Fabrication of high-performance supercapacitor of surface-engineered ZIF-8 for energy storage applications

Electrical conductivity and surface area of nanomaterials are two critical factors that affect their efficacy as energy storage devices. Metal-organic frameworks (MOFs) have gained significant interest in the field of highperformance supercapacitors due to their expansive specific surface area and adjustable pore structure. Enhancing the conductivity of MOFs can be achieved by incorporating conductive materials with it. Here, surface-engineered Ag-deposited Zeolitic imidazolate framework-8 (ZIF -8) was developed (1-Ag@ZIF-8 and 2Ag@ZIF-8) utilizing an electroactive biofilm for energy-storage applications. In this context, ZIF -8 was synthesized independently and then subjected to treatment with silver nanoparticles (Ag NPs) by applying the environmentally friendly approach. The Ag nanoparticles loaded onto ZIF -8 was tested for their performance based on the amount of Ag and assess its electrochemical performance. Spherical Ag NPs were successfully deposited on ZIF -8 and having the diameter in the rage of 6 - 12 nm with some large similar morphological characteristics. Further, an exceptionally high specific capacitance of 538.8 F g -1 was observed at a current density of 1 A g -1 , which was approximately two- and three-fold higher than those of 1-Ag@ZIF-8 and ZIF -8, respectively. A long cycle stability (83.3 % capacity retention at 10 A g -1 ) was obtained over 5000 cycles. This study provides interesting insights into the improvement of the overall performance of active materials by tuning their surface characteristics and conductivity via an electroactive biofilm approach.