Quantum-Sized Zinc Oxide Nanoparticles Synthesised within Mesoporous Silica (SBA-11) by Humid Thermal Decomposition of Zinc Acetate

A modified facile method is presented to synthesise quantum-sized zinc oxide nanoparticles within the pores of a mesoporous silica host (SBA-11). This method eliminates the 3 h alcohol reflux and the basic solution reaction steps of zinc acetate. The mesoporous structure and the ZnO nanoparticles were analysed by X-ray diffractometry, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, nitrogen sorption analysis and UV–VIS spectroscopy. These tests confirm the synthesis of ~1 nm sized ZnO within the pores of SBA-11 and that the porous structure remained intact after ZnO synthesis.</jats:p

Novel direct synthesis of mesoporous tin dioxide network intact up to 500°C

This project is supported by PAAET project no. BE-­‐13-­‐08 in collaboration with Kuwait University and the University of York. The support of the research administration of Kuwait University to the XPS instrument (Project No. GS02/08) is acknowledged.We present a direct soft templating method to synthesise mesoporous tin dioxide network that maintains a porous structure after calcination at 400 °C and 500 °C and has a relatively high BET surface area of 220 and 100 m2 g-1, respectively. TEM, BET and XRD results confirm that both crystal and pore sizes increase as a result of increasing the temperatures during the calcination step. This method is highly reproducible.PostprintPeer reviewe

Formation mechanisms of ZnO spherulites and derivatives

The authors thank EPSRC for a platform grant (EP/K015540/1) and a Capital Equipment Grant EP/L017008/1.ZnO microparticles have been solvothermally synthesized from zinc acetate and formic acid. The resulting microspherulites consist of radially arranged nanorods which undergo a range of re-crystallisation pathways to produce particles with different terminal morphologies. Crystallisation on the particle surface results in hex-agonal microdisc decorated hierarchical microspheres. These particles expose only the (0001) crystallographic plane of ZnO and further develop into a sea-urchin like morphology, when the microdiscs grow up along the [0001] direction into hexagonal microrods. Alternatively, crystallisation of the particle core into a ZnO plate, facilitates asymmetric assembly of nanocrystallites, forming a hexagonal cone on one side of the plate. The particle has a mushroom-like terminal morphology. When simultaneous surface and core re-crystallisation takes place, wood gyro-shaped particles are observed, in which all the surface discs face a single direction. The microstructures of the particles were investigated using XRD, electron microscopy and surface colouring with adsorbed charged dyes. Structural studies of the early growth stages and subsequent morphology evolution support a dipole field driven formation mechanism. This work offers an improved understanding of the for-mation of other spherulites, in particular, naturally occurring mineral calcium carbonate spherulites.PostprintPeer reviewe

Disparity of Cytochrome Utilization in Anodic and Cathodic Extracellular Electron Transfer Pathways of Geobacter sulfurreducens Biofilms.

Extracellular electron transfer (EET) in microorganisms is prevalent in nature and has been utilized in functional bioelectrochemical systems. EET of Geobacter sulfurreducens has been extensively studied and has been revealed to be facilitated through c-type cytochromes, which mediate charge between the electrode and G. sulfurreducens in anodic mode. However, the EET pathway of cathodic conversion of fumarate to succinate is still under debate. Here, we apply a variety of analytical methods, including electrochemistry, UV-vis absorption and resonance Raman spectroscopy, quartz crystal microbalance with dissipation, and electron microscopy, to understand the involvement of cytochromes and other possible electron-mediating species in the switching between anodic and cathodic reaction modes. By switching the applied bias for a G. sulfurreducens biofilm coupled to investigating the quantity and function of cytochromes, as well as the emergence of Fe-containing particles on the cell membrane, we provide evidence of a diminished role of cytochromes in cathodic EET. This work sheds light on the mechanisms of G. sulfurreducens biofilm growth and suggests the possible existence of a nonheme, iron-involving EET process in cathodic mode.N.K. was supported by a Royal Society Newton International Fellowship, NF160054. E.R., X.F. and N.H. acknowledge the European Research Council (ERC) Consolidator Grant “MatEnSAP” (682833). S. K. was supported by a Marie Skłodowska-Curie Fellowship (EMES, 744317). K. H. Ly acknowledges the Open Topic Postdoc Programme of the Technische Universität Dresden and the Marie Sklodowska Curie IF, GAN 701192. The TEM was funded through the EPSRC underpinning multi-user equipment call (EP/P030467/1

Disparity of Cytochrome Utilization in Anodic and Cathodic Extracellular Electron Transfer Pathways of Geobacter sulfurreducens Biofilms.

