Phosphine based covalent organic framework as an advanced electrode material for electrochemical energy storage

Covalent organic frameworks (COFs) are designable polymers that have received great research interest and are regarded as reliable supercapacitor (SC) electrode materials. However, the poor capacitive performance in pristine form due to their insoluble non-conductive nature is the primary concern that restricts their long term use for energy storage applications. Owing to the increased requirements for electrochemical energy storage systems, exploiting porous architectures with abundant channels, high surface areas, and electrical conductivities as a type of promising electrode material for pseudocapacitors is vital. Keeping this in mind, Phosphine (PPh₃)-based COF denoted as (Phos-COF-1) is being reported for the first time for SCs application. The as-prepared material was characterized by various characterization tools to gain insight into its textural and structural properties. The structural analysis revealed the crystalline nature of the sample. Remarkably, the BET analysis indicated a high surface area of ~ 818 m² g⁻¹ with the pore diameter centered at 1.56 nm, demonstrating the microporous structure of the sample. The SEM and TEM analysis further confirm the ordered micropore structure of the as-prepared sample as one of the most characteristic features of COFs materials. The average particle size ranges from 11 to 13 μm. The electrochemical analysis showed the pseudocapacitive nature of the Phos-COF-1 electrode with improved reversible redox properties that originated from the phosphine moieties. More importantly, when Phos-COF-1 was employed as an electrode material for SCs exhibited a specific capacitance of 100 F g⁻¹ at the current density of 1 A g⁻¹, a high energy density of 32 Wh kg⁻¹ at the power density 0.4 W kg⁻¹ within a potential window of 0.8 V. We discovered that the Phos-COF-1 electrode provides fast pathways for ion transport and shorten the ion diffusion path owing to its high surface area, and porous structure, demonstrating its great potential for electrochemical energy storage systems in the future.