Study On The Preparation Of Zn-Cd-S Porous Material System And Its Photocatalytic Water Splitting Performance

The solar photocatalytic conversion of water into hydrogen is one of the most important pathways to solve the ever-increasing energy crisis.Therefore,the design of high-performance photocatalyst becomes especially vital.In order to improve the utilization efficiency of the visible light,the sulfide semiconductor heterostructures and phase junction were selected for the water splitting photocatalysts.We explore effective methods to achieve the control of the morphology and semiconductor configurations of the sulfide semiconductor heterojunction,and the fabrication of the high-performance phase junction.Besides,ZnO,acting as cocatalyst,was embedded into sulfide heterojunction,and the existence of ZnO facilitate the transport of charge carriers and the utilization efficiency of the sulfide semiconductor heterojunction.The design and the property optimization of sulfide semiconductor heterojuction in this paper offer us an opportunity to pursue effective and stable solar conversion materials.The details of the dissertation are summarized as follows:1.Various ternary ZnS-CdS-Zn1-xCdxS heterostructures were synthesized with tunable morphology(0D-2D)and semiconductor configurations(randomly distributed,interface mediated,and CdS sensitized core-shell structure)via one-pot hydrothermal method for the first time.And the CdS sensitized porous Zm1-xCdxS@ZnS core@shell takes the advantages of ZnS,Zn1-xCdxS and CdS,and shows the maximal photocatalytic H2-production rate of 100.2 mmol/h/g and excellent stability over 30 h.2.The morphology of the sulfide heterojunction were controlled by the varied particle size of the precursors,and the photocatalysts with the smallest particle size shows the most exposed active sites and the optimal photocatalytic performance of 22.99 mmol/h/g.Moreover,the in-situ formation of ZnO cocatalyst on the Zn1-xCdxS/CdS heterojuction was achieved by a facile one-pot method.The ZnO nanocrystal,serving as cocatalyst,could effectively separate the charge carriers,and the oxygen vacancies in ZnO could act as H2-production sites.Consequently,the ZnO-embedded Zn1-xCdxS/CdS heterojuction shows tremendous enhancement on the photocatalytic activity in Na2S+Na2SO3 solution(84.17 mmol/h/g)and methanol solution.Notably,the ZnO-embedded Zn1-xCdxS/CdS shows distinct photocatalytic H2-production of 0.18 mmol/h/g even in the absence of sacrificial agent.3.When used as the photocatalyst,CdS suffers from the disadvantages including poor photocatalytic activity and limited lifetime.In this paper,for the first time,we afforded a facile yet effective strategy to improve the photocatalytic activity and stability of CdS via fabricating its hexagonal/cubic core/ultrathin shell phase junction through modulating the thermodynamically and kinetically parameters in one-pot hydrothermal process.The thickness of the cubic CdS shell of nanometer scale was facilely controlled by reaction time.The optimal core/shell phase junction with a shell thickness of 2.4 nm displays an extremely high photocatalytic activity of 742.5 ?mol/h.More significantly,it can keep stable over a period of 400 h.Notably,even in the aerobic environment,it still remains the stability over 100 h and excellent photocatalytic activity(109 times higher than that of the same CdS in the vacuum condition).