Boosting the electro-oxidation of 5-hydroxymethyl-furfural on a Co–CoS(x) heterojunction by intensified spin polarization

The conversion of biomass-derived platform molecules (e.g., 5-hydroxymethyl furfural (HMF)) represents a sustainable route to produce value-added chemicals. Here we report the fabrication of an N-doped carbon nanotube assembled yolk–shell polyhedron with embedded Co–CoS(x) nanoparticles (NPs) (Y-Co–CoS(x)@CN) for efficient HMF electrooxidation. DFT calculations demonstrate that the formation of the heterojunction could intensify spin polarization in Co–CoS(2), thus achieving effective d–p coupling between the catalyst and reactant/intermediate. As expected, Y-Co–CoS(x)@CN exhibits excellent HMF electro-oxidation activity at a low applied potential of 1.29 V vs. RHE at 10 mA cm(−2) in 0.1 M KOH with 5 mM HMF, affording an FDCA yield of 96% and FE of 93.5%. This work not only sheds light on the catalytic nature of the heterojunction and the underlying mechanisms for the enhancement of HMF electro-oxidation activity, but would also provide a descriptor for the rational design of advanced electro-catalysts.