The Fabrication of Au@C Core/Shell Nanoparticles by Laser Ablation in Solutions and Their Enhancements to a Gas Sensor

Abstract

A convenient and flexible route is presented to fabricate gold noble metal nanoparticles wrapped with a controllable ultrathin carbon layer (Au@C) in one step based on laser ablation of the noble metal targets in toluene-ethanol mixed solutions. The obtained metal nanoparticles were <20 nm in size after ablation, and the thickness of the wrapped ultrathin carbon layer was 2 nm in a typical reaction. The size of the inner noble metal nanoparticles could be controlled by adjusting the power of laser ablation, and the thickness of the ultrathin carbon layer can be controlled from 0.6 to 2 nm by laser ablation in different components of organic solution. Then the resultant Au@C core/shell nanoparticles were modified on the surface of In2O3 films through a sol-gel technique, and the hydrogen sulfide (H2S) gas-sensing characteristics of the products were examined. Compared to pure and Au-modified In2O3, the Au@C-modified In2O3 materials exhibited a revertible and reproducible performance with good sensitivity and very low response times (few seconds) for H2S gas with a concentrations of 1 to 5 ppm at room temperature. Evidence proved that the ultrathin carbon layer played an important role in the improved H2S sensor performance. Other noble metals wrapped by the homogeneous carbon shell, such as Ag@C, could also be prepared with this method.

The enhanced sensing properties of MOS-based resistive gas sensors by Au functionalization: a review

“…Compared with pure In 2 O 3 and Au-decorated In 2 O 3 , the Au@C-decorated In 2 O 3 film exhibits highly enhanced repeatability, good reversibility, and short response time to 1–5 ppm H 2 S at RT. 183 Wei et al 184 synthesized reduced graphene oxide (rGO)/SnO 2 /Au composite materials for the detection of methanol through a two-step method of hydrothermal reaction and in situ reduction. Compared with SnO 2 /rGO composite materials and pure SnO 2 samples, rGO/SnO 2 /Au composite materials exhibit better performance.…”

Fabrication of Au–Ag Bimetallic Nanoparticles Using Pulsed Laser Ablation for Medical Applications: A Review

“…Notably, PLAL conducted in ethanol tends to yield larger NPs compared to DI water [36,49,50], while isopropyl alcohol has also been explored as a viable alternative [51]. Furthermore, previous PLAL investigations have explored the use of various organic solvents including toluene, tetrahydrofuran, and dimethylformamide to investigate their effects on the resulting NP size and morphology [52,53], Additionally, non-organic solvents like hydrogen peroxide have garnered attention [54]. It is important to emphasize that the specific choice of liquid medium exerts influence over colloidal density, UV-Vis absorbance, NP size distribution, and surface chemistry, given the differing interactions these liquids exhibit with the laser, the ablated material, and the synthesized NPs [28].…”

Spheroidization of Nickel Powder and Coating with Carbon Layer through Laser Heating

“…Laser ablation of a metal target in liquid media has been regarded as an efficient and green way for coating carbon layers onto particles of various metals. Duan et al reported on preparation of Au@C nanostructures via laser ablation of a gold target in mixed solutions of toluene and ethanol [ 15 ]. Amendola and coworkers fabricated magnetic Fe@C nanoparticles (NPs) by ablating bulk iron in various organic solvents [ 16 ].…”