Facile synthesis of hierarchical flower-like NiMoO4-CoMoO4 nanosheet arrays on nickel foam as an efficient electrode for high rate hybrid supercapacitors

Abstract

• Flower-like NiMoO 4 CoMoO 4 nanosheet arrays (NSAs) are grown on Ni foam using facile chemical bath deposition route. • NiMoO 4 CoMoO 4 NSAs used as a battery-type material for supercapacitor applications. • Unique NiMoO 4 CoMoO 4 NSAs are favourable for rapid ion and electron transfer. • NiMoO 4 CoMoO 4 NSAs electrode exhibit the superior electrochemical properties than bare NiMoO 4 and CoMoO 4 . • Hybrid supercapacitor (NiMoO 4 CoMoO 4 NSAs//G-ink) delivers the high specific energy, specific power and long-term cycling stability. Binder-free hierarchical flower-like NiMoO 4 CoMoO 4 nanosheet arrays (NSAs) have been successfully grown on nickel (Ni) foam surface via a facile one-step chemical bath deposition method followed by calcination treatment. The as-prepared NiMoO 4 CoMoO 4 NSAs electrode material has been effectively used as a battery-type material for supercapacitor applications. Surface morphological and structural studies reveal that the as-fabricated NiMoO 4 CoMoO 4 electrode exhibits a flower-like heterostructures constructed with interconnected nanosheet arrays. In a three-electrode system, the potential plateaus from the cyclic voltammetry and galvanostatic charge–discharge measurements indicate that the obtained NiMoO 4 CoMoO 4 NSAs electrode exhibits Faradic battery-type redox behaviour, which is different form the profiles of carbon-based materials. As a battery-type material, NiMoO 4 CoMoO 4 NSAs electrode delivers a remarkable specific capacity of (~236.86 mA h g −1 at 2 A g −1 ), excellent rate capability (~92.44% retains even at 10 A g −1 ), and superior cycling stability (~97.19% at 6 A g −1 over 5000 cycles), which are much higher than those of the bare NiMoO 4 and CoMoO 4 electrodes. The superior electrochemical properties of the NiMoO 4 CoMoO 4 composite material are due to the synergetic effect from CoMoO 4 and NiMoO 4 and to the fact that the hierarchical nanosheet arrays provide abundant electroactive sites for rapid redox reactions. Additionally, hybrid supercapacitor (HSC) has been assembled using NiMoO 4 CoMoO 4 NSAs/Ni foam as the positive electrode and graphene-ink/Ni foam as the negative electrode. It is found to exhibit a good cycling stability and a high specific energy of 27.58 Wh kg −1 at a specific power of 636.05 W kg −1 . Thereby, these electrochemical performances suggest that the as-fabricated NiMoO 4 CoMoO 4 NSAs are promising candidates for electrodes in high-performance supercapacitors.