Raspberry-like composite spheres based on chemically-reactive poly(glycidyl methacrylate) (PGMA) colloids as the cores coated with tunable size of gold nanoparticles were synthesized via a controlled assembly method. Kinetic study of 4-nitrophenol reduction by NaBH4 in the presence of poly(allylamine hydrochloride)-modified PGMA composite with tunable size of AuNPs (PGMA@PAH@AuNPs) was demonstrated. Effects of gold nanoparticles size and PGMA colloid diameter on the reaction time, average reaction rate and average turnover frequency (TOF), order of reaction (n) and apparent rate constant (kapp) were systematically investigated. Experimental results of our study showed composites with 3.4 ± 0.9 nm AuNPs have the best catalytic efficiency with the highest reaction order and apparent rate constant. The poisoning of product 4-aminophenol on PAH-modified PGMA colloid-supported gold nanocatalysts was evaluated using 4-nitrophenol/NaBH4 reduction reaction for the reaction time, average reaction rate, average TOF, order of reaction and apparent rate constant.

Transparent UV protective coatings were developed by incorporating nano-TiO2 into waterborne acrylic systems to provide long-term UV protection for UV sensitive cool color roofing. Water based high crystalline TiO2 nanoparticle suspension was prepared via a gel-sol method at a basic pH. The TiO2 nanoparticles have an average size of 20 nm and are stable against agglomeration. As prepared TiO2 nanosuspension is ready to be well dispersed in commercial waterborne acrylic resin system without extra surface modification. The fabricated TiO2/acrylic nanocomposite coating achieved an UV cut-off below 350 nm with a visible transmission greater than 85% at 700 nm. It is also demonstrated that surface modification of Nano-TiO2 with a SiO2 insulation layer would suppress the catalytic activity of Nano-TiO2 and improve the UV protection for UV and photocatalysis sensitive dyes.

Carbon supported Pt-SnO2 electrocatalysts with different Sn/Pt molar ratios were prepared by an electron beam irradiation method. Dissolved gas conditions in the vials irradiated with electron beam were controlled to air or Ar. The results of the material analyses showed that both Pt and SnO2 were immobilized onto carbon support in all catalysts. Bubbling Ar to the precursor solution led to steady change of metal contents in response to the precursor concentrations. The ethanol oxidation activity plotted against Sn/Pt ratio behaved differently with dissolved gas condition of the vial. This difference is discussed with supposed existing state of SnO2 in connection with the reduction process of Pt and Sn.

Surface modified L@SiO2 particles bearing covalently attached functional groups (L) have been tested as co-catalysts for H2 production from Formic Acid (FA) by the homogenous FeII/P(CH2CH2PPh2)3 catalyst. The L@SiO2 particles induce remarkable increase of catalytic H2 production i.e. by 710 %, when L=a basic functionality such as Imidazoles, or NH2-groups. This effect is attributed to a thermodynamic promotion of FA deprotonation facilitating coordination of HCOO- anion on the FeII atom of active catalyst during catalysis.

TiO2-supported bimetallic Au-Rh and Au-Pd nanocrystals were synthesized using both impregnation and colloidal approaches employing HAuCl4 and RhCl3 as precursors. The as-obtained bimetallic catalysts were then supported onto TiO2 rutile nanorods in order to provide catalytic systems with well-defined metal-support interactions for HRTEM characterization. The results revealed the superiority of the colloidal approach over the impregnation technique to obtain bimetallic nanoparticles (4 nm in size) with tunable composition. However, for Au-Rh/TiO2, optimization of the procedure of the sol immobilization onto the TiO2 support was required to avoid possible Rh re-dissolution. Preparation of Au-Pd/TiO2 followed the same procedure but with more acidic conditions necessary to perform immobilization on the support. UV-vis spectroscopy and XRD results suggest formation of a Rh-rich shell over an Au core center for Au-Rh NPs, while Au-Pd NPs present a pure alloy structure. Au-Rh/TiO2 was used for performing the high-pressure hydroconversion of tetralin in the presence or not of H2S. The results indicate a strong thioresistance induced by the addition of Au to Rh.

Multi-functionalization of catalytically-active nanomaterials provides a valuable tool for enhancing reaction yield by shifting reaction equilibrium, and potentially also by adjusting reaction-diffusion kinetics. For example, multi-functionalization of mesoporous silica to make the interior pore surface hydrophobic can enhance yield in dehydration reactions. Detailed molecular-level modeling to describe the pore environment, as well as the reaction and diffusion kinetics is challenging, although we briefly discuss current strategies. Our focus, however, is on coarse-grained stochastic modeling of the overall catalytic process for highly restricted transport within narrow pores (with single-file diffusion), while accounting for a tunable interaction of the pore interior with reaction products. We show that making the pore interior unfavorable to products can significantly enhance yield due to both thermodynamic and kinetics factors.

