Gui Xu1, Guan-Cheng Xu2, Jin-Jin Ban1, Li Zhang1, He Lin1, Chun-Lin Qi1, Zhi-Peng Sun1, Dian-Zeng Jia1. 1. Key Laboratory of Energy Materials Chemistry, Ministry of Education, Key Laboratory of Advanced Functional Materials, Autonomous Region, Institute of Applied Chemistry, Xinjiang University, Urumqi, 830046 Xinjiang, PR China. 2. Key Laboratory of Energy Materials Chemistry, Ministry of Education, Key Laboratory of Advanced Functional Materials, Autonomous Region, Institute of Applied Chemistry, Xinjiang University, Urumqi, 830046 Xinjiang, PR China. Electronic address: xuguanchengxju@163.com.
Abstract
Metal-organic framework (MOF)-derived transition metal/metal oxide-carbon hybrids are promising cost-effective electrocatalysts to replace noble metal catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Co@CoO@Co3O4-N/C was prepared by two-step thermal treatment of Co-MOF ([Co(INA)2]·0.5EtOH) (INA: isonicotinic acid). Firstly, Co-MOF, as precursor, was pyrolyzed at different temperatures in N2 atmosphere to obtain Co-N/C-T (T = 700, 800, 900 °C) materials among which Co-N/C-800 shows remarkably high ORR activity. After oxidation treatment, Co-N/C-800 is transformed into Co@CoO@Co3O4-N/C which exhibits enhanced electrocatalytic activities for both ORR and OER. The as-obtained Co@CoO@Co3O4-N/C has more positive onset potential (-0.136 V vs. Ag/AgCl) and higher limit current density (4.9 mA cm-2) than Co-N/C-800 (-0.143 V vs. Ag/AgCl and 3.9 mA cm-2), as well as better tolerance to methanol and stability (80.0%) than those of Pt/C (63.2%) for ORR. Co@CoO@Co3O4-N/C also displays outstanding OER performances, with lower overpotential (450 mV) than that of Co-N/C-800 (492 mV) at a current density of 10 mA cm-2. The excellent electrochemical performance of Co@CoO@Co3O4-N/C can be ascribed to uniformly dispersed Co-Nx active sites, strong synergistic effects between N-doped carbon support and Co@CoO@Co3O4 as well as ordered mesoporous structure, boosting mass transfer and accelerating electrocatalytic reaction.
Metal-organic framework (MOF)-derived transitionn class="Chemical">metal/metal oxide-carbon hybrids are promising cost-effective electrocatalysts to replace noble metal catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Co@CoO@Co3O4-N/C was prepared by two-step thermal treatment of Co-MOF ([Co(INA)2]·0.5EtOH) (INA: isonicotinic acid). Firstly, Co-MOF, as precursor, was pyrolyzed at different temperatures in N2 atmosphere to obtain Co-N/C-T (T = 700, 800, 900 °C) materials among which Co-N/C-800 shows remarkably high ORR activity. After oxidation treatment, Co-N/C-800 is transformed into Co@CoO@Co3O4-N/C which exhibits enhanced electrocatalytic activities for both ORR and OER. The as-obtained Co@CoO@Co3O4-N/C has more positive onset potential (-0.136 V vs. Ag/AgCl) and higher limit current density (4.9 mA cm-2) than Co-N/C-800 (-0.143 V vs. Ag/AgCl and 3.9 mA cm-2), as well as better tolerance to methanol and stability (80.0%) than those of Pt/C (63.2%) for ORR. Co@CoO@Co3O4-N/C also displays outstanding OER performances, with lower overpotential (450 mV) than that of Co-N/C-800 (492 mV) at a current density of 10 mA cm-2. The excellent electrochemical performance of Co@CoO@Co3O4-N/C can be ascribed to uniformly dispersed Co-Nx active sites, strong synergistic effects between N-doped carbon support and Co@CoO@Co3O4 as well as ordered mesoporous structure, boosting mass transfer and accelerating electrocatalytic reaction.