A new concept of a solid catalyst with ionic liquid layer (SCILL) as a novel method to improve the selectivity of heterogeneous catalysts is presented. The sequential hydrogenation of cyclooctadiene (COD) to cyclooctene (COE) and cyclooctane on a commercial Ni catalyst coated with the ionic liquid [BMIM][n-C 8 H 17 OSO 3 ] was tested as first model system. Compared to the original catalyst, the coating of the internal surface with the ionic liquid (IL) strongly enhances the maximum intrinsic COE yield from 40 to 70 %. This effect is already achieved for a pore filling degree of only 10 % and cannot be explained by pore diffusion, as shown by experiments with different particle sizes and theoretical considerations. The IL layer is very robust and no leaching into the organic phase was detectable.
Developing cost-effective electrocatalysts for the oxygen reduction reaction (ORR) is a prerequisite for broad market penetration of low-temperature fuel cells. A major barrier stems from the poisoning of surface sites by nonreactive oxygenated species and the sluggish ORR kinetics on the Pt catalysts. Herein we report a facile approach to accelerating ORR kinetics by using a hydrophobic ionic liquid (IL), which protects Pt sites from surface oxidation, making the IL-modified Pt intrinsically more active than its unmodified counterpart. The mass activity of the catalyst is increased by three times to 1.01 A mg(-1) Pt @0.9 V, representing a new record for pure Pt catalysts. The enhanced performance of the IL-modified catalyst can be stabilized after 30 000 cycles. We anticipate these results will form the basis for an unprecedented perspective in the development of high-performing electrocatalysts for fuel-cell applications.
Outstanding mechanical and optical properties of diamond nanoparticles in combination with their biocompatibility have recently attracted much attention. Modification of the surface chemistry and incorporation into a polymer is required in many applications of the nanodiamond. Nanodiamond powder with reactive amino groups (∼20% of the number of surface carbon atoms in each 5 nm particle) was produced in this work by covalent linking of ethylenediamine to the surface carboxyl groups via amide bonds. The synthesized material was reacted with epoxy resin, yielding a composite, in which nanodiamond particles are covalently incorporated into the polymer matrix. The effect of amino groups grafted on the nanodiamond on the curing chemistry of the epoxy resin was analyzed and taken into consideration. Covalently bonded nanodiamond-epoxy composites showed a three times higher hardness, 50% higher Young's modulus, and two times lower creep compared to the composites in which the nanodiamond was not chemically linked to the matrix. Aminated nanodiamond produced and characterized in the present study may also find applications beyond the composites, for example, as a drug, protein, and gene delivery platform in biology and medicine, as a solid support in chromatography and separation science, and in solid state peptide synthesis.
In this review, we introduce photonic crystal fibre as a novel optofluidic microdevice that can be employed as both a versatile chemical sensor and a highly efficient microreactor. We demonstrate that it provides an excellent platform in which light and chemical samples can strongly interact for quantitative spectroscopic analysis or photoactivation purposes. The use of photonic crystal fibre in photochemistry and sensing is discussed and recent results on gas and liquid sensing as well as on photochemical and catalytic reactions are reviewed. These developments demonstrate that the tight light confinement, enhanced light-matter interaction and reduced sample volume offered by photonic crystal fibre make it useful in a wide range of chemical applications.
The vapour pressure and the thermal stability of liquids are important material properties. For high boiling organic and ionic liquids (ILs), the determination of these properties is laborious and it is not easy to discriminate between evaporation and thermal decomposition. In this work, a simple but accurate method is presented to determine the parameters of decomposition and evaporation by thermogravimetrical analysis (TGA). The mass transfer coefficient was calculated based on a new correlation for the Sherwood number for cylindrical crucibles in overflow of a carrier gas. This correlation is valid for any diameter-to-height ratio and for any filling degree of the crucible and was derived from numerical simulations and proven by experiments with hexadecane, dodecane, and anthracene. The TGA analysis of two ILs was conducted. [EMIM][EtSO(4)] decomposes at ambient pressure without a measurable contribution of evaporation. To the contrary, [BMIM][NTf(2)] is relatively volatile. The vapour pressure of [BMIM][NTf(2)] and the kinetics of decomposition of both ILs were determined.
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