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Owing to their facile reactants migration channels, large surface area, maximized exposure of reaction sites and efficient light utilization, three-dimensionally ordered macroporous (3DOM) materials have been extensively adopted in environmental fields such as pollutants removal, environmental detection as well as bacterial disinfection. In this review, the up-to-date 3DOM materials, the corresponding synthesis protocols and the related environmental applications involving photo electrocatalytic pollutants decomposition, thermocatalytic volatile organic compounds (VOCs) elimination, hazardous substances sensing and bacteria inactivation are completely presented. Simultaneously, the inherent advantages and mechanisms of 3DOM materials in different environmental utilization are thoroughly demonstrated and summarized. Furthermore, the improved performance of environmental applications and the methods of fabricating 3DOM materials are correlated in depth, being favorable for readers to obtain the fundamental knowledge and to motivate some innovative thoughts for modifying 3DOM materials with further elevated environmental remediation capability. Finally, the current difficulties and prospects of 3DOM materials for large-scale and commercial applications are outlooked. This critical review is anticipated to promote the optimization of 3DOM materials and to ripen the related environmental remediation techniques. [ABSTRACT FROM AUTHOR]

Alkene feedstocks are used to produce polymers with a market expected to reach 128.4 million metric tons by 2027. Butadiene is one of the impurities poisoning alkene polymerization catalysts and is usually removed by thermocatalytic selective hydrogenation. Excessive use of H2, poor alkene selectivity and high operating temperature (e.g. up to 350 °C) remain the most significant drawbacks of the thermocatalytic process, calling for innovative alternatives. Here we report a room-temperature (25~30 °C) electrochemistry-assisted selective hydrogenation process in a gas-fed fixed bed reactor, using water as the hydrogen source. Using a palladium membrane as the catalyst, this process offers a robust catalytic performance for selective butadiene hydrogenation, with alkene selectivity staying around 92% at a butadiene conversion above 97% for over 360 h of time on stream. The overall energy consumption of this process is 0.003 Wh/mLbutadiene, which is thousands of times lower than that of the thermocatalytic route. This study proposes an alternative electrochemical technology for industrial hydrogenation without the need for elevated temperature and hydrogen gas. Industrial thermocatalytic hydrogenation requires excessive H2 gas and high temperature operation. Here, the authors report a room-temperature electrochemistry-assisted hydrogenation process using a palladium membrane as the catalyst and water as the hydrogen source, eliminating the need for H2 gas. [ABSTRACT FROM AUTHOR]

The design of Pt-based nanoarchitectures with controllable compositions and morphologies is necessary to enhance their electrocatalytic activity. Herein, we report a rational design and synthesis of anisotropic mesoporous Pt@Pt-skin Pt3Ni core-shell framework nanowires for high-efficient electrocatalysis. The catalyst has a uniform core-shell structure with an ultrathin atomic-jagged Pt nanowire core and a mesoporous Pt-skin Pt3Ni framework shell, possessing high electrocatalytic activity, stability and Pt utilisation efficiency. For the oxygen reduction reaction, the anisotropic mesoporous Pt@Pt-skin Pt3Ni core-shell framework nanowires demonstrated exceptional mass and specific activities of 6.69 A/mgpt and 8.42 mA/cm2 (at 0.9 V versus reversible hydrogen electrode), and the catalyst exhibited high stability with negligible activity decay after 50,000 cycles. The mesoporous Pt@Pt-skin Pt3Ni core-shell framework nanowire configuration combines the advantages of three-dimensional open mesopore molecular accessibility and compressive Pt-skin surface strains, which results in more catalytically active sites and weakened chemisorption of oxygenated species, thus boosting its catalytic activity and stability towards electrocatalysis. Controlling the morphology of Pt-based nanostructures can provide a great opportunity to boost their catalytic activity and durability. Here the authors report anisotropic mesoporous Pt@Pt-skin Pt3Ni core-shell framework nanowires for oxygen reduction reaction with enhanced mass activity and stability. [ABSTRACT FROM AUTHOR]

Catalyst particle shapes and pore structure engineering are crucial for alleviating internal diffusion limitations in the hydrodesulfurization (HDS)/hydrodenitrogenation (HDN) of gas oil. The effects of catalyst particle shapes (sphere, cylinder, trilobe, and tetralobe) and pore structures (pore diameter and porosity) on HDS/HDN performance at the particle scale are investigated via mathematical modeling. The relationship between particle shape and effectiveness factor is first established, and the specific surface areas of different catalyst particles show a positive correlation with the average HDS/HDN reaction rates. The catalyst particle shapes primarily alter the average HDS/HDN reaction rate to adjust the HDS/HDN effectiveness factor. An optimal average HDS/HDN reaction rate exists as the catalyst pore diameter and porosity increase, and this optimum value indicates a tradeoff between diffusion and reaction. In contrast to catalyst particle shapes, the catalyst pore diameter and the porosity of catalyst particles primarily alter the surface HDS/HDN reaction rate to adjust the HDS/HDN effectiveness factor. This study provides insights into the engineering of catalyst particle shapes and pore structures for improving HDS/HDN catalyst particle efficiency. [ABSTRACT FROM AUTHOR]

