am6b14896_si_001.pdf (1021.81 kB)
Ultrathin LiCoO2 Nanosheets: An Efficient Water-Oxidation Catalyst
journal contribution
posted on 2017-01-27, 00:00 authored by Jianghao Wang, Liping Li, Haiquan Tian, Yuelan Zhang, Xiangli Che, Guangshe LiUltrathin cation-exchanged layered
metal oxides are promising for many applications, while such substances
are barely successfully synthesized to show several atomic layer thickness,
owing to the strong electrostatic force between the adjacent layers.
Herein, we took LiCoO2, a prototype cation-exchanged layered
metal oxide, as an example to study. By developing a simple synthetic
route, we synthesized LiCoO2 nanosheets with 5–6
cobalt oxide layers, which are the thinnest ever reported. Ultrathin
nanosheets thus prepared showed a surprising coexistence of increased
oxidation state of cobalt ions and oxygen vacancy, as demonstrated by
magnetic susceptibility, X-ray photoelectron, electron paramagnetic
resonance, and X-ray absorption fine spectra. This unique feature
enables a higher electronic conduction and electrophilicity to the
adsorbed oxygen than the bulk. Consequently ultrathin LiCoO2 nanosheets provided a current density of 10 mA cm–2 at a small overpotential of a mere 0.41 V and a small Tafel slope
of ∼88 mV/decade, which is strikingly followed by an excellent
cycle life. The findings reported in this work suggest that ultrathin
cation-exchanged layered metal oxides could be a next generation of
advanced catalysts for oxygen evolution reaction.