| Development of industrialization results in global environmental pollution and energy crisis,which seriously hinder further development of the society and economy.Photocatalytic technology is considered as one of the most effective methods to solve the above-mentioned problems,and thus,designed synthesis of efficient photocatalytic materials has attracted more and more attention.Especially,semiconductor materials that can utilize solar energy have been intensively investigated as promising photocatalysts.Among all kinds of semiconductors,TiO2 is undoubtedly the most widely used photocatalyst in the past decades owing to its non-toxicity,low cost,relatively high chemical stability,strong oxidizing power and bio-compatibility.Unfortunately,its wide band gap(3.2 eV)makes it only respond to the UV light(less than 7% of the solar spectrum).Therefore,it is essential to study other semiconductors with high utilization of solar energy and chemical stability.Recently,SnS2 has attracted increasingly more attention thanks to its narrow band gap(2.2e V),allowing the absorption of the visible light more efficiently.However,fast electron-hole recombination in Sn S2 can weaken the catalytic activity.According to the previous literature,noble metal nanocrystals,such as Au,Pt,Ag,have proved to be able to enhance the photocatalytic activity of semiconductors.The metal nanoparticles on the surface of the semiconductors can improve the absorption of light and promote the separation of electrons and holes.In this paper the SnS2 nanosheets were prepared by hydrothermal method.And the precursor Ag2S-Sn S2 was synthesized by cation exchange method,while controlling the reaction temperature,solvent type.By controlling the type of reducing agent and the type of inducer,Ag-Sn S2 nano-composites were prepared to control Ag nanoparticles' distribution on the surface of SnS2.At the same time,controlling the reduction reaction time in the process of in-situ reduction,could synthesize ternary complex Ag-Ag2S-Sn S2.The surface morphology was observed mainly by means of SEM and TEM,with its crystal shape was characterized by XRD and UV-Vis spectroscopy confirms the absorption intensity of the sample preliminarily.All the samples were explored their photocatalysis including photocatalytic degradation of MB and photocatalytic water splitting for hydrogenpreparation.In the study of photocatalytic,it found that in the process of Ag-Sn S2 photodegradation of methylene blue and water splitting for hydrogen preparation,the electron come form the surface plasma resonance of Ag nanoparticles under the light was transfered to the SnS2 vacancy band,which hindered the recombination of electrons and holes.Thus,Ag nanoparticles has enhanced the Sn S2 photocatalysis ability.While in the process of Ag-Ag2S-Sn S2 photodegradation of methylene blue and water splitting for hydrogen preparation,the electron come form Sn S2 and the hole come from Ag2 S were transfered to Ag and translated into heat energy.And the hole of SnS2 and the electron of Ag2 S are difficult to recombine,due to the bigger band gap,which improve the photocatalytic of Sn S2.According to the experiment,we can conclude that ?OH and ·O2-are the main active species in the degradation of MB under visible light irradiation.While it was the electron that react with H+ and generate H2. |
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