A renewable route to p-xylene from biomass-derived dimethylfuran and ethylene is investigated with zeolite catalysts. Cycloaddition of ethylene and 2,5-dimethylfuran and subsequent dehydration to p-xylene has been achieved with 75% selectivity using H–Y zeolite and an aliphatic solvent at 300 °C. Competitive side reactions include hydrolysis of dimethylfuran to 2,5-hexanedione, alkylation of p-xylene, and polymerization of 2,5-hexanedione. The observed reaction rates and computed energy barriers are consistent with a two-step reaction that proceeds through a bicyclic adduct prior to dehydration to p-xylene. Cycloaddition of ethylene and dimethylfuran occurs without a catalytic active site, but the reaction is promoted by confinement within microporous materials. The presence of Brønsted acid sites catalyzes dehydration of the Diels–Alder cycloadduct (to produce p-xylene and water), and this ultimately causes the rate-determining step to be the initial cycloaddition.

Shaped zeolite nanocrystals and larger zeolite particles with three-dimensionally ordered mesoporous (3DOm) features hold exciting technological implications for manufacturing thin, oriented molecular sieve films and realizing new selective, molecularly accessible and robust catalysts. A recognized means for controlled synthesis of such nanoparticulate and imprinted materials revolves around templating approaches, yet identification of an appropriately versatile template has remained elusive. Because of their highly interconnected pore space, ordered mesoporous carbon replicas serve as conceptually attractive materials for carrying out confined synthesis of zeolite crystals. Here, we demonstrate how a wide range of crystal morphologies can be realized through such confined growth within 3DOm carbon, synthesized by replication of colloidal crystals composed of size-tunable (about 10-40 nm) silica nanoparticles. Confined crystal growth within these templates leads to size-tunable, uniformly shaped silicalite-1 nanocrystals as well as 3DOm-imprinted single-crystal zeolite particles. In addition, novel crystal morphologies, consisting of faceted crystal outgrowths from primary crystalline particles have been discovered, providing new insight into constricted crystal growth mechanisms underlying confined synthesis.

A zeolite with structure type MFI is an aluminosilicate or silicate material that has a three-dimensionally connected pore network, which enables molecular recognition in the size range 0.5-0.6 nm. These micropore dimensions are relevant for many valuable chemical intermediates, and therefore MFI-type zeolites are widely used in the chemical industry as selective catalysts or adsorbents. As with all zeolites, strategies to tailor them for specific applications include controlling their crystal size and shape. Nanometre-thick MFI crystals (nanosheets) have been introduced in pillared and self-pillared (intergrown) architectures, offering improved mass-transfer characteristics for certain adsorption and catalysis applications. Moreover, single (non-intergrown and non-layered) nanosheets have been used to prepare thin membranes that could be used to improve the energy efficiency of separation processes. However, until now, single MFI nanosheets have been prepared using a multi-step approach based on the exfoliation of layered MFI, followed by centrifugation to remove non-exfoliated particles. This top-down method is time-consuming, costly and low-yield and it produces fragmented nanosheets with submicrometre lateral dimensions. Alternatively, direct (bottom-up) synthesis could produce high-aspect-ratio zeolite nanosheets, with improved yield and at lower cost. Here we use a nanocrystal-seeded growth method triggered by a single rotational intergrowth to synthesize high-aspect-ratio MFI nanosheets with a thickness of 5 nanometres (2.5 unit cells). These high-aspect-ratio nanosheets allow the fabrication of thin and defect-free coatings that effectively cover porous substrates. These coatings can be intergrown to produce high-flux and ultra-selective MFI membranes that compare favourably with other MFI membranes prepared from existing MFI materials (such as exfoliated nanosheets or nanocrystals).

Near-infrared (NIR) dye-sensitized upconversion nanoparticles (UCNPs) can broaden the absorption range and boost upconversion efficiency of UCNPs. Here, we achieved significantly enhanced upconversion luminescence in dye-sensitized core/active shell UCNPs via the doping of ytterbium ions (Yb3+) in the UCNP shell, which bridged the energy transfer from the dye to the UCNP core. As a result, we synergized the two most practical upconversion booster effectors (dye-sensitizing and core/shell enhancement) to amplify upconversion efficiency. We demonstrated two biomedical applications using these UCNPs. By using dye-sensitized core/active shell UCNP embedded poly(methyl methacrylate) polymer implantable systems, we successfully shifted the optogenetic neuron excitation window to a biocompatible and deep tissue penetrable 800 nm wavelength. Furthermore, UCNPs were water-solubilized with Pluronic F127 with high upconversion efficiency and can be imaged in a mouse model.

