Preparation And Photocatalytic Performance Of PtSe₂/FTO And MoS₂/PtSe₂/FTO Thin Films

In recent years,semiconductor photocatalysis technology has been gradually applied in the fields of solar energy conversion and environmental purification.However,its industrial application the has seriously hindered due to the wide band gap of the traditional semiconductor photocatalyst and low separation efficiency of photogenerated carrers.Therefore,exploring efficient and stable photocatalysts has become a challenge for renewable new energy utilization.Transition metal dichalcogenides(TMDs)are considered to be the most promising due to their excellent catalytic activity,abundant active sites,ideal electrical conductivity,good photo-corrosion resistance and low cost.A great deal of work has been focused to loading TMDs as cocatalysts on photocatalysts to promote the transport of photogenerated carrers.This thesis aims to develop efficient and stable cocatalysts to solve the problem of slow charge transfer in semiconductor photocatalysts and hence design a photocatalytic system for potential applications.The specific research contents are briefly summarized as follows:(1)In this paper,a series of PtSe2/FTO films were synthesized by vacuum evaporation and chemical vapor deposition(CVD),and the thickness of PtSe2 films was optimized.We found that the optimized PtSe2/FTO film has excellent HER rate(506 mmol h-1 m-2),much higher than FTO and PtSe2/Si films,and 7 times higher than Pt/FTO film(68 mmol h-1 m-2).The PtSe2/FTO films can stably run 15 photocatalytic hydrogen production cycles,and show no obvious decline in HER rate after storage for one year.Electron/spectral characterization demonstrate that PtSe2 with ultra-high electron mobility can facilitate the separation of the photogenerated electrons and holes of SnO2,provide a large number of active sites for photocatalytic reaction,and consequently improve the photocatalytic performance.(2)Based on the first research work,a series of MoS2/PtSe2/FTO(MP-F)films were synthesized by the same process.Under the synergistic effect of PtSe2 and MoS2,the separation efficiency of the holes and electrons is improved.By optimizing growth time of MoS2,the MP-F film is found to have a higher HER rate(1560 mmol h-1 m-2),than PtSe2/FTO and MoS2/FTO films.Moreover,the MP-F/40 film shows no obvious decay in HER rate during 100 h continual photocatalytic HER experient.(3)The PL,PEC,work function,XPS measurements shows that in the photocatalytic process,the photogenerated electrons 'in the SnO2 conduction band(CB)are rapidly transferred to PtSe2,which effectively facilitates the charge separation and inhibits the recombination of photogenerated charges in SnO2,thereby improving its photocatalytic performance.Compared with PtSe2/FTO,PtSe2 in MP-F acts as an electron transport medium,enabling photogenerated electrons by SnO2 to be rapidly transferred to MoS2 for photocatalytic reaction.