Study On Preparation,Properties And Mechanism Of Plasma Metal/Semiconductor Core-Shell Heterogeneous Structure Photocatalyst

Semiconductor and plasma metal heterostructure materials have become one of the most popular materials in photocatalysis field,which attributes to its excellent optical absorption characteristics and high electron mobility.However,the mechanism between noble metals and semiconductors is still unclear,which hinders the construction of highly efficient heterogeneous materials.Therefore,it is of great theoretical and practical significance to explore the structure-function relationship of these composites to enrich the scientific basis of photocatalysis and favor the designing and development of efficient photocatalyst.In this paper,we chose the representative band gap semiconductor--zinc oxide,combined with one of the common plasma metal--gold nanoparticles,to construct a core-shell heterogeneous structure:gold nanoparticles as the "nuclear" and zinc oxide as "shell".Thus,we performed studies as follows:(1)We prepared spherical and rod-like gold nanoparticles,wrapped them with ZnO,and characterized the structure and element composition of these two core-shell materials by using XRD,TEM and XPS methods,after that we explored the phtocatalytic reactivity difference between these two morphology.(2)We successfully synthesized clear structured Au rod @ZnO with different shell thickness which was nicely dispersed.Based on its activity in photocatalytic reduction of carbon dioxide and the characteristic results of electrochemistry tests,ESR,etc,we explored the relationship between activity and these two components.In this paper,the following results and conclusions were summarized as follows:(1)The Au@ZnO material was first been utilized in photocatalitic CO2 reduction.It was found that the presence of two "tips" in Au nanorod produced a stronger plasma resonance effect,so that catalysts encapsulated with Au nanorods possessed a superior activity to with Au spheres.(2)The effects of HMT and Au nanorods5 aspect ratio on successful packaging were firstly investigated.Through the comparison of the activity,it was revealed that the hot electrons excited from Au nanorods could transfer to the ZnO surface,which increased the electron mobility,and along with the strong synergistic effect between zinc oxide and gold nanoparticles,the photocatalytic reduction activity could be strongly enhanced.(3)It was shown for the first time that ZnO shell is an important factor for CO production in the case of core-shell structure,and Au nucleus plays a decisive role in the production of CH4.The thickness of ZnO shell was not necessarily linked to CO and CH4 yields in this system.Our experimental results explored the strong synergistic effect between zinc oxide and gold nanoparticles in the case of core-shell structure,which had a certain reference significance for deeper understanding of photocatalysis mechanism.It provided an important guiding significance for designing effective plasma metal-semiconductor heterostructure materials in the future as well.