Eva Koudelková

Activated interiors of clay nanotubes for agglomeration-tolerant automotive exhaust remediation†

Naturally occurring clay nanotubes, halloysite (Al2Si2O5(OH)4·2H2O), with exterior and interior surfaces, respectively, composed of SiOx and AlOx layers, act as an agglomeration-tolerant exhaust catalyst when copper–nickel alloy nanoparticles (Cu–Ni NPs, 2–3 nm) are immobilized at the AlOx interior. Co-reduction of Cu2+ and Ni2+ (respectively derived from CuCl2 and NiCl2) in the presence of sodium citrate (Na3C6H5O7·2H2O) and halloysite yielded the required nanocomposite, Cu–Ni@halloysite. Cu–Ni@halloysite efficiently catalyzes the purification of simulated motor vehicle exhaust comprising nitrogen monoxide (NO) and carbon monoxide (CO) near the activation temperature of Pt-based exhaust catalysts, ≤400 °C, showing its potential as an alternative to Pt-based catalysts. In contrast, a different halloysite nanocomposite with the SiOx exterior decorated with Cu–Ni NPs, Cu–Ni/halloysite, is poorly active even at >400 °C because of particle agglomeration. The enhanced exhaust-purification activity of Cu–Ni@halloysite can ultimately be attributed to the topology of the material, where the alloy NPs are immobilized at the tubular AlOx interior and protected from particle agglomeration by the tubular form and SiOx exterior.

Promoted C–C bond cleavage over intermetallic TaPt3 catalyst toward low-temperature energy extraction from ethanol

Novel intermetallic TaPt3 nanoparticles (NPs) are materialized, which exhibit much higher catalytic performance than state-of-the-art Pt3Sn NPs for electrooxidation of ethanol. In situ infrared-reflection-absorption spectroscopy (IRRAS) elucidates that the TaPt3 NPs cleave the C–C bond in ethanol at lower potentials than Pt NPs, efficiently promoting complete conversion of ethanol to CO2. Single-cell tests demonstrate the feasibility of the TaPt3 NPs as a practical energy-extraction catalyst for ethanol fuels, with more than two times higher output currents than Pt-based cells at high discharge currents.

SiO2 Fibers by Centrifugal Spinning with Excellent Textural Properties and Water Adsorption Performance

Facile and innovative route for large-scale synthesis of SiO2 fibers with excellent textural properties and H2O adsorption performance is presented. At first, a three-dimensional network of SiO2 precursor fibers was produced from tailored spun solutions (without any toxic elements and surfactants) by centrifugal spinning, which is a very modern fiber-synthesis technique, with numerous advantages over electrospinning. Upon thermal annealing of the precursor fibers, mesoporous amorphous SiO2 fibers with an ultrahigh surface area of up to 824 m2/g and pore size distribution in the range of 2–10 nm were produced. Owing to the high number of OH groups available on the surface, the produced SiO2 fibers showed significantly better performance in H2O adsorption compared to that of the reference silicagel.