Understanding photochemical pathways of laser-induced metal ion reduction through byproduct analysis

Abstract

Laser-induced reduction of metal ions is attracting increasing attention as a sustainable route to ligand-free metal nanoparticles. In this work, we investigate the photochemical reactions involved in reduction of Ag+...

Laser synthesis of nanoparticles in organic solvents – products, reactions, and perspectives

“…Schematic of different reaction pathways for the LRL of (b) Ag + and (c) AuCl 4 − and detected reaction products and reaction intermediates indicated for each reaction condition: femtosecond (pink) or nanosecond (green) laser excitation; water (top) or water–isopropyl alcohol (bottom). Figure 6 was reproduced from [ 121 ] (“Understanding photochemical pathways of laser-induced metal ion reduction through byproduct analysis”, © 2023 L. M. F. Batista et al, published by The Royal Society of Chemistry, distributed under the terms of the Creative Commons Attribution-NonCommercial 3.0 Unported License, https://creativecommons.org/licenses/by-nc/3.0/ ). This content is not subject to CC BY 4.0.…”

“…For the formation of Ag nanoparticles during LRL in isopropyl alcohol, they proposed a mechanism of electron transfer from the solvent, which produced acetone as a by-product. Since this transfer is not possible in water and only plasma reactions are available, Ag could not nucleate during LRL in water because of the oxidizing activity of hydroxyl radicals [ 121 ]. Overall, LSPC in organic solvents leads to higher gas volumes and a more complex gas mixture, consisting of hydrogen and highly volatile hydrocarbons, than in water.…”

“…While the production of gases might initially appear unrelated to the widespread observations of carbon shells surrounding nanoparticles produced by LSPC in organic solvents, another category of carbon-based molecules is formed that might link the two species, namely pyrolysis products. Pyrolysis products were previously found during photolysis of organic solvents [ 52 , 117 ] as well as laser ablation [ 122 – 123 ], laser fragmentation [ 124 ], laser melting [ 125 ], and laser reduction [ 120 – 121 ]. While the formation of short hydrocarbons during laser-based synthesis of nanoparticles in organic solvents is known, the amount of literature in this regard is scarce.…”

“…Suehara et al and Shakeri et al investigated the thermodynamic influence on the solvent’s decomposition. However, literature on laser chemistry often reports the use of few-picosecond and femtosecond lasers [ 52 , 115 , 117 – 121 172 ]. These ultrashort pulses induce a stronger interaction of the laser irradiation with the solvent and, hence, a higher fraction of by-products.…”

“…Frias Batista et al recently investigated the differences in by-product formation during ns- and fs-LRL of [AuCl 4 ] − and found results in line with the proposed stronger interaction. The mass spectra of fs-LRL in isopropyl alcohol not only showed a larger variety of by-products but also that the formation rate of, for example, acetone was higher than that for ns-LRL (see Figure 6 ) [ 121 ]. The same authors also found that few-picosecond pulses induce even more rapid formation of by-products than femtosecond pulses during the irradiation of organic solvents [ 117 ].…”