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Nanomaterials with cancer‐imaging and therapeutic properties have emerged as the principal focus of nanotheranostics. The past decade has experienced a significant increase in research in the design, formulation, and preclinical and clinical trials of theranostic nanosystems. However, current theranostic nanoformulations have yet to be approved by the FDA for clinical use. Consequently, the present review focuses on the importance of the careful examination of the in vivo preclinical status of specific nanotheranostic materials as a prerequisite for their clinical translation. The scope of coverage is structured according to all of the major organic, inorganic, 2D, and hybrid nanotheranostic materials and their in vivo preclinical status. The therapeutic advantages and limitations of these materials in animal models are considered and the various strategies to enhance the biocompatibility of theranostic nanoparticles are summarized. [ABSTRACT FROM AUTHOR]

Al‐Si3N4 couples were heat‐treated at 850‐1150°C for 250 hours. The thickness of the interacted area was measured by scanning electron microscopy (SEM) and scanning/transmission electron microscopy (TEM/STEM). The interaction rate increases exponentially with inverse temperature, with an activation energy of 194.23 kJ/mol and diffusion pre‐coefficient of 5 × 10−9 m2/s, indicating that the interaction is diffusion‐dependent. As the results showed, the interfacial area is comprised of Al alloy channels, Si precipitates, and AlN grains. Al‐Si transfer through the solid solution (Si3‐xAlxN4‐y) at the interface of Al alloy and β‐Si3N4 grains controls the kinetic of the interaction. When concentration of Al in solid solution exceeds a certain amount, it undergoes a topotactic phase transformation to form Al1‐xSixN1+y (viz., AlN). Next, the Al1‐xSixN1+y grains detach from the β‐Si3N4 grains and subsequently new Al‐Si3N4 interfaces are established. These interfaces repeat the interaction process, continuing until all the reactant is depleted. Thus, the interaction kinetics consist of a sequence of associated parabolic stages, precluding the observation of parabolic kinetics. [ABSTRACT FROM AUTHOR]

Since there is increasing concern for the impact of air quality on human health, the present work surveys the materials and technologies for air purification using photocatalytic materials. The coverage includes (1) current photocatalytic materials for the decomposition of chemical contaminants and disinfection of pathogens present in air and (2) photocatalytic air purification systems that are used currently and under development. The present work focuses on five main themes. First, the mechanisms of photodegradation and photodisinfection are explained. Second, system designs for photocatalytic air purification are surveyed. Third, the photocatalytic materials used for air purification and their characteristics are considered, including both conventional and more recently developed photocatalysts. Fourth, the methods used to fabricate these materials are discussed. Fifth, the most significant coverage is devoted to materials design strategies aimed at improving the performance of photocatalysts for air purification. The review concludes with a brief consideration of promising future directions for materials research in photocatalysis. [ABSTRACT FROM AUTHOR]

The present work reports the SEM, EPMA and TEM examination of reactions at the interface of Al7075 alloy and a 50/50 wt% mixture of BaAl2Si2O8 + CaAl2Si2O8feldspars at 850 °C, 1150 °C and 1250 °C. Sintering of the feldspar mixture at 1450 °C caused dissolution of ~1.0 wt% Ca in BaAl2Si2O8and 0.5 wt% Ba in CaAl2Si2O8. The interaction of the Al alloy with the sintered feldspars shifted the alloy composition to the Al–Si–αBaAl2Si2and Al–Si–βaAl2Si2compatibility triangles. The feldspars underwent a series of phase transformations, leading ultimately to the formation of Al2O3. [ABSTRACT FROM AUTHOR]

Anatase thin films were prepared by sol-gel, spin coated on glass, and annealed (450 °C/2 h). The effects of cobalt and vanadium doping (0.05–1.00 mol%) on the mineralogical (GAXRD, Raman), nanostructural (AFM), optical (UV-Vis), and chemical (XPS) properties were considered. A new perspective of the role of ionic size effects on substitutional (Co 2+ ) and interstitial (V 3+ ) solid solubility in the elongated TiO 6 octahedron and the consequent roles of lattice deformation and charge compensation is presented. The role of intervalence charge transfer (transient, permanent) and the effects of electronegativity and electron affinity on the presence and absence of ions of different valence states also are considered, explaining the detection of nonequilibrium V 4+ and the nondetection of Ti 3+ . The data are interpreted according to a model for nanostructural evolution during annealing, which allows interpretation of the film thickness and roughness, grain and crystallite sizes, and band gap as a function of dopant concentration. The detection of high levels of contamination from the glass substrates, which decreased during aqueous methylene blue (MB) testing (≤24 h), indicates the likelihood of mass transport by grain boundary diffusion of these ions (Na + , Mg 2+ , Ca 2+ , Si 4+ ). This leaching impacted on the loss of dopant ions precipitated on the grain surfaces following the achievement of saturation solubility, as suggested by the calculation of the relevant speciation and Pourbaix diagrams. The photocatalytic performance by MB testing revealed that Co (precipitated) had a deleterious effect at all levels while V (dissolved) showed slight improvements over undoped TiO 2 at most levels. [ABSTRACT FROM AUTHOR]

