Abstract
Rational design of advanced cobalt oxides/carbon nanocomposites toward electrocatalytic oxygen reduction has received increasing research attention largely due to the potential synergism between cobalt oxides and carbon support. An efficient CoO/Co-N-C hybrid electrocatalyst has been prepared by high-temperature pyrolysis of ZIF-8 (ZIF = Zeolitic Imidazolate Framework) involving cage-encapsulation of CoCl2 followed by KOH treatment. In the alkaline solution (0.1 M KOH), the optimal CoO/Co-N-C hybrid catalyst (namely C-Co (OH)(2)@ZIF-8-10%-100 0) delivers a half-wave potential (E-1/2) of 0.84 V (vs. RHE), and a high four-electron reduction selectivity. The control experiments reveal that the superb ORR activity with C-Co(OH)(2)@ZIF-8-10%-1000 is jointly contributed by strongly coupled CoO NPs and Co-Nx moieties. Compared to the Pt/C benchmark, C-Co(OH)(2)@ZIF-8-10%-100 0 exhibits comparable ORR performance but better methanol tolerance and electrochemical stability. Besides, the home-made zinc-air battery with C-Co(OH)(2)@ZIF-8-10%-1000 as the air-cathode catalyst displays an open-circuit voltage of 1.43 V and a maximal power density of 96 mW cm(-2). (c) 2022 Elsevier B.V. All rights reserved.
NSTL
Elsevier