Mn3O4@C Nanoparticles Supported on Porous Carbon as Bifunctional Oxygen Electrodes and their Electrocatalytic Mechanism

• Published in: ChemElectroChem Vol. 6; no. 2; pp. 359 - 368
• Main Authors: Li, Ms. Wanqing, Fu, Mr. Hongquan, Cao, Yonghai, Wang, Hongjuan, Yu, Hao, Qiao, Zhiwei, Liang, Hong, Peng, Feng
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 18.01.2019
• Subjects: Carbon; Current density; Density functional theory; Durability; electrocatalysis; Electrocatalysts; electrochemistry; Electrodes; energy conversion; Fourier transforms; Fuel cells; Graphene; Manganese oxides; Mathematical analysis; Nanoparticles; Nanospheres; oxygen evolution reaction; Oxygen evolution reactions; oxygen reduction reaction; Oxygen reduction reactions
• ISSN: 2196-0216; 2196-0216
• DOI: 10.1002/celc.201801464

Mn3O4 nanoparticles encapsulated inside carbon nanospheres supported on a carbon plate (Mn3O4@CS/CP) were designed, their bifunctional electrocatalytic performance for both, the oxygen evolution reaction (OER) at the anode and the oxygen reduction reaction (ORR) at the cathode were studied in alkaline solution. The prepared Mn3O4@CS/CP catalyst exhibits excellent electrocatalytic performance towards ORR, with less negative onset potential and long durability. Combining the results of in‐situ Fourier transform infrared spectroscopy (FTIR) and density functional theory (DFT) calculations, it is revealed that Mn3O4 acts as active site for ORR to promote the transformation of OH* into OH−. In addition, Mn3O4@CS/CP possesses an excellent electrochemical OER performances with the lower overpotential along with prosper Tafel slope and robust durability. DFT calculations show the transformation from O* to OOH* is the rate determining step for OER, and Mn3O4@CS/CP shows the minimum barrier, indicating that graphene sheet on the outer of Mn3O4 improves the transformation from O* to OOH*. The oxygen electrode activity parameter (potential difference between OER at current density of 10 mA/cm2 and ORR at current density of −2 mA/cm2) on Mn3O4@CS/CP is 0.72 V, which is superior to those of most bifunctional electrocatalysts reported to date, predicting a promising application in metal‐air batteries and fuel cells. Mn3O4 nanoparticles encapsulated inside carbon nanospheres supported on a carbon plate (Mn3O4@CS/CP) are designed, which exhibit exceptionally good stability and reversibility for ORR and OER. Furthermore, the electrocatalytic mechanism is analyzed.