Electrochemical Exfoliation of the Two-Dimensional Conjugated Metal-Organic Framework for High-Performance Urea Electrooxidation.

Li, Yong; Yu, Xiang; Fan, Yu; Zhang, Guangxun; Zhang, Songtao; Meng, Zhenyang; Qiu, Ziming; Su, Yi-Chun et al. · ACS Nano · 2025

basic_science · Level V

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Abstract

Two-dimensional (2D) conjugated metal-organic frameworks (c-MOFs) have attracted extensive interest in electrochemical fields due to their inherent electrical conductivity. However, the severe interlayer stacking still poses barriers toward their potential applications. The reliable synthesis of ultrathin c-MOF nanosheets is crucial yet remains challenging. Herein, we demonstrate an electrochemical exfoliation approach to obtain ultrathin nanosheets from layer-stacked c-MOF crystals. Our results reveal the electric field-induced ion intercalation mechanism and provide a viable method for the synthesis of ultrathin M-HHTP (M = Ni, Cu, Co; HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) nanosheets. To prove utility, the obtained Ni-HHTP nanosheets as urea oxidation reaction (UOR) catalysts achieve an ultrahigh current density of 165.7 mA cm<sup>-2</sup> at 1.35 V versus a reversible hydrogen electrode and nearly 100% selectivity of N-products. Experimental characterization and theoretical calculations reveal that the fully exposed square planar NiO<sub>4</sub> active centers effectively reduce the energy barrier of C-N bond cleavage for UOR and suppress the parasitic oxygen evolution reaction.