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. Issue 26 (12th September 2017)

• Record Type: Journal Article
• Authors: Kashyap, Varchaswal; Singh, Santosh K.; Kurungot, Sreekumar
• Is Part Of: ChemistrySelect. Volume 2:Issue 26(2017)
• Page Start: 7845
• Page End: 7853
• Publication Date: 2017-09-12
• Subjects: Nanocrystalline -- N-doped graphene -- oxygen reduction reaction -- solvothermal synthesis -- Zn substituted cobalt ferrite; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201701684
• Languages: English
• ISSNs: 2365-6549

Abstract

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 CoFe1.7 Zn0.3 O4 (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 CoFe2 O4 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. Abstract : Activity modulation of cobalt ferrite nanoparticles for electrochemical oxygen reduction reaction (ORR) through zinc substitution and synergistic interaction with nitrogen doped graphene as a conducting support is demonstrated. Zn substitution has a decisive role in controlling the ratio of Fe 2+ /Fe 3+ in the system, and this ratio has a direct influence on tuning the activity of the ferrite nanoparticles towards ORR.