A self-activation strategy to prepare ZIF-8 derived N,O co-doped meso–microporous carbon for zinc ion hybrid capacitors†

Abstract

Porous carbon derived from metal–organic frameworks (MOFs) is usually carbonized and then activated by additional introduction of potassium hydroxide. The use of a large amount of strong alkali during the reactivation process not only corrodes equipment but also pollutes the environment, which is not conducive to large-scale production. Herein, for the first time, we report a novel self-activation strategy for the fabrication of porous carbon derived from zeolitic imidazolate framework-8 (ZIF-8), where the activator ZnCl₂ is derived from the pickling step following the initial carbonization of ZIF-8. The optimized porous carbon (ZPC-800) materials show a high specific surface area with an interconnected micro/mesoporous structure and massive nitrogen (17.3 at%) and oxygen (9.5 at%) functional groups. As a result, the assembled Zn//ZnSO₄(aq)//ZPC-800 hybrid capacitor achieves a high capacity of 165.2 mA h g⁻¹ and an impressive energy density of 111.2 W h kg⁻¹. This study provides a new method for the preparation of porous carbon materials derived from MOFs for zinc ion hybrid capacitors.