Metal-Phthalocyanine-Based Two-Dimensional Conjugated Metal-Organic Frameworks for Electrochemical Glycerol Oxidation Reaction.

Electrochemical glycerol oxidation reaction (GOR) is a promising candidate to couple with cathodic reaction, like hydrogen evolution reaction, to produce high-value product with less energy consumption. Two dimensional conjugated metal-organic frameworks (2D c-MOFs), comprising square-planar metal-coordination motifs (e.g., MO ₄ , M(NH) ₄ , MS ₄ ), are notable for their programable active sites, intrinsic charge transport, and excellent stability, making them promising catalyst candidates for GOR. In this study, we introduce a novel class of 2D c-MOFs electrocatalysts, M ₂ [NiPcS ₈ ] (M=Co/Ni/Cu), which are synthesized via coordination of octathiolphthalocyaninato nickel (NiPc(SH) ₈ ) with various metal centers. Due to a fast kinetic and high activity of CoS ₄ sites for GOR, the electrocatalytic tests demonstrate that Co ₂ [NiPcS ₈ ] supported on carbon paper displays a low GOR potential of 1.35 V vs. RHE at 10 mA cm ^-2 , significantly reducing the overall water-electrolysis-voltage reduction by 0.27 V from oxygen evolution reaction to GOR, thereby outperforming Ni ₂ [NiPcS ₈ ] and Cu ₂ [NiPcS ₈ ]. Additionally, we have determined that the GOR activity of CoX ₄ linkage sites varies with different heteroatoms, following an experimentally and theoretically confirmed activity order of CoS ₄ >CoO ₄ >Co(NH) ₄ . The GOR performance of Co ₂ [NiPcS ₈ ] not only demonstrate superior performance among non-noble metal complex, but also provides critical insights on designing high-performance MOF electrocatalysts upon optimizing the electronic environment of active sites.
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