Electrocatalytic Ethanol Oxidation on Cobalt-Bismuth Nanoparticle-Decorated Reduced Graphene Oxide (Co-Bi@rGO): Reaction Pathway Investigation toward Direct Ethanol Fuel Cells

Direct ethanol fuel cells (DEFCs) are one of the resourceful and sustainable technologies for energy applications. Ethanol oxidation has been used to construct cost-effective and proficient electrocatalysts to substitute noble-based electrocatalysts like Rh, Pd, Ir, and Ag. Here in, we have presented a surface modification approach of doping a crucial oxophilic character metal onto a transition metal with carbon support. Noble metal-free cobalt-bismuth bimetallic nanoparticle-decorated reduced graphene oxide (Co-Bi@rGO) electrocatalysts were fabricated for enhanced ethanol oxidation reaction from their synergetic effect of rGO, Co, and Bi. A highly active, cost-effective, and efficient approach has been developed for the preparation of Co-Bi@rGO (Co NPs; similar to 2 nm), initially Bi@rGO (Bi NPs@rGO;similar to 50 nm), by a simple reduction method followed by Co, by Galvanic exchange of Bi atoms with Co. The as-synthesized nanocomposites were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and BET surface area measurement studies. Cyclic voltammetric studies show an ultralow onset potential of 0.28 V with a high current density of 10.25 mA/cm(2), having a higher enhancement factor for Co-Bi@rGO compared to other individuals, including Bi NPs, Bi@rGO, and rGO under similar electrolyte conditions, which could be due to their synergetic cooperative interactions at electrified interfaces. Combined results from chronoamperometry (i-t) and electrochemical impedance spectroscopy show that Co-Bi@rGO is highly durable and sensitive toward the ethanol oxidation reaction compared to individual counterparts. This work also provides the noble metal-free bimetallic electrocatalysts for ethanol oxidation and assists in hydrogen production from an agricultural base.

Automated summary

The study presents a surface modification approach for the fabrication of noble metal-free cobalt-bismuth bimetallic electrocatalysts for enhanced ethanol oxidation reaction. The synthesized Co-Bi@rGO electrocatalysts exhibit high activity, cost-effectiveness, efficiency, and durability, showing superior performance compared to individual counterparts. The synergistic interactions of rGO, Co, and Bi in the electrocatalysts contribute to their enhanced performance in the ethanol oxidation reaction.