Substrate-induced crystalline-amorphous interface constructed in nickel-cobalt hydroxide for synergistic enhanced 5-hydroxymethylfurfural electrooxidation

For the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF), the precise regulation of the catalyst surface-interface structure and reactant adsorption is crucial for its activity. Here, a KOH-soaking assisted immersion–electrodeposition strategy is developed to construct a nickel–cobalt bimetallic hydroxide catalyst on nickel foam (NF), denoted as s-NiCo@NF. Importantly, KOH-soaked NF (s-NF) undergoes surface reconstruction and provides abundant nucleation sites, thereby guiding subsequent electrodeposition to form uniformly distributed crystalline-amorphous phases and a short-range ordered crystalline-amorphous interface. Characterization results reveal that the amorphous regions, via interfacial charge transfer, stabilize the high proportion of Ni³ ⁺ (Ni³⁺/Ni²⁺=1.05) and Co³ ⁺ active sites. Notably, s-NiCo@NF exhibits exceptional HMF oxidation reaction (HMFOR) with the low onset potential of 1.25 V ( vs. RHE) and high current density of 108 mA cm⁻² at 1.5 V( vs. RHE). In-situ Raman test shows that the dynamically formed MOOH (M = Ni/Co) crystalline-amorphous interface achieves the structure self-renewal and drives the adsorption-dehydrogenation oxidation mechanism. Moreover, HMF molecule adsorption forms a protective layer that significantly slows the reduction and deactivation of NiOOH during the reaction, offering new insights into active phase stability. Based on the structural regulation induced by the substrate, this work provides a high-performance nickel-based material for biomass electrocatalytic conversion.