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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

WS wishes to thank University of St Andrews for a CSC-St Andrews scholarship. Cu2O spherulites are solvothermaly fabricated by using Cu(NO3)2 as the starting material and polyvinylpyrrolidone (PVP) as a multifunctional growth agent. The specimens at different growth stages are investigated by using X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy, soft X-ray emission spectroscopy and infrared spectroscopy. The formation mechanism of Cu2O spherulites is proposed accordingly. Hierarchically, the spherulites are composed of needle-like submicron-rods lying along the radial orientations. The submicron-rods are constructed by piling up of small Cu2O/PVP spheres. The embedded Cu2O nanocrystallites can generate a dipolar field in each along the [100] direction. They deposit at the surface of a negatively charged PVP-containing spherical core, and self-oriented along the radial directions. Therefore, all the Cu2O nanocrystallites would have their positively charged (100) facet facing to the core and their negatively charged (00) facet turning towards to the spherulite surface, leading to a negatively charged surface of spherulites. Unlike randomly oriented nanocrystallites embedded in polymer microspheres, the spherulites would not undergo surface recrystallisation into a single crystal shell due to the restricted potential of local shift and rotation of the nanocrystallites by the Coulomb force from the core. This work provides new perspective towards the formation of spherulites and their structural properties. Publisher PDF

Cu

JLC thanks Chinese Scholarship Council and University of St Andrews for financial support. Dendritic silver and copper crystals were produced via Galvanic replacement reactions on zinc and aluminum plates, respectively. The growth orientations of these metals were determined using electron microscopy. The results showed that a fast crystal growth associated with a high concentration of metal cations led to kinetically controlled growth along the axes of the cubic close-packed structures. However, a slow growth rate resulted in thermodynamically controlled growth along the [111] axis. The crystal growth was not found to rely upon the direct deposition of metal cations at crystallographic sites on crystal facets, but instead, hydrated metal cations deposited on the crystal surface to form an amorphous coating layer, followed by the reduction of metal cations and crystallization at the crystal/coating interface. Twin defects and stacking faults were often observed across the whole particle and commonly observed ⅓{422} diffraction spots were explained by stacking faults rather than by the possible presence of any superstructures. The present work offers evidences to claim that both the crystal growth rate and Coulomb interaction between negatively charged crystal surface and metal cations play an important role in the formation of metal dendrites in replacement reactions. Publisher PDF

Solar-driven CO2 reduction by abundant water to alcohols can supply sustainable liquid fuels and alleviate global warming. However, the sluggish water oxidation reaction has been hardly reported to be efficient and selective in CO2 conversion due to fast charge recombination. Here, using transient absorption spectroscopy, we demonstrate that microwave-synthesised carbon-dots (mCD) possess unique hole-accepting nature, prolonging the electron lifetime (t50%) of carbon nitride (CN) by six folds, favouring a six-electron product. mCD-decorated CN stably produces stoichiometric oxygen and methanol from water and CO2 with nearly 100% selectivity to methanol and internal quantum efficiency of 2.1% in the visible region, further confirmed by isotopic labelling. Such mCD rapidly extracts holes from CN and prevents the surface adsorption of methanol, favourably oxidising water over methanol and enhancing the selective CO2 reduction to alcohols. This work provides a unique strategy for efficient and highly selective CO2 reduction by water to high-value chemicals., Solar-driven CO2 reduction by abundant water to alcohols is hindered by the sluggish water oxidation reaction. Here, the authors demonstrate that the microwave-synthesized carbon-dots possess unique hole-accepting nature, allowing stoichiometric oxygen and methanol production from water and CO2 with nearly 100% selectivity to methanol.

K. McR. wishes to thank University of St Andrews for a scholarship. An investigation of the crystal growth of metal organic framework MIL-68(In) under solvothermal conditions revealed a non-classical reversed crystal growth mechanism via a route of nanorods – orientated aggregation into polycrystalline microrods – surface recrystallisation into a hexagonal shell – extension of recrystallisation from the surface to the core of the microrods. Terephthalic acid molecules which are adsorbed onto the surface of nanorods are believed to strengthen the inter-particle interaction, leading to an early stage aggregation of the monocrystalline nanorods. Publisher PDF

