Preparation Of Pt/GA Electrocatalysts And Their Oxygen Reduction Reaction Performance

Aerogel is an ultralight, porous three-dimensional material。It has been wildly studied because of their peculiar mechanical strength, low density, good elasticity, conductivity, and high BET surface area. The common preparation methods of aerogels include template method, self-assembly, chemical cross-linking and induced assembly method. Graphene Aerogels are mainly prepared by using graphene oxide as raw materials.Chemical reduction method was adopted in this paper to prepare graphene aerogels. Firstly, the reducing agent hydrazine hydrate was added drop by drop into graphene oxide solution to prepare graphene hydrogels, and then the obtained graphene hydrogels was freeze dried to get aerogels. We examine the morphology, structure and performance of graphene aerogels under different experimental conditions. Especially, we investigate the effect of reductant species, precursor concentration, reaction time and the amount of the reducing agent. Final results of the experimental conditions are optimized. We also prepared Pt/GA catalyst for oxygen reduction according to the similar procedure, with Pt loading on graphene aerogels carrier.In order to further improve the dispersion of Pt nanoparticles, the carbon nanotube(CNT) was mixed with graphene aerogels as a solute. In this way, it can not only improve the dispersity of Pt and the conductivity of the carrier and catalyst, but also has a good supporting function to the structure of the graphene aerogels. Ultimately, we prepared Pt/GA-CNT catalyst for oxygen reduction according to the similar procedure.The samples were characterized by SEM, TEM, XRD, BET and electrochemical testing. The results indicate that graphene aerogels are porous black spongy solid-state materials with average pore size of about 3.7nm. The Nitrogen adsorption-desorption isotherm presents a V type curve, and the mass specific surface areas is 597 m2·g-1 through BET method with P0/P= 0.05-0.3. Graphene aerogels are suitable as a support material because of their three-dimensional network, high surface area and porosity. The electrochemical performance of Pt/GO, Pt/GA and Pt/GA-CNT were tested in O2 saturated 0.1 M HClO4. The results indicate that Pt/GA-CNT and Pt/GA has a better catalytic performance than Pt/GO during oxygen reduction reaction.