Preparation Of CdS-based Nanocomposite Materials For Photoelectrocatalytic Applications

Photoelectrocatalytic hydrogen production using semiconductor is a novel green and sustainable technology for converting solar energy to chemical energy.As a classical II-VI semiconductor material,CdS has been regarded as a fascinating photocatalysts for solar water splitting due to its desired band gap(2.4 eV)and proper band edge.However,the photocatalytic activity of CdS is still restricted by high-rate photoinduced electron-hole pairs recombination and serious photocorrosion.Therefore,the appropriate modification of CdS to effectively enhance its photocatalytic activity has been widely concerned.In this paper,the photoelectrocatalytic performance of CdS was studied systematically by loading suitable cocatalysts and building heterojunction with other semiconductors.Concrete research contents are as follows:(1)ZnO/CdS/Au nanotube array composites using ZnO nanorods as template were prepared by electrodeposition method,chemical bath deposition method and simple reduction reaction.Au nanoparticles can serve as photosensitizers and enhance photoabsorption efficiency.Meanwhile,Au nanoparticles also can generate more hot electrons and then inject them to the conduction band of adjacent CdS,which enables the extended carrier density of composites.The hollow ZnO nanotube array structure can provide fast transfer channels for the photogenerated electrons of CdS and reduce the recombination of photogenerated carriers.The ZnO/CdS/Au nanotube array composites exhibited significantly improved photoelectrochemical performance due to the synergistic effect of the local plasmon resonance effect of Au nanoparticles and the specific nanotube array structure.(2)ZnO/CdS/BiOI nanorod array composites were prepared by electrodeposition,chemical bath deposition and solvothermal method.The introduction of BiOI can form p-n heterojunction with CdS to achieve rapid separation of photogenerated electron-hole pairs.Meanwhile,the narrow band gap BiOI can not only enhance the photoresponse range,but also improve the light absorption ability of the composites.Particularly,the BiOI nanosheets grown on the surface of CdS are interconnected to form a network,which can effectively expand the reaction area of composites and provide more reaction sites,thus resulting in superior photoelectrochemical performance.(3)A dual-cocatalysts CdS-based NiS/CDs/CdS composite photocatalyst was successfully prepared by simple hydrothermal method and chemical precipitation method.The NiS/CDs/CdS composite photocatalyst shows significantly enhanced photocatalytic hydrogen production activity,which is 5.38 times that of single CdS.The positive synergy between NiS and CDs in the composite photocatalyst favors the improvement of photocatalytic performance.Among them,the introduction of CDs can retard the recombination of photoelectron-hole pairs and enhance light absorption;The p-n heterojunction formed between NiS and CdS can greatly promote the effective separation of photogenerated carriers;The loaded NiS film can act as active sites of oxidation reaction and quickly consume the photogenerated holes generated by CdS,thereby further inhibiting the recombination of photogenerated electron-hole pairs.