Mesoporous ZnMn₂O₄ Nanospheres as a Nonprecious Bifunctional Catalyst for Zn–Air Batteries

Abstract

The rapid and effective transfer of chemical reactants to solid surfaces through a mesoporous structure is essential for enhancing the catalytic performance of nanomaterials. Such materials are essential for realizing durable, nonpreciousmetal-based bifunctional electrocatalysts for rechargeable Zn−air batteries. Herein, highly reactant-accessible and mesoporous ZnMn 2 O 4 nanospheres have been prepared via solvothermal synthesis. The nanospheres demonstrate excellent catalytic activity toward the oxygen reduction reaction and the oxygen evolution reaction in an aqueous alkaline solution. Moreover, compared with commercial 20 wt % platinum on carbon black, IrO 2 , and RuO 2 , the mesoporous ZnMn 2 O 4 catalyst exhibits lower charge− discharge voltage gaps, good cycling stability, and improved round-trip efficiency. The enhanced electrochemical performance of the developed catalyst is attributed to the high specific surface area, numerous reaction sites by defective O 2 − (O ads ) species, and sufficient structural stability of the ZnMn 2 O 4 material. The achievements presented in this work are of great importance for the development of outstanding non-noble spinel electrocatalysts for Zn−air batteries.

Zinc Manganate: Synthesis, Characterization, and Electrochemical Application toward Flufenamic Acid Detection

“…Zinc manganate­(ZnMnO)-based electrode materials have been well-recognized for their electrocatalytic redox characteristics and the nanoscale structure, which facilitates a fast electron transfer process that is advantageous for electrochemical applications. − Very recently, Li et al reported ZnMnO/graphene for the electrochemical detection of hydrogen peroxide (H 2 O 2 ) with good catalytic activity . Subsequently, Li et al explored a ZnMnO-based electrocatalyst for the determination of H 2 O 2 .…”

Regulating the Electronic Configuration of Spinel Zinc Manganate Derived from Metal–Organic Frameworks: Controlled Synthesis and Application in Anode Materials for Lithium-Ion Batteries

“…Among them, first is the construction of metal oxide hollow porous nanostructures with ultrahigh specific surface area and excellent structural stability in order to increase lithium storage capacity. For example, hierarchical Co 3 O 4 @NiCo 2 O 4 core–shell nanosheets were successfully manufactured on Ni-foam for supercapacitors by Xu et al to demonstrate excellent supercapacitor performances with an excellent specific capacitance of 1330 F g –1 at 3 mA cm –2 and an outstanding cycling stability of ∼100.7% after 5000 cycles, whereas a variety of porous nanoscale ZMOs with different morphologies, including nanospheres, − nanotubes, and nanowires, have been constructed in order to enhance the electrochemical efficiency of ZMO-based anodes through nanoscale strategies for an enhanced electrochemical performance. Second, a large number of researchers are trying to couple the material structure with conductive carbon substrates, such as carbon nanotubes (CNTs), , carbon nanofibers (CNFs), or graphene, , which can reduce the mechanical changes in the reaction process and boost the electrical conductivity of the transition metal oxide-based anodes.…”

Defect Engineering of Carbon‐based Electrocatalysts for Rechargeable Zinc‐air Batteries

“…Fortunately, TM compounds anchored on nanocarbon material have shown excellent electrocatalytic activity and durability in ORR and OER, due to their good electrical conductivity, superior chemical stability, high surface area, strong synergies between TM compounds and heteroatom-doped nanocarbons. [89][90][91] The role of oxygen vacancies in the electrochemical performance of Co 3 O 4 has been extensively studied. [92][93][94][95][96] DFT calculations showed that oxygen vacancies produce a new defect state located in the bandgap of Co 3 O 4 , which easily excites two electrons in the defect state and leads to enhanced conductivity and superior electrochemical activity (Figure 9a).…”

“…The assembly of TM compounds (e. g., oxides, alloys, hydroxides, sulfides, phosphates, nitrides, carbides, perovskites and spinels) on the heteroatoms‐doped carbon by chemical attachment and electrical coupling is another feasible way to introduce TM into carbon materials [68,88–108] . TM compounds have been widely reported as OER electrocatalysts [76,109] .…”

“…However, their inherent low conductivity and active sites greatly limit their rapid development in ZABs. Fortunately, TM compounds anchored on nanocarbon material have shown excellent electrocatalytic activity and durability in ORR and OER, due to their good electrical conductivity, superior chemical stability, high surface area, strong synergies between TM compounds and heteroatom‐doped nanocarbons [89–91] …”