Electrocatalytic C–C Coupled Oligomerization From Biomass Molecules Through Pd Single‐Atom Interfacial Regulation

ABSTRACT Fossil‐derived diesel raises sustainability and air‐quality concerns, motivating biomass‐based alternatives; however, current biodiesel routes suffer from food–fuel competition, poor fuel properties, and energy‐intensive upgrading. Electrocatalytic C─C coupling of biomass molecules followed by hydrodeoxygenation (HDO) offers a cleaner pathway, yet has been limited to dimer formation. Here, we successfully resolved this longstanding bottleneck through construction of Pd 1 Cu single‐atom alloy electrocatalyst, a trimer of 5‐hydroxymethylfurfural is obtained with 44.7% selectivity. The combined oligomer (dimer and trimer) selectivity reaches 95.0% with 93.2% Faradaic efficiency, production rate achieves a record high of ∼50 g g cat −1 h −1 . Subsequent HDO converts the oligomers into heteroatom‐free n‐dodecane and n‐octadecane diesel blendstocks. Operando spectroscopy reveals a surface‐confined ketyl‐radical pathway in which isolated Pd atoms regulate hydrogen‐atom supply and substrate adsorption, favoring C─C coupling over hydrogenation. This work establishes an electricity‐driven route for controlled carbon‐chain growth from biomass platforms.