Pt Nanoprticles Encapsulated Into Graphene:Preparation And Catalytic Application

Carbon nanomaterials sush as carbon nanotubes?CNTs?and graphene?GO?are widely used in catalysis,materials,energy and other fields due to their unique hollow tubular structure,two-dimensional structure and special physical and chemical properties.In recent years,the catalytic performance of metal nanoparticles in carbon nanotubes and graphene confinement systems has attracted wide attention at home and abroad.However,how to quickly and efficiently encapsulate a few layers of graphene on the surface of metal nanoparticles remains a challenging issue.In this paper,a simple and efficient method was developed to encapsulate graphene and nitrogen-doped graphene on Pt nanoparticles supported on carbon nanoparticles and graphene oxide?Pt/CNTs,Pt/GO?,and then prepare Pt-based catalysts?CN@Pt/CNTs and C@Pt/GO?encapsulated with few layers of graphene.At the same time,the selective hydrogenation of phenylacetylene and the low-temperature oxidation of CO with CN@Pt/CNTs and C@Pt/GO catalysts were systematically studied.It was found that the confined environment constructed by nanographene contributed to the desorption of reactant molecules on the surface of Pt nanoparticles,which could significantly enhance the activity and selectivity of phenylacetylene hydrogenation and the activity of CO low temperature oxidation.The main research includes the following three aspects:?1?A simple and efficient wet chemical reduction method was developed to prepare Pt nanoparticles catalytic materials supported on CNTs?Pt/CNTs?and graphene?Pt/GO?.Using CNTs and GO as carriers,chloroplatinic acid?H₂PtCl₆.6H₂O?as metal precursor and ethylene glycol?C₂H₆O₂?as reducing agent,Pt/CNTs and Pt/GO were prepared at 130?.Using ethanol?C₂H₅OH?and acetonitrile?C₂H₃N?as carbon sources,graphene and nitrogen-doped graphene were encapsulated on Pt-NPs by chemical vapor deposition at 750??CN@Pt/CNTs,C@Pt/GO and CN@Pt/GO?.The morphology,structure and elements were characterized by TEM,HRTEM,XRD and XPS.The results show that Pt/CNTs and Pt/GO nano catalytic materials are highly dispersed on the surfaces of CNTs and GO.Pt nanoparticles were coated with 2-4layers of graphene and nitrogen-doped graphene.?2?The catalytic performance and stability of Pt nano catalytic materials supported on CNTs for selective hydrogenation of phenylacetylene were systematically studied.The catalytic performance and stability of selective hydrogenation of phenylacetylene of Pt/CNTs prepared by wet chemical reduction and CN@Pt/CNTs prepared by chemical vapor deposition of were investigated.The results show that CN@Pt/CNTs>Pt/CNTs.The main reasons are:Pt-NPs are uniform in size and highly dispersed on CNTs.Density functional theory calculations show that the confinement environment of nitrogen-doped graphene leads to high styrene selectivity of CN@Pt/CNTs.Nitrogen-doped graphene can promote the desorption of styrene from the surface of Pt Nanoparticles and avoid excessive hydrogenation of styrene to styrene ethane.?3?The low temperature oxidation performance and stability of platinum-based catalytic materials supported on GO for CO were systematically studied.The catalytic properties and stability of low temperature CO oxidation of Pt/GO prepared by wet chemical reduction and C@Pt/GO and CN@Pt/GO prepared by chemical vapor deposition were investigated.The results show that:CN@Pt/GO>C@Pt/GO>Pt/GO.The main reasons are as follows:Pt-NPs are highly dispersed on the surface of GO,and the confined environments formed by a few layers of graphene and nitrogen-doped graphene on the surface of Pt-NPs contribute to the desorption of CO molecules,thus improving the low-temperature catalytic performance of C@Pt/GO and CN@Pt/GO catalysts.The electronic interaction between Pt-NPs and nitrogen-doped graphene enhances the electronic density of supported Pt-NPs,enhances CO desorption and promotes the low-temperature catalytic performance of CN@Pt/GO.