Trimetallic Spinel‐Type Cobalt Nickel‐Doped Manganese Oxides as Bifunctional Electrocatalysts for Zn‐Air Batteries
Soracha Kosasang, Harnchana Gatemala, Nattapol Ma, Praeploy Chomkhuntod, Montree Sawangphruk
Abstract
Abstract This work demonstrates the effect of trimetallic and bimetallic electrocatalysts of spinel‐type metal oxides towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The trimetallic spinel‐type Co 0.5 Ni 0.5 Mn 2 O 4 shows higher bifunctional electrocatalytic activity towards ORR and OER than bimetallic oxides such as CoMn 2 O 4 and NiMn 2 O 4 . The in situ X‐ray absorption spectroscopy was applied to observe the change in the oxidation number of Mn, Ni, and Co during the reactions to demonstrate the active metals on the ORR and OER. The Co plays a more important role in the ORR process than the Ni and Mn, while the three metals exhibit an equivalent contribution on the OER activity as observed from the oxidation state shift. Additionally, the practicality of Zn‐air batteries using the trimetallic spinel catalyst is demonstrated to power light‐emitting diode and spinning motor with a nominal voltage of 3 V. Bifunctional trimetallic electrocatalysts in this work may be useful for other metal‐air batteries.