Reaction of Decomposition of Hydrogen-containing Components of Aqueous-organic Mixture on Metal Nanoparticles Produced by Laser Synthesis and Ablation Methods.

Abstract

Background: The method of laser deposition of metal nanoparticles from a solution has been considered a promising approach for various applications in microelectronics since the end of the 20th century. Laser-assisted liquid deposition is characterized by very low process rates (millimeters per hour) and high electrical resistance-2-5 orders of magnitude higher than the original materials. This creates obstacles to the development of an efficient and economically attractive technology. In recent years, researchers have been actively looking for other applications for this promising method.

Objective: Therefore, we focused on another side effect of the process: the active release of gas phases of unsaturated hydrocarbons and hydrogen during the reaction. The goal was to explore the potential use of the effect of organic catalysis, which accompanies laser reactions in a liquid medium, in hydrogen energy and controlled organic synthesis.

Methods: The experiments were conducted with respect to water-organic alcohol mixtures of glycerin and isopropanol. V, Zr, Pb, Mo, Zn, and Nb were used as the tested nanocatalysts. A new laboratory laser setup based on a articulated scanner was used to conduct the experiment, allowing the process speed to be increased by 10,000 times. Liquid aqueous-organic phases were studied using GC-MS analysis methods, the gas atmosphere was studied using a portable quadrupole gas mass spectrometer (MS90-400), solid-phase surfaces were studied using a Scanning electron SUPRA 25 microscope, and gravimetric analysis was used.

Results: The results largely confirmed the assumptions regarding the high catalytic activity of metal nanoparticles formed as a result of two competing reactions occurring simultaneously in the laser beam focus in the solution. These are the reactions of liquid laser ablation of metal (PLAL) and liquid laser deposition of metal (LCLD). These reactions lead to the dehydrogenation of saturated hydrocarbons and water, resulting in the formation of hydrogen and unsaturated hydrocarbons. At the same time, a layer of nanoparticles of deposited metal is formed on the solid surface.

Conclusion: This opens up a new potential application for the process: a laser-assisted method for generating hydrogen with the simultaneous generation of unsaturated hydrocarbons for organic synthesis. This is accompanied by the recovery of trace amounts of precious metals, as demonstrated for gold. All three processes are environmentally friendly, which increases the potential positive impact of their practical application after scale-up.