Recyclable Green Synthesis of Cu₂O Octahedra via Coordination-Induced Surface Reconstruction With Exceptional Glucose...

Coordination-chemistry-driven reconstruction offers a powerful yet largely unexplored route for transforming bulk metals into functional nanomaterials with programmed surface states. Herein, we report a green, recyclable wet-chemical protocol that integrates top-down oxidative dissolution of copper with bottom-up crystallization to produce octahedral Cu₂O submicron crystals. In a strongly alkaline medium, transient Cu-NH₃ coordination promotes coordination-driven oxidative dissolution of scrap copper to generate a metastable [Cu(OH)₄]^2- aqueous precursor, while aldehyde-functionalized dextran (ODex) serves as a mild reductant and a surface-coordinating ligand. A self-catalytic acceleration pathway enables rapid room-temperature crystallization within minutes, ODex-regulated octahedral Cu₂O (ODex-Octa-Cu₂O) exposing {111} facets, decorated with ODex-Cu²⁺ complexes and stabilized Cu-vacancy-rich relaxed atomic layers. This coordination-induced surface reconstruction tailors the surface electronic and defect structure; density functional theory further reveals the Frontier orbital theory evolution upon ODex-Cu²⁺ modification of Cu₂O(111) and the concomitant work function regulation, which together stabilize the lattice and optimize interfacial adsorption-desorption kinetics. Meanwhile, ODex-Octa-Cu₂O exhibits ultrahigh mass-normalized activity for 4-nitrophenol hydrogenation (k_nor = 32.36 s^-1 mg^-1 mL), benefiting from the in situ generated surface-active hydrogen, and efficient glucose electrooxidation enabling a bifunctional glucose fuel cell. The fully recyclable alkaline medium further realizes a sustainable "metal-to-nanomaterial" conversion route.