Abstract: Adaptation of the photoresponse of anatase TiO2 to match the solar spectrum is an important scientific challenge. Modification of TiO2 with noble metal nanoparticles displaying surface plasmon resonance effects is one of the promising approaches. Surface plasmon resonance typically depends on chemical composition, size, shape and spatial organization of the metal nanoparticles in contact with TiO2. AuxAg(1 − x) alloy nanoparticles display strong composition-dependent surface plasmon resonance in the visible light region of the spectrum. In this work, a general strategy is presented to prepare plasmonic TiO2-based photocatalysts with a visible light response that can be accurately tuned over a broad range of the spectrum. The application as self-cleaning material toward the degradation of stearic acid is demonstrated for a plasmonic TiO2 photocatalyst displaying visible light photoactivity at the intensity maximum of solar light around 490 nm.

Abstract: Discrete electron tomography is a new approach for three-dimensional reconstruction of nanoscale objects. The technique exploits prior knowledge of the object to be reconstructed, which results in an improvement of the quality of the reconstructions. Through the combination of conventional transmission electron microscopy and discrete electron tomography with a model-based approach, quantitative structure determination becomes possible. In the present work, this approach is used to unravel the building scheme of Zeotile-4, a silica material with two levels of structural order. The layer sequence of slab-shaped building units could be identified. Successive layers were found to be related by a rotation of 120°, resulting in a hexagonal space group. The Zeotile-4 material is a demonstration of the concept of successive structuring of silica at two levels. At the first level, the colloid chemical properties of Silicalite-1 precursors are exploited to create building units with a slablike geometry. At the second level, the slablike units are tiled using a triblock copolymer to serve as a mesoscale structuring agent.

Abstract: Hexagonally ordered mesoporous silica with a very narrow mesopore size distribution and exceptionally high stability paired with unusually thin pore walls was prepared using piperidine and cetyltrimethylammonium bromide.

Abstract: A new hierarchical MOF consisting of Cu(II) centers connected by benzene-tricarboxylates (BTC) is prepared by thermoinduced solid transformation of a dense CuBTC precursor phase. The mechanism of the material formation has been thoroughly elucidated and revealed a transformation of a ribbon-like 1D building unit into 2D layers and finally a 3D network. The new phase contains excess copper, charge compensated by systematic hydroxyl groups, which leads to an open microporous framework with tunable permanent mesoporosity. The new phase is particularly attractive for molecular separation. Energy consumption of adsorptive separation processes can be lowered by using adsorbents that discriminate molecules based on adsorption entropy rather than enthalpy differences. In separation of a 11-component mixture of C-1-C-6 alkanes, the hierarchical phase outperforms the structurally related microporous HKUST-1 as well as silicate-based hierarchical materials. Grand canonical Monte Carlo (GCMC) simulation provides microscopic insight into the structural host-guest interaction, confirming low adsorption enthalpies and significant entropic contributions to the molecular separation. The unique three-dimensional hierarchical structure as well as the systematic presence of Cu(II) unsaturated coordination sites cause this exceptional behavior.

Abstract: In the field of photocatalytic air purification, the immobilisation of catalyst particles on support surfaces without loss of photon efficiency is an important challenge. Therefore, an immobilisation method involving a one-step suspension coating of pre-synthesised photocatalysts on glass beads was applied. The various benefits are exemplified in the gas phase photodegradation of ethylene. Coating of glass beads is easy, fast, cheap and offers a more efficient alternative to bulk catalyst pellets. Furthermore, this coating procedure allows to use porous, pre-synthesised catalysts to their full potential, as the surface area and morphology of the initial powder is barely altered after coating, in strong contrast to pelletising. With this technique it became possible to study the gas phase photocatalytic activity of commercial titanium dioxide, trititanate nanotubes and mixed phase anatase/trititanate nanotubes in a packed bed reactor towards the degradation of ethylene without changing the catalyst properties. Coating of glass beads with the photocatalyst revealed the superior activity of the as-prepared nanotubes, compared to TiO2 Aerolyst® 7710 in gaseous phase.

Abstract: In this paper, new insights of the photocatalytic oxidation pathway of acetaldehyde are obtained by means of an in-house constructed FTIR in situ reactor. It is shown that there are generally three different intermediates present: acetic acid, formic acid and formaldehyde. By means of FTIR in situ spectroscopy, this study revealed that these intermediates are bound on the TiO2 surface in different ways, resulting in the presence of more intermediate species, such as molecularly adsorbed acetic acid, bidentate acetate, molecularly adsorbed formic acid, monodentate formate, bidentate formate, formaldehyde and dioxymethylene. Furthermore, spectroscopic evidence is obtained concerning the formation of 3-hydroxybutanal and crotonaldehyde upon adsorption of acetaldehyde on TiO2 prior to UV illumination. The presented results thus give new insights in the photocatalytic oxidation pathway of acetaldehyde.

