Unraveling the Mechanisms of Electrocatalytic Oxygenation and Dehydrogenation of Organic Molecules to Value-Added Chemicals Over a Ni–Fe Oxide Catalyst

Electrocatalytic oxidative upgrading of organic molecules is a promising alternative process to water oxidation for clean hydrogen production. Yet, its underlying mechanism is still not fully understood, and suitable low-cost electrocatalysts with good product selectivity and activity are still sought after. Here, an active NiFeO_x-based catalyst is reported on as a general platform for the electro-oxidative upgrading of organic molecules through oxygenation and dehydrogenation, with hydrogen coproduction. Detailed mechanistic studies unveil that C–H bond oxidation (with a bond dissociation energy BDE_C–H of ≈88–96 kcal mol⁻¹) is involved in the rate-limiting step, which differs significantly from the oxygen evolution reaction mechanism. These findings show that the oxidation efficacy is linearly correlated with the BDE_C–H of the molecule. Thus, the catalyst can be used as a general platform for large-scale electro-oxidation of various substrates through oxygenation and dehydrogenation at high current density (25 mA cm⁻²), with a good Faradaic yield. The platform's generality is further demonstrated by the selective oxidation of 5-(hydroxymethyl)furfural into 2,5-furandicarboxylic acid with good efficiency.