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W.S. wishes to thank University of St Andrews for a CSC-St Andrews scholarship. Pseudo-icosahedral Cu microcrystals have been synthesized in a solvothermal system containing CuSO4·5H2O as the precursor, polyvinylpyrrolidone (PVP) as a reductant/capping agent, and dimethylformamide as the solvent. The structural and morphological evolutions over the reaction time are investigated, which enable us to establish a novel formation mechanism of pseudo-icosahedral crystals of Cu. The first crystalline phase that appeared in the solution is Cu4SO4(OH)6·H2O in the form of microflakes. The microflakes are reduced and decomposed to Cu2O nanocrystallites, which assemble with PVP into spherulites. The Cu2O crystals are further reduced to Cu nanocrystallites, which aggregate with PVP again into spherical particles. An extraordinary phenomenon is that 20 separated (111) triangular plates form on each particle during surface recrystallization of Cu, and their locations match to the final facets of the pseudo-icosahedron. The plates extend to cover the whole surface of the sphere, forming a pseudo-icosahedral shell, followed by extension of the recrystallization from the surface to the core. This reversed crystal growth process increases the thickness of the plates until all the Cu nanocrystallites in the core are consumed. It is found that, during the surface recrystallization of polycrystalline spheres, the particles preferentially select the (111) planes of the face-centered cubic structure of Cu as the exposed faces because these planes have the minimum surface binding energy. The particles then try to keep as small as possible the specific surface area, and a pseudo-icosahedral shape consisting of 20 (111) plates, which has a specific surface area, about 10% lower than that of an octahedron, formed by eight (111) plates. Accordingly, the overall surface free energy of a pseudo-icosahedron is about 10% lower than that of an octahedron. The formation of tetrahedra as building units of icosahedra, as predicted previously, has not been observed. The formation of ideal icosahedra, the so-called perfect Platonic solid, and the formation of twin defects between neighboring (111) plates are not possible. The newly proposed formation mechanism of pseudo-icosahedra Cu sheds light on the understanding of formation of many other polyhedral crystals. Publisher PDF

This work was financially supported by the Advanced Research Center of Green Materials Science and Technology from The Featured Area Research Center Program within the framework of the Higher Education Sprout Project by the Ministry of Education (107L9006), the Ministry of Science and Technology in Taiwan (Contracts MOST 109-2113-M-002-020-MY3, MOST 107-2113-M-002-008-MY3, MOST 110-2923-M-002-017-MY3, MOST 107-2923-M-002-004-MY3, and MOST 107-3017-F-002-001), the National Science Center Poland Grant Opus (nos. 2016/23/B/ST3/03911 and 2019/33/B/ST3/00406), and the National Center for Research and Development Poland Grant (no. PL-TW/VIII/1/2021). Cs4PbI6, as a rarely investigated member of the Cs4PbI6(X is a halogen element) family, has been successfully synthesized at low temperatures, and the synthetic conditions have been optimized. Metal iodides such as LiI, KI, NiI2, CoI2, and ZnI2, as additives, play an important role in enhancing the formation of the Cs4PbI6 microcrystals. ZnI2 with the lowest dissociation energy is the most efficient additive to supply iodide ions, and its amount of addition has also been optimized. Strong red to near-infrared (NIR) emission properties have been detected, and its optical emission centers have been identified to be numerous embedded perovskite-type α-CsPbI3 nanocrystallites (∼5 nm in diameter) based on investigations of temperature- and pressure-dependent photoluminescent properties. High-resolution transmission electron microscopy was used to detect these hidden nanoparticles, although the material was highly beam-sensitive and confirmed a “raisin bread”-like structure of the Cs4PbI6 crystals. A NIR mini-LED for the biological application has been successfully fabricated using as-synthesized Cs4PbI6 crystals. This work provides information for the future development of infrared fluorescent nanoscale perovskite materials. Postprint

Cu

Cs

Formation of Mn

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. Postprint

This work was financially supported by the EPSRC (EP/P510968/1). New nanocomposites have been prepared by combining tin selenide (SnSe) with graphene oxide (GO) in a simple aqueous solution process followed by ice templating (freeze casting). The resulting integration of SnSe within the GO matrix leads to modifications of electrical transport properties and the possibility of influencing the power factor (S2σ). Moreover, these transport properties can then be further improved (S, σ increased) by funtionalisation of the GO surface to form modified nanocomposites (SnSe/GOmod) with enhanced power factors in comparison to unmodified nanocomposites (SnSe/GO) and “bare” SnSe itself. Functionalising the GO by reaction with octadecyltrimethoxysilane (ODTS; C21H46O3Si) and triethylamine (TEA;(CH3CH2)3N) switches SnSe from p-type to n-type conductivity with an appreciable Seebeck coefficient and high electrical conductivity (1257 S·m-1 at 539 K); yielding a 20-fold increase in the power factor compared to SnSe itself, prepared by the same route. These findings present new possibilities to design inexpensive and porous nanocomposites based on metal chalcogenides and functionalized carbon-derived matrices. Postprint

