Role of LiCoO2 Surface Terminations in Oxygen Reduction and Evolution Kinetics.
Oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities of LiCoO2 nanorods with sizes in the range from 9 to 40 nm were studied in alkaline solution. The sides of these nanorods were terminated with low-index surfaces such as (003), while the tips were terminated largely with high-index surfaces such as (104), as revealed by high-resolution transmission electron microscopy. Electron energy loss spectroscopy demonstrated that low-spin Co(3+) prevailed on the sides, while the tips exhibited predominantly high- or intermediate-spin Co(3+). We correlated the electronic and atomic structure to higher specific ORR and OER activities at the tips as compared to the sides, which was accompanied by more facile redox of Co(2+/3+) and higher charge transferred per unit area. These findings highlight the critical role of surface terminations and electronic structures of transition-metal oxides on the ORR and OER activity.
Binghong
B
Han
∥Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States.
Danna
D
Qian
Marcel
M
Risch
⊥The Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
Hailong
H
Chen
#Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
Miaofang
M
Chi
∥Department of NanoEngineering, University of California San Diego, La Jolla, California 92093, United States.
Ying Shirley
YS
Meng
Yang
Y
Shao-Horn
EELS; lithium intercalation; nanorods; oxygen evolution reaction; oxygen reduction reaction