Platinum Selenide Nanoparticles Synthesis and Their Reaction with Butyllithium Breaking the Long-Range Ordering Structure

PtSe₂ is a Transition Metal Dichalcogenide (TMDC) material with potential applications in fields such as sensors, electronics, and catalysis¹. Despite significant progress in the production of 2D monolayers of PtSe₂, the synthesis of controlled PtSe₂ nanoparticles (NPs) remains unexplored². Here, we present a novel procedure for selenizing previously synthesized Pt NPs, resulting in high-quality crystalline PtSe₂ NPs. Pt NPs were initially synthesized using platinum acetylacetonate (II) as precursor and oleic acid and oleylamine as ligands. The reaction was performed using standard colloidal wet chemical synthesis ir air-free system. These Pt NPs were then combined with excess of selenium and sealed in a custom stainless-steel reactor with an interior composed of high-purity alumina (Al₂O₃) ceramic TGA pan, under an inert N₂ atmosphere inside a glovebox. Then, the reactor was heated at 400°C for two hours. After cooling, excess selenium was solubilized with trioctylphosphine (TOP) and separated via centrifugation under inert conditions. The material was further purified by adding acetone, followed by centrifugation and supernatant removal. PtSe₂reaction with n-butyllithium was also studied. The mixture was stirred at room temperature in an ultrasonic bath. Afterward, the mixture was washed sequentially with hexane, acetone, and deionized water to eliminate the LiOH byproduct. This reaction with butyllithium led to cleavage of the covalent bond along the ab-plane of the 2D material (intralayer) and disrupted the PtSe₂ long-range structure. The result was a PtSe_x nanomaterial with a minor deselenization process, retaining short-range ordering while altering the local structure, as confirmed by Raman and ePDF analyses. XPS analysis also revealed a decrase in the concentration of selenium a the surface compared to PtSe₂. Both types of nanoparticles exhibited improved performance in the hydrogen evolution reaction (HER) compared to bulk PtSe₂. TEM analyses indicated that PtSe_x kept the morphology of previouly PtSe₂ samples, however the crystallite volume are much smaller. Unusual crystallographic facets could apper in the PtSe_x sample potentially serving as additional active sites for hydrogen adsorption, in contrast to the standard catalytic performance on the basal plane (001) and its defects reported in the literature. The disruption of Long-Range Ordering (LRO) in PtSe_x, compared to PtSe₂ NPs, appears to enhance charge carrier mobility, further contributing to the improved catalytic performance as studied by electrochemical impedance spectroscopy (EIS). Consequently, the results presented here suggest that PtSe₂ NPs can be produced using a rapid and straightforward method compared to the conventional selenization process, making them valuable as catalysts³. Future advancements in PtSe₂ NPs, including doping, defect control, and nano-heterojunction studies, have the potential to enhance their performance.<br/>[1] MANZELI, S.; <i>et al</i>., <i>Nature Reviews Materials.</i> 2(8), 1–15, 2017.<br/>[2] GONG, Y.; <i>et al</i>., <i>Nano-Micro Letters</i>. 12(1), 1-34, 2020.<br/>[3] ZHU, Y.; <i>et al.</i>, <i>Advanced Materials</i>. 30(15), 2018.