Atomically Dispersed Iron–Nitrogen Species as Electrocatalysts for Bifunctional Oxygen Evolution and Reduction Reactions

Abstract

Rational design of non-noble materials as highly efficient, economical, and durable bifunctional catalysts for oxygen evolution and reduction reactions (OER/ORR) is currently a critical obstacle for rechargeable metal-air batteries. A new route involving S was developed to achieve atomic dispersion of Fe-N x species on N and S co-decorated hierarchical carbon layers, resulting in single-atom bifunctional OER/ORR catalysts for the first time. The abundant atomically dispersed Fe-N x species are highly catalytically active, the hierarchical structure offers more opportunities for active sites, and the electrical conductivity is greatly improved. The obtained electrocatalyst exhibits higher limiting current density and a more positive half-wave potential for ORR, as well as a lower overpotential for OER under alkaline conditions. Moreover, a rechargeable Zn-air battery device comprising this hybrid catalyst shows superior performance compared to Pt/C catalyst. This work will open a new avenue to design advanced bifunctional catalysts for reversible energy storage and conversion devices.

Atomically Dispersed Bimetallic FeNi Catalysts as Highly Efficient Bifunctional Catalysts for Reversible Oxygen Evolution and Oxygen Reduction Reactions

“…The performances of atomically dispersed FeNi electrocatalysts are also compared favarably with the bifunctional oxygen electrodes reported in the literature (see Table 2), [31] including Fe SACs supported on N-doped porous carbon (ΔE = 0.8 V at catalysts loading of 0.5 mg cm À 2 ), [18a] Fe SACs on N-CNTs (ΔE = 0.93 V at a catalyst loading of 0.6 mg cm À 2 ) and Fe SACs on N and S co-doped CNTs (ΔE = 0.75 V at a catalysts loading of 0.6 mg cm À 2 ). [16] Nevertheless, the ΔE of 0.81-0.82 V for FeNi catalysts in this study was obtained at a much lower catalyst loading of 0.2 mg cm À 2 , demonstrating the enhanced efficiency of the bimetallic FeNi atomic catalysts as bifunctional electrocatalysts for OER and ORR.…”

“…Single atom catalysts (SACs), emerging as a new class of efficient catalysts, have been recognised of great potential for CO oxidation, [13] CO 2 reduction, [14] ORR, [15] OER, [16] and hydrogenation. [17] Atomically dispersed iron atoms coordinated with nitrogen have long been known as efficient catalysts for ORR.…”

“…[15c,18] Chen et al synthesized Fe SACs on N and S codecorated hierarchical carbon layers as bifunctional OER/ORR catalysts and reported a good limiting current density with a half-wave potential of 0.85 V for ORR and a low overpotential of 0.37 V for OER at 10 mA cm À 2 under alkaline conditions. [16] Pan et al adopted a novel polymerization-pyrolysis-evaporation strategy to synthesize atomically dispersed FeÀ N 4 catalysts on N-doped porous carbon from bimetallic Zn/Fe polyphthalocyanine and reported good electrocatalytic activities for OER, ORR and hydrogen evolution reactions. [18a] Nevertheless, there has been a few reports on the development of bimetallic single atom catalysts as bifunctional catalysts for reversible OER and ORR.…”

Cobalt‐Based Metal–Organic Framework Nanoarrays as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn‐Air Batteries

“…[1] In principal, the energy efficiency of rechargeable Zn-air batteries is primarily dominated by their oxygen electrocatalysts on air electrodes, where the oxygen evolution reaction( OER) and oxygen reduction reaction (ORR) alternatelyp roceed for charging and discharging, respectively.U nfortunately,a saresult of their multi-step fourelectron transfer properties, the ORR and OER processes suffer from extremely sluggish kinetics, which leads to very large potential gaps (> 0.85 V) and low energy efficiency for rechargeable Zn-air batteries. [2] Currently,n oble-metalp latinum (Pt) and iridium (Ir)-based catalysts still serve as benchmark materials for the ORR and OER, respectively. [3] However,t he high cost, scarcity,a nd poor stability of the Pt and Ir-based composite catalysts seriously inhibitt heir widespreadu tilization in rechargeable Zn-air batteries.…”

Optimization of Catalytic Sites in Cobalt‐Modified Nitrogen‐Doped Carbon towards High‐Performance Oxygen Reduction Electrocatalysts for Zinc‐Air Batteries

“…The bonding status of N in NÀ C/Co-1 sample is analyzed by N 1s high-resolution spectrum (Figure 2c), which is deconvoluted into four components: pyridinic-N/CoÀ N (398.67 eV), pyrrolic-N (399.71 eV), graphitic-N (400.80 eV) and oxidized-N (402.05 eV), respectively. [33][34][35] Meanwhile, the Co 2p spectrum in Figure 2d gives evidence of the CoÀ N x coordination. The Co 2p peaks can be resolved into two pairs at 778.48 eV/780.45 eV and 795.47 eV/798.34 eV, corresponding to the Co 2p 3/2 and Co 2p 1/2 .…”