Room-temperature gas sensor using carbon nanotube with cobalt oxides

• The Co3O4 particles were directly deposited on CNT sheet by the electrodeposition method.
• Sensitivity of the sensor highly depends on the mean size of the Co3O4 particles.
• The mean size of the Co3O4 particles was controlled by the electro-deposition time.
• Annealing treatment could improve the performance of the sensor at room temperature.

Hydrogen gas (H2) sensors are fabricated using a carbon-nanotube (CNT) sheet decorated with cobalt oxide (Co3O4) nanoparticles. The proposed hybrid sensor is fabricated by electrodepositing Co3O4 on CNT sheets. With an annealing treatment, the CNTs/Co3O4 composite sensors exhibit a much higher response to H2 gas at room temperature than sensors that have not undergone the annealing treatment. The functional groups and oxygen defects that are formed during annealing serve as chemisorption sites for H2 at room temperature. Moreover, the annealing treatment results in strong interaction between Co3O4 and the CNTs, which allows carriers to easily diffuse from the Co3O4 nanoparticles to the CNTs.

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