Manipulating adsorbed hydrogen for enhanced HMF electrocatalytic hydrogenation

Doping Cu with Pt creates an environment with a high coverage of adsorbed hydrogen, which inhibits undesirable dimerization and enhances the selectivity of the hydrogenation of 5-hydroxymethylfurfural (HMF) to 2,5-dihydroxymethylfurfural (DHMF). 5-Hydroxymethylfurfural (HMF), derived from biomass, is a promising sustainable resource that can be converted into valuable chemical compounds. One such compound, 2,5-dihydroxymethylfuran (DHMF), produced through the electrocatalytic hydrogenation of HMF, is widely used in industrial polymer manufacturing. However, the hydrogenation of high-concentration HMF remains challenging due to the tendency for undesirable dimerization. Acknowledging the critical role of adsorbed hydrogen (H*) in HMF hydrogenation, a series of transition metal-doped dual-cubic Cu electrocatalysts (M-Cu, where M = Mo, Pd, Pt, Au, and Ag) were synthesized to systematically investigate the effect of varying H* reactivity on HMF hydrogenation. A pronounced correlation between DHMF selectivity and H* coverage was observed. Increasing H* coverage can enhance the selectivity for DHMF and prevent undesired dimerization of adsorbed HMF molecules. While elevated H* coverage enhanced DHMF selectivity, excessive coverage adversely impacted Faradaic efficiency due to competing hydrogen evolution reaction. This underscores the critical importance of finely tuning H* coverage. The optimal electrocatalyst, achieved by fine-tuning the doping amount of Pt on Cu, demonstrated a Faradaic efficiency of over 90% for DHMF in high-concentration HMF at −0.3 V, marking the highest record reported to date.