Hierarchical single-crystal ZSM-5 zeolites with different Si/Al ratios (Hier-ZSM-5-x, where x = 50, 100, 150 and 200) were synthesized using an ordered mesoporous carbon-silica composite as hard template. Hier-ZSM-5-x exhibits improved mass transport properties, excellent mechanical and hydrothermal stability, and higher catalytic activity than commercial bulk zeolites in the benzyl alcohol self-etherification reaction. Results show that a decrease in the Si/Al ratio in hierarchical single-crystal ZSM-5 zeolites leads to a significant increase in the acidity and the density of micropores, which increases the final catalytic conversion. The effect of porous hierarchy on the diffusion of active sites and the final catalytic activity was also studied by comparing the catalytic conversion after selectively designed poisoned acid sites. These poisoned Hier-ZSM-5-x shows much higher catalytic conversion than the poisoned commercial ZSM-5 zeolite, which indicates that the numerous intracrystalline mesopores significantly reduce the diffusion path of the reactant, leading to the faster diffusion inside the zeolite to contact with the acid sites in the micropores predominating in ZSM-5 zeolites. This study can be extended to develop a series of hierarchical single-crystal zeolites with expected catalytic performance. [ABSTRACT FROM AUTHOR]

Designing biocompatible materials to encapsulate xenogeneic insulin-releasing β-cells for transplantation has been considered as a promising alternative to avoid the immunosuppression and drawbacks of the treatment of Type 1 diabetes mellitus (T1D) by direct islet transplantation. The current work for the first time studied a hybrid alginate@TiO2 microcapsule as a reservoir for rat insulinoma-derived INS-1E cells, as a β-cell surrogate, towards the treatment of T1D. The hybrid microcapsule is composed of an alginate core as a biocompatible matrix for cell encapsulation and a crack-free TiO2 shell as a semipermeable membrane to prevent cell leakage, protect encapsulated cells from immune attacks, as well as allow the diffusion of nutrients and the secretion of insulin. Compared to most-commonly used pure alginate microcapsules, the insulin-secreting INS-1E cells encapsulated in our alginate@TiO2 microcapsules revealed higher metabolic activity and maintained the insulin secretion over more than 6 weeks. This study highlights that our designed alginate@TiO2 hybrid microcapsules can serve as an ideal reservoir for cell encapsulation towards the treatment of T1D, thus further promoting the development of artificial organs for cell therapy. [ABSTRACT FROM AUTHOR]

Heavy-metal removal from industrial wastewater is a major issue. The use of microbial biosorbent is a low cost, sustainable, and efficient way for water cleaning, but the living organisms are limited by their sensitivity and fragility and subjected to water contamination by other relevant bacteria. In order to improve the use of the powerful photosynthetic prokaryote, this work focused on the development of a new protection method of cyanobacterial strains of the genus Synechococcus sp. PCC7002 by a multiple coating including an external layer made of silica. This surfacing was performed using the layer-by-layer method and different polyelectrolytes. Polydiallyldimethylammonium chloride, a cationic polymer is used as a link between the cell wall and silica shell, while polystyrene sulfonate is inserted to play a protective role against ultraviolet light irradiation. This study discloses the synthesis of a highly efficient hybrid material and the excellent protection brought by the silica material. First of all, the layers, in particular four layers, deposited around single cells offer a strong protection against very harmful UV-C light irradiation while maintaining high viability and the same bioadsorption capacity for heavy-metal ions in solution. The long-term viability of this living material and its successful use for copper and lead sequestration, confirms the possibility of exploiting encapsulated cyanobacteria to improve current biotechnologies for wastewater purification.A single cyanobacterium@silica porous microcapsule synthesized via a sol-gel layer-by-layer method presents long-term viability, the resistance against UV-C light irradiation, and the bioadsorption capacity of heavy-metal ions in solution. Individual cyanobacterium encapsulation within hybrid porous layers via a sol-gel methodBiohybrid materials with UV-C irradiation resistanceBiohybrid materials with a long-term viabilityBiohybrid materials for wastewater treatment [ABSTRACT FROM AUTHOR]