Biochar, a charcoal-like product of the incomplete combustion of organic materials, is an increasingly popular soil amendment designed to improve soil fertility. We investigated the possibility that biochar could promote direct interspecies electron transfer (DIET) in a manner similar to that previously reported for granular activated carbon (GAC). Although the biochars investigated were 1000 times less conductive than GAC, they stimulated DIET in co-cultures of Geobacter metallireducens with Geobacter sulfurreducens or Methanosarcina barkeri in which ethanol was the electron donor. Cells were attached to the biochar, yet not in close contact, suggesting that electrons were likely conducted through the biochar, rather than biological electrical connections. The finding that biochar can stimulate DIET may be an important consideration when amending soils with biochar and can help explain why biochar may enhance methane production from organic wastes under anaerobic conditions.

Near-infrared (NIR) persistent luminescence nanoparticles (PLNPs), possessing unique NIR PL properties, have recently emerged as important materials for a wide variety of applications in chemistry and biology, for which they must endure high-temperature solid-state annealing reactions and subsequent complicated physical post-treatments. Herein, we report on a first direct aqueous-phase chemical synthesis route to NIR PLNPs and present their enhanced in vivo renewable NIR PL. Our method leads to monodisperse PLNPs as small as ca. 8 nm. Such sub-10 nm nanocrystals are readily dispersed and functionalized, and can form stable colloidal solutions in aqueous solution and cell culture medium for biological applications. Under biotissue-penetrable red-light excitation, we found that such nanocrystals possess superior renewable PL photoluminescence in vitro and in vivo compared to their larger counterparts currently made by existing methods. We believe that this solid-state-reaction-free chemical approach overcomes the current key roadblock in regard to PLNP development, and thus will pave the way to broad use of these advanced miniature “luminous pearls” in photonics and biophotonics.

p-Xylene, the precursor for PET bottles, was synthesized at 90% yield by [4 + 2] cycloaddition of biomass-derived ethylene and dimethylfuran followed by subsequent dehydration with Beta zeolite. Scheme 1 Diels-Alder cycloaddition of dimethylfuran [1] and ethylene produces an oxa-norbornene cycloadduct [2] which dehydrates to p-xylene [3]. Water hydrolyzes dimethylfuran [1] to 2,5-hexanedione [4] in equilibrium. † Electronic supplementary information (ESI) available. See

A liquid-phase method for preparing uniform-sized silica nanospheres (SNSs) 12 nm in size and their three-dimensionally ordered arrangement upon solvent evaporation have recently been pioneered by us. The SNSs are formed in the emulsion system containing Si(OEt) 4 (TEOS), water, and basic amino acids under weakly basic conditions (pH 9-10). Here, we report the formation mechanism of the SNSs; the reasons for the uniform size and the ordered arrangement are described in detail. The formation process is monitored by FE-SEM, SAXS, and liquid-state NMR. The FE-SEM observations reveal that silica nanoparticles ca. 4 nm in size are formed in the water phase at the early stage (∼0.5 h) of the reaction. The SAXS measurements suggest that the number density of the particles remains unchanged when they are gradually grown. Liquid-state 1 H NMR analyses suggest that TEOS are slowly hydrolyzed at the oil-water interface to continuously supply silicate species into the water phase. The silicate species are immediately consumed for the growth of the parent particles without forming new particles. The size of the SNSs can be tuned from 8 to 35 nm by varying the synthesis conditions and/or the amount of TEOS. The zeta potential and pH of the dispersion of SNSs throughout the solvent evaporation process are almost constant approximately at -40 mV and 9-10, respectively; the SNSs have been well-dispersed until the final stage of the evaporation process. The critical roles of basic amino acids in the formation and regular arrangement of SNSs are discussed based on the experimental results.