Synthesis of gold, platinum, and gold-platinum alloy nanoparticle colloids with high-power megahertz-repetition-rate lasers: the importance of the beam guidance method

Abstract

Nanoparticles of noble metals and their alloys are of particular interest for biomedicine and catalysis applications. The method of laser ablation of bulk metals in liquids gives facile access to such particles as high-purity colloids and is already used in industrial research. However, the method still lacks sufficient productivity for industrial implementation into series production. The use of innovative laser technology may help to further disseminate this colloid synthesis method in the near future. Ultrashort-pulsed lasers with high powers and megahertz-repetition-rates became available recently, but place high demands on the accurate optical laser pulse delivery on the target. Full lateral pulse separation is necessary to avoid a reduction of nanoparticle productivity due to pulse shielding. In this study, we compare flexible but rather slow galvanometer scanning with much faster but more expensive polygon-wheel scanning in their performance in the production of colloidal nanoparticles by laser ablation in liquid. Both beam guidance technologies are applied in the laser ablation of gold, platinum, and a gold-rich platinum alloy in micromolar saline water. We found that the dimensions of the scan pattern are crucial. A threshold pattern length exists, at which one scan technology becomes more productive than the other one. In addition, a much lower productivity was found for the ablation of gold compared to that of platinum. Alloying gold with only 10 at.% of platinum improved the productivity nearly to the level of platinum, reaching 8.3 g/h.

Influence of Pt Alloying on the Fluorescence of Fully Inorganic, Colloidal Gold Nanoclusters

“…Note that the EDX‐mapping pixel intensity is not linearly correlated with the composition, a pixel is displayed where the elemental threshold count rate is exceeded, showing homogeneous elemental distribution in the particle volume but no direct quantitative information. Such solid‐solution structure has been reported earlier for laser‐generated AuPt particles [25–27] …”

“…Such solid-solution structure has been reported earlier for laser-generated AuPt particles. [25][26][27] In addition, we prepared a 98 : 2 (Au : Pt) atomic mixture target and EDX-analysis of this target verified the 98 : 2 atomic ratio (Figure 1B). The Pt content in the nanoparticles fabricated from these targets was too low to be verifiably measured via EDX.…”

Photothermal and Photodynamic Therapy of Tumors with Plasmonic Nanoparticles: Challenges and Prospects

“…Specifically, full lateral pulse separation is necessary to avoid a reduction in nanoparticle yield caused by pulse shielding. This point has been addressed in a recent report by the Barcikowski group [139].…”

Platinum Nanoparticles in Biomedicine: Preparation, Anti-Cancer Activity, and Drug Delivery Vehicles

“…Materials exposed to a laser flux absorb the incident laser energy, turning the material to plasma. Laser ablation of solid metal has problems with aggregation and inadequate degradation, therefore in previous studies many researchers have shown generation of PtNPs by PLAL (pulsed laser ablation in liquid) ( Waag et al, 2021 ; Fedorova et al, 2020 ; N Madlum et al, 2021 ). The milling process involves gradually decreasing the particle size and mixing them into new phases ( Jan et al, 2021 ; Mathew et al, 2021 ).…”