This work is financially supported by National Natural Science Foundation of China (21573023). WZ thanks an equipment grant from EPSRC (EP/L017008/1) to University of St Andrews. Difficulty of growing metal oxides on intrinsic graphene due to few defects and functional groups on its surface was overcome by deposition of polymerized precursors via multiple interacting sites, followed by crystallization of metal oxides inside the aggregated polymer. As a typical example, Mn3O4-decorated electrochemically exfoliated graphene (EEG) was successfully prepared and served as an advanced anode material for lithium-ion batteries. Because EEG possesses higher electronic conductivity and stronger mechanical strength in comparison with commonly used reduced graphene oxide (rGO), the new composite of EEG-Mn3O4 exhibits much better electrochemical performance than rGO-Mn3O4, including superior reversible capacity and better cycling stability. Postprint

This work was financially supported by National Natural Science Foundation of China (21573023). WZ thanks EPSRC’s support to the electron microscopy Laboratory for a Capital Equipment Grant EP/L017008/1. As a new generation of high quality graphene, electrochemically exfoliated graphene is an ideal platform for constructing integrated high-performance nanocomposites as advanced electrode materials for energy storage and conversion devices. To take on a challenge of direct growth of nanoparticles on electrochemically exfoliated graphene with limited oxygen-containing functional groups and its hydrophobic nature, a systematic study is carried out on growth of SnO2 nanocrystallites on the surface of electrochemically exfoliated graphene. The results indicate that these nanocrystals can efficiently grow on the functional group-free surface of electrochemically exfoliated graphene, if the precursor molecules can polymerize into larger molecules and aggregate on electrochemically exfoliated graphene followed by decomposition and phase transformation into the final metal oxide nanocrystallites. Some key factors affecting this non-classical crystal growth are investigated. Addition of a small amount of water in a polar aprotic solvent to stimulate polymerization of the precursor molecules and a solvothermal treatment to facilitate decomposition of the disordered aggregates of the polymerized precursors are crucial to the growth of nanocrystals on electrochemically exfoliated graphene. The improved electrical conductivity and structural stability of the hybrids may promote the performance of the materials in various applications, such as exceptional lithium storage capability. Postprint

Large octahedral zeolite X crystals nucleate inside preformed spherical particles at the interface between an amorphous core and a shell of zeolite P nanorods. Triethanolamine enhances the sphere formation and is involved in the growth of zeolite X crystals. Postprint

Cs

This work was financially supported by National Natural Science Foundation of China (Nos. 21975030 and 11674005), and the Ministry of Science and Technology of China (No. 2016YFB0700600 (National Materials Genome Project)). Solving the polysulfide shuttle problem is one of the core challenges for the industrialization of lithium–sulfur batteries. In this work, a triphasic composite of LDH/sulfur/rGO (LDH: layered double hydroxide, rGO: reduced graphene oxide) with a crepe cake like structure is designed and fabricated as a positive electrode material for lithium–sulfur batteries. Sulfur nanoparticles are embedded in the interlayer space of the composite and thus are well protected physically via three-dimensional wrapping and chemically via strong interaction of LDH nanoflakes with lithium polysulfides, such as ionic bonds and S···H hydrogen bonds. In addition, the flexible lamellar structure of the composite with soft graphene layers can tolerate the volume expansion of sulfur during lithiation as well as facilitate ionic permeability and electron transport, which is favorable for the redox reactions of polysulfide. The present work sheds light on the future development and industrialization of lithium–sulfur batteries. Postprint

A general assembly shop in an aerospace industry has extremely unbalanced workstation time and several re-entry processes. The capacity allocation of buffer-like workstations has been identified as a crucial factor of production improvement. Experience based what-if analyses based on simulation of feasible alternatives are time-consuming and cannot get the optimization solutions. In this study, a data driven simulation-based optimization framework is presented and used to re-design the capacity of buffer-like workstations in the line. The assembly processes with distinct characteristics are introduced and a data driven method is adopted to build the different structures of the simulation model. An optimization problem with constraints is formulated and solved based on genetic algorithm, which uses self-adoptive refusal and penalty function strategy to improve the performance. The case study of the real system is carried out and the results show that the data driven simulation-based optimization is efficient to the problem.

