Constructing Pr-doped CoOOH catalytic sites for efficient electrooxidation of 5-hydroxymethylfurfural

Electrocatalytic conversion of renewable biomass is emerging as a promising route for sustainable chemical production; hence it urgently calls for developing efficient electrocatalysts with low potentials and high current densities. Herein, a Pr-doped Co(OH)₂ hexagonal sheet (Pr/Co = 1/9, in mole) is synthesized by electrodeposition as highly performant catalyst for 5-hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) to produce 2,5-furandicarboxylic acid (FDCA). This novel and low-cost catalyst possesses a rather low onset potential of 1.05 V (vs. RHE) and requires only 1.10 V (vs. RHE) to reach a current density of 10 mA cm⁻² for HMFOR, significantly outperforming Co(OH)₂ benchmark (i.e., 210 mV higher to reach 10 mA cm⁻²). The origin of Pr promotion effect as well as the evolution of CoOOH catalytic sites and HMFOR process has been deeply elucidated by physical characterizations, kinetic experiments, in situ electrochemical techniques, and theoretical calculations. The unique Pr-ameliorated CoOOH active centers enable 100% conversion of HMF, 99.6% selectivity of FDCA, and 99.7% Faraday efficiency, with a superior cycling durability toward HMFOR. This can be one of the most outstanding results for Co-based HMFOR catalysts to date in the literature. Thereby this work can help open up new horizons for constructing novel and efficient Co-based electrocatalysts by the utilization of lanthanide elements.