Preparation of a MnO2@C@MnO Core-shell Heterojunction as a Highly Efficient Electrocatalyst for the Oxygen Evolution Reaction

• Published in: International journal of electrochemical science Vol. 17; no. 10; p. 221050
• Main Authors: Hao, Hongjuan, Pu, Hongbin, Lu, Dingze, Zhou, Min, Wang, Qiuping, Wang, Jiuxin, Su, Yaoheng, Li, Lianbi, Tian, Mengqi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2022
• Subjects: Core-shell heterojunction; MnO2; OER activity; MnO2; C; OER activity; Core-shell heterojunction
• ISSN: 1452-3981; 1452-3981
• DOI: 10.20964/2022.10.52

Manganese-based cocatalyst decoration is an effective strategy for constructing an efficient electrocatalyst for the OER. A novel MnO2 nanowires@C@MnO nanosheet core-shell heterojunction with a unique interfacial microstructure was successfully constructed in this study. The structure and morphology of the as-prepared one-dimensional MnO2 nanowires and MnO2@Cx@MnO electrocatalyst were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform-infrared (FTIR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The results clearly revealed that the MnO2 nanowires@C@MnO nanosheet core-shell heterojunction was a mixture of one-dimensional MnO2 nanowires and 2D MnO nanosheets. Electrochemical performance tests showed that the electrochemical activity of the MnO2@20%C@MnO core-shell heterojunction for the OER was considerably enhanced over those of pristine one-dimensional MnO2 nanowires, MnO2@15%C@MnO and MnO2@30%C@MnO. MnO2@20%C@MnO had a lower overpotential (520 mV at 10 mA/cm2) and Tafel slope (66 mV/dec) than the one-dimensional MnO2 nanowires (650 mV at 10 mA/cm2 and 133 mV/dec, respectively). Electrochemical analyses showed superior OER performance for MnO2@20%C@MnO, which was mainly attributed to the introduction of C and the coexistence of MnO2 nanowires and MnO nanosheets. In addition, the MnO2 nanowires@C@MnO nanosheet core-shell heterojunction provided abundant transport channels for electrons, ions and electrolyte penetration, accelerating the separation of bubbles at the electrode surface.