ZnMn2O4 spinel nanocrystals-decorated multi-walled carbon nanotubes for oxygen reduction: Experimental and theoretical studies on the strong coupling facilitated four-electron selectivity

In this work, we have successfully formulated a single-step hydrothermal synthesis of mixed transition metal oxide nanocrystals (ZnMn2O4) strongly coupled on carbon support (MWCNTs) that acts as an efficient electrocatalyst for the electrochemical oxygen reduction reaction (ORR). The results depict...

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Bibliographic Details
Published in:International journal of hydrogen energy 2024-02, Vol.56, p.188-198
Main Authors: Singh, Smita, Shrivastava, Anshu, Singh, Devesh Kumar, Yadav, Mamta, Singh, Varsha, Rathour, Vikram, Tiwari, Ananya, Sinha, Indrajit, Ganesan, Vellaichamy
Format: Article
Language:English
Subjects:
Coupling effect
Electrocatalyst
Hydrodynamic voltammetry
Mixed transition metal oxides
Oxygen reduction reaction
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Summary:In this work, we have successfully formulated a single-step hydrothermal synthesis of mixed transition metal oxide nanocrystals (ZnMn2O4) strongly coupled on carbon support (MWCNTs) that acts as an efficient electrocatalyst for the electrochemical oxygen reduction reaction (ORR). The results depict that the composite, MWCNTs@ZnMn2O4 shows better electrocatalytic activity as compared to the activity exhibited by its individual components MWCNTs and ZnMn2O4 combined, attributed to the strong coupling between the two components. Transmission electron images of the composite depict that ZnMn2O4 nanocrystals have been successfully integrated on MWCNTs resulting in high conductivity and activity. The composite, MWCNTs@ZnMn2O4 exhibits an onset potential of 0.9 V vs. RHE, 99 % four-electron ORR selectivity, and high stability. The high selectivity and stability are assigned due to the strong coupling of ZnMn2O4 to MWCNTs through Zn/Mn–O–C bonds which are proved from DFT studies. The presence of Zn/Mn–O–C bonds is verified from X-ray photoelectron spectroscopy. [Display omitted] •MWCNTs@ZnMn2O4 is synthesized by a one-step hydrothermal route.•MWCNTs@ZnMn2O4 exhibits a highly four-electron selective oxygen reduction.•High selectivity is attributed to the strong covalent interaction through M-O-C bonds.•Presence of M-O-C bonds is supported by XPS analysis.•Weakening of O–O bond leading to the selective four-electron reduction is proved by computational studies also.
ISSN:0360-3199
1879-3487
DOI:10.1016/j.ijhydene.2023.12.157