Electrophysical properties of laser-structured carbon nanomaterials functionalized with LaB6 nanoparticles

Abstract

In this paper, we perform density functional theory (DFT)-calculations to study the effect of LaB6 nanoparticles on the electrophysical properties of carbon nanomaterial based on laser-structured multi-walled carbon nanotubes (MWCNTs). Based on the calculation results, the most energetically favorable landing sites for LaB6 nanoparticles on the surface of the carbon framework are determined. It is found that during the functionalization with LaB6 nanoparticles, the carbon framework takes on a charge from the atoms of lanthanum and boron, which leads to an increase in the density of electronic states of the MWCNT nanostructure. It is shown that even at low concentrations of LaB6 nanoparticles (4.5 %), the work function of the carbon nanomaterial decreases by 0.5 eV. The results of the calculations are verified in the course of a real experiment. To carry it out, using the original technology of laser irradiation, a hybrid nanomaterial was created from a vertical array of MWCNTs functionalized with LaB6 nanoparticles. Pulsed laser action on an array of MWCNTs with an adjusted energy density of 0.15 J/cm2 made it possible to shorten, align, and orient the upper ends of the nanotubes perpendicular to the substrate. The effect of binding of LaB6 nanoparticles to a carbon surface has been experimentally established. Laser exposure of the MWCNT array coated with LaB6 nanoparticles resulted in a ∼ 5 by times increase in electrical conductivity compared to the original MWCNT array. Recording the emission current-voltage characteristics of hybrid nanomaterials demonstrated a decrease in the total work function of the carbon nanomaterial after functionalization with LaB6 nanoparticles by 16 %. Field emission current density values were calculated for all samples based on their measured field emission CVC characteristics. The MWCNT array exhibited the highest current density of 0.37 A/cm2 after LaB6 deposition and laser exposure. It is predicted that the carbon nanomaterial based on laser-structured MWCNTs coated with LaB6 nanoparticles will be an excellent nanomaterial for field emission electronics.