Dispersion mechanism of polyacrylic acid-coated nanoparticle in protic ionic liquid, N,N-diethylethanolammonium trifluoromethanesulfonate

Concerns and breakthroughs of combining ionic liquids with microwave irradiation for the synthesis of Ru nanoparticles via decarbonylation

HYPOTHESIS

Combination of microwave irradiation (MWI) and ionic liquids (IL) is widely used for the synthesis of nanoparticles (NP) via decarbonylation of zero-valent metal carbonyl precursors. However, we carefully raise a question as to whether this combination is always beneficial. Upon MWI, highly-absorbing materials such as ILs would be subject to local intense heating, likely resulting in the occurrence of localized chemical decomposition. The decomposition is expected to influence the growth mechanism of NPs due to changes in the electrostatic and steric effects. If the assumption is valid, it should be possible to decompose IL and destabilize the NPs by modifying the amplitude of the incident microwaves. In other words, it should also be possible to control the particle aggregation by circumventing the decomposition of the IL.

EXPERIMENTS

A series of comparative studies were conducted using a model system (i.e. [BMIm][BF₄] and Ru₃(CO)₁₂). Variables were systematically controlled. After MWI, the decrease in colloidal stability of NPs was identified.

FINDINGS

In the formation of Ru NPs via decarbonylation, the association between incident microwave intensity, chemical decomposition of IL, and initiation of particle aggregation has been demonstrated. Conditions that can accelerate or alleviate the decomposition and the aggregation are also corroborated.

Nearly monodispersed MoS2 hierarchical architectures as superior anodes for electrochemical lithium-storage

In this paper, we developed a facile approach to synthesize well-dispersed 3D hierarchical porous MoS₂ architectures with assistance of polyacrylate and demonstrated their applications in lithium ion batteries (LIBs). It was confirmed that the uniform flower-like MoS₂ architectures were assembled by nanosheets comprising about ∼10 stacking layers. Polyacrylate was revealed to have a significant impact on controlling the formation of the uniform hierarchical flower-like architectures with desirable dispersity. It was believed that the polyacrylate could direct assembly of the MoS₂ nanosheets into hierarchical structures and could well stabilize and disperse MoS₂ architectures. Furthermore, a stable cycling capability (839 mAh g^-1 at 0.1 A g^-1 after 120 cycles) and superior rate ability of the MoS₂ architectures were achieved as anodes for LIBs. This remarkably enhanced electrochemical property could be ascribed to their beneficial structural features and surface-dominated capacitive contribution.

Hyperthermia Efficiency of Magnetic Nanoparticles in Dense Aggregates of Cerium Oxide/Iron Oxide Nanoparticles

Iron oxide nanoparticles are intended to be used in bio-applications for drug delivery associated with hyperthermia. However, their interactions with complex media often induces aggregation, and thus a detrimental decrease of their heating efficiency. We have investigated the role of iron oxide nanoparticles dispersion into dense aggregates composed with magnetic/non-magnetic nanoparticles and showed that, when iron oxide nanoparticles were well-distributed into the aggregates, the specific absorption rate reached 79% of the value measured for the well-dispersed case. This study should have a strong impact on the applications of magnetic nanoparticles into nanostructured materials for therapy or catalysis applications.