This work was financially supported by the National Natural Science Foundation of China (Grant No. 21203102), the Tianjin Municipal Natural Science Foundation (Grant No. 14JCQNJC06000), China Scholarship Council (Grant No. 201606200087), MOE (IRT13R30) and 111 Project (B12015). A thermoresponsive lipase catalyst with an upper critical solution temperature (UCST) of about 26 °C was exploited by covalent immobilization of an enzyme, Pseudomonas cepacia lipase (PSL), onto poly(acrylamide-co-acrylonitrile) via glutaraldehyde coupling. The experimental conditions for the PSL immobilization were optimized. The immobilized PSL was much more stable for wide ranges of temperature and pH than the free PSL. The material was also evaluated as an asymmetric catalyst in the kinetic resolution of racemic α-methylbenzyl butyrate at 55 °C in an aqueous medium and exhibited high catalytic performance and stability. Up to 50% conversion and 99.5% product enantiomeric excess were achieved, thus providing highly pure enantiomers. More importantly, this biocatalyst could be easily recovered by simple decantation for reuse based on temperature-induced precipitation. It showed good reusability and retained 80.5% of its original activity with a well reserved enantioselectivity in the 6th cycle. This work would shed light on the future development of new UCST-type enzyme catalysts. Postprint

This work is financially supported by the National Natural Science Foundation of China (Grant No. 51125005, 51472088, 51602104). Uniform perovskite core-shell nanocubes NaMn1-xMgxF3@NaMgF3 and NaMn1-xMgxF3:Yb3+@NaMgF3:Yb3+ have been successfully synthesized via a facile one-pot co-precipitation method at room temperature. The core-shell structures were carefully characterized by powder X-ray diffraction, transmission electron microscopy, scanning transmission electron microscopy and energy-dispersive X-ray elemental mapping. It was found that the formation mechanisms of the novel core-shell structures consisting of aggregation of precursor molecules/ions, multiple nucleation, surface re-crystallization and further phase transformation. In addition, the DFT calculations further showed that Mn2+ ions tend to aggregate in NaMgF3:Mn2+, and which may be one of important intrinsic factors for formation the unique NaMn1-xMgxF3@NaMgF3 structure in this case. Besides, the unique core-shell structures NaMn1-xMgxF3:Yb3+@NaMgF3:Yb3+ can obviously enhance near-infrared upconversion luminescence of Mn2+, that may find high potential in multiple high-resolution imaging applications. Postprint

Based on various experimental results, M3+O(–Mn4+)2 clusters in (Fe, Co, Ni)-doped MnOx catalysts were identified as the principal active sites for the aerobic oxidation of 5-hydroxymethylfurfural due to their special properties that make oxygen ‘easy come, easy go’.

This work was supported by the Ministry of Science and Technology of Taiwan (Contract No. MOST 104‒2113‒M‒002‒012‒MY3), EPSRC and STFC, UK. This research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Optimizing properties of phosphors for use in white-light‒emitting diodes (WLEDs) is an important materials challenge. Most phosphors have a low level of lattice disorder due to mismatch between the host and activator cations. Here we show that deliberate introduction of high levels of cation disorder leads to significant improvements in quantum efficiency, stability to thermal quenching, and emission lifetime in Sr1.98-x(Ca0.55Ba0.45)xSi5N8:Eu0.02 (x = 0 ‒ 1.5) phosphors. Replacing Sr by a (Ca0.55Ba0.45) mixture with the same average radius increases cation size variance resulting in photoluminescence emission increases of 20‒26% for the x = 1.5 sample relative to the x = 0 parent across the 25‒200 °C range that spans WLED working temperatures. Cation disorder suppresses nonradiative processes through disruption of lattice vibrations and creates deep traps that release electrons to compensate for thermal quenching. Introduction of high levels of cation disorder may thus be a very useful general approach for improving the efficiency of luminescent materials. Postprint

This work was supported by the Ministry of Science and Technology of Taiwan (Contract Nos. MOST 104-2113-M- 002-012-MY3 and MOST 104-2923-M-002-007-MY3). This research was also supported by National Centre for Re- search and Development, Poland (Grant No. PL- TW2/8/2015). Searching for a non-rare earth-based oxide red-emitting phosphor is crucial for phosphor-converted light- emitting diodes (LEDs). In this study, we optimized a blue and UV-light excited Sr4Al14O25:Mn phosphor exhibiting red emission peaked at ~653 nm, which was successfully synthesized by solid-state reaction. The crystal structure, micromorphology, and luminescent properties of Sr4Al14O25:Mn phosphors were characterized by X-ray Rietveld refinement, high-resolution transmission electron microscopy, and photoluminescence spectra. The band gap and electronic structure of Sr4Al14O25 were analyzed by density functional theory calculation using the hybrid exchange- correlation functional. The crystal field environment effect of Al sites from introducing activator Mn ions was investigated with the aid of Raman 27Al nuclear magnetic resonance spectra and electron spin resonance. The pressure dependent on the luminescent properties and decay time of this compound were presented. The tricolor display spectrum by combining blue InGaN chips, commercial β-SiAlON:Eu2+ green phosphor, and Sr4Al14O25:Mn red phosphor were evaluated for commercial applications: using the present Sr4Al14O25:Mn red phosphor converted LED as backlighting source. Postprint

This work was preliminarily supported by the National Key Research Program of China (2016YFA0202604), the Natural Science Foundation of China (21476271), NSFC-RGC (21461162003) and Natural Science Foundation (2014KTSCX004 and 2014A030308012) of Guangdong Province, China.

