Citation: Larichev, Y.V. Experience of Using DLS to Study the Particle Sizes of Active Component in the Catalysts Based on the Oxide and Non-Oxide Supports. Inorganics 2022, 10, 248. https://doi.org/10.3390/ inorganics10120248 Academic Editor: Sergey Kuznetsov Received: 14 November 2022 Accepted: 3 December 2022 Published: 8 December 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the author. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). inorganics Article Experience of Using DLS to Study the Particle Sizes of Active Component in the Catalysts Based on the Oxide and Non-Oxide Supports Yurii V. Larichev 1,2 1 Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Prospekt Akademika Lavrentieva 5, Novosibirsk 630090, Russia; ylarichev@gmail.com 2 Department of Physics, Novosibirsk State University, 1 Pirogov Street, Novosibirsk 630090, Russia Abstract: The present study reports the use of the dynamic light scattering (DLS) method to analyze metal nanoparticle sizes in supported catalysts (as a model system for different metal-oxide nanocom- posites, ceramics, etc.). The selective dissolution of matrices has been used to transform solids to sols for DLS analysis. DLS/STS (from solid to sol) technique was tested on a wide number of different sets of supported metal catalysts (Pt, Pd, Ru metals and Al 2 O 3 , SiO 2 , TiO 2 ,C 3 N 4 , carbon and polymers as supports). The transmission electron microscopy and X-ray diffraction (TEM/XRD) results for the initial supported catalysts and the DLS results for the sols prepared from them showed good agreement with each other. Moreover, it has been shown that this approach can identify the minor contamination of catalysts by large particles or aggregates which are difficult to detect by TEM/XRD. Keywords: DLS; STS; particle sizes; supported metal catalysts; porous oxide supports; carbon; polymers; selective dissolution; sols 1. Introduction The determination of heterogeneous catalysts, ceramics and other functional material particle sizes is one of significant tasks for catalysis and material science. The properties of nanosized materials and catalysts depend on the particle size of the active component [1–7]. Considering the importance of this problem, basic methods such as TEM (transmission electron microscopy) and XRD (X-ray diffraction) to determine particle sizes were devel- oped a long time ago [8,9]. Despite their popularity at the present time, these methods require costly hardware and qualified personnel. In addition, these methods are not sensi- tive enough in the case of the low quantity of active components or small contamination by fraction with noticeably different particle sizes. Simpler chemisorption methods are not always applicable in this case due to various negative reasons [8]. Therefore, the development of new simple analytical methods for particle size determination is quite an actual task, especially for the chemical industry. Currently, alternative methods and techniques for the determination of particle size are developing [10–12].However, it seems more interesting and promising for these purposes to use the method of dynamic light scattering (DLS) [13–16].It is an inexpensive and fast method of particle size determination. In addition, TEM and DLS results, as a rule, are in good agreement with each other [17–22]. The main problem in such a case is the applicability of DLS only for liquid systems; for solids, this method in a conventional version does not work. At best, the standard DLS anal- ysis of the ultrasonic dispersion of any powder in liquid media can give only approximate particle sizes of this initial powder or even their aggregates as an output [23–25]. Obviously, this technique in the initial state is unusable for determining the particle sizes of active components on the porous supports. Nevertheless, our recent work demonstrated how to avoid this problem and adapt DLS for the analysis of solid heterogeneous catalysts [26]. The main idea is to selectively dissolve the support and analyze the prepared sol with Inorganics 2022, 10, 248. https://doi.org/10.3390/inorganics10120248 https://www.mdpi.com/journal/inorganics