Navigating glycerol electrochemical oxidation roadmap and catalyst selection.

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Herein, we study the effect of adding bismuth to Ni-nanostructured catalysts (Ni x Bi1–x , x = 100–90 at. %) for glycerol electro-oxidation in alkaline solution by combining physiochemical, electrochemical, and in situ 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 x Bi1–x 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.

The composition effect of carbon supported Ni x M 1−x (M = Bi, Pd, and Au) nanomaterials toward glycerol electrooxidation (GEOR) was evaluated in alkaline media. Ni-rich catalysts with different atomic ratios (M atomic ratio ≤20%) were synthesized by the heatless coreduction method and characterized by various physicochemical and electrochemical techniques. All structures of the Ni x M 1−x /C catalysts were composed of a rich phase of Ni(OH) 2 , as evidenced by TDA-TGA and XPS. Among the different nanomaterials, the Ni 0.9 Au 0.1 /C catalyst provided the lowest onset potential (+0.12 V vs Hg/HgO) and the highest peak current density. In situ infrared spectroscopy experiments combined with electrochemical measurements exhibited the formation of formate for all catalysts, thus indicating the breakage of C− C bonds of glycerol. GEOR led to 100% selectivity for formate after 1 h electrolysis and 100% conversion of glycerol after 24 h at +1.55 V. Furthermore, when these inexpensive catalysts were tested in tandem with cathodic CO 2 electroreduction, the anodic Ni 0.9 Au 0.1 /C catalyst displayed the highest partial current density for CO and the lowest onset potential.

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