Cupric Oxide Nanowires Formed on Single-walled Carbon
Nanotube Substrate: Synthesis and Gas Sensing Properties
Nguyen Duc Hoa, Nguyen Van Quy, Yousuk Cho, Dojin Kim*
i
Department of Materials Science and Engineering, Chungnam National University, Daejeon,
305-764 Republic of Korea
Among the metal oxides used for gas sensors application, researchers have focused on
improving the gas sensing performance of n-type semiconductor. In contract to other n-type
semiconductor metal oxides, cupric oxide (CuO) is a p-type semiconductor with band gap of
~1.7 eV and reported to be suitable for catalysis, lithium-copper oxide electrochemical cells, and
gas sensors applications. The nanoparticles, plates and nanowires of CuO was found sensing to
NO2, H2S and CO. The nanowire of CuO can by synthesized by low temperature solid-phase
process, heating copper substrates in air or templates assisted electrodeposition. The cuprous
oxide nanoparticles could also be coated on multi-walled carbon nanotubes (MWNTs) by
chemical method in which the MWNTs was purified, functionalized and mixed with copper salt
following by reaction, washing and drying process. However, the gas sensing properties of CuO
nanowire structure deposited on carbon nanotubes have not been reported yet.
In this work, we report about the synthesis, characterization and gas sensors application
of nanowires structured CuO deposited on single-walled carbon nanotubes (SWNTs). The
nanowires structured CuO is synthesized by deposition of metal Cu layer on a porous thin film of
SWNTs substrate flowing by thermal oxidation process. The effects of oxidized temperatures on
the morphology, quality and gas sensing properties of synthesized materials are investigated and
discussed.
Nanostructure of CuO is synthesized by deposition of Cu on porous single-wall carbon
nanotubes (SWNTs) substrate flowing by thermal oxidation process. The oxidation process is
performed in air to oxidize the Cu and remove the SWNTs substrate. The nanostructure and
electrical properties of synthesized materials are investigated by SEM, TEM, XRD, Raman, XPS
spectroscopy and electrical measurements
The SEM, TEM, XRD and Raman spectroscopy data indicated that nanowires structured
CuO was successfully synthesized. The nanowires CuO have a diameter of 25 nm with the length
up to several micrometers. The electrical and gas sensing properties of nanowires structured CuO
was tested with H2 gas at temperature of 250 oC. Gas sensing properties of synthesized
nanostructured materials showed very high sensing to hydrogen with fast and reversible response
at operating temperature of 250 oC. In which, the nanowires CuO oxidized at 400 oC showed
highest sensitivity.
We have developed a simple method to synthesized nanowires structured CuO by
deposition Cu on SWNTs substrate followed by oxidation process. The nanowires structured
materials showed highest sensitivity and could detect the concentration of H2 down to ppm level.
*
E-mail: dojin@cnu.ac.kr