Hollow hierarchical zinc cobalt sulfides derived from bimetallic-organic-framework as a non-precious electrocatalyst for oxygen reduction reaction

초록

Herein, pyrolysis strategy assisted by a dual-metal-ZIF is developed to synthesize porous zinc cobalt sulfide supported on nitrogen and sulfur co-doped carbon (Zn-Co-S@NSC). A dodecahedral ZIF architecture is first constructed with two metal sources, followed by a pyrolysis process with thiourea to obtain hollow composite materials consisting of Zn-Co sulfide uniformly dispersed on nitrogen and sulfur co-doped carbon. Benefitting from the distinctive structure and synergistic effect of the binary metal system, the as-prepared Zn-Co-S@NSC displays excellent electrocatalytic performance on ORR in alkaline condition. The superior performances, which are evaluated in terms of onset-potential (0.955 V vs. RHE) and half-wave potential (0.831 V vs. RHE), are comparable to the conventional Pt/C catalyst. In addition, Zn-Co-S@NSC exhibits remarkable electrochemical durability and exceptional methanol tolerance compared to the commercial Pt/C. The DFT calculations further demonstrate that the binary metal system can promote electrocatalytic activity by optimizing the reaction free energy for intermediates of ORR.

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