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

- Pt and Pt-Cr nanomaterials were synthesized by microwave assisted polyol method.
- High electrochemical activity toward ORR on PtCr was revealed.
- IL-TEM investigations showed good durability for PtCr.
- Four-electron reduction mechanism with a very low amount of H2O2 was observed.

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 electrocatalysts 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 parameters were assessed through the Koutecký-Levich equation at 20, 30 and 40 °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.

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