Highly mesoporous structure nickel cobalt oxides with an ultra-high specific surface area for supercapacitor electrode materials

Abstract

Highly mesoporous structure nickel cobalt oxides with an ultra-high specific surface area are synthesized through a sol–gel method by using silica derived from tetraethoxysilane hydrolysis as a template. The structural and morphological characteristics of the oxides are determined using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, and N2 adsorption experiments. The electrochemical properties, including capacitance, of the oxides are analyzed through cyclic voltammetry, AC impedance spectroscopy, and charge–discharge tests in 7 M KOH under ambient conditions. The as-prepared nickel cobalt oxides possessing an ultra-high specific surface area of 438.3 m2 g−1 and a mesoporous structure exhibit a high specific capacitance of 1157.7 F g−1 and a long-term cyclic stability (97.13 % capacity retention after 5000 cycles). Thus, the prepared oxides are promising for supercapacitor applications.