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

Formation of MnxCo3−xO4 yolk–shell microspheres via a solvothermal reaction of hydrated cobalt and manganese nitrates in ethanol is investigated. Spinel nanocrystals of cobalt oxide or cobalt-rich ternary oxide preferentially develop in the system, while manganese-rich hydroxide form Mn(OH)2-type nanosheets. Instead of continuing to grow individually, the nanocrystallites and nanosheets aggregate into large microspheres due to their strong inter-particle interaction. When the proportion of Mn-rich nanosheets is high, therefore the overall density is low, dehydration of hydroxide nanosheets and a surface re-crystallisation lead to formation of a dense and rigid shell, which is separated from a solid or hollow core via a further Ostwald ripening process. The proposed formation mechanism of the yolk–shell structures based on electron microscopic studies would help us to develop yolk–shell structure based multifunctional materials. 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) and the Ministry of Science and Technology in Taiwan (MOST 107-2113-M-002-008-MY3, MOST 107-2923-M-002-004-MY3, and MOST 107-3017-F-002-001), the National Centre for Research and Development Poland Grant (No. PL-TW/V/1/2018), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB20000000), the CAS/SAFEA International Partnership Program for Creative Research Teams, and the NSFC (Nos. U1805252 and 11774345). J.P.A. acknowledges financial support from EPSRC, U.K. Cs4PbBr6 is regarded as an outstanding luminescent material with good thermal stability and optical performance. However, the mechanism of green emission from Cs4PbBr6 has been controversial. Here we show that isolated CsPbBr3 nanoparticles embedded within a Cs4PbBr6 matrix give rise to a “normal” green luminescence while superfluorescence at longer wavelengths is suppressed. High-resolution transmission electron microscopy shows that the embedded CsPbBr3 nanoparticles are around 3.8 nm in diameter and are well-separated from each other, perhaps by a strain-driven mechanism. This mechanism may enable other efficient luminescent composites to be developed by embedding optically active nanoparticles epitaxially within inert host lattices. Postprint

Funding: UK Engineering and Physical Sciences Research Council (Grant Number(s): EP/P022637/1, EP/K503162/1), Science and Technology Facilities Council (Grant Number(s): RB1820307), China Scholarship Council (CN). The layered perovskite LaTaO4 has been synthesized to be stable in both (polar) orthorhombic and (nonpolar) monoclinic polymorphs at ambient conditions. Although the structural transition between monoclinic and orthorhombic phases has been well established, there is some controversy regarding a further, unidentified transition around 500 K. Here this is identified as an incommensurate–commensurate first‐order transition between incommensurate Cmc21(α00)0s0 and commensurate Cmc21 orthorhombic phases. Transmission electron microscopy indicates partially ordered stacking of different structural units in a, identifying the local cause for the modulation, whereas variable temperature powder neutron diffraction has shown the overall macroscopic modulation vector, q ≈ (0.456, 0, 0)—roughly a 2.2 × expansion in a, corresponding to an approximate 11a commensurate superunit cell dimension. The modulation shows a continuous temperature dependence until transitioning to the basic (commensurate) cell at TIC‐C. Doping the interlayer La sites with smaller Nd cations stabilizes the incommensuration to higher temperature, suggesting the modulation is geometrically driven at the A site. Publisher PDF

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

STW thanks China Scholarship Council and University of St Andrews for a CSC-St Andrews scholarship. Naturally occurring calcite spherulitic particles were collected from East Kirkton Quarry in Bathgate, Scotland. Their microstructure has been revealed, by using XRD, EDX, SEM and HRTEM, to consist of a low crystallinity core with deposition of multilayer radially oriented calcite microrods. The sur-rounding materials of the spherulites are mainly Ca-free silicates. To understand the formation mechanism of this construction of calcite crystals, biomimetic synthesis of similar spherulites have been carried out by using alginate and stevensite as structure directing agents. It is found that algi-nate is essential for growth of the spherulites, since the spherulites are developed only when they are embedded in the alginate network, a soft matter substrate. Stevensite also plays an important role of adjusting the hardness of the alginate substrate, offering a suitable network for the self-aggregation and self-orientation of the calcite nanocrystals. Possible inter-particle interactions or driving force of the particle aggregation and self-orientation are discussed. Postprint

This work was financially supported by the National Natural Science Foundation of China (21771139), Tianjin Natural Science Foundation (17JCYBJC22800), and the Program for Innovative Research Team in University of Tianjin (TD13-5074). A porous cationic Ag(I) coordination polymer, [Ag(1,2,4,5-p4b)](SbF6) (TJNU-302) with the ligand 1,2,4,5-p4b (1,2,4,5-tetra(pyridin-4-yl)benzene), is reported that shows high sorption capacity (211 mg g–1) and distribution coefficient Kd (5.8 × 105 mL g–1) as well as outstanding selectivity in 500 times excess of CO32– or PO43– anion for perrhenate removal. TJNU-302 can act as a crystalline turn-off sensor for perrhenate upon UV radiation. In this way, a test paper strip for sensing ReO4– could be produced. In water solution, TJNU-302 shows an efficient fluorescence quenching response to ReO4– ion, with the highest quenching percentage (86%) among all reported ReO4– sensors. These results could be elucidated by the bonding properties of single-crystal structures of TJNU-302 before and after perrhenate sorption, as well as density functional theory (DFT) calculations. Postprint

