Facile electrochemical conversion strategy for fabricating cobalt-based double metal sulfide nanosheets with high capacity and low electrochemical impedance

• Main Authors: Han, Dandan, Wang, Ping, Dang, Yupeng, Zhu, Feng, Wang, Dongxu, Shen, Zexiang, Wei, Yen
• Other Authors: School of Physical and Mathematical Sciences
• Format: Article
• Language: English
• Published: 2024
• Subjects: Physics; Hybrid supercapacitors; Electrochemical conversion
• Online Access: https://hdl.handle.net/10356/180647
• Institution: Nanyang Technological University

The transformation of metal-organic frameworks (MOFs) into customizable metal compounds with tailored pore structures is considered an effective approach for enhancing electrical conductivity as electrode materials. However, conventional MOF conversion methods often involve intricate high-temperature reactions, posing challenges in precisely controlling the composition, pore structure, and active sites of MOF-derived energy storage materials. Here, we propose a novel electrochemical conversion method for MOFs to be converted into cobalt-based bimetallic sulfides, thereby improving the low conductivity of MOFs and inheriting a porous skeleton for high-energy water-based charge storage. The extent of MOF transformation was assessed using X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy at varying Ar+ etching depths. Consequently, a zinc-cobalt sulfide (ZnCoS/NF) on highly porous nickel foam can be engineered for water-phase supercapacitor energy storage. Furthermore, the electrode exhibits a specific capacity of 566.5 mAh·g−1 at 1 A·g−1 and demonstrates excellent operational stability under large current fluctuations. Additionally, hybrid supercapacitors coupled with ZnCoS//AC can deliver a maximum energy density of 56.9 Wh·g−1 and a power density of 232.4 W·kg−1.