W.Z. thanks EPSRC for financial support to purchase the FEG SEM (EP/F019580/1). The detailed process of the hydrolysis of ferricyanide into dendritic α-Fe2O3 (hematite) crystals with snowflake-like, feather-like and leaf-like morphologies has been investigated. [Fe(CN)6]3– anions were found to polymerize into large, disordered soft matter aggregates at an early stage. The nucleation of hematite crystals took place near the surface of these aggregates via further hydrolysis. After the crystals grew to a certain size, branches started to appear. When the concentration of ferricyanide was low (i.e. 2 mM to 3.8 mM), growth was preferentially along the six equivalent directions, resulting in a flat snowflake-like shape, while high concentrations (i.e. 9 mM to 500 mM) of ferricyanide led to the growth of selective directions along the zone axes, forming a feather-like or leaf-like morphology. Highly selective adsorption and surface hydrolysis of [Fe(CN)6]3– anions on α-Fe2O3 crystals was found to be a crucial process in the formation of these novel morphologies. It was found that the polymeri- sation of ferricyanide led to a reduction of pH value and that the formation of Fe2O3 increased pH value. The pH value of the solution at the point when the branches start to grow can significantly affect the distribution of Lewis acidic sites on different surfaces and, therefore, change the growth direction. The newly established mechanism is complementary to the classical theories of crystal growth. Postprint

The structural study of monosodium urate monohydrate, as the principal component in gout stones, reveals that a simple and biocompatible way to breakdown the crystals into polymerised molecules at pH of 7.4 (the acidity of normal human blood) is to peel off them along the [001] direction by sonication. Postprint

Carboxyl Fe

KS would like to thank the University of St Andrews for the studentship, WZZ thanks EPSRC for the financial support to purchase the FEG SEM (EP/F019580/1). Cu2O crystals are synthesised hydrothermally with an 8-branched morphology, which can undergo a transition to a cubic shape by increasing the reaction time. The rapid branch formation of these structures is studied over time using SEM, TEM, SAED, PXRD and TGA. The formation of Cu2+/PVP soft matter clusters is shown to play a key role in the reduction of Cu2+, the nucleation of Cu2O crystals and the rapid growth of branches along all eight equivalent directions of the cubic Cu2O struc- ture, due to the presence of negatively charged hydroxyl sites on the {111} surfaces. This non-classical crystal growth mechanism, which relies on aggregation of the precursor on the crystal surface, may help us to understand the formation of many abnormal crystal morphologies. Postprint

JG would like to thank the EPSRC for provision of a studentship via the doctoral training grant (EP/K503162/1). The research data (and/or materials) supporting this publication can be accessed at [http://dx.doi.org/10.17630/a7a9bc13-b5cb-485d-914a-923832f25190] Combined temperature-dependent structural and electrical characterization of a series of “empty” ferroelectric tetragonal tungsten bronzes (TTBs) of composition Ba4(La1- xNdx)0.67□1.33Nb10O30 are reported. The La-material exhibits a temperature dependent crossover from relaxor-ferroelectric to polar (but non-ferroelectric) to linear dielectric behavior. The loss of ferroelectric switching in the polar, non-ferroelectric phase is accompanied by disorder associated with structural relaxation due the significant vacancy concentration at the A1-perovskite-like site. In this disordered regime, large polarization can be re-established with application of sufficient electric field, however relaxation back into the disordered phase occurs on removal of the field as indicated by the loss of remenant polarization. The field against which “backswitching” (depolarization) occurs increases with temperature indicating increasing stability of the disordered regime. The disordered phase can be de-stabilized by substituting Nd for La at the A1-site and which reintroduces “normal” ferroelectric behavior. Postprint

