Porous Carbon Nanosheets Derived from ZIF‐8 Treated with KCl as Highly Efficient Electrocatalysts for the Oxygen Reduction Reaction

Abstract

Developing advanced electrocatalysts for the oxygen reduction reaction (ORR) is a critical reaction in fuel cells. Metal–organic framework (MOF)‐derived nitrogen‐doped carbons have been widely reported as promising electrocatalysts for ORR. Herein, a KCl‐assisted pyrolysis method is reported to prepare N‐doped porous carbon nanosheets (NCNS). During pyrolysis preparation, KCl crystals act as templates and activator, penetrating the ZIF‐8‐derived carbon material via capillarity, which facilitates the formation of micro‐ and mesopores carbon nanosheets. By adjusting the KCl dosage and pyrolysis temperature, the carbon material structure, nitrogen species, and graphitization degree are effectively controlled. The optimal NCNS‐10‐900 catalyst exhibits a higher half‐wave potential (≈0.88 V) in alkaline solution, which is even better than Pt/C (≈0.86 V). The NCNS‐10‐900 also exhibits outstanding long‐term stability with an only 17 mV shift in half‐wave potential after a 10K cycle durability test. All of these high properties are ascribed to the high specific surface area, the abundant microporous and mesoporous nanosheet structure, and the synergistic effects of the N species with intrinsic activity. This strategy of using a KCl‐assisted pyrolysis MOF provides a feasible method to explore highly efficient and robust non‐noble metal catalysts for energy‐conversion reactions.