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BACKGROUND Glycerol, a by‐product of biodiesel production, is produced in large quantities, exceeding its demand. The saturation of glycerol resulted in a sharp reduction in its market value and the surplus waste may pose a risk to the environment. By means of electrochemical technologies, glycerol could be oxidized into value‐added products such as glycerate, tartronate and lactate. In the present work, carbon‐supported NiBi catalysts with different atomic ratios (NixBi1−x/C, wherex = 100, 95, 90 and 50 at%) were fabricated and utilized in a 25 cm2 electrolysis cell. RESULTS The as‐fabricated catalysts were characterized and analyzed by various physicochemical and electrochemical characterizations. Using a three‐electrode electrochemical cell, Ni95Bi5/C showed the highest current density of 104 mA cm−2, with an onset potential of 1.32 V versus a reversible hydrogen electrode. Long‐term chronoamperometry was performed in a glycerol electrolysis cell accompanied by the product analysis using high‐performance liquid chromatography. It was found that Ni95Bi5/C had higher selectivity to glycerate C3 product compared to Ni/C. Additionally, optimizing experimental conditions (applied potential, residence time and temperature) to achieve higher selectivity to C3 products was thoroughly studied. The selectivity to C3 value‐added products was enhanced by adjusting the operating conditions. CONCLUSION Small addition of bismuth to Ni/C enhanced both catalytic activity and selectivity to C3 products. The main products formed on NixBi1−x/C were formate and glycerate, while the secondary products were glycolate, tartronate, oxalate and lactate. By running electrolysis under optimal conditions, the selectivity to C3 products was significantly enhanced. © 2022 Society of Chemical Industry (SCI).

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Glycerol partial electro-oxidation to produce various chemicals has attracted a great amount of attention in the decade [1]. Glycerol is the main by-product of biodiesel production and could be converted into high value-added chemicals. The control of catalyst selectivity and activity could be achieved through formulation of novel, nano-structured electrocatalysts. Nickel (Ni) is an attractive material for glycerol electro-oxidation (GEOR) in alkaline media [2], due to its natural abundance, anti-poising and good stability in alkaline media. Designing inexpensive nano-structured 3D Ni electrodes could improve the catalytic activity of Ni, whereas its selectivity could be modified by adding second metal [1]. In the present work, GEOR was investigated on Ni-based mono and bi-metallic Ni x Au 1-x, Ni x Bi 1-x and Ni x Pd 1-x (x = 98, 95 and 90 at. %) nanoparticles in 1M KOH. Ni nanoparticles were synthesized by heatless chemical reduction in ethanol using sodium borohydride (NaBH4) as the reducing agent. Resulting Ni-based NPs were characterized using XRD, XPS, TEM, SEM, EDS mapping, HAADF imaging and EELS. Electrochemical measurements were carried out on Ni-based NPs using cyclic voltammetry (CV), chronoamperometry (CA) and linear sweep voltammetry (LSV) at room temperature. Results showed that Ni, NiAu and NiBi NPs are active for GEOR and that reaction proceeds through the formation of NiOOH active phase similar to bulk Ni electrodes [3]. Coupling CA with in-situ polarization modulation infrared-reflection absorption spectroscopy (PM-IRRAS) for the simultaneous analysis of products in the bulk electrolyte solution and on the Ni surface demonstrated that the main reaction products on Ni surface are glyceraldehyde, carbonyl and carboxylate ions. Whereas HPLC analysis reveals that Au, Bi and Pd adatoms strongly influence the reaction products by suppressing the pathways with C–C bond cleavage, hindering the formation of formate and enhancing the production of C2 and C3 products at different applied potentials (1.3, 1.4 and 1.55 V) and temperatures (25 and 50 oC). The correlation of electrocatalytic activity and selectivity with nanoparticle will be discussed in terms of mass activities and product distribution during GEOR. References [1] M. S. E. Houache, K. Hughes, E. Baranova, Sustainable Energy & Fuels, 3 (2019) 1892-1915. [2] M. S. E. Houache, K. Hughes, A. Ahmed, R. Safari, H. Liu, G. A. Botton, E. A. Baranova, ACS Sustainable Chemistry & Engineering, 7 (2019) 14425-14434. [3] M. S. E. Houache, E. Cosar, S. Ntais, E. A. Baranova, J. Power Sources, 375 (2018) 310-319.