This work was supported by the National Natural Science Foundation of China (Grant No. 21306072, 21203081) and Development Program of Lanzhou University of Technology for excellent teachers (Grant No. Q201113). WZ thanks EPSRC for financial support to upgrade the SEM facilities (No. EP/F019580/1). We cordially thank the Reviewers and Editors for providing us with valuable comments and suggestions. LTA-type aluminophosphate molecular sieve has been successfully synthesized by improvedionothermal method from a gel containing low-dosage ionic liquids. The optimum syntheticconditions of this material are refined. The resultant LTA molecular sieves were characterized byXRD, SEM, TG-DTA, CHN elemental analysis, solution 13C NMR, EDX, TEM and N2physisorption. The composition of the resulting LTA-type molecular sieves is determined to be(Al12P12O48)(C4H9NO)2(C8H15N2+)2(F-)2, for which morpholine together with1-butyl-3-methylimidazolium cations act as the structure-directing agent. The high zeolite yield, as well as the high specific surface area and micropore volume for the calcined LTA-type materials imply that these zeolitic materials have a high potential in applications. Postprint

This work was financially supported by the National Nature Science Foundation of China (No: 51302280, 51574286), Natural Science Foundation in Qinghai province (No: 2014-ZJ- 936Q). CAS "Light of West China" Program and Youth Innovation Promotion Association (2016377), CAS. α-Fe2O3 nanoparticle with different morphologies, such as hollow spheres, nanotubes with limited {0001} plane exposed, nanoplates and nanorings with the {0001} plane predominantly exposed, have been synthesised by using NaH2PO4 and urea in a facile hydrothermal method. The mechanism of the morphology evolution from hollow sphere to nanoring has been investigated. It is proposed that the polymerisation of Fe3+/H2PO4− plays an important role in the formation of these morphologies. The adsorption of Cr (VI) from aqueous solution onto these α-Fe2O3 nanoparticles showed that the α-Fe2O3 with nanoring morphology has the highest removal efficiency, and the adsorption capacity reached to 16.9 mg/g. These results indicate that the adsorption mechanism of Cr (VI) onto hematite nanoparticles is a chemisorption process through doubly and triply coordinated hydroxyl groups on the outer surface of α-Fe2O3. Postprint

Morphology evolution is an important process in naturally occurring biominerals. To investigate the interaction between biomolecules and inorganic components in the construction of biominerals, biomimetic hexagonal prism vaterite crystals were hydrothermally prepared through a reaction of urea with calcium nitrate tetrahydrate, whilst gelatin was added as a structure directing agent. An extraordinary morphology evolution was observed. The time dependent growth was investigated by using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis. In the early stages, vaterite nanocrystallites, ~5 nm in diameter, underwent aggregation with gelatin molecules and precursor molecules into 50 nm sized clusters. Some nanoneedles, consisting of self-orientated nanocrystallites embedded within a soft gelatin matrix, were developed on the surface of disordered cores to form spherulite particles, with a similar morphology to natural spherulite biominerals. Further growth was affected by the high viscosity of gelatin, resulting in ellipsoid particles composed of spherulitically ordered needles. It is proposed that surface adsorbed gelatin induces the formation of dipoles in the nanocrystallites and interaction between the dipoles is the driving force of the alignment of the nanocrystallites. Further growth might create a relatively strong and mirror-symmetric dipolar field, followed by a morphology change from ellipsoidal with a cell-division like splitting, to twin-cauliflower, dumbbell, cylindrical and finally to hexagonal prism particles. In this morphology evolution, the alignment of the crystallites changes from 1D linear manner (single crystal like) to 3D radial pattern, and finally to mirror symmetric 1D linear manner. This newly proposed mechanism sheds light on the microstructural evolution in many biomimetic materials and biominerals. Postprint

This work was financially supported by the Fundamental Research Funds for the Central Universities, and National Natural Science Foundation of China (21101014 and 21273022). As a novel anode material for lithium-ion batteries, CeO2 displays imperceptible volumetric and morphological changes during the lithium insertion and extraction processes, and thereby exhibits good cycling stability. However, the low theoretical capacity and poor electronic conductivity of CeO2 hinder its practical application. In contrast, Co3O4 possesses high theoretical capacity, but undergoes huge volume change during cycling. To overcome these issues, CeO2 and Co3O4 nanoparticles are formed inside the pores of CMK-3 and display various electrochemical behaviors due to the different morphological structures of CeO2 and Co3O4 within CMK-3. Moreover, the graphene/metal oxide/CMK-3 composites with a hierarchical structure are then prepared and exhibit better electrochemical performances than metal oxides with or without CMK-3. This novel synthesis strategy is hopefully employed in the electrode materials design for Li-ion batteries or other energy conversion and storage devices. Postprint

