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Oxygen Reduction Reaction Activity of Mesostructured Cobalt‐Based Metal Oxides Studied with the Cavity‐Microelectrode Technique
Author(s) -
Behnken Julian,
Yu Mingquan,
Deng Xiaohui,
Tüysüz Harun,
Harms Corinna,
Dyck Alexander,
Wittstock Gunther
Publication year - 2019
Publication title -
chemelectrochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.182
H-Index - 59
ISSN - 2196-0216
DOI - 10.1002/celc.201900722
Subject(s) - cobalt , metal , catalysis , specific surface area , materials science , spinel , oxygen , microelectrode , chemical engineering , absorption (acoustics) , inorganic chemistry , chemistry , electrode , metallurgy , composite material , organic chemistry , engineering , biochemistry
Cobalt oxides are known as abundant and stable catalysts for the oxygen reduction reaction (ORR) in an alkaline environment. Here, the ORR activity of Co 3 O 4 and mixed metal oxides NiCo 2 O 4 and CuCo 2 O 4 was studied. Synthesis by using the nanocasting procedure resulted in a mesostructured spinel phase with uniform morphology and high surface area. However, the evaluation of the specific activity of this material class is often hampered by limitations in determining the real surface area. The cavity‐microelectrode technique did not require the addition of any additives to the catalytic material. Thus, measuring the double layer capacitance was used to assess the surface area. This approach showed comparable and reliable values for all samples and different cavity depths. Furthermore, the in situ derived surface area enabled the determination of the specific ORR activity, which is more accurate than utilizing the geometric and nitrogen absorption derived surface area. Although the activity of Co 3 O 4 was rather low, the presence of Ni 2+ and Cu 2+ in the mixed metal oxides led to a substantial activity enhancement, possibly by providing additional active sites.