Abstract
-
Electrochemical gas generation and consumption at carbon nanotube (CNT) electrodes was investigated
as a means of powering pneumatic actuators. Two different types of carbon nanotubes were evaluated in
a variety of aqueous electrolytes. Chlorine gas generation from aqueous sodium chloride electrolyte was
found to be the most suitable systeminvestigated, based on the ability to electrochemically reduce the gas
generated. Carbon nanotubes produced by different techniques exhibit different chlorine oxidation and
reduction capabilities with HiPCO nanotubes showing a higher electrochemical activity than nanotubes
made by the laser ablation method. In a closed electrochemical cell fitted with a pressure transducer, the
oxidation of Cl− ions to Cl2 gas was ∼40% efficient based on the charge passed. In contrast, the reduction
of Cl2 gas pressurewas almost 100% efficient, although the exact mechanisms of gas reductionwere complicated
by side reactions and kinetic processes. A carbon nanotube electrode of 2.4mm3 was capable of
producing 0.5cm3 of gas at atmospheric pressure, or an increase of up to 50 kPa in a closed cell depending
upon the headspace volume. Thework capacity based on the size of the electrodewas 5000 kJ/m3, which
is nearly two orders of magnitude larger than other low voltage electrochemical actuators.