Nitrogen-doped carbons nanoballs were synthesized from an organic liquid precursor (a mixture of benzene and pyrazine) by solution plasma process. After synthesis, they were further annealed at 700 and 900 °C under N2 atmosphere. The nitrogen-doped carbon nanoballs before and after thermal annealing process exhibit a similar morphological feature, and their diameters are in the range between 20 and 40 nm. With higher annealing temperature, the graphitization of the nitrogen-doped carbon nanoballs increases. For the electrocatalytic activity in an alkaline solution, the limiting current density and onset potential for the ORR activity can be significantly improved for the samples after thermal annealing at 900 °C. We anticipate that solution plasma process will be a viable alternative way for synthesizing heteroatom-doped carbon electrocatalysts for broad application in the field of fuel cells, metal-air batteries, and supercapacitors.

Here we report the first membrane-less biofuel cell made by using three-dimensional carbonaceous foam electrodes. We first developed a new synthetic pathway to produce a new carbonaceous foam electrode material with increased porosity both in the meso and macroporous scale. We proved that by increasing the porosity of our three-dimensional foams we could increase the current density of our modified electrodes. Then, by choosing the right combination of enzyme and mediator, and the right loading of active components, we achieved unprecedentedly high current densities for an anodic system. Finally, we combined the improved cathode and anode to build a new membrane-less hybrid enzymatic biofuel cell consisting of a mediated anode and a mediator-less cathode.

ZnO and ZnO/ZnFe2O4 nanocomposites were synthesized by mechanical-assisted thermal decomposition method. The results show that this method is a simple and low cost method to prepare ZnO and ZnO/ ZnFe2O4 nanocomposites. The nanorod's shape and size have been identified through SEM and TEM. The photocatalytic activity of ZnO and ZnO/ZnFe2O4 nanocomposites were tested by the degradation of methylene blue (MB) in aqueous medium under almost-visible light and the efficiency of the catalyst has been discussed in detail.

Electrode catalysts composed of carbon supported PtRu nanoparticles (PtRu/C) synthesized by radiochemical process were annealed to control the PtRu substructure to enhance catalytic activity. The substructure of the PtRu nanoparticles synthesized by using high-energy electron beam under acidic condition was Pt-rich core/Ru-rich shell type, reflecting the redox potentials of each precursor ions. The material characterization techniques revealed that the reductive annealing led to the mixing of PtRu both in the core and on the surface. The sample with annealing temperature of 300°C for 5 hour showed the highest methanol oxidation current, 2.3 times higher than that obtained with before annealing.

The present study details facile synthesis of hollow Cu2O nanospheres decorated with Ag nanoparticles using a simple surfactant technique for enhanced photocatalytic activity. The morphology and structure is studied via XRD and SEM. Cu2O hollow nanospheres with a diameter of 500-800 nm were synthesized via Ostwald ripening using CuSO4 aqueous solution. The catalytic activity of Cu2O is studied in the presence of UV and visible light using Methyl Orange (MO) as a model pollutant. Ag decorated Cu2O particles showed a 49% increase in photocatalytic activity over the undecorated Cu2O. The improved photocatalytic activity is achieved by surface plasmon resonance effects in the silver nanoparticles, allowing utilization of the lower energy portion of the solar spectrum.

Here, we propose novel mesoporous Au-loaded TiO2 nanoparticle assemblies (Au-MTA) as highly effective catalysts for the reduction of nitroaromatic compounds into the corresponding aryl amine products. The obtained materials possess a continuous network of interconnected gold and anatase TiO2 (ca. 9 nm in size) nanoparticles with controllable gold particle size (i.e. ranging from ∼3.2 to ∼9.4 nm) and exhibit large and accessible pore surface area (ca. 100–160 m2/g), as evidenced by SAXS, XRD, TEM and N2 physisorption measurements. Interestingly, the Au-MTA mesophases have exhibited remarkable activity and selectivity for the reduction of nitro into amine groups using NaBH4 as reducing agent. Indeed, the Au loading and particle size have a key effect on hydrogenation reactions, affecting significantly the yield and product composition.

The combined focused ion beam/scanning electron microscopy/energy dispersive X-ray spectroscopy (FIB/SEM/EDX) system is a novel tool for the automotive catalysis field. Automotive emissions such as SOx, NOx, and particulate matter (PM) are regulated to various extents throughout the world, requiring the use of multiple aftertreatment components such as the diesel particulate filter (DPF), diesel oxidation catalyst (DOC), three-way catalytic converter (TWC), Lean NOx trap (LNT) and selective catalytic reduction (SCR). While these aforementioned aftertreatment components are generally multifunctional and robust in design, thermal and chemical aging over the components’ useful lifetimes results in significantly degraded performance leading to increased engine emissions levels and decreased fuel economy. While the component sizes themselves are generally large (10s of cm to ≈1/2 m), component aging mechanisms usually dominate on the nm-µm scales. In particular, this study has used the FIB/SEM/EDX system to investigate the aging of the diesel particulate filter (DPF) due to engine lubricant-derived inorganic ash accumulation. The FIB/SEM/EDX system has been used in the automotive aftertreatment field for the first time with many surprising and significant findings. Although the samples used in this study are quite different to those typically found in FIB studies, the authors have shown that the FIB/SEM/EDX system is a valuable tool in this research area, especially for the investigation of µm-size intra-particle structure and nm-µm interfacial/sub-surface details around the aged catalyst surface.