared by a simple precipitation method.The prepared composite photocatalyst was analyzed by its morphological characteristics,structure and electro-optic properties.It was found that CuS/CA composites with a loading of 35 wt%exhibited higher photocatalytic activity than pure CuS,and the reaction rate constant k was 0.00912 min^-1,about 4.7 times that of pure Cu S.The improvement of the photocatalytic properties of composite materials can be attributed to the three-dimensional porous structure of biomass carbon-based aerogels,which allows CuS nanoparticles to disperse well and form close interface contacts,which contributes to the rapid generation of photogenerated charge carriers.Separation and transport,and avoid photo-etching of sulfides during photocatalytic reactions.At the same time,the combined action of superoxide radical and hydroxyl radical active species has become a key factor in improving photocatalytic performance.3.Novel hollow sphere morphologied zinc sulphide@carbonaceous aerogel?ZnS@CA?composites with different ZnS content were fabricated using a simple hydrothermal carbonization treatment following by a facile in situ growth method.The fabricated composites were used as catalysts for chemical degradation of the methylene blue?MB?and for hydrogen evolution.Our photocatalytic studies are found,from the photocatalytic results obtained by different ZnS@CA materials,that 55 wt%ZnS@CA exhibits the excellent photocatalytic performances for MB degradation and the highest rate of hydrogen production that are correspondingly 1.7-fold and 8.1-fold higher than that of pure Zn S.The hollow microsphere structured ZnS nanoparticles allow multi-reflections of light within the interior cavity and increases the capture efficiency of visible light.A possible photocatalytic mechanism of the main active radicals?·OH and·O₂^-?has also been proposed.