Syntheses And Catalytic Activities Of Several Inorganic Composite Nanomaterials Utilizing The Transition Metals

The solution of environmental pollutions and current energy crisis has attracted extensive attention.It has become important to explore composite materials with excellent catalytic properties.Among these composite materials,noble metals have best catalytic properties,which are strongly dependent on the structure and properties of their supports.And the high price and limited resources of noble metals limite their large-scale applications.A large number of experiments are conducted to explore the synthesis of efficient composite carbon materials and transition metal catalysts instead of the noble-based materials.There is also a lot of work on noble metals combined with other materials and other means to enhance the activity of noble metal based catalysts.We synthesized several efficient composite nanocatalysts by different transition metals to solve the current environmental problems.The main points are outlined as following:1.S-N-codoped hollow carbon nanosphere/graphene aerogel(SNC-GA)has been successfully fabricated using a clean solid ion transition route.In this method,Hydrothermal reduction of the graphenen oxide sheets loaded the ZnS@polydopamine core-shell nanospheres(ZnS@PDA)affords a three-dimensions bulk graphene aerogel.After a high annealing temperature,SNC-GA can be obtained.The sample calcined at 1000 ℃ exhibits much higher catalytic activity to the organic reaction,compared to other samples.The catalytic activity is enhanced by a fixed proportion of S and N doped and the synergistic effect of hollow carbon spheres and graphene.More importantly,due to the 3D structural nature,such nanocatalyst can be easily separated and recycled.2.Au@CeO2 half-coated core@shell nanomaterial is designed and synthesised by controlled hydrolysis of the cenum acetate utilizing the cetyltrimethyl ammonium bromide as soft template,which has a mushroom-like structure.Besides exhibiting plasmon-enhanced photothermal properties,h-Au@CeO2 also has good p-nitrophenol catalytic reduction activity under near infrared laser.This is because the specific aspect ratio of the Au nanorods have a strong absorption in the near infrared region,which are synergy with coated CeO2.The anisotropy structure of h-Au@CeO2 promotes the plasmon produced hot-electron transfer and separation of electron-hole pairs resulting in better photocatalytic effect towards 4-NP reduction compared with totally-encapsulated Au NRs@CeO2 nanostructures.3.The synthesis of ZnCO2O4@ZnCo-layered double hydroxide(ZnCo-LDH)yolk-shell nanospheres composite materials utilizes a controllable hydrolyzing process of mixed metal glycolates.The best sample exhibits a good oxygen evolution reaction(OER)activity,which is with an overpotential(η)of 375 mV at 10 mA cm-2 vs.RHE and a Tafel slope of 73 mV dec-1 in 1.0 M KOH.The composited materials have a shell composed of interconnected nanosheets and a hollow structure,which provide a large surface area to increase the number of active sites.The micropores and mesopores on the nanosheets effectively reduce the transport path of electrolyte ions to the active sites and facilitate the transport of reactants and products.As a complex with bimetal,a synergestic effect exists between the two metals.