Multicomponent Spinel Metal Oxide Nanocomposites as High-Performance Bifunctional Catalysts in Zn–Air Batteries

Abstract

Although multicomponent transition-metal oxides have been widely studied as electrocatalysts in both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER), precise control of catalytic activities by varying the composition of these metal elements is not an easy task. In this work, we introduce a generic and scalable synthetic method by dealloying a series of Al-rich precursor alloys to produce Mn 3 O 4 -based and FeCo-based spinel oxide nanocomposites. It is found that these Mn 3 O 4 -based oxides are highly active for the ORR; doping Mn 3 O 4 with Co further enhances the activity while doping with Fe decreases it. For the OER, doping the FeCo-based oxides with Cr, V, or Ni significantly enhances the activity among which Cr is the most effective dopant. Moreover, the addition of Ni into the precursor alloy would inhibit the doping of the negative Fe element into the obtained Mn 3 O 4 after dealloying an AlFeCoNiMn precursor. The obtained (FeCoNi) 3 O 4 /Mn 3 O 4 nanocomposite exhibits a high bifunctional electrocatalytic performance, which is comparable with that of the commercial Pt/C + IrO 2 combination. When incorporated into a Zn−air battery, the battery can be stably discharged/charged over 400 h with an open-circuit voltage of 1.44 V and a narrow voltage gap of ∼0.7 V at 2.0 mA cm −2 .

Determining the Role of Fe‐Doping on Promoting the Thermochemical Energy Storage Performance of (Mn1−xFex)3O4 Spinels

“…In particular, Mn oxides are of interest in electrochemistry, [1,2] (photo) catalysis, [3][4][5][6][7] and for the development of batteries and magnetic devices. [8][9][10] The phase diagram of the Mn-O system shows several oxides with well-defined stoichiometry, ranging from MnO 2 to MnO, which are stable in definite intervals of temperature and oxygen partial pressure. [11,12] This variety of structures and redox states is essential to explain the interest of these systems in multiple energy applications.…”

Recent Advances in Nanoscale Based Electrocatalysts for Metal-Air Battery, Fuel Cell and Water-Splitting Applications: An Overview

“…The HR-TEM image indicates that Mn3O4 nanosheets exist as the elongated sphere-like nanoparticles with a size of 50 nm and a thickness estimated to be 10-20 nm (Figure 1b). Based on the polarization studies, the AlFeCoNiMn modified electrode showed a higher open-circuit potential (1.44 V) compared to the commercial Pt/C + IrO2 electrode (1.41 V) (Figure 1c) [41]. Copyright 2020 by American Chemical Society [41].…”

“…Based on the polarization studies, the AlFeCoNiMn modified electrode showed a higher open-circuit potential (1.44 V) compared to the commercial Pt/C + IrO2 electrode (1.41 V) (Figure 1c) [41]. Copyright 2020 by American Chemical Society [41].…”

“…In this regard, Zahoor and co-workers [44] proposed a nitrogen-doped porous ultrathin nanosheet oriented MnO2/N-rGO composite for ORR applications. In terms of ORR activity, MnO2/N-rGO exhibited the onset potential at −0.05 V vs Hg/HgO and the observed specific capacity value of 5250 mAh g −1 at 0.2 mA Copyright 2020 by American Chemical Society [41].…”

“…Moreover, multi-components incorporated transition-metal oxide-based electrocatalysts have been widely employed for battery-related applications. Li et al introduced a generic and scalable synthetic approach to produce Mn 3 O 4 -based and FeCo-based spinel oxide nanocomposites by dealloying Al-rich precursors such as Al 92 Fe 2 Co 2 Ni 2 Mn 2 [41]. As reported, the aluminium metal has an inherent drawback in the metal-air batteries due to the formation of a passive oxide film which decreases the overall battery performance [42].…”