To identify the intrinsic active sites in oxides or oxide supported catalysts is a research frontier in the fields of heterogeneous catalysis and material science. In particular, the role of oxygen vacancies on the redox properties of oxide catalysts is still not fully understood. Herein, some relevant research dealing with M1–O–M2 or M1–□–M2 linkages as active sites in mixed oxides, in oxide supported single‐atom catalysts, and at metal/oxide interfaces of oxide supported nanometal catalysts for various reaction systems is reviewed. It is found that the catalytic activity of these oxides not only depends on the amounts of oxygen vacancies and metastable cations but also shows a significant influence from the local environment of the active sites, in particular, the symmetry of the oxygen vacancies. Based on the recent progress in the relevant fields, an “asymmetric oxygen vacancy site” is introduced, which indicates an oxygen vacancy with an asymmetric coordination of cations, making oxygen “easy come, easy go,” i.e., more reactive in redox reactions. The establishment of this new mechanism would shed light on the future investigation of the intrinsic active sites in oxide and oxide supported catalysts., Asymmetric oxygen vacancies in metal oxide catalysts act as intrinsic catalytic active sites for redox reactions by making oxygen species easy come, easy go. Some relevant work focused on the active sites with asymmetric bonding situations in doped oxides, in oxide stabilized single‐atom catalysts, and at metal/oxide interface is reviewed.

HFG would like to thank the University of St Andrews for the studentship and Mr Ross Blackley for his help on using the SEM and TEM microscopes. WZZ thanks EPSRC for financial support on FEG-SEM equipment (EP/F019580/1) and a Platform (EP/K015540/1). A travertine specimen collected from the western part of Yunnan Province of China was subjected to microstructural analysis by powder X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. A new formation mechanism was proposed whereby polycrystalline rhombohedral particles of magnesium-containing calcite underwent a phase transformation into sheaf-like clusters of aragonite microrods. It is proposed that a high concentration of magnesium ions and embedded biological matter poisoned the growth of calcite and therefore instigated the phase transformation of the core of the rhombohedral calcite particles to an aragonite phase with a higher crystallinity. The single crystalline aragonite microrods with a higher density than the Mg-calcite nanocrystallites grew at the expense of the latter to generate sheaf-like clusters. This newly discovered formation mechanism is expected to enhance previous knowledge on this geologically important phase transformation from a morphology point of view. Postprint

This work was supported by the NNSF of China (No. 51302280), NSF of Qinghai (2014-ZJ-936Q), and Young Scholar Project of Qinghai Institute of Salt Lakes, Chinese Academy of Sciences. WZ thanks EPSRC for financial support to the Electron Microscopy Laboratory (EP/F019580/1). Selective adsorption and surface hydrolysis of [Fe(CN)6]3− anions on α-Fe2O3 crystals was found to be a crucial process in the formation of a snowflake-like morphology, and the established mechanism is complementary to the classical theories of crystal growth. Publisher PDF

The effect of a hydrogen pre-treatment step on an iron based Fischer–Tropsch catalyst applied to the CO hydrogenation reaction at 623 and 723 K has been investigated by inelastic neutron scattering (INS). The catalyst cannot support methane production over a 6 h period of reaction at 623 K but it is active at 723 K. The INS spectrum indicates the presence of a predominantly aliphatic hydrocarbonaceous overlayer for the post-reaction 623 K sample, whereas the spectrum for the 723 K sample is assigned to an overlayer comprising partially hydrogenated polycyclic aromatic compounds. The hydrocarbonaceous overlayer associated with the active phase of the catalyst is modified by the hydrogen pre-treatment step. The INS spectra are interpreted with reference to microreactor studies, powder X-ray diffraction, temperature-programmed oxidation and transmission electron microscopy. The hydrogen pre-treatment stage favours the formation of amorphous carbon and is deemed not to convey any advantage with respect to CO hydrogenation activity.

Red Ca0.99Al(1-4δ/3-x)Si(1+δ+x)N(3-x)C(x):Eu(2+)0.01 (δ = 0.345; x = 0-0.2) nitride phosphors exhibit a blue-shifted emission with increased eye sensitivity function and excellent thermal stability. The variations in the photoluminescence in the Ca0.99Al(1-4δ/3-x)Si(1+δ+x)N(3-x)C(x):Eu(2+)0.01 (δ = 0.345; x = 0-0.2) system are thoroughly investigated. The enhanced emission energy and the improved thermal stability with increasing x are dominated by the second-sphere shrinkage effect via the substitution of small Si(4+) for large Al(3+) with simultaneous charge compensation. Related proofs of the second-sphere shrinkage effect control for photoluminescence are confirmed via high-resolution neutron powder diffraction, EXAFS, and (29)Si solid-state NMR techniques.

Mn

Dehydrogenation or oxidative dehydrogenation (ODH) of alkanes to produce alkenes directly from natural gas/shale gas is gaining in importance. Ti3AlC2, a MAX phase, which hitherto had not been used in catalysis, efficiently catalyzes the ODH of n‐butane to butenes and butadiene, which are important intermediates for the synthesis of polymers and other compounds. The catalyst, which combines both metallic and ceramic properties, is stable for at least 30 h on stream, even at low O2:butane ratios, without suffering from coking. This material has neither lattice oxygens nor noble metals, yet a unique combination of numerous defects and a thin surface Ti1−yAlyO2−y/2 layer that is rich in oxygen vacancies makes it an active catalyst. Given the large number of compositions available, MAX phases may find applications in several heterogeneously catalyzed reactions.

