Tunable Ni(OH)2/N,W-Ni3S2 heterostructures to balance the competitive adsorption of 5-hydroxymethylfurfural and OH− for biomass valorization

The electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) constitutes a pivotal pathway for biomass valorization. However, its advancement is kinetically hindered by the competitive adsorption between HMF and OH − on active sites, causing a conflict between substrate activation and oxidant supply. To circumvent this impediment, a series of Ni(OH) 2 /N,W-Ni 3 S 2 composite catalysts are designed via electrodeposition. This strategy enables the in-situ growth of amorphous Ni(OH) 2 overlayer on the nitrogen and tungsten co-modulated Ni 3 S 2 (N,W-Ni 3 S 2 ) substrate, realizing the precise construction of heterostructure. The Ni(OH) 2 component possesses strong affinity for OH − , while the Ni 3 S 2 substrate preferentially adsorbs HMF. By tuning the electrodeposition duration, the Ni(OH)₂ layer thickness can be regulated, thereby enabling the overall adsorption strengths of both HMF and OH − to be finely optimized. The superior catalyst, Ni(OH) 2 /N,W-Ni 3 S 2 –500, demonstrates exceptional catalytic activity, achieving 100 % HMF conversion, 97.2 % FDCA yield and 97.3 % Faradaic efficiency. Furthermore, it displays a wide operational potential window, maintaining FDCA yields and Faradaic efficiencies above 90 % over 1.45–1.60 V vs. RHE. This remarkable activity is attributed to an optimized adsorption behavior for HMF and OH − . Specifically, the enhanced affinity for OH − accelerates the generation of the true active species, high-valent nickel oxyhydroxide (NiOOH), and ensures a sufficient localized supply of the oxygen source. Simultaneously, the catalyst retains a moderate adsorption capacity for HMF molecules, ensuring effective substrate activation without inhibiting product desorption. This study proposes a novel and effective interfacial engineering paradigm to resolve the adsorption imbalance in biomass electrooxidation, offering a rational blueprint for superior electrocatalysts.