Methanol Oxidation Reaction Performance on Graphene-Supported PtAg Alloy Nanocatalyst: Contrastive Study of Electronic and Geometric Effects Induced from Ag Doping

In Pt-based alloy catalyst, the electrocatalytic performance is highly related to the Pt d-band center, whose position can be modulated by the synergetic interaction of electronic and geometric effects. In this study, graphene-supported PtAg (PtAg/graphene) alloy nanocatalyst was prepared by a facile galvanic replacement reaction. Due to the introduction of Ag component, the PtAg/graphene exhibits a higher specific/mass activity (1.48 mA cm(-2), 580 mA mg(Pt)(-1)) and better CO tolerance (CO stripping potential: 0.45V vs. Ag/AgCl) than those of commercial Pt/C catalyst (0.86 mA cm(-2), 270 mA mg(Pt)(-1), 0.50V vs. Ag/AgCl) when being applied for catalyzing methanol oxidation reaction (MOR). On the basis of component and structure characterization, the PtAg alloy catalyst model was constructed, and first-principles density function theory calculation was applied to study the relative influence of electronic and geometric effects on the Pt d-band center and CO binding energy, respectively. It is found that the electronic effect, i.e. the charge transfer from Ag to Pt, is the decisive factor to enhance the electrocatalytic performance of PtAg alloy towards MOR.