Extracellular electron transfer (EET) in microorganisms is prevalent in nature and has been utilized in functional bioelectrochemical systems. EET of Geobacter sulfurreducens has been extensively studied and has been revealed to be facilitated through c-type cytochromes, which mediate charge between the electrode and G. sulfurreducens in anodic mode. However, the EET pathway of cathodic conversion of fumarate to succinate is still under debate. Here, we apply a variety of analytical methods, including electrochemistry, UV-vis absorption and resonance Raman spectroscopy, quartz crystal microbalance with dissipation, and electron microscopy, to understand the involvement of cytochromes and other possible electron-mediating species in the switching between anodic and cathodic reaction modes. By switching the applied bias for a G. sulfurreducens biofilm coupled to investigating the quantity and function of cytochromes, as well as the emergence of Fe-containing particles on the cell membrane, we provide evidence of a diminished role of cytochromes in cathodic EET. This work sheds light on the mechanisms of G. sulfurreducens biofilm growth and suggests the possible existence of a nonheme, iron-involving EET process in cathodic mode.N.K. was supported by a Royal Society Newton International Fellowship, NF160054. E.R., X.F. and N.H. acknowledge the European Research Council (ERC) Consolidator Grant “MatEnSAP” (682833). S. K. was supported by a Marie Skłodowska-Curie Fellowship (EMES, 744317). K. H. Ly acknowledges the Open Topic Postdoc Programme of the Technische Universität Dresden and the Marie Sklodowska Curie IF, GAN 701192. The TEM was funded through the EPSRC underpinning multi-user equipment call (EP/P030467/1

Rapid synthesis of BiOBrxI1-x photocatalysts : insights to the visible-light photocatalytic activity and strong deviation from Vegard’s Law

This work was supported by the Royal Society for international collaboration grants (IE160277 and IE/CNSFC170670) and Sir John Houghton Fellowship in Jesus College at University of Oxford. ZJ appreciated the institutional GCRF fund from EPSRC and JG appreciates the EUSTICE scholarship from University of Southampton.A series of visible-light-responsive BiOBrxI1-x solid solutions were prepared by a rapid and efficient ultrasonication synthesis and applied in photodegradation of Rhodamine B in aqueous solution. The detailed characterisations showed that the lattice parameters and their band structures of the BiOBrxI1-x solid solutions significantly deviated from the well-established Vegard’s law for solid solution materials. The Mulliken electronegativity and valence band XPS analyses revealed that the substitution of Br by less electronegative iodine can simultaneously modulate the edges of conductance and valence band of the BiOBr, leading to nonlinear dependence of bandgap (Eg) on the halogen anion concentrations. Although the solid solution displayed superior RhB photodegration activity to BiOI, only Br-rich BiOBrxI1-x solid solutions (x>0.5) were more active than BiOBr and BiOI, with the optimal one is BiOBr0.75I0.25. The Br-dependence of bandstructure and photocatalytic activity for the BiOBrxI1-x solid solutions as well as their rate-limiting radical species were also clarified based on experimental and theoretical analyses.PostprintPeer reviewe

Effect of ultrasonication time on microstructure, thermal conductivity, and viscosity of ionanofluids with originally ultra-long multi-walled carbon nanotubes

The stability along with thermal and rheological characteristics of ionanofluids (INFs) profoundly depend on the protocol of preparation. Therefore, in this work, the effect of ultrasonication time on microstructure, thermal conductivity, and viscosity of INFs containing 0.2 wt% of originally ultra-long multi-walled carbon nanotubes (MWCNTs) and four different ILs, namely 1-propyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1- butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1-ethyl-3-methylimidazolium thiocyanate, or 1- ethyl-3-methylimidazolium tricyanomethanide, was studied. The INFs were obtained by a two-step method using an ultrasonic probe. The ultrasonication process was performed for 1, 3, 10, or 30 min at a constant nominal power value of 200 W. The obtained results showed that for the shortest sonication time, the highest thermal conductivity enhancement of 12% was obtained. The extended sonication time from 1 to 30 min caused the cutting of MWCNTs and breaking the nanoparticle clusters, leading to a decrease in the average length of the nanotube bundles by approx. 70%. This resulted in a decline in thermal conductivity even by 7.2% and small deviations from the Newtonian behavior of INFs

