Medium Modulated Oxygen Reduction Activity of Fe/Co Active Centre‐engrafted Electrocatalysts. Issue 11 (13th June 2019)

• Record Type: Journal Article
• Authors: Kashyap, Varchaswal; Anand, Aljo; Soni, Roby; Sreekumar, Kurungot
• Is Part Of: ChemElectroChem. Volume 6:Issue 11(2019)
• Page Start: 2956
• Page End: 2964
• Publication Date: 2019-06-13
• Subjects: oxygen reduction reaction -- transition state -- active centers -- half-wave potential -- mechanism; Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.201900260
• Languages: English
• ISSNs: 2196-0216

Abstract

Abstract: Iron and cobalt metal atoms are effective active centers for the synthesis of carbon‐based noble‐metal‐free catalysts for the oxygen reduction reaction (ORR) owing to their cost‐effective intrinsic activity and tunable properties. Annealing of the active center with the conducting carbon enhances the ORR activity significantly. Herein, we have engrafted Fe and Co active centers in the homemade conducting carbon and the ORR performance has been closely observed under acidic and basic pH conditions to understand the influence of the medium and participating moieties towards the performance. In the half‐cell reaction, the onset potential and half‐wave potential for ORR are governed by the surface intermediates and concomitantly driven by the adsorption energies of the intermediates over the active centers. The iron and cobalt active center‐engrafted carbon catalyst behaves differently in acidic and basic electrolytes owing to the dissociation of the surface intermediates. The iron‐based catalyst shows improved onset potential against the cobalt‐based one. Similarly, the cobalt‐based catalyst shows improved half‐wave potential against the iron active‐center‐grafted catalyst. The combined synergistic effect of the two catalysts is realized in the composition represented as Fe/2Co−N‐GVC, where improved onset and half‐wave potentials are noted in basic medium. A significant variation in the activity of the catalyst is observed as the medium changes from acidic to basic and the effect is directly associated with the surface adsorption of the intermediates. Abstract : Catalysts for the oxygen reduction reaction (ORR) are prepared by incorporating Fe and Co active centers into a graphene‐based composite. The figure shows the molecular mechanism of the ORR in basic and acidic medium at those active centers.