This study described a template-free method for the synthesis of hierarchically macro-mesoporous Mn-TiO catalysts. The promoting effect of Mn doping and the hierarchically macro-mesoporous architecture on TiO based catalysts was also investigated for the selective reduction of NO with NH. The results show that the catalytic performance of TiO based catalysts was improved greatly after Mn doping. Meanwhile, the Mn-TiO catalyst with the hierarchically macro-mesoporous architecture has a better catalytic activity than that without such an architecture. [ABSTRACT FROM AUTHOR]

Solar-driven hydrogen (H) generation utilizing photocatalysts has received extensive attention because of its potential to mitigate the global energy crisis and environmental problem. The implementation of efficient H production strongly relies on stable, active, and low-cost photocatalysts. In this work, we report the designed synthesis of macroporous ZnO/ZnS/CdS composite spheres as a highly active photocatalyst for H production via solar-driven water splitting. The composite spheres were synthesized by a facile solvothermal reaction paired with controllable ion-exchange processes. The resulting material exhibits superior photocatalytic activity, delivering a high H production rate of ~11.37 mmol h g under light illumination (250-780 nm, with an ultraviolet light intensity of 34 mW cm and visible light intensity of 158 mW cm). Such performance enhancement can be mainly ascribed to the synergic effects of the composite structure: (1) formation of coherent ZnO/CdS and ZnS/CdS heterojunctions at nanoscale, facilitating charge separation of photoinduced electron/hole pairs, (2) highly accessible inner surface of the meso/macroporous ZnO/ZnS/CdS composites for rapid mass transfer of electrolyte, and (3) enhanced visible light scattering capability induced by their large particle size. [ABSTRACT FROM AUTHOR]

CePrO ( x = 0, 0.1, 0.5, 0.9) mesoarchitectures built from nanoparticles with crystalline framework have been synthesized by the self-assembly method assisted by surfactants and hydrothermal treatment. Cetyltrimethylammonium bromide (CTAB) was used as template, urea as hydrolyzing agent and tetraethylammonium hydroxide (TEAOH) as pH mediator to obtain pH 9. The inorganic precursors have been co-assembled with surfactant template to produce mesoarchitectures which have uniform pore size distribution, crystalline channel walls, high thermal stability, and high catalytic activity in the oxidation reaction of methane. The resulting powders, calcined at 550 °C, were characterized by X-ray diffraction (XRD), Raman spectroscopy, N adsorption/desorption isotherms (BET), thermogravimetric analysis (TG-DTG), scanning and transmission electron microscopy (SEM, TEM, and HRTEM), and X-ray photoelectron spectroscopy (XPS). The as-synthesized mesoporous nanoparticles are single-phase fluorite CePrO solid solution without additional Ce- or Pr-based oxides, or secondary phases with different lattice symmetry or stoichiometry. A clear morphology of dispersed nanoparticles, with uniform grain size between 5 and 7 nm, and mean pore size around 5 nm, have been observed. The specific surface area of the as-synthesized mesoporous samples after calcination at 550 °C remains in the range 60-150 m g. All the spectroscopic methods clearly confirm the homogeneous incorporation of Pr into the CeO lattice of the nanocrystallites, to form a single-phase solid solution with fluorite structure, modifying the absorption spectra of the nanocrystallites. All the samples showed high catalytic activity in the oxidation reactions of methane. [ABSTRACT FROM AUTHOR]

High surface area titanium glycolate microporous multi-faceted nanorods were synthesized from the reaction of titanium alkoxides (Ti(OEt)4, Ti(O iPr)4, or Ti(O nBu)4) with ethylene glycol, using a sol–gel reflux method. The specific surface area of the as-synthesized titanium glycolate nanorods obtained from Ti(OEt)4 is ~480 m2/g. A hot water treatment at 90 °C for 1 h transformed the titanium glycolate microporous nanorods into mesoporous anatase TiO2 nanorods. The shape of the nanorods was conserved after hot water treatment and the microporous to mesoporous transformation took place without significant change in the surface area (477 m2/g). Micro Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, solid state NMR, and nitrogen adsorption/desorption were used to characterize the samples. As a demonstration of potential applications, the thus formed mesoporous anatase TiO2 nanorods were tested for their photocatalytic efficiency in the degradation of crystal violet, and a photodegradation mechanism is proposed. [ABSTRACT FROM AUTHOR]

