In Situ Tracking of Programmable Reconstruction in Metal-Organic Frameworks Toward Ampere-Level Urea Oxidation

Understanding the dynamic evolution of catalyst coordination structures during electrochemical nucleophilic oxidation reactions (NORs) is essential for deliberately controlling phase reconstruction to define active motifs, yet remains elusive to date. Herein, a lattice-strained NiMn-based metal-organic framework (L/NiMn-MOF) engineered with abundant unsaturated coordination motifs was used as a model system to systematically investigate the dynamic phase transformation pathway during urea oxidation reaction (UOR). By integrating a multimodal in situ and operando diagnostic platform, we reveal a programmable phase evolution from the pristine MOF to metal hydroxides and subsequently to active oxyhydroxide phases, ultimately driving chemical hydrogen transfer via a three-step chemical-electrochemical-chemical (C-E-C) oxidation mechanism toward UOR. Enabled by a programmable in situ reconstruction pathway that yields well-defined active phases, the L/NiMn-MOF-derived NiMnOOH achieves 1.5 A cm^-2 at 2.1 V in a urea-assisted membrane-electrode assembly-based device (MEA) and maintains robust stability across a broad operational window of 200-1000 mA cm^-2. This work outlines a general in situ framework for clarifying reconstruction-activity relationships toward an efficient urea-assisted MEA device, with potential extension to related NOR catalysis.