Unraveling the role of oxygen vacancy in the electrooxidation of 5-hydroxymethyfurfural on Co3O4

Abstract The electrooxidation of 5-hydroxymethylfurfural (HMF) offers a promising green route to attain high-value chemicals from biomass. The HMF electrooxidation reaction (HMFOR) is a complicated process involving the combined adsorption and coupling of organic molecules and OH- on the electrode surface. An in-depth understanding of these cooperative adsorption behaviors and reaction processes is fundamentally essential. Herein, the adsorption behavior of HMF and OH-, and the role of oxygen vacancy on Co3O4 are initially unraveled. Correspondingly, instead of the competitive adsorption of OH- and HMF on the metal sites, it is observed that the OH- could fill into oxygen vacancy (Vo) before couple with organic molecules through the lattice oxygen oxidation reaction process, which could accelerate the rate-determining step of the dehydrogenation of 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) and enhance the overall conversion of HMF on Vo-Co3O4. This work sheds a depth insight on the catalytic mechanism of oxygen vacancy, which benefits designing a novel strategy to modulate the multi-molecules combined adsorption behaviors.