The present work reports an investigation of the interactions of Al 7075 alloy and anorthite at 850°C (150 h) and 1150°C (24 h). Transmission electron microscopy, electron probe microanalysis, X-ray diffraction, and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to identify the mineralogical and microstructural changes at the metal-ceramic interface. At 850°C, the phase formation mechanisms were (a) Si4+-Al3+ interdiffusion between the Al alloy and anorthite to form calcium dialuminate ( CA2) and Ca2+-Mg2+ interdiffusion between the Al alloy and calcium dialuminate to form spinel. At 1150°C, spinel + Al2O3 and calcium hexaluminate ( CA6) + CA2 were the major and minor phase mixtures, respectively in the corroded area. A thin layer of calcium monoaluminate ( CA), gehlenite, and Si was present in the immediate vicinity of anorthite. The early stages of corrosion at 1150°C and 850°C were identical. However, due to thickening of the corroded region ( viz., spinel formation) and enhanced evaporation of Mg at the higher temperature, the interdiffusion path evolves from Si4+-Al3+ + Ca2+-Mg2+ to Si4+-Al3+ + Ca2+-Al3+, thus establishing the following phase evolution path at the interface: [ABSTRACT FROM AUTHOR]

Transparent TiO films (~50-540 nm thick) were spin-coated in multiple cycles by sol-gel on soda-lime-silica glass and annealed at 450 °C for 2 h. Analyses included mineralogy (XRD), optics (UV-Vis), chemistry (XPS), microstructure and topography (SEM, AFM), and hydrophilicity (sessile drop). The microstructures were discontinuous (1 cycle), continuous (4-11 cycles), and damaged (13-15 cycles), with the highest quality films being those fabricated using 7-11 cycles. The thickest films were damaged as a result of shrinkage during annealing, which may have occurred from a two-stage process of dehydroxylation followed by pyrolysis. The single-crystal grain sizes were ~27 nm for the films and the roughness increased with increasing thickness. The hydrophilicity showed clear correlations with the roughness and surprisingly, not with the Ti, -OH, and Na contents. The role of the glass also was critical to the absorption/transmission of radiation as well as the wetting. That is, the discontinuous and damaged films showed high wetting angles and the continuous films showed low wetting angles. Correlation was observed between the amounts of different contaminants from glass and the free energies of formation for TiO to TiO under the influence of these contaminants. This relation was attributed to the driving force for oxide bond formation, where the only slightly negative free energy of reaction with Na allowed its relatively free diffusion through the microstructure until it achieved saturation solubility, although all of the main glass components effectively achieved saturation solubility under the modest kinetics of equilibration that were used. [ABSTRACT FROM AUTHOR]

Co- and V-codoped TiO 2 thin films were prepared by sol–gel, spin coated on glass substrates, and annealed at 450 °C for 2 h. The data suggest substitutional solid solution formation in the anatase films. Macroscopic roughening at the highest dopant levels was attributed to oversaturation, precipitation, and grain boundary pinning. Methylene blue decomposition correlated directly with the grain size and this was attributed to the associated changes in surface area and number of active sites as well as partial amorphisation. X-ray photoelectron spectroscopy data revealed the presence of Ti 4+ , Co 2+ , possibly Co 3+ , V 3+ , and V 4+ , where the three clearly detected dopant valences were present as thermodynamically non-equilibrium valences under the annealing conditions used. The present work introduces the concept of intervalence charge transfer to explain the presence of these non-equilibrium species. The present work also considers briefly the potential roles of crystal field stabilization and defect equilibria relative to intervalence charge transfer. [ABSTRACT FROM AUTHOR]

