A carbon nanomaterial functionalized needle tip modified with a low work function material, which is formed by combining a carbon nanomaterial with a material of a needle tip by means of a covalent bond, wherein the interior or outer surface of the carbon nanomaterial is modified with a low work function material;
- wherein, the material of the needle tip is a metal which is one or more selected from tungsten, iron, cobalt, nickel, and titanium;
- the carbon nanomaterial is carbon nanocone or carbon nanotube;
- and the low work function material is one or more selected from metals, metal carbides, metal oxides, borides, nitrides, and endohedral metallofullerene.