Preparation Of Nickel (Nickel Oxide) Foamfor As A Has (High Surfacearea) Material

Sustainable energy is becoming of increasing concern world-wide. The rapidgrowth of global climate change along with the fear of energy supply shortage iscreating a large consensus about the potential benefits of a hydrogen economycoming from renewable energy sources. A promising route is to use the energy ofsunlight to split water into its constituent elements, oxygen and hydrogen. For thedecrease of energy consumption during the water electrolysis, besides platinum, themost important and most studied electrode material is nickel, its alloys andcompounds. A novel nickel foam material with open pore structure was prepared bysol-gel method in this thesis.Two kinds of composition were adopted to synthesize the nickel foam in thisthesis. First, nickel foam was formed when a gel was heated at the temperature morethan 100℃. In this process, three different kinds of compositions were used: nickelchloride and ethylene diamine tetraacetic acid(EDTA), nickel nitrate and EDTA,nickel nitrate,nickel chloride and EDTA. In the process, nickel foam was formedwhen the gel was heated at 450℃. In the second process, two kinds of compositionwere used: nickel nitrate,nickel acetate and triethanolamine(TEA), and nickelnitrate,citric acid,ethylene glycol and TEA.Many different compositions were made up using different proportions. Themorphology,structure and composition of foam were characterized by SEM,EDXand XRD. The relationship between the composition, temperature, atmosphere andmicrostructure of nickel foam will be discussed in the following.In the first process, results from the nickel chloride and EDTA showed thatwith the increase of EDTA, the gels became clear and uniform in color. When theconcentration of EDTA is equal to 0.1 and nNiCl₂: nEDTA=1:5, the best gel and the bestfoam were obtained. The result from nickel nitrate and EDTA showed with theincrease of Ni(NO₃)₂, the gels is clear and uniform in color. When the concentration of Ni(NO₃)₂ and EDTA equal to 0.1 and nNi(NO₃)₂: nEDTA=5:1, the best gel and the bestfoam were obtained. The result from nickel nitrate,nickel chloride and EDTAshowed the pore size of samples heated under 5%H2 +95%N₂ atmosphere were largethan the pores of samples heated under 100%N₂ atmosphere. A change inconcentration of less than 0.05mol/L does not affect the microstructure of the foam,but can affect the microstructure of foam which was heated under 100% N₂atmosphere.In the second process, samples of nickel nitrate,nickel acetate and TEAshowed that an increase of temperature and time, the diameter of particles increasesand the percentage of residual carbon percent decreases. The smallest diameters ofparticles are about 150nm and the samples had magnetism. Sample of nickel nitrate,citric acid,ethylene glycol and TEA showed that with the increase of temperature,the diameters of particles decrease in some area with some particle diameter isaround 20nm.