期刊
ACS CATALYSIS
卷 4, 期 2, 页码 457-463出版社
AMER CHEMICAL SOC
DOI: 10.1021/cs400938s
关键词
oxygen reduction reaction; manganese oxide; surface manganese valence; electrode potential; alkaline medium
资金
- Strategic Priority Research Program of the Chinese Academy of Sciences [XDA09030104]
- National Basic Research Program of China [2012CB215500]
- Natural Science Foundation of China [21106142, 20973169]
- External Cooperation Program of the Chinese Academy of Sciences [GJHZ1135]
In this article, manganese oxide nanorods with different crystalline structures, i.e., beta-MnO2, alpha-Mn2O3, and a composite of Mn3O4 and alpha-Mn2O3, were successfully synthesized via controlling the heat-treatment procedure starting from a manganese oxide composite, containing gamma-MnOOH and Mn(OH)(4). The oxygen reduction reaction (ORR) polarization curves measured by a rotating disk electrode (RDE) setup show that those MnOx catalysts with higher Mn valent states, i.e., gamma-MnOOH and Mn(OH)(4) composite and beta-MnO2, exhibit better catalytic activity toward the ORR than those with lower Mn valences. Furthermore, we testify that the surface Mn valence of MnOx could be tuned by applying proper potential cycling to the MnOx electrode and thus leads to different activities, i.e., the MnOx surface is rich in Mn(II) after treatment at relatively negative potentials, resulting in degradation in ORR activity, while it is rich in Mn(IV) after treatment at positive potentials, resulting in improvement in activity. Compared with the heat-treatment approach, the electrochemical approach is more facile and energy-saving to tune the surface metal valence and thus ORR activity.
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