Zeolitic-imidazolate Framework (ZIF)@ZnCo-ZIF Core-shell Template Derived Co, N-doped Carbon Catalysts for Oxygen Reduction Reaction
Abstract
Exposure of the active sites directly determines the catalytic activity of porous carbon electrocatalysts for oxygen reduction reaction (ORR). How to maximally expose these active sites in as-synthesized carbons is still a great challenge. Here we propose an efficient strategy to maximally expose the active sites of porous carbon catalysts, in which we use core-shell ZIF-8@ZnCo-ZIF (op-ZnCo-ZIF) as a precursor to synthesize Co, N-doped carbon catalysts (op-ZnCo-950) by pyrolysis. The low boiling metal Zn in the core-shell template can serve as the activation agent to yield the micropores and mesopores, and the cobalt in the shell is therefore dispersed well in the surface of as-synthesized carbons during the pyrolysis. As a result, the resultant op-ZnCo-950 exhibits a relatively high catalytic activity towards ORR with a half-wave potential of 0.846 V (vs RHE), and the higher methanol resistance and better stability than 20% Pt/C. This work provides an efficient core-shell template strategy for synthesis of carbon catalysts with highly exposed active sites for electrochemical applications including ORR, hydrogen evolution reaction and oxygen evolution reaction.
