Expanding the operational horizon of ampere-scale biomass electrorefining via decoupling competing pathways on cuprous-integrated spinel heterostructures

Effectively separates biomass oxidation from parasitic OER using cuprous-integrated spinel heterostructures. • Suppresses OER by thermodynamically elevating the energy barrier for *OH deprotonation. • Unlocks a record-broad anodic potential window for stable high-voltage electrosynthesis. • Sustains ampere-scale currents (>4 A) with near-unity FDCA selectivity (>90%). • Demonstrates exceptional stability up to 2200 mV in a high-flux flow electrolyzer. The industrial viability of electrochemical biomass valorization is fundamentally throttled by the parasitic oxygen evolution reaction (OER), which severely confines the stable operational window. Here, we report a strategy for expanding the operational horizon of ampere-scale biomass electrorefining using a cuprous-integrated NiCo-spinel heterostructure (Ni 1.5 Co 1.5 O 4 -Cu 2 O) that effectively decouples these competing pathways. By engineering a cuprous-integrated heterostructure, we establish a functional dichotomy wherein synergistic Ni/Co sites activate 5-hydroxymethylfurfural, while the Cu 2 O moiety selectively suppresses OER by thermodynamically elevating the *OH deprotonation barrier. This design unlocks a record-broad anodic window and, when integrated into a flow cell, delivers an exceptional 2,5-furandicarboxylic acid yield (> 90%) at industrial-scale currents (> 4 A) across an extended voltage range (up to 2200 mV). In situ spectroscopy and density functional theory calculations validate this mechanism, confirming that optimized interfacial coupling drives the selective 5-hydroxymethyl-2-furancarboxylic acid pathway. This work provides a generalizable electronic-structure engineering strategy for high-performance, scalable organic electrosynthesis. Download: Download high-res image (227KB) Download: Download full-size image Interfacial engineering of a Cu 2 O-integrated NiCo-spinel heterostructure enables a functional-dichotomy strategy to decouple 5-hydroxymethylfurfural oxidation from parasitic oxygen evolution. By thermodynamically suppressing water oxidation, this design unlocks a record-wide operational window for stable, ampere-scale 2,5-furandicarboxylic acid production with near-quantitative yield, significantly expanding the operational horizon of biomass electrorefining.