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, M(NH), MS), 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[NiPcS] (M=Co/Ni/Cu), which are synthesized via coordination of octathiolphthalocyaninato nickel (NiPc(SH)) with various metal centers. Due to a fast kinetic and high activity of CoS sites for GOR, the electrocatalytic tests demonstrate that Co[NiPcS] supported on carbon paper displays a low GOR potential of 1.35 V vs. RHE at 10 mA cm, significantly reducing the overall water-electrolysis-voltage reduction by 0.27 V from oxygen evolution reaction to GOR, thereby outperforming Ni[NiPcS] and Cu[NiPcS]. Additionally, we have determined that the GOR activity of CoX linkage sites varies with different heteroatoms, following an experimentally and theoretically confirmed activity order of CoS>CoO>Co(NH). The GOR performance of Co[NiPcS] 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.