Research On The Preparation And Application Of Graphene/metal-based Nanoparticle Hybrid Materials

As a new member of carbon materials family,graphene has aroused more and more attention due to its unique and outstanding physical properties,such as high carrier mobility,high electrical conductivity,high thermal conductivity and excellent chemical stability.In this article,metal nanoparticles/graphene composites were taken as the research object.Firstly,novel Ni O@Ni@graphene core-shell nanohybrids were fabricated via in situ reduction and subsequent chemical vapor deposition(CVD)processes.Nickel oxide(Ni O)nanoparticles with an average diameter of 30 nm were firstly reduced by H2 at 500 °C to form a metallic nickel(Ni)layer,followed by the generation of graphene layer via a CVD process in the presence of CH4 and H2 at 650 °C to afford the Ni O@Ni@graphene core-shell nanohybrids(35 nm in diameter).As revealed by high-resolution transmission electron microscopy(HRTEM),the thickness of graphene layer generated on the Ni surface of Ni O@Ni was 2.48 nm,corresponding to five layers of graphene.This special design endowed the nanohybirds with improved electrochemical capacitive properties via the synergistic effects between core-shell Ni O@Ni and highly conductive graphene layer.As a battery-type supercapacitor electrode,the Ni O@Ni@graphene nanohybrids exhibited a high specific capacitance of 903 F g-1 at a discharge current of 0.5 A g-1.Next,in the second experiment,a simple,scalable and effective method was explored to generate silver nanoclusters(~3.57 nm)directly on reduced graphene oxide(r GO)(denoted as Ag NC@HSG-r GO)using glutathione(GSH)as a green and mild co-reduction agent.Due to the superb electrical conductivity of r GO,the extremely small particle size of silver nanoclusters and the synergistic effect between silver nanoclusters and r GO,high catalytic activity and stability for reduction of 4-nitrophenol had been achieved for Ag NC@HSG-r GO with a very low silver loading of 8.67 wt% on r GO.The conversion could reach 96.69% in 16 min and the apparent rate constant based on r GO was up to 0.55 min-1.Moreover,the Ag NC@HSG-r GO nanocomposite was also proven to be the efficient antibacterial and photothermal ablation agents.Finally,a uniform porous highly oriented pyrolytic graphite(HOPG)electrode was prepared via diazonium salt assisted electrochemical etching method and firstly utilized to immobilize enzymes for the construction of a high-performance glucose biosensor firstly.The formation mechanism and morphology structure of the porous HOPG electrode were investigated using atomic force microscopy(AFM),X-ray photoelectron spectroscopy(XPS)and X-ray diffraction(XRD)characterizations.The glucose oxidase(GOx)was functionalized with pyrene groups and then immobilized on the porous HOPG substrate through ?-? stacking interactions and hydrogen bonding.As a result,eight times higher oxidation current density can be obtained for a given glucose concentration for the porous HOPG electrode than the pristine one.Detection limit of 5 m M for glucose was achieved for the as-fabricated biosensor.It was obtained that 78% biocatalytical activity of GOx can be retained after the pyrene functionalization and 65.7% one can even be maintained after four weeks,which confirmed the high efficiency and good stability of the as-prepared biosensor.What's more,it can be anticipated that various other enzymes can be loaded into this porous HOPG platform using the same enzyme modification methodology for the construction of efficient biosensors.