Tri-metal centers governed Zn-Co oxide/HfO2@bimetallic Ni-Pd alloy catalyst synthesized herringbone carbon nanofiber for supercapacitor electrode

초록

In order to develop cutting-edge electrode materials for potential supercapacitors application, innovative design and smart combination of pseudocapacitive-type mixed transition metal oxide with nanocarbons are technically essential undertakings. In this context, we propose a facile and economically viable approach is proposed for synthesizing a ternary hybrid composite electrode based on bimetallic Zn-Co mixed oxide, herringbone carbon nanofibers (CNFs), and ferroelectric HfO2 (ZnCoO/HfO2@CNF) for supercapacitor applications. Herringbone CNFs having small diameters (similar to 9 nm) were synthesized using Ni-Pd alloy catalyst. The growth process shifted from surface diffusion to bulk diffusion in presence of alloy catalysts and subsequently, herringbone CNFs were formed instead of CNTs. Taking advantages of the synergistic contributions of herringbone nanocarbons and bimetallic metal oxide, the hierarchical ZnCoO/HfO2@CNF offered excellent structural integrity and effective platform for the diffusion of ions/electrons for reversible Faradaic reactions and surface charge storage mechanism. Notably, the hybrid electrode displayed better electrochemical performance than its binary counterpart as well as the ternary CNT-based composite. Furthermore, the corresponding asymmetric supercapacitor (ASC) device exhibited promising electrochemical performances with a superior energy density (62 Wh/kg) and enhanced cyclic stability (capacitance retention of similar to 86.5 % after 30000 GCD cycles). Additionally, a flexible ASC prototype was fabricated using ionic electrolyte, demonstrating its potential for wearable and flexible supercapacitors.

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