Unlocking the potential of mixed-valence silver oxide for electrochemical valorization of 5-hydroxymethylfurfural into valuable products

The burgeoning interest in the electrocatalytic conversion of biomass-derived compounds, exemplified by 5-hydroxymethylfurfural (HMF), into economically valuable products underscores the significance of such studies. Within this context, the electrocatalytic oxidation of HMF into 2,5-diformylfuran (DFF) using the mixed-valence silver (I, III) oxide (AgO) as the catalyst is presented for the first time. A thorough investigation has been carried out to explore the complex factors influencing the electrochemical transformation of the HMF to DFF, involving applied potentials, reactant concentrations, and the significant implications of mass transfer phenomena. Under optimized conditions, DFF, one of the highest value-added intermediates, can be produced with selectivity as high as 54%. Additionally, a yield of 10.8 μmol cm⁻² h⁻¹ was obtained under mild basic condition. Another pivotal aspect of this work involves meticulously examining the reaction process, bolstered by a comprehensive analytical approach that integrates high-performance liquid chromatography (HPLC), and operando Raman spectroscopy. The amalgamation of operando Raman spectroscopy with advanced simulation techniques represents a novel endeavor, offering a groundbreaking pathway to unravel the complexities inherent in these compounds and contribute substantially to the understanding of HMF oxidation and its intermediates. By looking closely at the catalyst surface during the reaction, a valuable insight into the steps involved was developed, helping in proposing an in-depth reaction pathway.