The Research On Preparation Of Ni Aerogel With High Surface Areas From Cellulose Templates

Metal aerogels are novel porous metal materials which integrate unique characteristics of metals?such as highly electric and catalytic properties?and aerogels?such as low densities and high surface areas?.The interest in metal aerogels has drawn widely research to develop preparation methods and potential applications in the fields of catalysis,fuel cell and so on.So far,dealloying and self-assembly of metal nanoparticles?NPs?and template synthesis,have been involved to create metal aerogels.Among them,template synthesis is a classical approach to fabricate metal aerogels because it can synthesize and control the pore structure of the metal aerogels by sacrificing template materials.It is reported that template synthesis method can be used to prepare the nonprecious metal aerogels.Despite many great successes,the major disadvantage of template synthesis is the limitation of surface areas and macroscopic dimensions?monoliths or films?for metal aerogels.In fact,the surface areas are quite important for metal aerogels,while the restriction of macroscopic dimensions lead to serious limitations of application and processing.Therefore,how to design and prepare the nonprecious metals aerogels films or bulks with large surface areas becomes a real challenge.In this study,we demonstrate a novel approach,which uses two different cellulose aerogels as template to prepare self-supporting monolithic Ni aerogel with considerable surface areas by electroless plating.The effects of different electroless plating parameters and template removal methods on the specific surface area and morphology of Ni aerogel were further studied in detail.The resultant Ni aerogel was used as catalyst to explore their catalytic performance in ethanol electrooxidation.The specific research contents and experimental conclusions are as follows:1.Using microcrystalline cellulose aerogel?CA?prepared by 2wt%of microcrystalline cellulose/ionic liquid as template,then Ni aerogel can be obtained by electroless plating.The results show that the specific surface area of the obtained Ni aerogel is up to 100.1 m²·g^-1,when the amount of electroless Ni plating is 37.1 mg·mL^-1.The Ni aerogel has a self-supporting three-dimensional porous network structure composed of Ni nanoparticles and ultrathin Ni?OH?₂ nanofilms.2.Because the ionic liquid used for preparing the CA template is expensive,a new cellulose triacetate?CTA?gel with density of 10 mg·cm^-3 is prepared and used as template,in order to reduce the cost and simplify the preparation process.The effects of different amounts of electroless Ni plating and the methods of template removal on the specific surface area and morphology of Ni aerogel were studied in detail.3.The electrocatalytic experiment was used to investigate the catalytic effect of Ni aerogel catalyst on the electrooxidation of ethanol.Electrochemical test results show that the anodic peak current density of Ni aerogel in the solution of 1.0 M KOH+0.1 M ethanol reached 27.6mA·cm^-2,which is 4 times higher than commercial Ni nanoparticles.At the same time,the charge transfer resistance(R_ct)of Ni aerogel catalyst was only 0.88?·cm^-2,which is much smaller than other similar catalysts reported.