Electroreductive C–C Coupling of Furfural to Jet Fuel Precursors in Neutral Media via Synergistic Catalysis of the Polyoxotungstate and Cu Complex

The electrochemical coupling of biomass platform molecules to biofuels provides a promising method for addressing energy crises and environmental issues. However, achieving high yields of C–C coupling products under ambient conditions remains a challenge. Herein, we present a highly efficient electrocatalyst, Cu(pz)3PW12O40 (Cu-PW12), fabricated by combining a Cu-pz complex (pz = pyrazine), a redox catalytic center, with Keggin-type PW12O40, and an electron sponge. Cu-PW12 exhibits remarkable catalytic activity for the electroreductive C–C coupling of furfural (FF), a bulk and low-cost biomass platform chemical, to produce a jet fuel precursor, hydrofuroin (HDF). Under neutral and ambient conditions, over 99% of FF is converted and the selectivity of HDF reaches 91.2%. Furthermore, experimental and theoretical studies, including control experiments, kinetic isotope studies, electrochemical and spectral analyses, and DFT calculations, reveal a synergistic catalysis effect between Cu center and PW12. The introduction of PW12 not only facilitates electron transfer, improving FF conversion, but also changes the rate-determining step, favoring the formation of HDF. Under turnover conditions, the Cu-PW12 catalyst is initially reduced and then FF is reduced by the Cu center to ketyl radical after protonation on the electrode surface. Finally, the self-coupling of two ketyl radicals in solution leads to the generation of HDF.