Barium-functionalized multiwalled carbon nanotube yarns were fabricated by drawing and twisting multiwalled carbon nanotube forests through a solution containing barium nitrate. After heat activation under vacuum, the functionalized yarns were enriched in barium oxide due to the high surface-to-volume ratio of the nanotubes. The cathodes exhibited good thermionic properties, with a work function as low as 1.732.06eV and thermionic current density that exceeded 185mAcm2 in a field of 850V5mm at 1317K. The barium-functionalized yarns had high tensile strength of up to 420MPa and retained strength of 250MPa after a 2h activation process.

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