Unilamellar MnO nanosheets confined Ru-clusters combined with pulse electrocatalysis for biomass electrooxidation in neutral electrolytes.

The electrochemical oxidation of 5-hydroxymethylfurfural (HMFOR) in alkaline electrolyte is a promising strategy for producing high-value chemicals from biomass derivatives. However, the disproportionation of aldehyde groups under strong alkaline conditions and the polymerization of HMF to form humic substances can impact the purity of 2,5-furandicarboxylic acid (FDCA) products. The use of neutral electrolytes offers an alternative environment for electrolysis, but the lack of OH ions in the electrolyte often leads to low current density and low yields of FDCA. In this study, a sandwich-structured catalyst, consisting of Ru clusters confined between unilamellar MnO nanosheets (S-Ru/MnO), was used in conjunction with an electrochemical pulse method to realize the electrochemical conversion of 5-hydroxymethylfurfural into FDCA in neutral electrolytes. Pulse electrolysis and the strong electron transfer between Ru clusters and MnO nanosheets help maintain Ru in a low oxidation state, ensuring high activity. The increased *OH generation led to a groundbreaking current density of 47 mA/cm at 1.55 V vs. reversible hydrogen electrode (RHE) and an outstanding yield rate of 98.7% for FDCA in a neutral electrolyte. This work provides a strategy that combines electrocatalyst design with an electrolysis technique to achieve remarkable performance in neutral HMFOR.