Promotional effect of auxiliary metals Bi on Pt, Pd, and Ag on Au, for glycerol electrolysis

In the search for active, stable, and selective electrocatalysts for glycerol electro-oxidation, this study focuses on the favorable effect that the addition of auxiliary metals, Bi for Pt and Pd, and Ag for Au, exerts on these three aspects. Electrocatalysts (Pt/C, Pt3Bi/C, PtBi/C, Au/C, Au3Ag/C, Pd/C and Pd3Bi/C) were successfully prepared by chemical reduction with NaBH4, resulting in nanoparticulate materials. Furthermore, in the case of the Pd3Bi/C, a high degree of Pd-Bi alloy was achieved. When applied to glycerol electrochemical reforming, the electrochemical performance was enhanced so reducing the energy requirements for hydrogen production. Furthermore, in 24 h potentiostatic electrolysis, a smaller decay of the current was observed compared to the monometallic material, especially in the case of the Au3Ag/C and Pd3Bi/C electrocatalysts. Finally, the presence of the auxiliary metals altered the selectivity of the glycerol electro-oxidation. Bismuth added to Pt and Pd leads to an increase in the selectivity toward C-3 carboxylates, especially potassium tartronate in Pt-Bi materials operating at 30 degrees C. When the temperature is increased, this effect is counterbalanced by the larger amount of energy available, leading to a more heterogeneous product distribution in which oxalate and formate appear in higher percentages. Conversely, Ag leads to a more complex distribution product with large percentages of oxalate and formate. (c) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.