Temperature-dependence of oxygen reduction activity on Pt/C and PtCr/C electrocatalysts synthesized from microwave-heated diethylene glycol method

This work reports first the synthesis of carbon supported Pt and Pt-Cr electrode materials from microwave-heated diethylene glycol (DEG) without additional protective agents. The prepared electro-catalysts have superior electrochemical activity and stability than those previously reported in acidic medium. Transmission electron microscopy (TEM) characterizations of these materials reveal uniformly dispersed particles with a mean size of ca. 1.20 nm. The morphological changes of these two materials were investigated by identical location-transmission electron microscopy (IL-TEM) after classical durability test. The electrocatalytic activity towards the oxygen reduction reaction (ORR) was investigated using rotating disk electrode (RDE) and rotating ring disk electrode (RRDE) techniques in 0.1 mol L-1 HClO4. The kinetic parametdrs were assessed through the Koutecky-Levich equation at 20, 30 and 40 degrees C. Electrochemical measurements demonstrate that significantly higher catalytic activity was observed on the Pt-Cr/C electrocatalyst than on Pt/C. The RRDE analysis shows that the ORR mainly involves a four-electron reduction mechanism to water with the formation of a very low H2O2 amount as reaction intermediate. (C) 2016 Elsevier B.V. All rights reserved.