Electrocatalytic oxidation of 5-hydroxymethylfurfural by MnO2 with tunable surface oxidation states†

The electrochemical catalytic oxidation of 5-hydroxymethylfurfural (HMF) to generate high-value products like 2,5-furandicarboxylic acid (FDCA) has become a prominent research interest. In this work, an economical and efficient transition metal ε-MnO₂ catalyst was used to electrocatalyze the oxidation of HMF in acidic environments. The results revealed a highly efficient HMF conversion rate of 92.95% and a FDCA yield of 23.03% under the specific conditions of 60 °C, 0.5 M H₂SO₄ and 1.6 V (vs. RHE). Furthermore, the study outlined the oxidation pathway for HMF, which progresses through the following sequence: HMF → DFF → FFCA → FDCA. The apparent activation energies associated with each oxidation stage were found to be 25.52, 22.12 and 16.21 kJ mol⁻¹, respectively. Moreover, the findings indicated a favorable relationship between the electrocatalytic oxidation activity of HMF and the average surface oxidation state of ε-MnO₂.