Interfacial Engineering in Ag₂S-bridged Ni₃S₂/Ag₂S-Ag Heterostructure for Promoting 5-Hydroxymethylfurfural...

The electrochemical oxidation of 5-hydroxymethylfurfural (HMF) to high-valued 2,5-furandicarboxylic acid (FDCA) represents a sustainable route to petroleum-derived monomers, yet optimized adsorption and interface-regulated indirect oxidation to promote HMF oxidation reaction (HMFOR) remains a critical challenge. A unique Ag₂S interfacial structure finely tuning Ag and Ni₃S₂ surface (named Ni₃S₂/Ag₂S-Ag) is successfully fabricated at the metal-support junction. The unique Ag₂S interfacial layer serves as an electronic bridge to facilitate directional electron transfer from Ni₃S₂ to metallic Ag, thus promoting the activation of Ni sites. The dynamic Ni²⁺/Ni³⁺ driven HMFOR in Ni₃S₂/Ag₂S-Ag (indirect oxidation), leading to an industrial-grade current density (549.7 mA·cm^-2) and high FEs (FE_HMFOR of 90.2% and FE_4-NPRR of 83.5% within 266 h regeneration) in the coupled HMFOR and 4-nitrophenol reduction reaction (4-NPRR) system. Techno-economic analysis reveals a net profit of $2,637/ton HMF converted, with the strong feasibility for large-scale application. In situ Raman spectroscopy confirms the valence-state-mediated indirect oxidation mechanism. Density functional theory calculations and transient electrochemical analysis demonstrate that the metal phase (Ag) significantly optimizes the substrate adsorption. Furthermore, the deactivation reasons and the regeneration methods for Ni₃S₂/Ag₂S-Ag have been explored. The regenerated bifunctional catalyst developed in this study provides a feasible strategy for the large-scale sustainable production of high-value-added chemicals.