Highly exposed active sites of MOFs-derived N-doped nanoporous carbon decorated with platinum for enhanced energy storage application

Abstract

The depletion of traditional energy sources, such as fossil fuels, has prompted the direct synthesis of materials with high-capacity performance for energy storage applications. Nitrogen-doped porous carbon (NPC) derived from Zeolite imidazole framework ZIF-8 stands out as a prime candidate for the development of electrochemical double-layer capacitors (EDLCs) due to their high stability and versatile morphology. In this study, the surface of NPC supported onto nickel foam (NF) was decorated with platinum nanoparticles (PtNPs) using an efficient and cost-effective electrodeposition method. The electrodeposition conditions were evaluated in the form of deposition potential and time. PtNPs-decorated NPC electrode deposited at −0.4 V for 120 s shows outstanding properties compared to other electrodes. The electrochemical properties of fabricated electrodes were assessed in 6 M KOH using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). The PtNPs-NPC at −0.4 V electrode demonstrated a remarkable characteristic specific capacitance (Cs) of 1700 ± 1.12 F g−1 at 0.2 A g−1. This electrode displayed high cyclic stability, with only a 2.0 % reduction in its capacitance retention over 5000 cycles. The Cs of PtNPs-NPC at −0.4 V smoothly declined in the first 1000 cycles from 1164.73 ± 1.02 to 1153.20 ± 1.16 F g−1, with a retention of 99.01 %. Even after 5000 cycles, it becomes 1142.25 ± 1.16 F g−1 with a retention of 98.07 %. PtNPs-decorated NPC at −0.4 V also showcased the highest energy density (E) and power density (P) of 80 ± 1.11 Wh kg−1, and 1038.42 ± 1.32 W kg−1, respectively. In contrast, the pristine NPC exhibited an E, and P of 25.0 ± 1.92 Wh kg−1, and 882.0 ± 1.52 W kg−1, respectively. Our strategy demonstrates a new strategy for decoration of NPC surface, opening up possibilities for further exploration of different NPs to engineer promising electrode materials for supercapacitor (SCs) applications.