W-Doped CaMnO_2.5and CaMnO₃Electrocatalysts for Enhanced Performance in Oxygen Evolution and Reduction Reactions

Abstract

Sluggish kinetic of oxygen redox reactions, namely, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is often a main reason for the low efficiency of oxygen electrocatalysts. It hinders the wide-spread applications of renewable energy conversion devices. For those electrocatalysts that are made of transition metal oxides, poor electrical conductivity further compounds the problem. In this study, we show a strategy, in which low level of dopants is used to increase the electrical conductivity of both perovskite CaMnO3 and reduced, oxygen-deficient perovskite CaMnO2.5 electrocatalysts. Introduction of tungsten cation to replace B-site manganese up to 3% in CaMn1-xWxOy (x = <0.03; y = 2.5 and 3) results in enhanced ORR and OER performance, due to the increase of electrical conductivity of these oxide catalysts via double-exchange mechanism. The concept of using low-level dopants to increase the electrical conductivity, thus the activity, should be a quite useful strategy for designing the transition metal oxide electrocatalysts for enhanced performance in OER and ORR.

Single-Phase Pyrochlore Y2Ir2O7 Electrocatalyst on the Activity of Oxygen Evolution Reaction

“…Sluggish oxygen evolution reaction (OER) in acid has been long considered a major obstacle in the generation and storage of renewable energy technology, such as regenerative fuel cells, , metal–air batteries, , and water electrolyzers. − Most early transition-metal-based OER catalysts undergo rapid dissolution in acid under the operating potential windows. , RuO 2 and IrO 2 compounds are known as viable electrocatalysts in acid media, where IrO 2 is recognized as the catalyst with the best stability . The scarceness of Ir, however, results in a high cost for manufacturing these catalysts and limits the wide range of implementations of water electrolysis devices.…”

Perovskite Oxides for Cathodic Electrocatalysis of Energy‐Related Gases: From O2 to CO2 and N2

“…As a common strategy, the substitution of B‐site cation by transition metal cations has been applied in other perovskite oxides, such as LaMnO 3 [ 69 ] and CaMnO 3 . [ 70 ] The successful demonstrations comply with the theoretical understanding, which encourages further exploration.…”

Surface Interrogation of Electrodeposited MnOx and CaMnO3 Perovskites by Scanning Electrochemical Microscopy: Probing Active Sites and Kinetics for the Oxygen Evolution Reaction

“…The potential for the Mn V generation in the perovskite is also less positive as demonstrated in Figure 6 b. Based on previous studies, a possible model is that the introduction of Ca II in the perovskite changes the electronic structure of the Mn site because of the interaction of Mn‐Ca [36, 37] . Calcium is one of the best known redox‐inactive metals found in the chloroplast Mn 4 Ca cluster, a natural oxygen‐evolving complex of photosystem II (PSII), but is regarded as a critical component in modulating the redox potential of Mn species [38–40] .…”