A corrosion cup test was undertaken using BaAl2Si2O8 and Al4.1Zn3.2Mg alloy, heated in air for 150 h at 850°C. Electron probe microanalysis, X-ray diffraction, and scanning electron microscopy coupled with energy dispersive spectroscopy were used to identify the mineralogical and microstructural changes at the interfaces. The microstructural results revealed three microstructural areas: (1) Spinel layer with large numbers of Al alloy channels; (2) interfacial area with mainly alumina, spinel, and BaAl2Si2O8; and (3) interdiffusion zone chemically close to barium hexaaluminate. The principal observations are: BaAl2Si2O8 was highly resistant to molten Al alloy corrosion owing to sluggish kinetics, as evidenced by the observation of unreacted BaAl2Si2O8 grains in the interfacial area., The nature of the microstructure, particularly an interdiffusion zone instead of a continuous layer of precipitated alumina at the interface between the Al alloy channels and the unreacted BaAl2Si2O8 supports the conclusion that the corrosion mechanism is governed by interdiffusion (Si/Ba and Al/Mg) and substitution., The formation and limited retention of an MgO layer at the metal-ceramic interface played a critical role in alloy oxidation and the consequent interfacial phenomena. [ABSTRACT FROM AUTHOR]

CeO 2 films doped with 0–9 mol% Ga/Mn were fabricated by spin coating on 3D-printed Ti6Al4V, calcined at 650 °C for 2 h, and characterised by TEM, FESEM, 3D laser scanning confocal microscopy, GAXRD, and XPS. The results depend on the roles of several factors: (1) Sol-gel precursor viscosity affected pore filling and surface coverage. (2) Lattice contraction and resultant intervalence charge transfer increased the Ce3+ concentration as a minority effect. (3) Substitutional solid solubility and associated redox charge compensation controlled the defect equilibria, which highlight the majority role of this solid solubility mechanism in decreasing the Ce3+ concentration. (4) Electronegativity played a negligible role in affecting the valences but was important in initiating intervalence charge transfer. (5) Multivalence charge transfer combined electron exchanges between film matrix, dopants, and Ti substrate. The present work provides a foundation to interpret the effects of extrinsic effects from both dopant and substrate on the properties of films. The present work reports the results of Ga and Mn extrinsic doping on CeO 2 thin films deposited on 3D printed Ti6Al6V biomedical-grade substrates, which themselves contaminated the films. The novel outcomes are as follows: • The viscosity of the precursor sol-gel plays in important role in the deposition and resultant dopant distribution. • XPS data with the defect equilibria used in the verification of the mechanisms of solid solubility and charge compensation. • Intervalence and multivalence charge transfer represent secondary charge transfer mechanisms and affect the ionic valences. • Concentration of Ce3+ derives from redox charge compensation, IVCT, and MVCT, none of which generates oxygen vacancies. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates the effects of AlPO4 addition on the corrosion resistance of andalusite LCC refractories. Corrosion tests using the Alcoa cup test (850°C and 1160°C for 150h and 72h, respectively) were conducted to determine the extent of penetration. The addition of AlPO4 was shown to improve the corrosion resistance of the castables in contact with molten Al-alloy. SEM/EDS analyses of the interfacial reaction zone showed the formation of corundum in the interfacial layer, along with a significant decrease in the phosphorus content in the interface. Thermodynamic calculations revealed that reaction with the alloy leads to the formation of corundum as the reaction product along with gaseous products (phosphorus trioxide gas) and small amounts of aluminum phosphide. Corundum formation at the interface enhances the corrosion resistance of sample due to high stability of corundum against molten Al alloy, while the metal quality is enhanced due to absence of dissolved phosphorus in the metal. [Copyright &y& Elsevier]

The reduction of FeO-containing slag by blends of metallurgical coke and end-of-life tyres (RT) have been investigated through experiments conducted in a laboratory-scale horizontal tube furnace. Composite pellets of EAF slag (47.1% FeO) with coke, RT, and blends of coke/RT (in four different proportions) were rapidly heated at 1550°C under high purity argon gas and the off gas was continuously analyzed for CO and CO2using an online infrared (IR) gas analyzer. The extent of reduction after 10 min, level of carburization and desulfurization, and the total amount of CO2 emissions were determined for each carbonaceous reductant. The results indicate that the extent of reduction, level of carburization and desulfurization of the reduced metal are significantly improved when coke is blended with RT. Blending of coke with RT resulted in a decrease in direct CO2 emissions from the reduction reactions. [ABSTRACT FROM AUTHOR]

[Display omitted] • ROS elevation in HT-1080 by Ce-based nanoparticle treatment. • H 2 DCFDA-mediated detection of ROS by laser scanning confocal microscopy. • Writing of custom-built MATLAB software for image analysis of ROS fluorescence intensities. • Processing of images for quantification of fluorescence intensities. • Statistical analysis by ANOVA to confirm statistical significance. [ABSTRACT FROM AUTHOR]

