Self-Reconstructed CuO@Ni-Metal–Organic Framework Heterostructures for Scalable and Versatile Electrocatalytic Biomass Valorization

The electrochemical upgrading of 5-hydroxymethylfurfural (HMF) to high-value 2,5-furandicarboxylic acid (FDCA) offers a sustainable route for biomass valorization. However, the development of robust, energy-efficient electrocatalysts capable of industrial-scale operation remains a significant challenge. Herein, we report a hierarchical CuO@Ni-MOF heterostructure grown in situ on a conductive copper foam substrate via a self-reconstruction strategy. This design strategically couples the conductive network of the substrate with the porous, active-site-rich architecture of Ni-MOF. Crucially, the intimate contact at the heterostructure interface induces significant electronic interactions and charge redistribution, as evidenced by the binding energy shifts in XPS and reduced charge transfer resistance. In a standard three-electrode system, the optimized catalyst delivers exceptional intrinsic activity, achieving near-unity HMF conversion (100%) and FDCA yield (99%) with a Faradaic efficiency of 99% at a low potential of 1.43 V vs RHE. To demonstrate practical scalability, the electrode was integrated into a membrane electrode assembly flow reactor. The system maintained stable electrolysis at a high current density of 100 mA cm–2 for over 50 h, outperforming conventional batch reactors. Furthermore, the CuO@Ni-MOF electrode displays exceptional versatility in upgrading various biomass-derived polyols, including glycerol and ethylene glycol, into value-added organic acids. This work highlights the potential of interface-engineered MOF-based heterostructures for energy-efficient and scalable biomass refining.