Formation ofAu–carbon nanoparticles by laser ablation under pressurizedCO₂

Abstract

Pulsed laser ablation is known to be a promising method for synthesizing metal nanoparticles. Here, Au–carbon nanoparticles were synthesized by pulsed laser ablation under pressurized carbon dioxide. Au plate was ablated using a Nd:YAG laser with a wavelength of 532 nm and energy of 0.83 mJ in a high‐pressure chamber. The experiments were performed at temperatures and pressures of 21–25 °C and 7–15 MPa, corresponding to carbon dioxide densities of 0.75–0.89 g/cm3, respectively. The synthesized products were collected on a silicon wafer and analyzed using field emission scanning electron microscopy, transmission electron microscopy, and a scanning transmission electron microscopy system equipped with energy‐dispersive X‐ray spectroscopy. The results showed that the generated metal nanoparticles exhibited spherical and nanocluster structures. Au, C, and O were clearly found on the nanoparticle products.

Carbon coated TiO2nanoparticles prepared by pulsed laser ablation in liquid, gaseous and supercritical CO2

“…The average particle size when plotted for nanoparticles synthesized at 5-40 MPa CO 2 pressures at 50 °C temperature showed a decreasing trend from 19 nm to 14.5-15 nm with increasing pressures (figure 7). This is in agreement with the reduction in size of Sn [48], ZnO [49], and Au [26] nanoparticles with an increase in ambient fluid pressure (CO 2 , H 2 O) as reported in literature by PLA in pressurized fluids. This was attributed to smaller volume and shorter lifetimes of the cavitation bubbles at higher solvent (CO 2 , H 2 O) pressures [49,50].…”

“…This is observable from the lognormal fitted curves for each size distribution and decreasing trend in the variation of the standard deviation (figure 7 inset). This is in agreement with the narrowing of size distribution with increasing pressures reported for ablation of gold in pressurized CO 2 [26].…”

“…However, there are no studies on generation of core-shell nanoparticles by PLA when CO 2 is in the supercritical regime, to the best of our knowledge. Previously, PLA in pressurized CO 2 has been demonstrated to form metal-core carbon-shell nanoparticles of Ni-carbon in gaseous CO 2 [25] and Au-carbon in liquid and gaseous CO 2 [26].…”