Enhanced oxygen evolution reaction and lithium-ion storage performance of MOF-derived NiCo2O4-NiO-Co@graphene composites: Effect of carboxylic ligand group

Metal-organic framework (MOF) derived composites have attracted significant attention due to their potential in electrochemical energy storage and conversion applications because of their unique properties, including high surface area, tunable pore size, and functionalized ligand groups. We synthesized graphene-coated transition metal oxides (NiCo2O4-NiO-Co) composites (C-NiCo) using a straightforward MOF precursor method and unraveled the effect of carboxylic ligand groups on their electrochemical performance. The results showed that the numbers and positions of carboxylic groups in the ligands could modulate the exposure level of the active metal centers and their local reduction environment, which led to improved oxygen evolution reaction (OER) and lithium-ion storage performances. Notably, the C-NiCo135 composite, derived from 1,3,5-benzene tricarboxylic acid as the organic linker, exhibited a remarkable specific capacity of 1058 mAh g−1 in lithium-ion storage, while the C-NiCo14 composite, derived from 1,4-benzene dicarboxylic acid, displayed a significantly reduced overpotential for OER. This work highlights the importance of rational design and synthesis of MOF-derived composites for optimizing their electrochemical properties and provides insights for developing efficient and sustainable energy storage and conversion materials.