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Nanosized metal （Pt or Pd）-decorated TiO2 nanofibers （NFs） were synthesized by a wet impregnation method. CdSe quantum dots （QDs） were then anchored onto the metal-decorated TiO2 NFs. The photocatalytic performance of these catalysts was tested for activation and reduction of CO2 under UV-B light. Gas chromatographic analysis indicated the formation of methanol, formic acid, and methyl formate as the primary products. In the absence of CdSe QDs, Pd-decorated TiO2 NFs were found to exhibit enhanced performance compared to Pt-decorated TiO2 NFs for methanol production. However, in the presence of CdSe, Pt-decorated TiO2 NFs exhibited higher selectivity for methanol, typically producing -90 ppmg^-1.h^-1 methanol. The CO2 photoreduction mechanism is proposed to take place via a hydrogenation pathway from first principles calculations, which complement the experimental observations.

In this work the activity of ruthenium decorated carbon foam (Ru/CF) catalyst was studied in three phase hydrogenation reaction of d-xylose to d-xylitol. The developed catalyst was characterized by using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, inductively coupled plasma optical emission spectrometry and nitrogen adsorption–desorption measurement. Kinetic measurements were carried out in a laboratory scale pressurized reactor (Parr®) assisted by SpinChem® rotating bed reactor (SRBR), at pre-defined conditions (40–60 bar H2 and 100–120 °C). The study on the influence of reaction conditions showed that the conversion rate and selectivity of hydrogenation reaction of d-xylose was significantly affected by temperature. These results have been proved by a competitive kinetics model which was found to describe the behavior of the novel system (Ru/CF catalyst used together with the SRBR) very well. Besides, it was revealed that the catalytic activity as well as the stability of our Ru/CF-SRBR is comparable with the commercial ruthenium decorated carbon catalyst (Ru/AC) under identical reaction conditions. Moreover, all steps from catalyst preparation and catalyst recycling as well as catalytic testing can be performed in an easy, fast and elegant manner without any loss of materials. Briefly, the developed Ru/CF catalyst used together with the SRBR could be used an excellent alternative for the conventional Raney nickel catalyst in a slurry batch reactor and offers an attractive concept with obvious industrial applicability.

Steam reforming of biofuels such as bioethanol offers a clean and sustainable route to improve hydrogen production capacity for the hydrogen economy. In this work, the influence of the carbon support type (carbon nanotube [CNT], activated carbon [AC] and graphitic carbon black [GCB]) and the addition of Pt (1 wt.%, 1.5 wt.% and 2 wt.%) and ZnO (10 wt.%) to Ni /CNT (10 wt.% Ni) are studied in steam reforming of ethanol (SRE) at low temperatures (≤450°C). The prepared CNT-based catalysts were characterized by nitrogen physisorption, X-ray powder diffraction (XRD), energy-dispersive X-ray (EDX) and energy filtered transmission electron microscopy (EFTEM) analyses. Ni supported on CNTs was found to be highly active for SRE compared to other conventional carbon supported catalysts. The promotional effect of Pt in the Ni Pt /CNT catalysts was found to be unexpectedly insignificant in terms of ethanol conversion, hydrogen production and selectivity. By contrast, the hybrid (ZnO) Ni /CNT catalyst showed superior catalytic performance below 450°C with high H selectivity and low CO selectivity compared to all other CNT-based catalysts. The Ni /CNT catalyst undergoes rapid deactivation compared to the ZnO promoted Ni /CNT due to the large amounts of carbon deposition on the catalyst. The ZnO promoted Ni /CNT catalyst enhances the hydrogen production and reduces the carbon formation, making the catalyst attractive for the SRE reaction.

Platinum (Pt), palladium (Pd/PdO), and rhodium (Rh) decorated carbon nanotube (CNT) based catalysts were prepared, characterized and their activity was tested in ammonia (NH3) and ethanol (EtOH) assisted selective catalytic reduction (SCR) of nitric oxide (NO) at low temperatures (30–300 °C). In addition, the influence of sulphur on NH3-SCR activity was investigated. The catalysts were characterized by transmission and scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction techniques. In addition, IR measurements were done to determine the adsorbed species on the catalyst surface. The maximum NO conversions over the catalysts were as high as 85 % for Pt/CNT (at 192 °C), 54 % for Pd/PdO/CNT (at 291 °C), and 48 % for Rh/CNT (at 292 °C) with NH3 as the reducing agent. The SO2 deactivation was the most severe in the case of Pd/PdO/CNTs. In the EtOH assisted SCR the maximum NO conversions were 100 % for Pt/CNT, 98 % for Pd/PdO/CNT and 85 % for Rh/CNT.

In the present work electrically conductive, flexible, lightweight carbon sponge materials derived from open-pore structure melamine foams are studied and explored. Hydrophobic and hydrophilic surface properties - depending on the chosen treatment conditions - allow the separation and storage of liquid chemical compounds. Activation of the carbonaceous structures substantially increases the specific surface area from ~4 m 2 g −1 to ~345 m 2 g −1 , while retaining the original three-dimensional, open-pore structure suitable for hosting, for example, Ni catalyst nanoparticles. In turn the structure is rendered suitable for hydrogenating acetone to 2-propanol and methyl isobutyl ketone as well for growing hierarchical carbon nanotube structures used as electric double-layer capacitor electrodes with specific capacitance of ~40 F/g. Mechanical stress-strain analysis indicates the materials are super-compressible (>70% volume reduction) and viscoelastic with excellent damping behavior (loss of 0.69 ± 0.07), while piezoresistive measurements show very high gauge factors (from ~20 to 50) over a large range of deformations. The cost-effective, robust and scalable synthesis - in conjunction with their fascinating multifunctional utility - makes the demonstrated carbon foams remarkable competitors with other three-dimensional carbon materials typically based on pyrolyzed biopolymers or on covalently bonded graphene and carbon nanotube frameworks.

Metal nanoparticles supported on surfaces often undergo sintering even at moderate temperatures. The degree of sintering is typically influenced by the surface chemistry indicating that besides the commonly believed Ostwald ripening also other processes associated with metal surface diffusion are responsible for the nanoparticle size growth. In addition to the deterioration in metal dispersion, carbon supports can show chemical instability leading to their partial degradation in the proximity of the nanoparticles both in reducing and oxidizing environments at elevated temperatures. This work reports a study of Pd, Pt and Ni nanoparticles anchored on carbon (activated carbon, graphite and carbon nanotubes) as well as titania (nanoparticles and microparticles) surfaces frequently applied as catalyst materials in heterogeneous catalysis and photocatalysis, and evaluate the potential events causing metal sintering and degradation of the supports using transmission electron microscopy analysis.