Electrocatalytic
Oxygen Evolution at Surface-Oxidized
Multiwall Carbon Nanotubes
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Abstract
Large-scale storage of renewable
energy in the form of hydrogen
(H<sub>2</sub>) fuel via electrolytic water splitting requires the
development of water oxidation catalysts that are efficient and abundant.
Carbon-based nanomaterials such as carbon nanotubes have attracted
significant applications for use as substrates for anchoring metal-based
nanoparticles. We show that, upon mild surface oxidation, hydrothermal
annealing and electrochemical activation, multiwall carbon nanotubes
(MWCNTs) themselves are effective water oxidation catalysts, which
can initiate the oxygen evolution reaction (OER) at overpotentials
of 0.3 V in alkaline media. Oxygen-containing functional groups such
as ketonic CO generated on the outer wall of MWCNTs are found
to play crucial roles in catalyzing OER by altering the electronic
structures of the adjacent carbon atoms and facilitates the adsorption
of OER intermediates. The well-preserved microscopic structures and
highly conductive inner walls of MWCNTs enable efficient transport
of the electrons generated during OER