Dense Crystalline-Amorphous Interfaces Modulate Competitive Adsorption for Efficient Biomass Upgrading

The 5-hydroxymethylfurfural oxidation reaction (HMFOR) is a promising approach for biomass upgrading. However, the mechanistic complexity of HMFOR poses limitations on its widespread adoption. In particular, the competitive adsorption between HMF molecules and hydroxyl species on electrocatalyst surfaces critically governs the reaction kinetics and selectivity. Herein, a dense crystalline-amorphous (c-a) Ag/NCM heterointerface is engineered to modulate competitive adsorption for efficient HMFOR. The introduction of crystalline Ag not only promotes the electrochemical formation of active NiCo(OOH)₂ species but also preferentially adsorbs HMF via the aldehyde group. As a result, the Ag/NCM catalyst delivers a markedly reduced onset potential (1.05 V_RHE) and a fivefold enhancement in current density compared to NCM. In-situ Raman spectroscopy, in-situ 2-D FTIR, multipotential electrochemical measurements, and density functional theory calculations collectively reveal that Ag modulates the competitive adsorption of HMF and OH* on the c-a interface, and accelerates the rate-determining HMFCA-to-FFCA step. This study not only illuminates the adsorption facilitation mechanism at the c-a interfacial sites but also offers invaluable insights for advancing the field of biomass electrocatalysis, paving the way for more efficient and sustainable utilization of biomass resources.