One Step Process for Infiltration of Magnetic Nanoparticles into CNT Arrays for Enhanced Field Emission

The complexities and functionalities of carbon nanotube (CNT) architectures can be enhanced even further by the addition of nanoparticles of different kinds. Here, a simple and easily scalable energy efficient infiltration technique is demonstrated to incorporate iron oxide (Fe<inf>3</inf>O<inf>4</inf>) particles into aligned forests of CNTs grown by chemical vapor deposition. Scanning electron microscopy and in situ confocal microscopy confirm the presence of Fe<inf>3</inf>O<inf>4</inf> and also explain the mechanism of infiltration and entrapment in the nanotube films. The obtained hybrid films are demonstrated to be excellent field emitters. The infiltration of nanoparticle results in an order of magnitude improvement in the turn-on field, which can be attributed to several advantageous factors such as reduced screening effects, improved conductivity, and local electric field enhancement in the proximity of the particles. The present method is generic and thus can be applied to other magnetic particles and porous host materials aiming at innovative sensor, electrical and environmental applications.