The Study Of Noble Metal-based Nanoclusters And Surface/interface Structures By The First-principles Theory

The demand for fossil fuels around the world has increased dramatically,and the desire for efficient energy use has become more and more urgent.It has become an urgent need to find suitable catalysts for chemical reactions.Due to that they can combine the advantages of the two components,alloy nanoclusters and core-shell nanoclusters have gained more attention,otherwise,the structure is more stable.Whether as a chemical reaction catalyst or other structural functional materials,the stability and anti-toxicity of nanostructures are both critical factors.Under the premise of high catalytic activity,adapting to the complex reaction environment of chemical reaction and preventing the toxic effects of various intermediate products has become the main research direction of experimental inquiry and computational simulation.Traditional chemical reaction catalysts use multi-loaded noble metal catalysts,even pure noble metal materials,which have high manufacturing costs.The innovative catalyst materials reduce the catalyst manufacturing cost by alloying non-noble metals with noble metals,at the same time,the stability and anti-toxicity of the catalyst are improved.The cathode catalyst of the oxyhydrogen fuel cell controls the difficult degree of the reaction and the utilization of energy.Currently,commercialized and most efficient catalytic material is a Pt nanoparticle attached to an amorphous high specific surface area carbon(C).Due to the scarcity of Pt content and expensive price,whether it can improve catalytic activity under the premise of reducing Pt content,has become the research direction of fuel cell cathode catalyst.The core-shell structure formed by the main group metal/transition metal and Pt atoms have become the most promising alternative materials for pure Pt catalysts due to their unique stability and high catalytic activity.Experiments and calculations have show that the W element and the Pt element can form a stable alloy compound.In this paper,we studied the structural stability and catalytic activity of W13@Pt42 structure,and explored the working mechanism of its catalytic Oxidation Reduction Reaction(ORR).Excellent magnetic nanoparticles have a wide range of applications in medicine and biology.Due to the large magnetic moment of Fe and Co atoms,the Fe@FeCo core-shell structure naturally becomes a good magnetic nanoparticle.As these characteristics,magnetic nanoparticles are used in drug carriers,cell separation and purification,magnetoelectric transfection and hyperthermia of malignant tumors.However,the oxygen-rich environment of medical applications could cause oxidized of outer layer Fe and Co atoms,which limiting its use.Ensure that the magnetic moment of the nanoparticles is not destroyed,and non-toxic,harmless and biocompatible are ensured,which becomes the basic requirement of medical magnetic materials.The former study have shown that coated the Fe@FeCo core-shell structure with Au layer could stable core-shell structure and improve resistance oxidative.On the other hand,covered Fe@FeCo core-shell with Au atoms could protect the magnetic moment of the Fe@FeCo core-shell structure while enhancing the optical properties of the core-shell structure.In this paper,the comparison between the bonding strength of Fe@FeCo and Fe@FeCo@Au nanoparticles with O2 molecule and the change of magnetic moment after oxidation prove that the Au layer covers the Fe@FeCo core-shell structure is an ideal choice.With the rapid development of the automotive industry and industrial manufacturing,the treatment of automobile exhaust and industrial exhaust has become an urgent problem to be solved.Taking CO as an example,which is the mainly composition of exhaust gas,the best way to deal with CO is to oxidize CO to non-toxic and harmless CO2 and other non-toxic and harmless organic substances.Among most catalysts,the core-shell structure of noble metal@semiconductor(such as Au@ZnO)exhibits excellent catalytic activity.The ZnO cage structure wrap the structure of the Au cluster core,which can further promote the catalytic ability of the ZnO structure,and the Au atom cluster of the core plays a good role for structural support,which ensures the structural stability of the catalyst.After obtaining a stable Au@ZnO core-shell structure,as a catalyst the catalytic activity CO oxidation reaction was calculated and analysed.In general,the surface/interface structure can also be used as a good catalyst material.As a control,we also calculated the reaction process of the Au/ZnO interface structure as a reaction for the CO oxidation reaction.Due to the special band structure of ZnO materials,it has always been the focus of research in the field of photocatalysis.Meanwhile,the structure of caged ZnO-coated Au clusters also has excellent optical properties.After the catalytic activity of core-shell structure and Au/ZnO interface structure are calculated,their optical properties were further calculated.The calculations show that the Au@ZnO core-shell structure has a strong absorption in the visible region,which greatly expands its application in photocatalytic reactions.Similarly,the optical band gap of ZnO can be modified by constructing the Au/ZnO interface structure while promoting absorption of visible light.The calculations show that the Au/ZnO interface structure exhibits different absorption intensity to the visible region with the changes of the Au and ZnO layers thickness.