Effective Nickel and Ruthenium Modified Palladium Anode Catalysts for Ethylene Glycol Oxidation in Alkaline Medium

As one of the attractive fuels in the direct alcohol fuel cell applications, the ethylene glycol electrooxidation was investigated in alkaline medium on Pd-based bimetallic catalysts (PdM/C, where M = Ni, Ru). These electrode materials were synthesized by polyol method, using ethylene glycol as both solvent and reducing agent. The resulted anode catalysts displayed effectiveness toward the oxidation of ethylene glycol. The latter molecule was also scrutinized as potential fuel which can be converted by cogeneration into energy (5.2 kWh kg^-1) and particularly to added value product. Ex situ analytical measurements with liquid chromatography/Mass spectrometry provided evidences on the identification of glycolate as the main reaction product on the PdM/C anode materials (Figure 1).

Figure 1: Glycolate¹ isolated and identified by LC-MS as the main compound issued from the ethylene glycol oxidation at the Pd-M/C (M = Ni and Ru) catalysts in alkaline medium.

The identification of some adsorbed intermediates and the final reaction products, was also supported by combining electrochemical (cyclic voltammetry, chronoamperometry) and in situ reflectance infrared spectroscopy experiments. The PdNi/C catalyst showed the highest intrinsic catalytic activity for the ethylene glycol oxidation. From FTIR experiments our findings gave evidences that the initial molecule skeleton was conserved and carbon monoxide was observed in a low amount.

Acknowledgements: Da Silva R.G. gratefully acknowledges FAPESP (2012/07464-0; 2013/25632-0) and CNPq for his fellowship.

1. L.M. da Palma, T.S. Almeida, V.L. Oliveira, G. Tremiliosi-Filho, E.R. Gonzalez, A.R. de Andrade, K. Servat, C. Morais, T.W. Napporn, K.B. Kokoh, RSC Adv., 4, 64476 (2014).