MO‐Co@N‐Doped Carbon (M = Zn or Co): Vital Roles of Inactive Zn and Highly Efficient Activity toward Oxygen Reduction/Evolution Reactions for Rechargeable Zn–Air Battery |
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Authors: | Biaohua Chen Xiaobo He Fengxiang Yin Hao Wang Di‐Jia Liu Ruixing Shi Jinnan Chen Hongwei Yin |
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Affiliation: | 1. State Key Laboratory of Organic–Inorganic Composites, Beijing University of Chemical Technology, Beijing, P. R. China;2. Beijing Key Laboratory of Energy Environmental Catalysis, Beijing University of Chemical Technology, Beijing, P. R. China;3. Changzhou Institute of Advanced Materials, Beijing University of Chemical Technology, Changzhou, P. R. China;4. Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL, USA |
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Abstract: | A highly efficient bifunctional oxygen catalyst is required for practical applications of fuel cells and metal–air batteries, as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are their core electrode reactions. Here, the MO‐Co@N‐doped carbon (NC, M = Zn or Co) is developed as a highly active ORR/OER bifunctional catalyst via pyrolysis of a bimetal metal–organic framework containing Zn and Co, i.e., precursor (CoZn). The vital roles of inactive Zn in developing highly active bifunctional oxygen catalysts are unraveled. When the precursors include Zn, the surface contents of pyridinic N for ORR and the surface contents of Co–Nx and Co3+/Co2+ ratios for OER are enhanced, while the high specific surface areas, high porosity, and high electrochemical active surface areas are also achieved. Furthermore, the synergistic effects between Zn‐based and Co‐based species can promote the well growth of multiwalled carbon nanotubes (MWCNTs) at high pyrolysis temperatures (≥700 °C), which is favorable for charge transfer. The optimized CoZn‐NC‐700 shows the highly bifunctional ORR/OER activity and the excellent durability during the ORR/OER processes, even better than 20 wt% Pt/C (for ORR) and IrO2 (for OER). CoZn‐NC‐700 also exhibits the prominent Zn–air battery performance and even outperforms the mixture of 20 wt% Pt/C and IrO2. |
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Keywords: | catalysis metal– organic frameworks oxygen evolution reactions oxygen reduction reactions zinc– air batteries |
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