Orienting Reactant Adsorption via a Bipolar Synergistic Effect for Efficient 5-Hydroxymethylfurfural Electrooxidation

The electrochemical oxidation of 5-hydroxymethylfurfural (HMFOR) offers a promising route for biomass upgrading. However, its kinetics are severely hindered by the competitive adsorption between key reactive species on catalyst surfaces. Herein, we report a CoO/Ni 3 N-2:3 heterojunction catalyst that enables efficient and selective conversion of HMF to 2,5-furandicarboxylic acid (FDCA). A “bipolar synergistic adsorption effect” is identified at the CoO/Ni 3 N-2:3 interface. This effect is driven by a built-in electric field (BIEF) generated through interface polarization and the work function difference (ΔΦ) between Ni 3 N and CoO. In situ spectroscopic studies and theoretical calculations reveal that the BIEF acts as an electron sorter, directing OH − and HMF to respectively adsorb at oppositely charged regions while strengthening their adsorption. This spatially oriented adsorption effectively lowers the reaction energy barrier and suppresses competitive adsorption of key reactive species, thereby enhancing both activity and selectivity. As a result, the CoO/Ni 3 N-2:3 catalyst initiates HMFOR at a low potential of 1.18 V RHE and achieves complete HMF conversion at 1.408 V RHE with 99.2% FDCA yield and 97.2% Faradaic efficiency. This work provides an innovative strategy for designing high-performance electrocatalysts for biomass valorization.