Impact of Ligand in Bimetallic Co, Ni-Metal-Organic Framework towards Oxygen Evolution Reaction

Emerging materials based on metal-organic frameworks (MOFs) have the potential to be used in electrocatalytic energy storage applications. Nevertheless, a large-scale feasible useage of MOFs is hampered by the low conductivity and masking of the active metal centre by the organic linker. In this study, a NiCo-based benzene tricarboxylic (BTC) electrocatalyst was successfully synthesized, and the properties were fine-tuned with 4,4 '- bipyridine as a second ligand which benefits the charge transfer kinetics through non-covalent 7C-7C interaction. This approach yields an exceptional performance towards oxygen evolution reaction (OER) at three different KOH concentrations 1, 0.5, and 0.1 M. The electrocatalyst NiCo-Bpy-BTC when tested under three different concentrations of KOH, exhibited overpotentials of 292, 343, and 407 mV to reach the 10mA cm-2 current density respectively. The obtained Tafel slope values were lower than those of Ni-Bpy-BTC, Co-Bpy-BTC, and bare NiCo-BTC respectively. Moreover, we have achieved long-term durability for up to 16 h in all KOH concentrations. Our strategy interconnects reticular chemistry and materials electrochemistry and this new approach is useful in the design of new materials for energy-related applications.