Field emission enhancement in hydrogen ambience for multi-walled carbon nanotubes

The field emission behaviors in hydrogen, oxygen, and nitrogen ambiences are investigated for multi-walled carbon nanotubes (CNTs) synthesized directly on catalytic substrates. The study is conducted experimentally and theoretically from the first-principal simulation. The enhancement and recovery of field emission are observed with operating the CNT emitters in hydrogen ambience. The low emission currents could rise in proportional to hydrogen partial pressures above 10^-9 Torr. Chemisorptions of atomic and ionized hydrogen on CNTs are considered the key factor for the field emission improvement, which is associated with the drops of effective work functions with the increase of hydrogen pressure. A low pressure hydrogen sensing concept is demonstrated with simple setup, tiny structure and high sensitivity.