Catalytic activity of Pt/graphene prepared by strong electrostatic adsorption technique for proton exchange membrane fuel cells

Abstract

Abstract In the proton exchange membrane (PEM) fuel cell development, the catalytic activity requires the smaller particle size, the better metal dispersion, the higher conductivity and the longer durability. With these, platinum on graphene was synthesized using the strong electrostatic adsorption (SEA) technique. The pH shifts of graphene was evaluated and the point of zero charge (PZC) was obtained at pH about 5.2. This was a mid-low PZC, where the positive charge of Pt (i.e, platinum tetraamine, [NH3]4Pt2+or PTA) was chosen as the metal precursor. The adsorption of PTA precursor on graphene was carried out at pH of 12 for one hour at room temperature. PTA on graphene was reduced in hydrogen environment, and transferred to Pt metal particle. The adsorption and reduction steps were repeat until the Pt metals percentage closed to 20%wt Pt/C (i.e, 19.3 % wt. for this work). The prepared Pt/graphene catalyst shows the smaller particle size that average particle size as 2.4 nm and highly better dispersion than the Pt/C-commercial. The Pt metal dispersion on the graphene support were inspected by transmission electron microscopy (TEM). The crystal structures and crystalline size were investigated by X-ray diffraction (XRD). Moreover, the electrochemical properties were tested using cyclic voltammetry (CV) and the accelerated durability test (ADT) was also carried out after 4000 cycles of reduction and oxidation reaction. Finally, the results were compared with the 20% wt. Pt/C-commercial catalysts. It was observed that the oxidation reduction reaction (ORR) activity in terms of mass activity (MA) and specific activity (SA) were better than Pt/C-commercial.