PtAg/MnOx/C as a promising electrocatalyst for glycerol electro-oxidation in alkaline medium

This study shows the positive effect that Ag possesses on Pt in order to promote the glycerol electro-oxidation in alkaline medium and how this effect can be boosted with an appropriate catalyst support, such as MnOx/C. The addition of Ag to the catalyst formulation firstly impacts on the structural and electronic features of the bimetallic PtAg/C catalyst. The diffractograms evidence the formation of a PtAg nanometric alloy, which alters the electronic environment of Pt as evidenced by the reduction of the Pt L-III white line hump in the XANES spectrum. This effect is intensified at high potential in the PtAg/MnOx/C catalyst, indicative of the low affinity of Pt to form surface PtOx species, leading to a Pt surface in which the intermediates formed are less strongly adsorbed. Moreover, MnOx can act as a source of oxygenated species required by the glycerol electro-oxidation reaction (GEOR), leading to an optimum catalytic surface. Such combination of factors leads to a very electroactive material for glycerol electro-oxidation as demonstrated by the cyclic voltammetry, chronoamperometric curves and in the actual fuel cell, in addition to a different product distribution characterised by in-situ electrochemical Fourier transform infrared spectroscopy (EC-FTIR). (C) 2016 Published by Elsevier B.V.