Abstract: The concept of an all-gas-phase photo-electrochemical cell (PEC) producing hydrogen gas from volatile organic contaminated gas and light is presented. Without applying any external bias, organic contaminants are degraded and hydrogen gas is produced in separate electrode compartments. The system works most efficiently with organic pollutants in inert carrier gas. In the presence of oxygen gas, the cell performs less efficiently but still significant photocurrents are generated, showing the cell can be run on organic contaminated air. The purpose of this study is to demonstrate new application opportunities of PEC technology and to encourage further advancement toward photo-electrochemical remediation of air pollution with the attractive feature of simultaneous energy recovery and pollution abatement.

Abstract: Photocatalysis assisted oxidation of carbon black was performed using TiO2 photocatalyst under UV illumination in an atmosphere with NO, O-2 and water vapor at 150 degrees C. Carbon is oxidized mainly to CO2 while NO is selectively converted to N-2. Enhanced O-2 and NO concentrations have a positive effect on the carbon oxidation rate. At a concentration of 3000 ppm NO and 13.3% O-2 in the gas phase the carbon oxidation rate reaches 2.3 mu g(carbon)/mg(TiO2) h, at a formal electron/photon quantum efficiency of 0.019. HR SEM images reveal uniform gradual reduction of the carbon particle size irrespective of the distance to TiO2 photocatalyst particles in the presence of NO, O-2 and H2O. (C) 2016 Elsevier B.V. All rights reserved.

Abstract: A plasma-enhanced atomic layer deposition (ALD) process using the Ag(fod)(PEt3) precursor [(triethylphosphine)(6,6,7,7,8,8,8-heptafluoro-2,2-dimethy1-3,5-octanedionate)silver(I)] in combination with NH3-plasma is reported. The steady growth rate of the reported process (0.24 +/- 0.03 nm/cycle) was found to be 6 times larger than that of the previously reported Ag ALD process based on the same precursor in combination with H-2-plasma (0.04 +/- 0.02 nm/cycle). The ALD characteristics of the H-2-plasma and NH3-plasma processes were verified. The deposited Ag films were polycrystalline face-centered cubic Ag for both processes. The film morphology was investigated by ex situ scanning electron microscopy and grazing-incidence small-angle X-ray scattering, and it was found that films grown with the NH3-plasma process exhibit a much higher particle areal density and smaller particle sizes on oxide substrates compared to those deposited using the H-2-plasma process. This control over morphology of the deposited Ag is important for applications in catalysis and plasmonics. While films grown with the H-2-plasma process had oxygen impurities (similar to 9 atom %) in the bulk, the main impurity for the NH3-plasma process was nitrogen (similar to 7 atom %). In situ Fourier transform infrared spectroscopy experiments suggest that these nitrogen impurities are derived from NH surface groups generated during the NH3-plasma, which interact with the precursor molecules during the precursor pulse. We propose that the reaction of these surface groups with the precursor leads to additional deposition of Ag atoms during the precursor pulse compared to the H-2-plasma process, which explains the enhanced growth rate of the NH3-plasma process.

Abstract: Surface photovoltage (SPV) measurements can contribute to a better understanding of electronic properties of photocatalysts under illumination. Direct linking of SPV data to the actual photocatalytic activity remains troublesome. This work aims to discuss SPV measurements from a photocatalytic point of view. By means of several application-based scenarios we illustrate that the trend between SPV and photocatalysis strongly depends on parameters such as the crystal structure, surface modifications, morphology and humidity. This makes the interpretation far from straightforward.

Abstract: Conventional CO2 separation in the petrochemical industry via cryogenic distillation or amine-based absorber-stripper units is energy-intensive and environmentally unfriendly. Membrane-based gas separation technology, in contrast, has contributed significantly to the development of energy-efficient systems for processes such as natural gas purification. The implementation of commercial polymeric membranes in gas separation processes is restricted by their permeability-selectivity trade-off and by their insufficient thermal and chemical stability. Herein, we present the fabrication of a Matrimid-based membrane loaded with a breathing metal-organic framework (MOF) (NH2-MIL-53(Al)) which is capable of separating binary CO2/CH4 gas mixtures with high selectivities without sacrificing much of its CO2 permeabilities. NH2-MIL-53(Al) crystals were embedded in a polyimide (PI) matrix, and the mixed-matrix membranes (MMMs) were treated at elevated temperatures (up to 350 degrees C) in air to trigger PI cross-linking and to create PI-MOF bonds at the interface to effectively seal the grain boundary. Most importantly, the MOF transitions from its narrow-pore form to its large-pore form during this treatment, which allows the PI chains to partly penetrate the pores and cross-link with the amino functions at the pore mouth of the NH2-MIL-53(Al) and stabilizes the open-pore form of NH2-MIL-53(Al). This cross-linked MMM, with MOF pore entrances was made more selective by the anchored PI-chains and achieves outstanding CO2/CH4 selectivities. This approach provides significant advancement toward the design of selective MMMs with enhanced thermal and chemical stabilities which could also be applicable for other potential applications, such as separation of hydrocarbons (olefin/paraffin or isomers), pervaporation, and solvent-resistant nanofiltration.