This work was supported by Natural Science Foundation of Tianjin (Grant No. 17JCYBJC22600) and the Fundamental Research Funds for the Central Universities. Computational support was provided by the Beijing Computing Center (BCC). Four types of Ca-Mn oxides, including CaMnO3, CaMn2O4, CaMn3O6 and Ca2Mn3O8, have been prepared and used as supports for Pd nanoparticles. The oxygen activation capacity of these oxides and the catalytic activity of the oxide supported Pd nanocatalysts have been investigated using the aerobic oxidation of 5-hydroxymethyl-2-furfural as a model reaction. It is found that the local coordination environment of lattice oxygen sites plays a crucial role on their redox property and charge transfer ability from Pd nanoparticles to the support. In particular, the Ca-Mn oxide with lower oxygen coordination number, weaker metal-oxygen bonds and tunnel crystal structure, e.g. CaMn2O4, exhibits promoted oxygen activation capacity, and stronger electron transfer ability. Consequently, Pd/CaMn2O4 exhibits the highest catalytic activity among these catalysts, providing a promising yield of 2,5-furandicarboxylic acid. This work may shed light on the future investigation on the design of local structure of active oxygen sites in oxides or oxide supported catalysts for redox reactions. 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 (21571158 and 21771139), Tianjin Natural Science Foundation (17JCYBJC22800), and the Program for Innovative Research Team in University of Tianjin (TD13-5074). A methodology was developed to design superior sorbents of oxoanions. To integrate the high efficiency of chemisorption, selectivity, and recyclability into one sorbent, understanding the nature of oxoanions–sorbent interactions and the structural evolution of the sorbents is essential. Three cationic Ag(I) coordination polymers (CPs) are synthesized for dichromate (Cr2O72–) removal, and three distinct oxoanion-exchange mechanisms are identified, namely, the replacement, breath, and reconstruction processes, depending on the degree of framework distortion induced by the dichromate–CP interactions. The single crystal to single crystal transformation during the oxoanion exchange has been investigated by using single-crystal X-ray diffraction and energy-dispersive X-ray microanalysis. The replacement process, due to a weak chemisorption, shows excellent recyclability at the cost of reduction of efficiency and selectivity of adsorption. The reconstruction process may achieve a high efficiency and selectivity, but it loses recyclability. Due to the formation of a Ag–O(dichromate) bond and the breathing effect of the framework, the sorbent with the breath mechanism shows both superior efficiency and high recyclability in dichromate removal. The study of perrhenate (ReO4–) removal using the same CPs demonstrates that one CP performing the reconstruction process during dichromate removal turns to the breath process in removal of perrhenate anions. These results of mechanism–property correlation provide an insight into improvement of the methodology to fabricate a superior CP sorbent for oxoanion removal. Postprint

H. F. G. and W.Z. thank the EPSRC for a Capital Equipment Grant EP/L017008/1. Light alkenes are important raw materials for the synthesis of polymers and other chemical products. Traditionally they are obtained mainly from steam cracking and catalytic cracking units. However, dehydrogenation or oxidative dehydrogenation (ODH) of alkanes is gaining more importance to produce alkenes directly from natural gas/shale gas. Here we report that Ti3AlC2, a MAX phase, which hitherto had not used in catalysis, efficiently catalyses the ODH of n-butane to butenes and butadiene, 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. Publisher PDF

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

This work was supported by Natural Science Foundation of Tianjin (Grant No. 17JCYBJC22600) and the Fundamental Research Funds for the Central Universities. The aerobic oxidation of alcohols and aldehydes over noble metal catalysts is a critical reaction for the catalytic conversion of carbohydrates into value-added chemicals from biomass. However, to fully understand the reaction mechanism, in particular the role of O2 and the generated active oxygen species in these reactions is still a challenging target. In the present work, the sub-10 nm Pt nanocrystals with cubic (Pt-NCs), octahedral (Pt-NOs) and spherical (Pt-NSs) morphologies were synthesized and used as catalysts in aerobic oxidation of HMF. Through experimental and computational investigations, the facet-dependent O2 conversion pathway and catalytic oxidation performance were discussed. The molecular O2 tends to be dissoci-ated to generate •OH on Pt(100) surface, but prefers to be reduced to •O2- on Pt(111) surface. Moreover, Pt-NCs enclosed by the {100} facets exhibited significantly enhanced catalytic activity than Pt-NOs enclosed by the {111} facets and Pt-NSs, in particular for alcohol oxidation step. Based on the experimental data and density functional theory (DFT) calculations, an active oxygen species promoted dehydrogenation mechanism for aerobic oxidation of HMF was proposed. The dehydrogena-tion of alcohol group is more favourable on the Pt(100) surface with an assistance of •OH, which are the dominant active oxygen species on the Pt(100) surface. We anticipate that this work would provide a new insight into the role of active oxy-gen species in aerobic oxidation of alcohols and aldehydes over noble metal catalysts. 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

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. 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

C.H.M. acknowledges the National Council of Science and Technology, Mexico (Consejo Nacional de Ciencia y Tecnología CONACyT) for financial support (Scholarship 216968). WZ and HFG thank the EPSRC for a Platform grant (EP/K015540/1). Effective dispersion of the active species over the support almost always guarantees high catalytic efficiency. To achieve this high dispersion, favourable interaction of the active species with the support is crucial. We show here that the crystal structure of the titania support determines the interaction and consequently the nature of Ru deposited on the support. Similar crystal structures of RuO2 and rutile titania lead to a good lattice matching and ensure a better interaction, maintaining the initial good dispersion of the active species on the support and leading to better activity and selectivity. This highlights the importance of understanding the physico-chemical processes during catalyst preparation steps. Publisher PDF