Cerium-Doped CoMn<sub>2</sub>O<sub>4</sub> Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER Reactions
Low-cost and highly efficient electrocatalysts for oxygen reactions are highly important for oxygen-related energy storage/conversion devices (e.g., solar fuels, fuel cells, and rechargeable metal-air batteries). In this work, a range of compositionally-tuned cerium-doped CoMn<sub>2</sub>...
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MDPI AG
2022-09-01
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| author | Xiao Chen Fengshuang Han Xi Chen Chenxi Zhang Wangyan Gou |
| author_facet | Xiao Chen Fengshuang Han Xi Chen Chenxi Zhang Wangyan Gou |
| author_sort | Xiao Chen |
| collection | DOAJ |
| description | Low-cost and highly efficient electrocatalysts for oxygen reactions are highly important for oxygen-related energy storage/conversion devices (e.g., solar fuels, fuel cells, and rechargeable metal-air batteries). In this work, a range of compositionally-tuned cerium-doped CoMn<sub>2</sub>O<sub>4</sub> (Ce-CMO-X) spinels were prepared via oxidizing precipitation and subsequent crystallization method and evaluated as electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The Ce modification into the CMO spinels lead to the changes of surface electronic structure. And Ce-CMO-X catalysts display better electrochemical performance than that of pristine CMO spinel. Among them, Ce-CMO-18% shows the best activity. The Ce-CMO-18% processes a higher ratio of Co<sup>3+</sup>/Co<sup>2+</sup>, Mn<sup>4+</sup>/Mn<sup>3+</sup>, which is beneficial to ORR performance, while the higher content of oxygen vacancies in Ce-CMO-18% make for better OER performance. Thus, the Ce-doped CMO spinels are potential candidates as bifunctional electrocatalysts for both ORR and OER in alkaline environments. Then, the hybrid Ce-CMO-18%/MWCNTs catalyst was also synthesized, which shows further enhanced ORR and OER activities. It displays an ORR onset potential of 0.93 V and potential of 0.84 V at density of 3 mA cm<sup>−2</sup> (at 1600 rpm), which is comparable to commercial Pt/C. The OER onset potential and potential at a current density 10 mA cm<sup>-2</sup> are 183 mV and 341 mV. The superior electrical conductivity and oxygen functional groups at the surface of MWCNTs can facilitate the interaction between metal oxides and carbon, which promoted the OER and ORR performances significantly. |
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| spelling | doaj.art-b2e33742d2ce4b2180df0bec5c4cdbc32023-11-23T23:23:57ZengMDPI AGCatalysts2073-43442022-09-011210112210.3390/catal12101122Cerium-Doped CoMn<sub>2</sub>O<sub>4</sub> Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER ReactionsXiao Chen0Fengshuang Han1Xi Chen2Chenxi Zhang3Wangyan Gou4School of Materials Science and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, ChinaSchool of Materials Science and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, ChinaSchool of Materials Science and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, ChinaSchool of Materials Science and Engineering, North China University of Water Resources and Electric Power, Zhengzhou 450045, ChinaKey Laboratory of Special Functional and Smart Polymer Materials of Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi’an 710072, ChinaLow-cost and highly efficient electrocatalysts for oxygen reactions are highly important for oxygen-related energy storage/conversion devices (e.g., solar fuels, fuel cells, and rechargeable metal-air batteries). In this work, a range of compositionally-tuned cerium-doped CoMn<sub>2</sub>O<sub>4</sub> (Ce-CMO-X) spinels were prepared via oxidizing precipitation and subsequent crystallization method and evaluated as electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The Ce modification into the CMO spinels lead to the changes of surface electronic structure. And Ce-CMO-X catalysts display better electrochemical performance than that of pristine CMO spinel. Among them, Ce-CMO-18% shows the best activity. The Ce-CMO-18% processes a higher ratio of Co<sup>3+</sup>/Co<sup>2+</sup>, Mn<sup>4+</sup>/Mn<sup>3+</sup>, which is beneficial to ORR performance, while the higher content of oxygen vacancies in Ce-CMO-18% make for better OER performance. Thus, the Ce-doped CMO spinels are potential candidates as bifunctional electrocatalysts for both ORR and OER in alkaline environments. Then, the hybrid Ce-CMO-18%/MWCNTs catalyst was also synthesized, which shows further enhanced ORR and OER activities. It displays an ORR onset potential of 0.93 V and potential of 0.84 V at density of 3 mA cm<sup>−2</sup> (at 1600 rpm), which is comparable to commercial Pt/C. The OER onset potential and potential at a current density 10 mA cm<sup>-2</sup> are 183 mV and 341 mV. The superior electrical conductivity and oxygen functional groups at the surface of MWCNTs can facilitate the interaction between metal oxides and carbon, which promoted the OER and ORR performances significantly.https://www.mdpi.com/2073-4344/12/10/1122Ce-doped CoMn<sub>2</sub>O<sub>4</sub> spinelsoxygen vacancyoxygen reduction reactionoxygen evolution reaction |
| spellingShingle | Xiao Chen Fengshuang Han Xi Chen Chenxi Zhang Wangyan Gou Cerium-Doped CoMn<sub>2</sub>O<sub>4</sub> Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER Reactions Catalysts Ce-doped CoMn<sub>2</sub>O<sub>4</sub> spinels oxygen vacancy oxygen reduction reaction oxygen evolution reaction |
| title | Cerium-Doped CoMn<sub>2</sub>O<sub>4</sub> Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER Reactions |
| title_full | Cerium-Doped CoMn<sub>2</sub>O<sub>4</sub> Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER Reactions |
| title_fullStr | Cerium-Doped CoMn<sub>2</sub>O<sub>4</sub> Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER Reactions |
| title_full_unstemmed | Cerium-Doped CoMn<sub>2</sub>O<sub>4</sub> Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER Reactions |
| title_short | Cerium-Doped CoMn<sub>2</sub>O<sub>4</sub> Spinels as Highly Efficient Bifunctional Electrocatalysts for ORR/OER Reactions |
| title_sort | cerium doped comn sub 2 sub o sub 4 sub spinels as highly efficient bifunctional electrocatalysts for orr oer reactions |
| topic | Ce-doped CoMn<sub>2</sub>O<sub>4</sub> spinels oxygen vacancy oxygen reduction reaction oxygen evolution reaction |
| url | https://www.mdpi.com/2073-4344/12/10/1122 |
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