Selective Electrooxidation of Glycerol to Formic Acid over Carbon Supported Ni_{1- x}M_x(M = Bi, Pd, and Au) Nanocatalysts and Coelectrolysis of CO₂

The composition effect of carbon supported NixM1-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 NixM1-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 Ni0.9Au0.1/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 CO2 electroreduction, the anodic Ni0.9Au0.1/C catalyst displayed the highest partial current density for CO and the lowest onset potential.