Electrocatalytic oxidation of furfural on Co₃O₄/nickel foam catalyst: performance and mechanistic study

The electrocatalytic conversion of furfural into value-added chemicals, such as furoic acid, shows significant potential for sustainable chemical production. Furfural, derived from biomass, is a critical platform molecule for manufacturing biofuels, pharmaceuticals, and biodegradable plastics, making it economically and environmentally significant. However, understanding the catalyst's behavior during furfural oxidation remains challenging since furfural is high unstable and easily decomposes. In acidic environments often used for the catalysis of furfural, catalysts suffer from leaching and deactivation. The objective of the present study was to investigate cobalt oxide/nickel foam (Co₃O₄/NF) as a new catalyst due to its redox properties, high activity, and ability to easily transition between oxidation states, making it ideal for furfural electro-oxidation. We hypothesized that the unique redox properties of Co₃O₄, combined with the conductive nature of the NF substrate, would synergistically enhance catalytic performance for furfural oxidation. Our results showed that the Co₃O₄/NF composite had high activity and stability in furfural oxidation. Electrochemical tests revealed that the Co₃O₄/NF catalyst had a large electrochemical surface area, indicating a high number of active sites. Pulse tests showed that Co₃O₄ oxidized more easily than cobalt hydroxide carbonate (Co₂(OH)₂CO₃) or pristine nickel foam. As suggested, broken circuit process tests revealed that the Co³⁺ species that formed during electrocatalysis enhanced the spontaneous non-electrochemical oxidation rate of furfural. These results demonstrate the catalyst's high activity and selectivity, offering insights into the design of efficient, stable electrocatalysts for biomass-derived chemicals. This study also advanced an understanding of surface dynamics in transition metal oxides during electrocatalysis, paving the way for the next generation of catalysts.