Ionic Liquid Assisted Synthesis of Au-Pd Bimetallic Particles with Enhanced Electrocatalytic Activity

Review on recent progress in metal-organic framework-based materials for fabricating electrochemical glucose sensors

Diabetes is a type of disease that threatens human health, which can be diagnosed based on the level of glucose in the blood. Recently, various MOF-based materials have been developed as efficient electrochemical glucose sensors because of their tunable pore channels, large specific surface area well dispersed metallic active sites, etc. In this review, the significance of glucose detection and the advantages of MOF-based materials for this application are primarily discussed. Then, the application of MOF-based materials can be categorized into two types of glucose sensors: enzymatic biosensors and non-enzymatic sensors. Finally, insights into the current research challenges and future breakthrough possibilities regarding electrochemical glucose sensors are considered.

Optimization of gold-palladium core-shell nanowires towards H2O2 reduction by adjusting shell thickness

Designable bimetallic core-shell nanoparticles exhibit superb performance in many fields including industrial catalysis, energy conversion and chemical sensing, due to their outstanding properties associated with their tunable electronic structure. Herein, Au-Pd core-shell (Au_richPd@AuPd_rich) nanowires (NWs) were synthesized through a one-pot facile chemical reduction method in the presence of cetyltrimethyl ammonium bromide (CTAB) surfactant. The thickness of the Pd shell could be adjusted by directly controlling the Au/Pd feeding ratio while maintaining the nanowire morphology. The as-obtained Au₇₅Pd₂₅ core-shell NWs with a thin Pd_rich shell showed significantly enhanced activities towards the reduction of hydrogen peroxide with the sensitivity reaching 338 μA cm^-2 mM^-1 and a linear range up to 10 mM. In sum, Pd shell thickness could be used to adjust the electronic structure, thereby optimizing the catalytic activity.

An aqueous synthesis of porous PtPd nanoparticles with reversed bimetallic structures for highly efficient hydrogen generation from ammonia borane hydrolysis

Fine construction of porous bimetallic nanomaterials with tunable components and structures is of great importance for their catalytic performance and durability. Herein, we present a facile and mild one-pot route for the preparation of porous PtPd bimetallic nanoparticles (NPs) with reversed structures in aqueous solution for the first time. To this end, a common ionic liquid (IL) 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl) is utilized to direct the growth and assembly of porous structures of PtPd NPs. It is shown that the as-prepared porous Pt25Pd75 NPs have obvious hierarchical structures with nanoflowers as subunits and nanorods as basic units. The elemental components and structures of the porous PtPd NPs can be tuned by the precursor ratio and the [C16mim]Cl concentration. Furthermore, various porous PtPd bimetallic structures from Pd-on-Pt to Pt-on-Pd may be efficiently switched by controlling the concentration of glycine. Owing to their high specific surface area, porous hierarchical structures (including mesopores and micropores), and probable electronic effects between Pt and Pd, the porous Pt25Pd75 NPs (Pd-on-Pt structure) are found to exhibit prominent catalytic activity and high stability for hydrogen production from hydrolysis of ammonia borane.

Ionic Liquid-Modulated Synthesis of Porous Worm-Like Gold with Strong SERS Response and Superior Catalytic Activities

Porous gold with well-defined shape and size have aroused extensive research enthusiasm due to their prominent properties in various applications. However, it is still a great challenge to explore a simple, green, and low-cost route to fabricate porous gold with a “clean” surface. In this work, porous worm-like Au has been easily synthesized in a one-step procedure from aqueous solution at room temperature under the action of ionic liquid tetrapropylammonium glycine ([N₃₃₃₃][Gly]). It is shown that the as-prepared porous worm-like Au has the length from 0.3 to 0.6 μm and the width of approximately 100–150 nm, and it is composed of lots of small nanoparticles about 6–12 nm in diameter. With rhodamine 6G (R6G) as a probe molecule, porous worm-like Au displays remarkable surface enhanced Raman scattering (SERS) sensitivity (detection limit is lower than 10⁻¹³ M), and extremely high reproducibility (average relative standard deviations is less than 2%). At the same time, owing to significantly high specific surface area, various pore sizes and plenty of crystal defects, porous worm-like Au also exhibits excellent catalytic performance in the reduction of nitroaromatics, such as p-nitrophenol and p-nitroaniline, which can be completely converted within only 100 s and 150 s, respectively. It is expected that the as-prepared porous worm-like Au with porous and self-supported structures will also present the encouraging advances in electrocatalysis, sensing, and many others.

