Modulating hydrocarbon coverage on Mo-doped RuO2 anodes enables energy-efficient and selective Kolbe electrolysis

The development of efficient and low-energy-consumption electrocatalytic decarboxylation (Kolbe electrolysis) is of great significance for the conversion of biomass-derived carboxylic acids into high-grade hydrocarbon fuels. RuO₂ is considered a promising anode material. However, its intrinsic high activity towards the oxygen evolution reaction (OER) poses challenges in terms of reaction selectivity and high driving potentials in practical applications. This study investigated the modulation of RuO₂ electrode performance through the systematic screening of various metal dopants (Mo, Ta, Zr, W, Sn). Results show that while doping generally enhances the OER, certain dopants sustain decarboxylation under high potentials by suppressing the OER via hydrocarbon product coverage. Among them, the Mo-doped RuO₂ coating improved decarboxylation selectivity and faradaic efficiency to some extent while facilitating product desorption to inhibit interface resistance increase. By further optimizing the doping ratio and calcination temperature, the resulting RuO₂-5%Mo anode achieved a remarkable reduction in cell voltage (by approximately 1 V) in the presence of OA during constant-current electrolysis, leading to a ∼20% decrease in energy consumption per unit product compared to undoped RuO₂, alongside good stability over 10 cycles. This work provides new material design strategies and mechanistic insights for developing Kolbe electrolysis anodes with high selectivity and low energy consumption.