Liquid‐Phase Synthesis of Highly Reactive Rare‐Earth Metal Nanoparticles

Abstract

The first liquid-phase synthesis of high-quality, small-sized rare-earth metal nanoparticles (1-3 nm)-ranging from lanthanum as one of the largest (187 pm) to scandium as the smallest (161 pm) rare-earth metal-is shown. Size, oxidation state, and reactivity of the nanoparticles are examined (e.g., electron microscopy, electron spectroscopy, X-ray absorption spectroscopy, selected reactions). Whereas the nanoparticles are highly reactive (e.g. in contact to air and water), they are chemically stable as THF suspensions and powders under inert conditions. The reactivity can be controlled to obtain inorganic and metal-organic compounds at room temperature.

Large and Small Solids: A Journey Through Inorganic Chemistry

“… Liquid‐phase synthesis of base‐metal nanoparticles: a) suspension of metal nanoparticles in THF, b) red‐marked metals available with the aforementioned synthesis strategies, c) electron microscopic characterization of base‐metal nanoparticles with Sm(0) as specific example (modified reproduction from [16d] ). …”

“…Especially powder samples of the nanosized metals show violent reactions with air or water, which are comparable or even more violent than known for bulk alkali metals. In the liquid phase under inert atmosphere, however, the reactivity and reactions can be well‐controlled and, for instance, result in bimetallic nanoparticles as well as metal‐oxide and metal‐sulfide nanoparticles or single‐crystalline metal iodides and metal alkoxides [16b‐d] . Moreover, the base‐metal nanoparticles offer the option to prepare coordination compounds in the liquid phase at mild conditions (20–100 °C) (Figure 7).…”

“…Having all the reactive base‐metal nanoparticles available since recently, [16d] their use as potential starting materials in follow‐up reactions became an interesting question. Due to the small size of the base‐metal nanoparticles, a high reactivity – even higher than for the respective bulk metals – can be expected.…”

“…Another question is if the follow‐up reactions are dominated, if not deteriorated by the ingredients and remains of the initial nanoparticle synthesis (e. g., naphthalene, THF, pyridine, LiCl/NaCl). First of all, the reactivity was probed with conventional oxidizing agents such as O 2 , S 8 , I 2 , H 2 O, or C 2 H 5 OH [16d] . Especially powder samples of the nanosized metals show violent reactions with air or water, which are comparable or even more violent than known for bulk alkali metals.…”

Colloidal synthesis of nanoparticles: from bimetallic to high entropy alloys

“…10 As a result, this spectrum of impressive properties makes this new broad class of structural materials attractive. [11][12][13][14][15][16][17][18] To take full advantage of their potential as structural and functional materials for future nanotechnologies, it is crucial to thoroughly understand the structure-property relationship in HEA-NPs. 19 Consequently, the development of innovative synthesis protocols is required to gain control over the size, shape composition and structural phase of HEA NPs.…”