Gas ionization sensors with CNT/Ni field cathodes

A simple and low cost method to fabricate gas ionization sensors with CNT/Ni field cathodes on corning glasses using composite plating technique was first developed. The field emission characteristics of the initial CNT/Ni field cathode showed a low turn-on electric field E_on of about 1.2 V/¿m with an emission current density of 1 ¿A/cm².It was found that the breakdown voltage (V_b) of the H₂ gas was decreased as the pressure increased from 0.5 to 100 Torr. However; on the contrary, the V_b of the O₂ gas was increased as the pressure increased. It was observed from the Raman spectra that I_D/I_G increased for both of the H₂ and O₂ gases. The full width half maximum (FWHM) around 1580 cm^-1 was also increased for both of the H₂ and O₂ gases. Moreover, a shoulder of 1620 cm^-1 appeared after the H₂ and O₂ gases sensing measurements. This phenomenon, indicating the degradation of the graphitization, was more obvious for the O₂ gas sensing. The fabrication of the ionization sensors with CNT/Ni field cathode was relatively simple and inexpensive and could be mass-produced.