One-Step Synthesis of 2D Nanosheet-Constructed FeNi-S@NF Nanoflowers for the Electrocatalytic Oxidation of 5-Hydroxymethylfurfural.

Electrocatalytic oxidation of 5-hydroxymethylfurfural to prepare high-value-added chemicals is an effective solution for a sustainable alternative to fossil fuels. We report a novel one-step hydrothermal sulfurization strategy to construct hierarchical FeNi-S@NF nanoflower architectures comprising interconnected 2D nanosheets. This catalyst design synergistically integrates high conductivity (i.e., nickel foam (NF) substrate), abundant active sites (i.e., 2D nanosheet), and optimized electronic structure (i.e., sulfur doping), achieving exceptional electrocatalytic 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) conversion. By optimizing the classical two-step hydrothermal sulfidation approach through precise control of metal ratios and sulfidation duration, we significantly enhanced the catalytic performance for the HMF oxidation reaction (HMFOR). Sulfur doping was found to substantially improve the catalyst's adsorption capability for HMFOR intermediates, thereby enhancing both activity and selectivity toward FDCA production. The optimized FeNi-S@NF nanoflower catalyst demonstrated superior electrocatalytic performance in 1 M KOH + 50 mM HMF, achieving 98.41% conversion rate, 92.08% FDCA yield, and 89.19% Faradaic efficiency at an applied potential of 1.45 V vs a reversible hydrogen electrode (RHE), surpassing most reported transition metal-based electrocatalysts. This research work provides a new strategy for the rapid and low-cost synthesis of two-dimensional sulfide nanoelectrocatalysts for the efficient electrooxidation process of biomass derivatives.