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

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.