| The limited optical response range and the fast recombination of photogenerated electron-hole pairs of traditional semiconductor materials hinder the further utilization of solar energy.Hollow structure semiconductor may enhance light absorption and multi-component semiconductor-based composites can increase the contact between components,promote charge transfer and enrich the active sites.Therefore,semiconductor composites with multi-components and multi-level hollow structure are considered to have the potential for highly active photocatalysis.Based on the above considerations,a Ti O2-bimetallic sulfide composite with a double-shell hollow structure was synthesized by a simple two-step templating method in this thesis,and the influence of the morphology and composition of the composites on the activity of hydrogen production by photocatalytic water splitting was investigated.The main research contents and findings include:（1）Ti O2hollow nanospheres（Ti O2HNPs）were synthesized by using polystyrene（PS）spheres as sacrificial template.A bimetallic zeolite imidazole frame（Zn Co-ZIF）was grown on the outer layer,which was then used as the precursor and template for further sulfidation.Finally,the zinc-cobalt sulfide（Zn Co S）hollow particles were stacked on the outer layer of the Ti O2HNPs.The results of XRD,XPS and SEM/TEM analysis results show that the Zn Co-ZIF grown in situ and Zn Co S particles are uniformly covered on the outer layer of Ti O2,which have no significant influence on the morphology,size and phase of Ti O2HNPs.（2）The Ti O2@ZnxCo0.625-xS composites with different Zn/Co ratios were prepared by adjusting the molar ratio of Zn/Co.In addition,in order to prove the influence of the structure and composition of the materials synthesized by the two-step templating method on the photocatalytic reaction,Ti O2@Zn Co S-s obtained Zn Co-ZIF derived Zn Co S without using the Zn Co-ZIF template were also prepared.The morphology and composition of the related materials were characterized by XRD,XPS,SEM/TEM,etc.By comparing the results of SEM/TEM and BET tests of Ti O2@ZnxCo0.625-xS,it is demostrated that only Zn S phase was formed in the absence of cobalt salt.However,with an increase in the Co component,the hollow Zn Co S particles are gradually formed on the outer layer.The higher the Co content,the higher the BET specific surface area and pore volume of the composites.Moreover,the cavity of Zn Co S hollow polyhedron is also larger.XPS results show that there is a strong interaction between Ti O2HNPs and Zn Co S hollow particles.（3）Through a series of photoelectrochemical techniques,it is further verified that Ti O2@Zn Co S composite materials can enhance the light-response range and utilization of photons,promote the separation and transfer of photogenerated electrons and holes,and enhance the photocatalytic activity of the material.Under the irradiation of Xe lamp,the optimal hydrogen production rate of the double-shell hollow Ti O2@Zn0.325Co0.325S composite reached 24.2 mmol h-1g-1.After 25 hours of 5 successive runs,it still maintained more than95%of the initial activity,showing good stability and recoverability. |
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