Preparation And Catalytic Properties Of Nickel-based Graphene Composite Nanomaterials

The development of noble metals was limited due to its limited availability.in the field of catalysis.Therefore,non-precious metals such as Ni and Co are selected to replace precious metals.However,single nickel nanoparticles are extremely easy to aggregate during the preparation process,which reduces the catalytic activity.Graphene as a carrier can significantly decline the aggregation and effectively improve catalytic activity of the catalyst.In this paper,through three different methods,nickel-based graphene nanomaterials were prepared,and characterized by TEM,XRD,SEM,EDX,BET and H₂-TPD techniques.Ni-B/rGO with the controlled mass ratio between nickel metal and graphene were prepared by chemical reduction.The rate of hydrogen production as high as ca.1135ml/min·g_cat was obtained using as-prepared Ni-B/rGO catalysts with a mass ratio of1:25.The activation energy of the catalytic hydrolysis reaction of sodium borohydride was42.88 kJ·mol^-1 under the following condition:0.01mol·L^-1 NaBH₄,1.0mol·L^-1 NaOH and0.1g catalyst.Based on the co-reduction method the Ni-Co-B/rGO nanomaterials were prepared with the tunable molar ratio of Ni/Co.A hydrogen production rate as high as ca.1792ml/min·g_catat was obtained using the prepared catalyst with a molar ratio of 1:1 prepared.The activation energy of the catalytic hydrolysis reaction of sodium borohydride was34.35 kJ·mol^-1.The catalyst composition with a molar ratio of 1:1 showed the best activity toward electrocatalytic oxidation of ethanol,The oxidative peak current was up to 15.2mA·cm^-2.The synergistic action between Ni and Co metals lead to the increased activity.Novel layered structure Ni-Co-B/rGO was successfully synthesized by displacement method with suitable reaction time.The rate of hydrogen production as high as ca.2250ml/min·g_cat was obtained by using as-prepared Ni-Co-B/rGO catalysts with the reaction time of 20 minutes.The activation energy of the catalytic hydrolysis reaction of sodium borohydride was 28.65kJ·mol^-1.The results showed that the novel layered structure Ni-Co-B/rGO has better activity toward electrocatalytic oxidation of ethanol.The oxidation peak current density was 23.8 mA·cm^-2.The layered structure has a more active site as compared to the spherical structure generated by the co-reduction process.