Glycerol electrooxidation on carbon-supported Pt-CuO and PtCu-CuO catalysts

SIEBEN, JUAN MANUEL; ALVAREZ, ANDREA E.; SANCHEZ, MIGUEL D.

Buenos Aires

Congreso; 8th Symposium on Hydrogen, Fuel Cells and Advanced Batteries, HYCELTEC 2022; 2022

Universidad de Buenos Aires, CNEA e INTI

The growing global production of glycerol from biodiesel manufacture has sparked renewed interest in the development of low-temperature fuel cells powered by this alcohol. Glycerol is the main by-product (10 % by weight) generated during the transesterification process of vegetable oils and fats in biodiesel plants. In addition, it is non-toxic, easy to handle, store and transport, and possesses high volumetric energy density (i.e., 6.26 kW h L-1).Among the different types of fuel cells, anion exchange membrane fuel cells (AEMFCs) fed with aqueous solutions of ethanol or glycerol have emerged as promising power sources to supply clean energy for portable, stationary, and perhaps even automotive applications because of the fastelectrode kinetics, the lower corrosion of the cell components in an alkaline environment and the possibility of using non-noble catalysts in the cathode, when compared to proton-exchange membrane fuel cells (PEMFCs). However, the activity and performance of the anodic catalyst must be enhanced, and the platinum-group-metal (PGM) loading in the electrode must be reduced to make them a cost-competitive alternative technology to batteries. Several strategies havebeen implemented to boost the performance of platinum catalysts, including designing particles with controllable shape and structure, allowing with non-precious metals or combination with metal oxides, and employing different catalyst supports. In this respect, we have paid particular attention in this work to the addition of metal oxide promoters to enhance the catalytic activity and long-term stability of Pt and PtCu electrocatalysts for the oxidation of glycerol in alkaline medium. A recent investigation showed that the presence of spinel oxide NiCo2O4 nanoparticles onto a three-dimensional hierarchically porous graphene-like carbon boosts the catalytic activity of platinum toward glycerol electrooxidation [1]. Garcia et al. determined that MnOx acts as a source of labile oxygenated species, which facilitate the oxidation of glycerol on PtAg/MnOx/C electrocatalysts [2].Whereas, Li and coworkers found that YOx/MoOx decoration of ultrathin platinum nanowires enables the brake of the CC bonds of ethanol and glycerol and also improves the antiCO poisoning ability of the catalytic sites [3]. Velázquez-Hernández et al. found that the presence of Ni(OH)2 in a platinum catalyst favors the electrooxidation of glycerol to glycolate and mesoxalate via the bifunctional mechanism [4].Herein, we synthesized Pt and Pt0.7Cu0.3 catalysts supported on hybrid CuO/C materials with different CuO contents. The as-prepared electrocatalysts were characterized by XRD, HR-TEM, EDX, ICP-OES, and XPS. The experiments showed that the presence of CuO boosts the activity and stability of Pt and PtCu particles in the electrooxidation of glycerol in alkaline environment. The current density of the most active catalyst was found to be 1.73 A mgPt-1, which is ca. 3 times higher than that of Pt/C.