Hierarchical Mo-decorated Co3O4 nanowire arrays on Ni foam substrates for advanced electrochemical capacitors

Abstract

Herein, we report the synthesis of hierarchical small quantity Mo-decorated Co3O4 nanowire arrays on nickel foam substrates by a powerful two-step solution-based method. The "oriented attachment" and "self-assembly" crystal growth mechanisms are proposed to discuss the growth of the Mo-decorated Co3O4 heterostructures. This heterostructure material with a high specific surface areas provides an extraordinarily high area capacitance of 3.5 F cm−2 at a current density of 17 mA cm−2 (∼2000 F g−1 at a current density of 10 A g−1) in the initial cycles, compared with a bare Co3O4 nanowire array electrode with 2.2 F cm−2 at 17 mA cm−2 (∼1257 F g−1 at 10 A g−1), exhibiting a significant increase in the capacitance of around 60%. When the current density of the hybrid array is increased by 20 times (1.7 to 34 mA cm−2), more than 73% of the specific capacitance can be maintained, which shows a good rate performance. Such a growth approach offers a versatile technique for the design and synthesis of metal oxide hierarchical nanoarrays for electrochemical energy storage applications.