High-performance fiber optic gas sensor-based Co3O4/MWCNT composite by a novel microwave technique

A novel one-pot microwave irradiation method has been adapted to synthesize cubic spinel cobalt oxide/multi-walled carbon nanotube composite. X-ray diffraction and scanning electron microscope results reveal that cubic spinel structure of Co3O4 with nanodimensional and well implanted over the multi walled carbon nanotubes (MWCNTs) metrics. The N-2 adsorption-desorption results exhibit that Co3O4/MWCNT composite confirms the highest specific area (135 m(2) g(-1)) and lower pore size 7.8 nm compared with pure Co3O4 (surface area 88 = m(2) g(-1) and pore size = 10.5 nm). The XPS result demonstrates that Co is 2+ in state in the spinel Co3O4. The gas-detecting test displayed that Co3O4/MWCNT composite indicated high sensitivity toward ethanol (35 counts/ppm) and ammonia (51 counts/ppm) gases as compared with pure Co3O4 (24 counts/ppm and 43 counts/ppm for ethanol and ammonia gases, respectively). It also exhibits excellent long-term stability with small deviations (less than 5%) for the evaluation of a 2-month period. The enhanced gas-sensing mechanism of Co3O4/MWCNT was also discussed in detail.