Covalent functionalization tailors carbon nanotubes for a wide range of applications in varying environments. Its strength and stability of attachment come at the price of degrading the carbon nanotubes sp2 network and destroying the tubes electronic and optoelectronic features. Here we present a non-destructive, covalent, gram-scale functionalization of single-walled carbon nanotubes by a new [2+1] cycloaddition. The reaction rebuilds the extended π-network, thereby retaining the outstanding quantum optoelectronic properties of carbon nanotubes, including bright light emission at high degree of functionalization (1 group per 25 carbon atoms). The conjugation method described here opens the way for advanced tailoring nanotubes as demonstrated for light-triggered reversible doping through photochromic molecular switches and nanoplasmonic gold-nanotube hybrids with enhanced infrared light emission.
Light interacting with metallic nanoparticles creates a strongly localized near-field around the particle that enhances inelastic light scattering by several orders of magnitude. Surface-enhanced Raman scattering describes the enhancement of the Raman intensity by plasmonic nanoparticles. We present an extensive Raman characterization of a plasmonic gold nanodimer covered with graphene. Its two-dimensional nature and energy-independent optical properties make graphene an excellent material for investigating local electromagnetic near-fields. We show the localization of the near-field of the plasmonic dimer by spatial Raman measurements. Energy-and polarization-dependent measurements reveal the local near-field resonance of the plasmonic system. To investigate the far-field resonance we perform dark-field spectroscopy and find that near-field and far-field resonance energies differ by 170 meV, much more than expected from the model of a damped oscillator (40 meV).
Novel K-promoted bimetallic Fe-and In-based catalysts on a Ce− ZrO 2 support were prepared and tested for higher alcohol synthesis from CO 2 and hydrogen. The FeIn/Ce−ZrO 2 precursors with different Fe contents were characterized in detail, and well-dispersed Fe 2 O 3 and In 2 O 3 phases with oxygen vacancies were observed. The catalysts were tested in a continuous setup at extended times on stream (up to 100 h) at 300 °C, 10 MPa, a gas hourly space velocity of 4500 mL g −1 h −1 , and a H 2 /CO 2 ratio of 3. The effect of K loading, the pretreatment atmosphere, Fe/(Fe + In) molar ratios, and calcination temperature on CO 2 conversion and product selectivity were studied. Best performance with a CO 2 conversion of 29.6% and a higher alcohol selectivity of 28.7%, together with good stability, was obtained over a K-0.82-FeIn/Ce−ZrO 2 _900 catalyst after activation under a CO atmosphere. These findings were rationalized by considering the effects of the individual catalyst components (K, Fe, and In) on catalyst performance. Surprisingly, the presence of calcined SiC, used as a diluent in the packed bed reactor, was shown to have a positive effect on catalyst performance and as such also is catalytically active. The best performance in terms of higher alcohol yield (8.5%) obtained in this work ranks in the top three of reports on CO 2 hydrogenation to higher alcohols in a continuous setup. Moreover, light olefins with 20.3% selectivity (6.0% yield) were coproduced over the optimized catalyst, which has a positive effect on the economic potential of the catalysts.
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