Recent developments in the processing of porous transition metal oxide thin films have opened up new opportunities in the construction of electrochromic (EC) devices with enhanced properties. Tungsten oxide (WO3) is one of the most promising materials for EC devices. In this work, we report on the synthesis of meso-/macroporous WO3 thin films using tungstic acid as precursor and organically modified silane (ORMOSIL) as a templating agent. Calcination of the film at 500 °C resulted in nanocrystalline monoclinic tungsten oxide (m-WO3) with crystallite sizes of ~16 nm. The meso-/macroporous structure is retained after calcination. An asymmetric EC device based on the meso-/macroporous m-WO3 thin film was constructed. Thus constructed EC device was characterized by micro-Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction (XRD). Detailed micro-Raman and XRD studies of the intercalation and deintercalation of lithium (Li) in the meso-/macroporous m-WO3 layer of the EC device as a function of the applied voltage were performed. The meso-/macroporous WO3 layer, which was found to be monoclinic before Li intercalation, transforms to its higher symmetric phase of tetragonal and toward cubic phase when Li is intercalated into it. Upon complete deintercalation, these phase transitions were reversed and m-WO3 is recovered. Optical transmission studies were performed in conjunction with Raman and XRD studies. This study shows that meso-/macroporous m-WO3 layer-based EC device exhibit a high color contrast during the coloration and bleaching. [ABSTRACT FROM AUTHOR]

Benzene adsorption behavior in a large family of 12R window zeolites (X, Y, EMT, Beta and LTL) has been examined by means of in-situ FTIR spectroscopy and correlated with the zeolite structure, the type and number of counter-ions, and the negative charge on framework oxygen atoms of zeolites. The effect of coadsorption of HCl, NH3 and CH3NH2 on the benzene location has also been studied. The present work illustrates that besides the benzene adsorption on counter ions of zeolites, the 12R windows could also be the adsorption sites for benzene. Upon adsorption of coadsorbates such as HCl, NH3 and CH3NH2, the migration of preadsorbed benzene molecules from one type of adsorption sites towards another, i.e. from 12R windows towards the cations for HCl and opposite direction for NH3 and CH3NH2, has been evidenced. The lack of adsorption of benzene on 12R windows of NaBeta even upon coadsorption of a series of basic molecules reveals that benzene adsorption on 12R windows is most likely governed by a molecular recognition effect where benzene molecule and 12R window should have the adapted chemical and structural properties like in enzyme-substrate system and zeolites can be referred to as solid enzymes or zeo-enzymes. This paper indicates also that the adsorption properties of zeolites can be modified and accommodated by introduction of a co-adsorbate. [ABSTRACT FROM AUTHOR]

Pure propane was rarely used as an alkylating agent of benzene for the formation of cumene. However, by means of FTIR spectroscopy, Ga-modified MFI zeolite was shown to be a very active and selective catalyst for this reaction compared with H-MFI, H-Beta and Ga-modified Beta zeolites which lead to more coke formation. [ABSTRACT FROM AUTHOR]

Both plants and animals possess analogous tissues containing hierarchical networks of pores, with pore size ratios that have evolved to maximize mass transport and rates of reactions. The underlying physical principles of this optimized hierarchical design are embodied in Murray's law. However, we are yet to realize the benefit of mimicking nature's Murray networks in synthetic materials due to the challenges in fabricating vascularized structures. Here we emulate optimum natural systems following Murray's law using a bottom-up approach. Such bio-inspired materials, whose pore sizes decrease across multiple scales and finally terminate in size-invariant units like plant stems, leaf veins and vascular and respiratory systems provide hierarchical branching and precise diameter ratios for connecting multi-scale pores from macro to micro levels. Our Murray material mimics enable highly enhanced mass exchange and transfer in liquid-solid, gas-solid and electrochemical reactions and exhibit enhanced performance in photocatalysis, gas sensing and as Li-ion battery electrodes. [ABSTRACT FROM AUTHOR]

The author discusses the highlights of a symposium on mesostructured materials held in Namur, Belgium in September 2008 and was jointly organized by the Laboratory of Inorganic Materials Chemistry at the University of Namur in Belgium and the Laboratory of Controlled Porosity Materials at the University of Haute-Alsace in France, under the auspices of the International Mesostructured Materials Association. The symposium addressed oxide mesostructured materials, non-oxide mesostructured materials and hierarchical mesostructured materials, among others.

Hierarchically structured porous TiO2-B spheres have been synthesized via a hydrothermal process using amorphous titania/oleylamine composites as a self-sacrificing template. The TiO2-B spheres are constructed by interconnected nanotubes and possess a high specific surface area of 295 m2 g-1. When evaluated as an anode material in lithium-half cells, the as-obtained TiO2-B material exhibits high and reversible lithium storage capacity of 270 mA h g-1 at 1 C (340 mA g-1), excellent rate capability of 221 mA h g-1 at 10 C, and long cycle life with over 70% capacity retention after 1000 cycles at 10 C. The superior electrochemical performance of TiO2-B material strongly correlates to the synergetic superiorities with a combination of TiO2-B polymorph, hierarchically porous structure, interconnected nanotubes and spherical morphology. Post-mortem structural analyses reveal some discrete cubic LiTiO2 nanodots formed on the outer surfaces of TiO2-B nanotubes, which might account for the slight capacity loss upon prolonged electrochemical cycling. [ABSTRACT FROM AUTHOR]