Research On The Preparation And Applied Foundation Of Metal Nanoparticles/Graphene Composites

Metallic?gold,silver,copper,etc.?nanoparticles?NPs?have been widely used in catalysis,sensing and other fields due to their unique optical,electrical and magnetic properties.Meanwhile,graphene is an ideal carrier for metallic nanoparticles due to its large specific surface area,high electrical and thermal conductivity,excellent chemical stability and mechanical properties.The combination of metallic nanoparticles and graphene not only helps to improve the agglomeration problem of metal nanoparticles but also obtains more excellent catalytic and sensing properties through the proper use of their synergistic effects.In this paper,three-dimensional graphene/nickel foam?3DGr/NiF?prepared by chemical vapor deposition?CVD?and two-dimensional graphene/peanut shell?RGO/PS?prepared by redox method were used as the base materials.Gold,silver and copper NPs/graphene composites were prepared by hydrothermal method,one-step reduction method and displacement reaction,respectively.The composites were used for catalytic reduction of organic pollutants 4-nitrophenol?4-NP?,methylene blue?MB?and Rhodamine B?RhB?.The effects of temperature,initial concentration,pH value and the catalyst amount on the catalytic performance of the composites were systematically investigated.The sensing properties of the composites to hydrogen peroxide?H₂O₂?were investigated as well.The main results are as follows:?1?Ag NPs,Gr/NiF and Ag NPs/Gr/NiF composites were prepared by polyol method,CVD method and polyvinylpyrrolidone?PVP?assisted hydrothermal method,respectively.Ag NPs were uniformly distributed on the surface of Gr/NiF with an average particle scale about 45 nm in diameter.The composites exhibited high catalytic activity,excellent durability and repeatability for 4-NP(K=1.641 min^-1),MB(K=1.503 min^-1)and RhB(K=1.525 min^-1),and showed high sensitivity for hydrogen peroxide sensing as electrode materials.?2?Copper NPs/RGO/PS composites were prepared by one-step reduction method.Cu NPs are spherically,uniformly and densely distributed on the surface of RGO/PS substrate and the internal micropores of PS without agglomeration.The composites presented high catalytic activity and good reusability for both organic pollutants and dyes.The catalytic rate constant K for 4-NP,MB and RhB reached5.061 min^-1,3.891 min^-1 and 3.590 min^-1,respectively.After six cycles of catalysis,the catalytic activity for 4-NP,MB and RhB decreased by only 18.85%,17.21%and10.84%,respectively.?3?Petal-like Cu NPs/Gr/NiF composites were prepared by displacement reaction method.Cu NPs are petal-shaped,with a lamellar thickness of 30-50 nm and no agglomeration was observed.The catalytic rate constants K of the composites for4-NP,MB and RhB are 16.094 min^-1,10.496 min^-1 and 10.606 min^-1,respectively,which indicats the excellent catalytic activity and stability of the composites.The catalytic rate constant K increases with the increases of temperature,initial concentration and catalyst amount,while it rises first and then decreases with the increase of pH value under alkaline conditions.NaBH₄ shows higher stability with the increase of pH value and the decrease of the self-decomposition amout and the rise of the amout that involved in the catalytic reactions.The adsorption performance of organic pollutants and dyes on copper NPs decreases with the increase of pH value.Through the interaction of these two competing factors,the optimal pH value was determined as 12.?4?Spherical Au NPs/Gr/NiF composites were prepared by displacement reaction.Without any reducing agent,surfactant or organic solvent,the entire reaction process lasts only 20 s,and the average particle size of the prepared Au NPs is less than 100 nm in diameter.The catalytic rate constants K of the composite for 0.25 mM and 0.05 mM 4-NP were 0.534 min^-1 and 0.569 min^-1,respectively.The composite was used as a reusable catalyst.After six cycles of catalysis,the catalytic activity of the composite for 4-NP with concentration of 0.25 mM and 0.05 mM was decreased by only 5.99%and 7.73%,and the catalytic activity remained stable.