Novel Pt/Graphene Nanocomposites:Preparation And Catalytic Application

As a new type of carbon nanomaterials,Graphene has become a research hotspot in the fields of catalysis,energy,and sensors due to its unique two dimensional structure and physical and chemical properties.In recent years,through the use of graphene as a carrier of catalysts,metal nanoparticles have been uniformly assembled on the surface of graphene.The indepth study of the interaction between graphene carriers and metal nanoparticles and their impact on catalytic performance have attracted widespread attention.However,how to uniformly load metal nanoparticles on the graphene surface and controllably adjust the interaction between the metal nanoparticles and the graphene carrier is still a challenging issue.This research paper starts from the idea of efficient and green preparation design.First,platinum nanoparticles are evenly loaded on the surface of graphene,and then the subsequent controllable assembly of metal/graphene nanocomposites is mainly through two ways.One way is to use a simple chemical vapor deposition（CVD）method to coat the surface of platinum nanoparticles（Pt-NPs）with a small amount of nitrogen-doped graphene layer,through a small layer of nitrogen-doped graphene on the surface of platinum nanoparticles.The confinement effect enhances the stability of platinum nanoparticles;another way is to use high-temperature controlled water etching method,using platinum nanoparticles to catalyze the reaction of water molecules with carbon atoms on the surface of graphene,on the flat graphene carrier surface digging pits,and then embedding platinum nanoparticles into the pits on the graphene surface,and systematically studying the selective hydrogenation of phenylacetylene and the dehydrogenation of n-butane on the prepared new platinum/graphene nanocomposites.The main research includes the following aspects:（1）In this paper,the wet chemical reduction method is used to load Pt nanoparticles on the surface of graphene to prepare graphene-loaded Pt nanocomposites（Pt/GO）.The carrier of the catalyst is GO,the metal precursor is chloroplatinic acid（H₂PtCl₆·6H₂O）,the reducing agent is ethylene glycol（C₂H₆O₂）,and Pt/GO has been developed under certain conditions.Then,a small amount of nitrogen-doped graphene is coated on the surface of the loaded Pt-NPs by chemical vapor deposition to prepare the CN@Pt/GO nanocomposite,and the water is etched on the surface of the graphene,and the digging is performed on the surface of the graphene Pt-NPs were embedded in graphene to obtain Pt/GO-H₂O nanocomposites,and the appearance,structure and elements of the catalyst were characterized by TEM,XRD and Raman.The measurement results found that the prepared Pt/GO nanocomposites had uniform Pt nanoparticle sizes and were highly dispersed on the GO surface.After being coated with nitrogen-doped graphene,the surface of Pt-NPs was successfully coated with 2-4 layers of nitrogen-doped graphene.In the Pt/GO-H₂O nanocomposite material obtained after water etching,most of the Pt-NPs were embedded into the holes of the graphene carrier.（2）In this paper,the catalytic activity and stability of graphene-supported platinum nanocomposite catalyst for the hydrogenation of phenylacetylene are studied.The effects of supported catalysts（C@Pt/GO,CN@Pt/GO）developed by wet chemical reduction method Pt/GO and CVD method on the catalytic activity and stability of phenylacetylene hydrogenation reaction were investigated.The study found that:CN@Pt/GO>C@Pt/GO>Pt/GO.This is mainly due to the uniform particle size of Pt-NPs and high dispersion on the surface of GO.This localization effect of nitrogen-doped graphene improves the selectivity of styrene of CN@Pt/GO composite catalyst.This restricted effect can not only promote the desorption of styrene from the catalyst,but also effectively prevent the excessive hydrogenation of styrene to form styrene.（3）This thesis studies the catalytic performance of Pt/GO and Pt/GO-H₂O nanocomposites for the dehydrogenation of n-butane.The effects of Pt/GO developed by wet chemical reduction and Pt/GO-H₂O nanocomposites prepared by water etching on the catalytic activity and stability of n-butane dehydrogenation were investigated.The results show that:Pt/GO-H₂O>Pt/GO;mainly due to the uniform particle size of Pt-NPs and high dispersion on the surface of GO,Pt-NPs are embedded in the pits on the surface of the graphene etched by water,thereby improving Pt/GO-H₂O nanocomposite catalyzes the high temperature stability of n-butane dehydrogenation.