Synthesis of Nanoporous Carbon-Cobalt-Oxide Hybrid Electrocatalysts by Thermal Conversion of Metal-Organic Frameworks

Nanoporous carbon–cobalt‐oxide hybrid materials are prepared by a simple, two‐step, thermal conversion of a cobalt‐based metal–organic framework (zeolitic imidazolate framework‐9, ZIF‐9). ZIF‐9 is carbonized in an inert atmosphere to form nanoporous carbon–metallic‐cobalt materials, followed by the subsequent thermal oxidation in air, yielding nanoporous carbon–cobalt‐oxide hybrids. The resulting hybrid materials are evaluated as electrocatalysts for the oxygen‐reduction reaction (ORR) and the oxygen‐evolution reaction (OER) in a KOH electrolyte solution. The hybrid materials exhibit similar catalytic activity in the ORR to the benchmark, commercial, Pt/carbon black catalyst, and show better catalytic activity for the OER than the Pt‐based catalyst. Hybrid‐material transformers: Thermal conversion of a cobalt‐based metal–organic framework (ZIF‐9) yields nanoporous carbon–cobalt‐oxide hybrid electrocatalysts (see figure). The resulting hybrid materials exhibit excellent catalytic activities comparable to the benchmark catalysts for both oxygen reduction and evolution reactions, and accordingly may be candidate catalysts for fuel‐cell applications.