Synergistic Ni-Co interaction and phase control in bimetallic catalyst for ethanol electrooxidation reaction

In this study, bimetallic nickel-cobalt electrocatalysts with different Ni:Co ratios were elec­tro­deposited onto indium tin oxide substrates coated by polyethylene terephthalate and evaluated as cost-effective catalysts for ethanol electrooxidation reaction. The physical fea­tures of the catalysts were studied using X-ray diffraction (XRD), Raman spectroscopy and field-emission scanning electron microscopy, along with energy-dispersive X-ray spec­tro­scopy. XRD analysis revealed a phase transition from a mixed face-cantered cubic (FCC) and hexagonal close-packed structure to a single FCC phase, as the cobalt content decre­ased. This change in phases greatly affected the shape of the catalyst, changing from a peb­bly texture in the mixed-phase samples to a smooth, rounded shape in the single-phase FCC samples. The electrochemical properties and catalytic performance of ethanol oxidation in alkaline medium were investigated using cyclic voltammetry and electrochemical impe­dan­ce spectro­scopy. The tested electrocatalysts revealed that NiCo B having Ni:Co ratio 82:18 possess the best catalytic activity compared to the other catalysts, reaching a current den­sity of 14.82 mA cm-2 for ethanol electrooxidation reaction and showing great stability. This better performance is due to its improved physical structure, which boosts the inter­action between nickel and cobalt, and lowers resistance to charge transfer. These findings demon­strate the promise of NiCo as an efficient electrocatalyst for ethanol electrooxidation reaction.