Morphology engineering of Co-MOF nanostructures to tune their electrochemical performances for electrocatalyst and energy-storage applications supported by DFT studies

Cobalt (Co) based materials are promising candidates for energy-related applications because of its inexpensiveness, and promising activities, such as redox properties, electrocatalytic, energy storage and so on. The simple approach with enhanced performance of Co-based materials is highly desirable for real-world energy-related applications. In this work, we have prepared the shape-controlled cobalt phenylphosphonate (CP) organic framework nanostructures (CP-nanosheets in H₂O, CP-nanoflakes in C₂H₅OH, CP-nanorods in H₂O/C₂H₅OH and CP-triangular nanosheets in CH₃OH) by changing the solvent polarity in a simple hydrothermal/solvothermal (HS) method. The prepared CP nanostructure materials were utilized for the methanol oxidation and supercapacitor applications. It was observed that CP-nanorods exhibited excellent catalytic performance towards methanol electro-oxidation and energy storage performance when compared to other CP nanostructures due to the availability of large electroactive sites, which was also supported by density functional theory (DFT) studies. The fabricated CP-nanorods based electrode exhibited a good catalytic constant (7.79 × 10⁵cm³⋅mol⁻¹⋅s⁻¹), higher oxidation peak current (2.97 ± 0.11 mA cm⁻²) for methanol oxidation and also delivered high specific capacity of 218 C g⁻¹ at 0.25 A/g, good long-term stability (82 %) up to 8000 cycles when used as electrode materials for supercapacitor application.