Hybrid SnO2@NiCo2O4 Heterostructure With Improved Capacitive Performance

Abstract

In this paper, a two-step, solution-based method and post-calcination were employed to coat NiCo2O4 nanowires arrays onto dense SnO2 thin films which were grown on Ni foam substrates. Owing to the low charge transfer resistance and good electronic conductivity of the SnO2 thin films, the specific SnO2 thin films were used as the supporting backbone. X-ray diffraction and elemental mapping were applied to demonstrate the existence of Ni, Co, O, Sn while the hierarchical structure and morphology of SnO2@NiCo2O4 were analyzed by field emission scanning electron microscopy. The electrochemical performance of SnO2@NiCo2O4 was also investigated in a three-electrode system. The as-formed SnO2@NiCo2O4 electrode had outstanding electrochemical performance (1.49 F cm−2 at 1 mA cm−2) and good cycling stability (retaining 86% after 2000 cycles). On the one hand, the excellent pseudocapacitive performance was mainly due to the addition of the SnO2 thin films, which served as a conducting oxide thin film to provide low charge transfer resistance. On the other hand, the SnO2 thin films offered a more effective place for the growth of NiCo2O4 nanowires arrays than the bare Ni foam substrates. The perfect electrochemical performance of these hybrid nanomaterials showed their potential in supercapacitor electrodes.