Cubic imidazolate frameworks-derived CoFe alloy nanoparticles-embedded N-doped graphitic carbon for discharging reaction of Zn-air battery

Abstract

The construction of transition metal-based catalysts with high activity and stability has been widely regarded as a promising method to replace the precious metal Pt for oxygen reduction reaction (ORR). Herein, we synthesized CoFe alloy nanoparticle-embedded N-doped graphitic carbon (CoFe/NC) nanostructures as ORR electrocatalysts. The ZIF-67 (zeolitic imidazolate framework, ZIF) nanocubes were first synthesized, followed by an introduction of Fe 2+ ions to form CoFe-ZIF precursors via a simple ion-exchange route. Subsequently, the CoFe/NC composites were synthesized through a facile pyrolysis strategy. The ORR activity and the contents of cobalt and iron could be effectively adjusted by controlling the solution concentration of Fe 2+ ions used for the ion exchange and the pyrolysis temperature. The CoFe/NC-0.2-900 composite (synthesized with 0.2 mmol of FeSO 4 •7H 2 O at a pyrolysis temperature of 900°C) exhibited ORR activity that was superior to the other samples owing to a synergistic effect of the bimetal, especially considering the extremely high limiting current density of 6.4 mA cm-2 compared with that of Pt/C (5.1 mA cm-2). Rechargeable Zn-air batteries were assembled employing CoFe/NC-0.2-900 and NiFeP/NF (NiFeP supported on nickel foam (NF)) as the catalysts for the discharging and charging processes, respectively, The above materials achieved reduced discharging and charging platforms, high power density, and prolonged cycling stability compared with conventional Pt/C+RuO 2 /C catalysts.

Self-assembled α-MnO2 urchin-like microspheres as a high-performance cathode for aqueous Zn-ion batteries

“…1d-g). Such porous morphology could enlarge the specific surface area and inside pores of the active materials [22,23], and thus promote the insertion/ extraction of Zn 2+ ions from the electrolyte.…”

Multi-dimensional hierarchical CoS2@MXene as trifunctional electrocatalysts for zinc-air batteries and overall water splitting

“…Electrochemistry provides a viable method for the interconversion between chemical energy and electricity under the ambient condition. Of particular interest is the integrated energy system, for example, the electrolytic water splitting [1-3] powered by lithium storage units [4] or metal-air batteries [5][6][7][8][9][10], which holds promise in the next-generation of power supply, conversion, and distribution featured with high efficiency, low cost, sustainability, and environmental benignity. In particular, hydrogen (H 2 ), the product of electrolytic water splitting [11], is an infinitely renewable and relatively pollutionfree fuel source to alleviate the reliance on traditional fuels.…”

Insight on the active sites of CoNi alloy embedded in N-doped carbon nanotubes for oxygen reduction reaction

“…Pt-based precious metal catalysts are consistently used to drive the effective four-electron process (rather than the ineffective two-electron pathway). However, the disadvantages of these Pt-based catalysts that limit their commercial application are high cost, scarcity, and poor stability [6]. Recently, lots of studies have focused on discovering highly effective nonprecious materials to replace Pt-based catalysts [7][8][9].…”