Wall-like hierarchical metal oxide nanosheet arrays grown on carbon cloth for excellent supercapacitor electrodes

Abstract

Recently, considerable efforts have been made to satisfy the future requirements of electrochemical energy storage using novel functional electrode materials. Binary transition metal oxides (BTMOs) possess multiple oxidation states that enable multiple redox reactions, showing higher supercapacitive properties than single component metal oxides. In this work, a facile hydrothermal method is provided for the synthesis of wall-like hierarchical metal oxide MMoO₄ (M = Ni, Co) nanosheet arrays, which are directly grown on flexible carbon cloth for use as advanced binder-free electrodes for supercapacitors. By virtue of their intriguing structure, the resulted active material nanosheets with a high specific surface area can provide a large electroactive region, which could facilitate easy accession of electrolyte ions and fast charge transport, resulting in an enhanced electrochemical performance. Separately, the as-synthesized MMoO₄ (M = Ni, Co) samples have exhibited superior specific capacitances (1483 F g⁻¹ of NiMoO₄ and 452 F g⁻¹ of CoMoO₄ at a current density of 2 A g⁻¹), as well as excellent cycling stability (93.1% capacitance retention of NiMoO₄ and 95.9% capacitance retention of CoMoO₄ after 2000 cycles). The results show that the binder-free electrodes constructed by deposition of MMoO₄ (M = Ni, Co) nanosheets on carbon cloth are promising candidates for the application of supercapacitors.