From lab and up : superior and economic heat transfer performance of ionanofluids containing long carbon nanotubes and 1-ethyl-3-methylimidazolium thiocyanate

The optimization of energy systems and the efficiency enhancement of energy conversion processesare still huge challenges. The ionanofluids (INFs) composed of the long multi-walled carbon nanotubes(MWCNTs) and 1-ethyl-3-methylimidazolium thiocyanate ionic liquid ([C 2 C 1 im][SCN]) are innovative sys- tems with proven remarkably enhanced thermal conductivity and attractive rheological characteristics.Therefore, as an extension of our previous study, this work aims to examine the overall heat transfer per- formance of these INFs as working fluids for energy conversion processes and design sustainable energysystems. The new measuring set was designed and constructed to determine the convective heat transfercoefficient and pressure drop during the flow of INFs, using the heat exchanger with saturated steam at100 °C. The obtained results showed that the heat transfer of INFs is prevailed by the convection mecha- nism. According to a new thermo-economic efficiency-price index proposed in this work, the amalgama- tion of MWCNTs with [C 2 C 1 im][SCN] is justified from both thermophysical and economic points of view

Size-dependent activity of carbon dots for photocatalytic H2 generation in combination with a molecular Ni cocatalyst

Carbon dots (CDs) are low-cost light-absorbers in photocatalytic multicomponent systems, but their wide size distribution has hampered rational design and the identification of the factors that lead to their best performance. To address this challenge, we report herein the novel use of gel filtration size exclusion chromatography to separate amorphous, graphitic, and graphitic N-doped CDs depending on their lateral size to study the effect of their size on photocatalytic H2 evolution with a DuBois type Ni cocatalyst. Transmission electron microscopy and dynamic light scattering confirm size-dependent separation, while UV-vis and fluorescence spectroscopy of the more monodisperse fractions show a distinct response which computational modelling attributed to a complex interplay between CD size and optical properties. A size-dependent effect on the photocatalytic H2 evolution performance of the CDs in combination with a molecular Ni cocatalyst is demonstrated with a maximum activity at approximately 2-3 nm CD diameter. Overall, size separation leads to a two-fold increase in the specific photocatalytic activity for H2 evolution using the monodisperse CDs compared to the as synthesized polydisperse samples, highlighting the size-dependent effect on photocatalytic activity towards H2 evolution

STA-20 : an ABC-6 zeotype structure prepared by co-templating and solved via a hypothetical structure database and STEM-ADF imaging

This work has been supported by Johnson Matthey PLC, UK. AEW acknowledges funding from an EPSRC/Johnson Matthey Industrial CASE PhD award EP/N50936X/1. We acknowledge Diamond Light Source for time on beamline I11 under the funded Proposal EE11830-1.A microporous silicoaluminophosphate with a novel topology type, STA-20, has been prepared via a dual templating method using hexamethylene bisdiazabicyclooctane (diDABCO-C6) and trimethylamine as co-templates. Its structure has been solved and confirmed using a multi-technique approach that included the use of a hypothetical zeolite database to obtain a candidate starting structure, followed by scanning transmission electron microscopy with annular dark field imaging and Rietveld refinement. STA-20 is a member of the ABC-6 family of zeotype structures. The structure has trigonal symmetry, P-31c, with a = 13.15497(18) Å and c = 30.5833(4) Å in the calcined form. It has a 12-layer stacking sequence of 6-rings (6Rs), AABAABAACAAC(A), which contains single and double 6R units. As well as d6r, can and gme cages, STA-20 possesses the longest cage observed in an ordered ABC-6 material, giving a 3D-connected pore system limited by 8R windows. Models for the location of the templates within cages of the framework were obtained by combining elemental analysis, 13C MAS NMR, computer modelling and Rietveld refinement.PostprintPostprintPeer reviewe