Modification of Nickel Surfaces by Bismuth: Effect on Electrochemical Activity and Selectivity toward Glycerol

Abstract

Herein, we study the effect of adding bismuth to Ni-nanostructured catalysts (Ni<i>_x</i>Bi_1-<i>x</i>, <i>x</i> = 100-90 at. %) for glycerol electro-oxidation in alkaline solution by combining physiochemical, electrochemical, and <i>in situ</i> infrared spectroscopy techniques, as well as continuous electrolysis with HPLC (high-performance liquid chromatography) product analysis. The addition of small quantities of Bi (<20 at. %) to Ni nanoparticles led to significant activity enhancement at lower overpotentials, with Ni₉₀Bi₁₀ displaying an over 2-fold increase compared to Ni. Small quantities of bismuth actively affected the reaction selectivity of Ni by suppressing the pathways with C-C bond cleavage, hindering the production of carbonate and formate and improving the formation of tartronate, oxalate, and glycerate. Furthermore, the effect of aging on Ni<i>_x</i>Bi_1-<i>x</i> catalysts was investigated, resulting in structural modification from the Ni-Bi double shell/core structure to Bi decorated on the folded Ni sheet, thus enhancing their activity twice after 2 weeks of aging. NiBi catalysts are promising candidates for glycerol valorization to high-value-added products.