The conversion of α-pinene to cis-pinane using a nickel catalyst supported on a discarded fluid catalytic cracking catalyst with an ionic liquid layer

The concept of a solid catalyst coated with a thin ionic liquid layer (SCILL) was applied to the stereoselective hydrogenation of α-pinene. Nickel, a non-noble metal, was supported on a discarded fluid catalytic cracking catalyst (DF3C) and then modified with different loadings of the ionic liquid 1-ethanol-3-methylimidazolium tetrafluoroborate ([C2OHmim][BF4]). The resulting catalysts showed a range of conversions and selectivities for the hydrogenation of α-pinene. The SCILL catalysts afforded cis-pinane with high selectivity and their activity depended on the ionic liquid loading. For an ionic liquid loading of 10 wt%, although the catalytic activity was suppressed, the selectivity and conversion could reach above 98% and 99%, respectively. In addition, the catalyst remained stable after 13 runs and the activity was almost unchanged with the conversion maintained at approximately 99%. Thus, the ionic liquid layer not only improved the selectivity for cis-pinane but also protected the active site of the catalyst and prolonged the service lifetime of the catalyst. The SCILL catalytic system provides an example of an ionic liquid catalytic system which eliminates organic solvents from the catalytic process.

l-Arginine-assisted one-pot synthesis of hierarchical Ag1Pt2 nanocorallines for surface-enhanced Raman spectroscopy

The hierarchical multi-branched Ag₁Pt₂ nanocorallines (NCs) were prepared in a large scale by a rapid aqueous method, using l-arginine as the eco-friendly shape-directing agent. The product was mainly characterized by microscopy measurements, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The architectures exhibited superior surface-enhanced Raman scattering (SERS) with 4-nitrothiophenol (4-NTP), the enhancement factor (EF) of 1.3×10⁵, a wide linear range of 10-100μM and a low detection limit of 0.01μM. Meanwhile, the SERS-active substrate was explored for the assay of 4-mercaptobenzoic acid (4-MBA) with significantly enhanced SERS performance. It means Ag₁Pt₂ NCs as a good Raman-active platform for sensing in food and environment analysis, owing to their rough surfaces and unique multi-branched structures.

Current status and future challenges in ionic liquids, functionalized ionic liquids and deep eutectic solvent-mediated synthesis of nanostructured TiO2: a review

This review is on current advancements in IL-mediated synthesis of TiO₂, and the potential for future research in this area.

Freestanding CuS nanowalls: ionic liquid-assisted synthesis and prominent catalytic performance for the decomposition of ammonium perchlorate

Freestanding CuS nanowalls, with excellent catalytic activity for AP thermal decomposition, were grown and assembled at the [C₁₀mim]Br-modulated liquid–liquid interface.

Thermal reaction of the ionic liquid 1,2-dimethyl-(3-aminoethyl) imidazolium tetrafluoroborate: a kinetic and theoretical study

