Synthesis of porous NiCoS nanosheets with Al leaching on ordered mesoporous carbon for high-performance supercapacitors

Abstract

The ordered mesoporous carbon (SBA-C) with parallel channels, synthesized using mesoporous silicon (SBA-15) as a hard template, is decorated with nanoflowers assembled by porous nickel cobalt sulfide (NiCoS) nanosheets with Al leaching through an oil bath following by a hydrothermal method. The nickel cobalt aluminum layered double hydroxide (NiCoAl LDH) precursor is successfully in-situ transformed into NiCoS nanosheets with Al leaching due to the replace of OH− and CO32− ions of the NiCoAl LDH precursor by S2− and the Kirkendall effects to etch and dissolve Al hydroxide. The NiCoS@SBA-C electrode shows surprising electrochemical performance, such as an excellent specific supercapacitance of 1757 F g−1 at a current density of 1 A g−1, superior rate capacity of 79.68% retention at 20 A g−1, and good cycling stability. An asymmetric supercapacitor (ASC) is assembled employing NiCoS@SBA-C as positive electrode and SBA-C as negative electrode, which delivers a high energy density of 38.8 Wh kg−1 at a power density of 800 W kg−1. The above results revel that incorporating ordered mesoporous carbon with transition metal sulfides is a candidate electrode material for application of energy storage devices.