Electron microscopic investigations of zeolites are reviewed. Scanning electron microscopy can show the appearance of zeolite crystals, e.g. their sizes and morphologies, and can also be used to look into the cores of crystals, revealing any abnormal microstructures, which often help us to elucidate actual crystal growth mechanisms. High resolution transmission electron microscopy is a powerful tool to directly image many pore systems and local defects in zeolites. The more advanced techniques, including spherical aberration corrected scanning transmission electron microscopy, high angle annular dark field imaging, high resolution energy dispersive X-ray spectroscopy, 3D electron tomography, etc., allow us to reveal much more structural details of zeolites and other porous materials such as metal–organic frameworks.

Funding: Royal Society for provision of an industry fellowship and the EPSRC for funding (EP/K025112/1 and EP/L014475/1) (R.E.M.); Czech Science Foundation for (P106/12/G015) (J.Cˇ.); European Community under a Marie Curie Intra-European Fellowship (A.B.P.). Zeolites are important materials whose utility in industry depends on the nature of their porous structure. Control over microporosity is therefore a vitally important target. Unfortunately, traditional methods for controlling porosity, in particular the use of organic structure-directing agents, are relatively coarse and provide almost no opportunity to tune the porosity as required. Here we show how zeolites with a continuously tuneable surface area and micropore volume over a wide range can be prepared. This means that a particular surface area or micropore volume can be precisely tuned. The range of porosity we can target covers the whole range of useful zeolite porosity: from small pores consisting of 8-rings all the way to extra-large pores consisting of 14-rings. Publisher PDF

Novel promising blue MSiAl2O3N2:Ce3+ (M = Sr, Ba) and green BaSiAl2O3N2:Eu2+ oxynitride phosphors with broad band emission for white light-emitting diodes are obtained in this study. The detailed energy transfer mechanism from Ce3+ to Eu2+ in SrSiAl2O3N2 is reported. Moreover, the unexpected red shift emission when the compositional variable x is increased from 0 to 0.92 in the Sr0.92-xBaxSiAl2O3N2:Ce3+0.04,Eu2+0.04 system is well investigated. The decrease in emission energy and the increase in thermal quenching barrier height of x are caused by a dominant chemical pressure compression effect on the activator sites, through which the replacement of Sr2+ (occupied by activators) by larger Ba2+ enhances the covalency of Sr–N/O bonding in spite of unit cell enlargement. The chemical pressure compression effect control for photoluminescence is verified by the ionic-radii equilibrium between 9-coordinate IXSr2+ and (IXCa2+, IXBa2+).

Metal–organic framework, MOF-5, is re-synthesised using an established method, which reveals an extraordinary formation mechanism. The earliest detected crystalline phase is Zn5(OH)8(NO3)2·2H2O, in the form of nanoplatelets 5 to 10 nm in diameter, which aggregate with surface adsorbed organic molecules into a layered inorganic–organic composite. Multiple nucleation of MOF-5 takes place inside the composite via intercalation of 1,4-benzenedicarboxylate molecules and phase transformation from Zn5(OH)8(NO3)2·2H2O. The as-formed MOF-5 nanocrystallites aggregate into cubic polycrystalline particles, which undergo surface re-crystallisation followed by extension of re-crystallisation from the surface to the core. This newly established formation mechanism may shed light on the crystal growth of many other MOFs. It may enable scientists to precisely control the microstructures and morphologies of these materials and gain a better understanding of their properties for future applications.

Developing low cost oxygen reduction catalysts that perform with high efficiency is highly desirable for the commercial success of environmentally friendly energy conversion devices such as fuel cells and metal–air batteries. In this work a three-dimensional, 3D, self-assembled Mn3O4 hierarchical network has been grown on nitrogen doped reduced graphene oxide (NrGO), by a facile and controllable electrodeposition process and its electrocatalytic performance for oxygen reduction reaction (ORR) has been assessed. The directly electrodeposited MnOx on a glassy carbon electrode (GCE) exhibits little electrocatalytic activity, whereas the integrated Mn3O4/NrGO catalyst is more ORR active than the NrGO. The resulting electrode architecture exhibits an “apparent” four-electron oxygen reduction pathway involving a dual site reduction mechanism due to the synergetic effect between Mn3O4 and NrGO. The 3D Mn3O4/NrGO hierarchical architecture exhibits improved durability and methanol tolerance, far exceeding the commercial Pt/C. The enhanced ORR performance of the room temperature electrodeposited Mn3O4 nanoflake network integrated with NrGO reported here offers a new pathway for designing advanced catalysts for energy conversion and storage.

