Synthesis And Heterogeneous Catalytic Properties Of Thiolate-Protected Copper Clusters

Identification of catalytic active sites is crucial for uncovering the reaction mechanism involved in the catalytic process.To acquire an in-depth understanding of the active sites in the catalytic process,it is essential to obtain well-defined catalysts.The advent of atomically accurate metal nanoclusters offers new opportunities to unlock the mysteries of the catalytic mechanism.Benefited from explicit chemical composition and structure of nanoclusters,which helps us to study the relationship between cluster size,structure,and catalytic activity,and provides a strong guarantee for the identification of active sites on the surface of the catalyst.Recently,gold nanoclusters have been gained extensive attention in catalytic area,due to the high stability and catalytic activity.However,most of the catalysts reported to date are noble nanoclusters,which restricts their large-scale application.Copper is abundant and cheap,and copper nanoclusters-based catalysts are also seen as promising catalytic materials.Therefore,the research direction of this paper focuses on the synthesis of copper nanoclusters and their catalytic mechanism at the atomic level.The specific research contents and results are as follows:1.We reported a 54-nuclei copper nanocluster,[Cu54S13O6(tBuS)20(tBuSO3)i2](Cu54),which is the largest Cu(Ⅰ)/Cu(Ⅱ)mix-valent cluster reported up to date.Collective techniques including near edge X-ray absorption fine structure,singlecrystal X-ray diffraction,and high-resolution ESI-TOF-MS confirmed the atom-precise structure of Cu54 and verified the mixed-valence of Cu(Ⅰ)/Cu(Ⅱ)with a ratio of 16:38.For further understand the influence of the electronic and geometric structure of the Cu(Ⅰ)/Cu(Ⅱ)mixed-valence copper clusters on the properties,Cu54 was deposited on TiO2 to prepare the catalyst for the study of phenol photodegradation.The Cu54 nanocluster supported by TiO2 exhibits decent photocatalytic activity for phenol degradation under visible light.Cu54 acted as a co-catalyst and a phototrapping device in the photocatalytic process,which made Cu54/TiO2 catalyst exhibits good photocatalytic activity and stability in the degradation of phenol.2.We synthesized three identical size copper clusters,Cu8(H)(L1)6PF6,Cu8(tBuS)4(L1)4,Cu8(tBuS)4(L2)4,(Cu8-1,2,3,L1=9H-carbazole-9-carbodithioate,L2=O-ethyl carbonodithioate).Isostructural copper clusters with the same size but different surface structures and atomic morphology provide us a platform to reveal the relationship between structure and catalytic performance at the atomic level.According to the arrangement of kernel copper atoms,these clusters can be divided into two categories:(1)Cu8-1 belongs to Cu8 cube;(2)Cu8-2,3 belongs to Cu8 ditetrahedron.Therefore,this work investigates two kinds of copper clusters with same size as electrocatalysts for CO2 reduction.Interestingly,Cu8 ditetrahedral configuration showed higher activity and selectivity of CO2 reduction than the cube,which suggest that the properties of clusters are closely related to the number and structure of metal atoms.The UV-vis spectra showed that the main absorption peaks of the clusters were no significant change before and after the catalysis,indicating that the copper clusters maintained excellent stability during the catalytic process.