Trimetallic Mn‐Fe‐Ni Oxide Nanoparticles Supported on Multi‐Walled Carbon Nanotubes as High‐Performance Bifunctional ORR/OER Electrocatalyst in Alkaline Media

Abstract

Discovering precious metal-free electrocatalysts exhibiting high activity and stability toward both the oxygen reduction (ORR) and the oxygen evolution (OER) reactions remains one of the main challenges for the development of reversible oxygen electrodes in rechargeable metal-air batteries and reversible electrolyzer/fuel cell systems. Herein, a highly active OER catalyst, Fe 0.3 Ni 0.7 O X supported on oxygen-functionalized multi-walled carbon nanotubes, is substantially activated into a bifunctional ORR/OER catalyst by means of additional incorporation of MnO X . The carbon nanotube-supported trimetallic (Mn-Ni-Fe) oxide catalyst achieves remarkably low ORR and OER overpotentials with a low reversible ORR/ OER overvoltage of only 0.73 V, as well as selective reduction of O 2 predominantly to OH − . It is shown by means of rotating disk electrode and rotating ring disk electrode voltammetry that the combination of earthabundant transition metal oxides leads to strong synergistic interactions modulating catalytic activity. The applicability of the prepared catalyst for reversible ORR/OER electrocatalysis is evaluated by means of a fourelectrode configuration cell assembly comprising an integrated two-layer bifunctional ORR/OER electrode system with the individual layers dedicated for the ORR and the OER to prevent deactivation of the ORR activity as commonly observed in single-layer bifunctional ORR/OER electrodes after OER polarization.

Induced electron transfer by oxygen vacancy gradient on SnO2 conductive glass for electrocatalytic reduction

“…O V can change the electronic structure of MOxs and affect the electron transport rate in the EC process [13]. F-doped tin oxide (FTO) conductive glass is commonly used in PEC devices [14]. The main component of FTO surface coating is tin dioxide (SnO 2 ), a wide bandgap MOx, which has been widely used in ceramic glass, LIB, and conductive glass coating industries [15][16][17].…”

Electrodeposited Trimetallic NiFeW Hydroxide Electrocatalysts for Efficient Water Oxidation

“…The Fe2p spectra (Figure 5b) show two major peaks at 712.2 eV and 725.5 eV, which correspond to Fe2p 3/2 and Fe2p 1/2 . In general, the peak at 712.2 eV can be further deconvoluted into two peaks at 711.1 eV (Fe 2+ ) and 713.8 eV (Fe 3+ ) [45] . The calculated area ratios of Fe 2+ /Fe 3+ in NiFe, NiFeW1, NiFeW2, and NiFeW3 are 2.3, 3.05, 2.2, and 2.02, respectively [46] .…”

Oxygen vacancies engineering by coordinating oxygen-buffering CeO2 with CoO nanorods as efficient bifunctional oxygen electrode electrocatalyst

“…To date, transition metal oxides (TMOs), which stand out as a type of potential candidates for ORR and OER, such as NiO, MnO x , Co 3 O 4 , and so on, have been extensively investigated [12][13][14][15][16][17][18]. Among the TMOs, cobalt oxides are recognized as one of the most promising bifunctional electrocatalysts, specially Co 3 O 4 spinel because of its ratio variability of Co 2+ /Co 3+ ions, which can influence the adsorption of OHspecies during the reaction process [19,20].…”