5-Hydroxymethylfurfural (HMF) serves as an important bridge connecting biomass resources with fossil fuels. Its downstream product, 2,5-furandicarboxylic acid (FDCA), is a renewable alternative to terephthalic acid (TPA) in the synthesis of various polymer materials. In this study, we successfully synthesized four ruthenium-based catalysts with varying valence states supported on carbon nanotubes (CNTs) and compared the performance of HMF electrooxidation. Among these, the Ru^+2.9 catalyst demonstrated the highest activity for the electrochemical oxidation of HMF to FDCA in the neutral medium (0.1 M K₂SO₄). Notably, the FDCA yield reached 90.2% under an applied potential of 0.95 V (vs. Ag/AgCl) after 24 h. Mechanistic analysis revealed that the superior specific capacitance of the Ru^+2.9 catalyst significantly facilitated the reaction process. This work represents a more cost-effective approach to avoid the need for excessive alkaline additives during catalyst preparation and the HMF oxidation process, and FDCA separated easily after cooling the reaction solution down.

In pursuit of sustainable energy, electrochemical hydrogen production is a promising route to generate clean hydrogen fuel. This study presents a novel catalyst, Cu@Ni/MoN, with a pine-needle-like architecture for high-current-density hydrogen evolution reaction (HER) in alkaline media. Copper-based catalysts are cost-effective and abundant but typically exhibit limited intrinsic HER activity. By depositing Cu onto a nickel/molybdenum nitride (Ni/MoN) support, we create a unique needle-like structure that greatly increases the electrochemically active surface area and enhances mass transfer, leading to significantly improved catalytic performance. Experimental results demonstrate that Cu@Ni/MoN outperforms commercial Pt/C, exhibiting an overpotential 165 mV lower at 500 mA cm−2. The enhancement arises from the synergistic interaction between copper species and the Ni/MoN support, along with favorable electronic modulation induced by Cu deposition, which optimizes hydrogen adsorption kinetics. Density functional theory (DFT) calculations confirm the downshift of the d-band center and reduced hydrogen binding strength, elucidating the origin of the improved HER activity. This work demonstrates an effective strategy for designing non-noble metal catalysts to achieve high-performance, industrial-scale hydrogen production.