We have demonstrated that three-dimensional (3D) surface engineering of silicon nanocrystals (SiNCs) by direct current microplasma processing in water with poly(3,4-ethylenedioxythiophene) doped by poly(styrenesulfonate) (PEDOT:PSS) can lead to nanocomposites with enhanced optoelectronic performance. Specifically, we have successfully shown improved photoluminescence properties of SiNCs inside water-based solution. The results also confirm that SiNCs become stable in water with potential application impact for biorelated applications. We have also shown that the microplasma processing in the presence of the polymer helps prevent the fast oxidation process over a longer period of time in comparison to the unprocessed sample. Furthermore, the assessment of transport properties confirmed the improvement of exciton dissociation after microplasma surface engineering; this can have direct implications for higher performance optoelectronic devices including solar cells.

Considerable efforts have been exerted in the development of non-noble metal catalysts (NNMCs) for oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs). The effects of the preparation strategy, including carbon support, metal and nitrogen precursors, as well as heat-treatment conditions, on the ORR activity for such NNMCs have also been extensively explored. In this review, we mainly focused on the recent advances in carbon-incorporated NNMCs, specifically carbon-incorporated iron nitride (FeCN)-based catalysts. Influences of pyrolysis temperature on the crystalline and local structures, chemical environment, morphology, and ORR activity of FeCN-based catalysts were discussed, and the ORR mechanism was also proposed.

The crystallization of zeolite TUN with 1,4-bis(N-methylpyrrolidinium)butane as template proceeds through an intermediate, designated IPC-3P, following the Ostwald rule of successive transformations. This apparently layered transient product has been thoroughly investigated and found to consist of MWW monolayers stacked without alignment in register, that is, disordered compared with MCM-22P. The structure was confirmed based on X-ray diffraction and high-resolution (HR)TEM analysis. The layered zeolite precursor IPC-3P can be swollen and pillared affording a combined micro- and mesoporous material with enhanced Brunauer-Emmett-Teller (BET) surface area (685m(2)g(-1)) and greater accessibility of BrOnsted acid sites for bulky molecules. This mesoporous material was probed with 2,6-di-tert-butylpyridine (DTBP). IPC-3P and its modification create a new layered zeolite sub-family belonging to the MWW family. FTIR data indicate that (Al)MWW materials MCM-22 and IPC-3 with Si/Al ratios greater than 20 exhibit a lower relative ratio of BrOnsted to Lewis acid sites than MCM-22 (with Si/Al ratios of around 13), that is, less than 2 versus more than 3, respectively. This is maintained even upon pillaring and warrants further exploration of materials like IPC-3P with a higher Al content. The unique XRD features of IPC-3P indicating misaligned stacking of layers and distinct from MCM-22P, are also seen in other MWW materials such as EMM-10P, hexamethonium-templated (HM)-MCM-22, ITQ-30, and UZM-8 suggesting the need for more detailed study of their identity and properties. Postprint

Bimetallic CuPt nanocrystals with size ranging from 3 to 30 nm were synthesized in the presence of either hexadecylamine or poly(vinylpyrrolidone) as a capping agent. Different growth stages of CuPt nanoparticles prepared with hexadecylamine have been investigated and a non-classic mechanism governing the formation of the metal alloy was revealed. It was found that the precursor molecules aggregate into amorphous spheres at a very early stage, followed by surface multiple nucleation, formation and combination of crystalline islands to produce a core–shell structure with surface-to-core extension of the crystallization to achieve single crystals. CuPt nanocrystals synthesized with poly(vinylpyrrolidone) grew via the classic route. Dealloying treatment was applied on these CuPt nanoalloys to selectively remove Cu. Large particles (~30 nm) with Cu-rich cores exhibited hollow structures after dealloying while 3 nm particles remained solid, demonstrating that particle size and composition have a great influence on the final morphology of dealloyed particles.

Mesoporous silica SBA-15 was synthesised by the true liquid crystal templating method, yielding a material with reduced microporosity compared with that produced by the more conventional liquid crystal templating route. Further advancements allow the generation of metal nanoparticle-doped SBA-15 materials with well-defined metal particle sizes, which posses potential as catalytic systems.

This contribution reports new methodology we have developed for the disassembly of 3-D UTL framework into 2-D lamellae followed by structure modification including pillaring. This may be widely applicable, particularly to other zeolites that have D4R units present, and so should have great impact also on other porous solids. Specifically, controlled hydrolysis of D4R units in the interlayer space provides individual ultrathin layers with UTL structure by a chemically selective method. Further manipulation of the layers gives a completely novel approach (3D to 2D to pillared) offering hitherto unprecedented opportunities for the preparation of modified zeolites with diverse chemical and structural properties.