Salt shielded preparation of MOF-derived open hollow carbon structure in air for high-performance supercapacitors

Abstract

N-doped open hollow carbon structure is superb electrode material for supercapacitors due to its unique structure; however, it is often synthesized in an inert atmosphere at high temperature to be protected oxidation, resulting in massive inert gas consumption. Herein, a salt shielding strategy is developed to synthesize N-doped open hollow carbon structure by pyrolysis of zinc-containing zeolitic imidazolate framework at high temperature in air, saving massive inert gas. ZIF-8 template as well as the corrosion of molten salt and oxygen on the carbon structure is demonstrated to play the major role on the formation of the open hollow structure with a high specific surface area of 1589.23 m2 g−1. Applied as electrode material for symmetrical supercapacitors, as-sythesized carbon structure exhibits a high three-electrode specific capacitance of 339 F g−1 at 1 A g−1, a two-electrode capacitance performance of 315 F g−1 at 1 A g−1 and a long-term cycling stability with 98.9% of initial capacitance retention undergo 20 000 cycles at 5 A g−1 in 1 M H2SO4. This salt shielding strategy may be expanded to other non-oxide material synthesis field for energy storage applications to solve the bottleneck problems in industrial production.