Study On Preparation And Modification Of Cadmium Sulfide Photocatalysts

Environmental pollution and energy shortage are two key factors restricting thedevelopment of today’s society. The hydrogen attracted much attention due to itsadvantages such as renewable, wide source, and the advantages of clean. Comparedwith the traditional electrolysis of water, the use of catalytic decomposition of waterin rich solar energy for making hydrogen is a kind of strategy with a broadapplication prospect. Since the report of photocatalytic decomposition of water in1972, a large number of semiconductor photocatalyst were developed, however,only a few of them can respond to visible light. Among them, the metal sulfidesemiconductor especially CdS has received the widespread attention because of itsnarrow band gap, can respond to visible light, and the advantages of high catalyticactivity. Therefore, CdS was taken as the research subject in this work, in thepreparation of excellent photocatalyst with visible light response and high catalyticefficiency.In this work， Bi2S3/CdS composite photocatalyst and highly active, highstability of CdS photocatalysts have been prepared by means of ultrasonic assistedmethod and Sodium hydroxide assisted method respectively. The systematicresearch has been carried out on the crystal structure, microstructure, light livingcarrier of separation condition’s influence on the catalytic performance of catalysts.Bi2S3/CdS composite photocatalyst wasprepared by ultrasonic assisted method atroom temperature with high BET specific surface area of96m2/g. Results fromFESEM and TEM test showed that the photocatalyst has morphology ofmicrospheres composed of microcrystalline. The individual phases of Bi2S3andCdS can be observed obviously in HRTEM image. Gas chromatography-massspectrometric (GC-MS) is employed in the qualitative determination of the organiccompounds in reaction solution to clarify the possible formation mechanism of thephotocatalyst during the ultrasonic preparation process. PL test found thatphotogenerated charge carriers were effectively separated in Bi2S3and CdSheterostructure. In an optimal situation, Bi2S3/CdS (x=0.15) showed the highestphotocatalytic hydrogen evolution rate of5.5mmol·h-1·g-1, supposed to be a kind ofphotocatalytic materials with potential application.CdS with high photocatalytic efficiency and stability was prepared via NaOHassisted method. The as-prepared was determined to be hexagonal phase by XRD. The photocatalysts was found to be bulk wich is the aggregation of nanoparticlesfrom FESEM and TEM tests. The optimized synthetic condition was determined assodium hydroxide inventory for the mole ratio of1:1, reaction temperature300℃,reaction time is4h. Optimizing the reaction parameters in the process of catalyticreaction, the optimized catalytic conditions for the catalyst dosage is0.015g,sacrifice agent concentration of Na2S1.0mol/L, Na2SO30.6mol/L. Theas-prepared CdS showed a high stability in the long-time photocatalytic hydrogenevolution from water-splitting and the highest performance was found to be7.1mmol·h-1...