Multi-site synergy in high-entropy alloys drives integrated biomass valorization and CO2-to-C2 conversion.

Integration of renewable biomass valorization with CO2 reduction offers a transformative path toward carbon neutrality. However, orchestrating the simultaneous production of high-value 2,5-furandicarboxylic acid (FDCA) and multi-carbon (C2+) chemicals represents a significantly uncharted frontier. Unlike traditional coupling systems, this specific dual-production is severely hampered by the substantial kinetic mismatch and competing reaction pathways, leaving the efficient co-electrolysis of 5-hydroxymethylfurfural (HMF) and CO2 to high-order products virtually unexplored. Herein, we report a catalyst comprising high-entropy alloy nanoparticles with five elements (Co, Ni, Fe, Cr, Mn) supported on carbon nanofibers (HEA/CNF), which is employed to couple the HMF oxidation reactions (HMFOR) with the CO2 reduction reaction (CO2RR). Endowed with the distinctive electronic structure induced by the high-entropy atomic environment and the collaborative mechanism of multi-site division of labor, the catalyst achieves completely conversion for HMFOR, yielding FDCA with a selectivity of 99.2% and a Faradaic efficiency of 98.8%, surpassing the vast majority of state-of-the-art electrocatalysts reported to date. CO2 is efficiently reduced to two-carbon (C2) products, which exhibit a Faradaic efficiency of 61.3% at CO2RR. Combined in situ spectroscopic analyses and theoretical calculations demonstrate that the Co sites with modulated electronic structures serve as the dominant active centers for the adsorption and HMFOR. The Ni sites assist the reaction via the adsorption of hydroxyl species (OHads), while the Fe sites, benefiting from their optimized d-band center positions, act as the key active sites for facilitating the activation of CO2 and C-C coupling. This work not only presents a high-performance bifunctional high-entropy alloy catalyst, but also uncovers the atomic-scale synergy of its active sites, thereby providing a new design paradigm for integrated biorefining-CO2 electrocatalysis.