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Activity Tuning of Cobalt Ferrite Nanoparticles Anchored on N‐Doped Reduced Graphene Oxide as a Potential Oxygen Reduction Electrocatalyst by Zn Substitution in the Spinel Matrix
Author(s) -
Kashyap Varchaswal,
Singh Santosh K.,
Kurungot Sreekumar
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201701684
Subject(s) - electrocatalyst , spinel , materials science , catalysis , cobalt , nanoparticle , oxide , graphene , chemical engineering , inorganic chemistry , electrochemistry , nanotechnology , electrode , chemistry , metallurgy , engineering , biochemistry
Abstract Development of highly efficient and durable ORR catalysts by using non‐platinum group metals (such as Co, Fe, Mn, and Zn) is a challenging task in the forward path towards the realization of low‐cost energy devices in the commercial stream. The present work deals with an effective strategy wherein an efficient Pt‐free electrocatalyst for oxygen reduction reaction (ORR) is prepared by stoichiometrically substituting some fraction of Fe with Zn in cobalt ferrite and anchoring these spinel nanoparticles on nitrogen doped reduced graphene oxide (N‐rGO). Zn substitution is found to be significantly altering the ratio of Fe 2+ /Fe 3+ in the cobalt ferrite nanocrystal system with a concomitant promotional influence on its electrocatalytic activity towards ORR. The nanoparticle composition with a Co, Fe and Zn molar ratio of 1.0:1.7:0.3, represented by the formula CoFe 1.7 Zn 0.3 O 4 (CFZn(0.3)), supported over N‐rGO has shown 10 mV and 20 mV positive shift in the onset and half‐wave potentials, respectively, for ORR in 0.1 M KOH in comparison to the nanoparticles of CoFe 2 O 4 supported over N‐rGO (CF/N‐rGO). The optimum Zn substitution is found to be narrowing down the difference with the state‐of‐the‐art Pt/C for ORR by 100 and 110 mV in terms of the onset and half‐wave potentials, respectively. Most significantly, the homemade catalyst is found to be clearly outperforming the Pt catalyst in terms of the limiting current density and electrochemical durability.