Since the thermal stabilities of ionic liquids (ILs) are of significance for their application, an amine-functionalized IL 1,2-dimethyl-(3-aminoethyl) imidazolium tetrafluoroborate [aEMMIM][BF4] was chosen to study thermal decomposition mechanisms via the methods of FT-IR, (1)H NMR, TGA, TGA-MS and density functional theory (DFT) calculations. Theoretical and experimental results indicated that amine-functionalization reduces the thermal stability of [aEMMIM][BF4] compared to its non-functionalized counterpart. Moreover, we found that [aEMMIM][BF4] follows a unimolecular nucleophilic substitution (SN1) decomposition (98.8 %), whereas the bimolecular nucleophilic substitution (SN2) decomposition (1.2 %) is unfavorable. The SN1 and SN2 reactions were fully optimized at B3LYP/6-311++G(d,p) level, and the energies of reactant (R), intermediates (IM), transition state (TS) and product (P) were obtained and analyzed by reaction mechanism. The energy of the intermediate is higher than that of the reactants by 18.92 kJ mol(-1), and the energy of the TS is higher than that of the IM by 155.23 kJ mol(-1). This result indicates that the IM are also more stable than the P2 product, thus the reaction is endothermic. The chemical nature of the covalent and hydrogen bonds was analyzed by vibrational modes analysis (VMA), nature bond orbital (NBO) and the theory of atoms in molecules (AIM). Graphical Abstract Proposed thermal decomposition of [aEMMIM][BF4] via unimolecular ( SN1) and bimolecular( SN2) nucleophilic substitution mechanisms. The electrostatic potential surface (ESP) of the transition state illustrates that hydrogen bonds are generated when [BF4](-) is close to [aEMMIM](+), and SN1 decomposition is much favorable than SN2 decomposition.

Synthesis of Functional Nanomaterials in Ionic Liquids

Utilization of ionic liquids (ILs) in material synthesis is a promising field. The unusual properties of ILs provide new opportunities for the design of functional materials, and much excellent work has been reported. Here, the progress in material design and synthesis using ILs, especially nanomaterials, is discussed, including the unitization of ILs as synthetic media, templates, precursors, or components in the synthesis of various categories of nanomaterials. The challenges and opportunities in this interesting and rapid developing area are also discussed.

Stable monodisperse colloidal spherical gold nanoparticles formed by an imidazolium gemini surfactant-based water-in-oil microemulsion with excellent catalytic performance

A facile and versatile method for the synthesis of stable monodisperse colloidal gold nanoparticles was developed using a water-in-oil microemulsion-templating strategy.

A Green Synthesis of Nanosheet-Constructed Pd Particles in an Ionic Liquid and Their Superior Electrocatalytic Performance

The ionic liquid 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) is investigated as a solvent for the synthesis of Pd particles. Interestingly, nanosheet-constructed Pd particles could be successfully synthesized in [EMIM]Ac without any additional reducing agent and template under ionothermal conditions. [EMIM]Ac itself works as the solvent, the reducing agent, and the template for the formation of these interesting Pd particles, making this method complementary to the well-known ionic-liquid-precursor approach. Furthermore, [EMIM]Ac can be recycled with no loss of activity for the formation of nanosheet-constructed Pd particles within our studied cycles. Specifically, the nanosheet-constructed Pd particles exhibit superior electrocatalytic activity and stability towards ethanol oxidation and formic acid oxidation compared with commercially available Pd black catalyst, thus demonstrating their promising applications in fuel-cell area. The current approach, thus, presents a green approach towards the synthesis of Pd particles, using only a simple palladium salt and an ionic liquid.

Ionic liquid-assisted synthesis of morphology-controlled TiO2 particles with efficient photocatalytic activity

A facile ionic liquid-assisted route is proposed for the controllable synthesis of anatase TiO₂ particles with efficient photocatalytic activity.

CO2 as a regulator for the controllable preparation of highly dispersed chitosan-supported Pd catalysts in ionic liquids

A controllable synthetic route has been developed for the preparation of chitosan supported Pd catalysts in 1-butyl-3-methylimidazolium acetate by using compressed CO₂ as the anti-solvent and regulator.

Ionic liquid-mediated synthesis of unique PtPd bimetallic particles with tiny subunits for efficient electrocatalytic and catalytic applications

Unusual PtPd bimetallic particles with enhanced catalytic properties are achieved with the ionic liquid-based synthesis route.

Mesoporous CeO2 nanoparticles assembled by hollow nanostructures: formation mechanism and enhanced catalytic properties

In this paper, novel hierarchically mesoporous CeO₂ nanoparticles assembled by hollow nanocones were prepared through a facile solvothermal strategy using Ce(HCOO)₃ as the precursor.