Abstract: Interfacial reactions between Al-alloy and andalusite low-cement castables (LCC) containing 5wt% V2O5 were analyzed at 850°C and 1160°C using the Alcoa cup test. Interfacial reaction products and phases formed during heat treatment of the refractory samples were characterized using scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) and X-ray diffraction (XRD) analysis. V2O5 addition resulted in the formation of glassy phases, which significantly improved the corrosion resistance. These phases were preferentially corroded by the alloy, due to their glassy nature. However, vanadium formed from reduction, formed intermetallic alloys (V–Al–Si–Mg), which formed an interfacial physical barrier to further alloy penetration. [Copyright &y& Elsevier]

The performance of high-alumina refractories used for aluminium casting significantly impacts the efficiency of metal production. The interfacial reactions with Al-alloys cause corundum and magnesium spinel deposition on the refractory surface, leading to refractory degradation. An experimental study was conducted to investigate the influence of varying barium sulphate (BaSO) concentrations in a high-alumina refractory on its interfacial reactions with molten Al-alloy in a horizontal tube furnace at 1523 K (1250 °C) under inert conditions. This study showed that the Al-alloy reactions with pure BaSO would form barium aluminates at the interface. However, in the Al-alloy/refractory system, the interfacial behaviour was strongly influenced by the relative amount of BaSO, such that up to 5 wt%, the extent of alloy penetration into the refractory increased with increasing BaSO contents. Electron-probe micro-analyser and X-ray diffraction studies indicated that the composition of the interface for these refractories was augmented with barium silicates and diminishing anorthite phases. In the presence of 10 wt% BaSO, the extent of metal penetration into the refractory decreased, whilst for 20% BaSO, the penetration was higher; these results were attributed to the interfacial presence of celsian (BaAlSiO) and unreacted barium sulphates, respectively. This study suggests that maximising the celsian formation at the interface is critical for optimising the BaSO concentration for improving the refractory's performance for Al-casting. [ABSTRACT FROM AUTHOR]

Fly ash is an aluminosilicate and the major by-product from coal combustion in power stations; its increasing volumes are major economic and environmental concerns, particularly since it is one of the largest mineral resources based on current estimates. Mullite (3Al2O3·2SiO2) is the only stable phase in the Al2O3-SiO2 system and is used in numerous applications owing to its high-temperature chemical and mechanical stabilities. Hence, fly ash offers a potential economical resource for mullite fabrication, which is confirmed by a review of the current literature. This review details the methodologies to utilise fly ash with different additives to fabricate what are described as porous interconnected mullite skeletons or dense mullite bodies of approximately stoichiometric compositions. However, studies of pure fly ash examined only high-Al2O3 forms and none of these works reported long-term, high-temperature, firing shrinkage data for these mullite bodies. In the present work, high-SiO2 fly ashes were used to fabricate percolated mullite, which is demonstrated by the absence of firing shrinkage upon long-term high-temperature soaking. The major glass component of the fly ash provides viscosities suitably high for shape retention but low enough for ionic diffusion and the minor mullite component provides the nucleating agent to grow mullite needles into a direct-bonded, single-crystal, continuous, needle network that prevents high-temperature deformation and isolates the residual glass in the triple points. These attributes confer outstanding long-term dimensional stability at temperatures exceeding 1500 °C, which is unprecedented for mullite-based compositions. [ABSTRACT FROM AUTHOR]

The present work analyses the effects of curing temperature (25, 40, 60 °C for 24 h), silicate modulus Ms value (1.5, 1.7, 2.0), and slag content (10, 20, 30, 40 wt%) on the compressive strength development (1, 7, 14, 28 days) of low-alkali geopolymer mortars with matrices from fly ash and blast furnace slag. These data were used to generate predictive models for 28-day compressive strength as a function of curing temperature and slag content. While the dominant variable for the 1-day compressive strength was the curing temperature, the slag content was dominant for the 28-day compressive strength. The ratio of the 1-day and 28-day compressive strengths as a function of curing temperature, Ms value, and slag content allows prediction of the maximal possible curing temperature and shows cold-weather casting to present an obstacle to setting. These data also allow prediction of the 28-day compressive strength using only the 1-day compressive strength. [ABSTRACT FROM AUTHOR]

The present work applies a focal point of materials-related issues to review the major case studies of electron transport layers (ETLs) of metal halide perovskite solar cells (PSCs) that contain graphene-based materials (GBMs), including graphene (GR), graphene oxide (GO), reduced graphene oxide (RGO), and graphene quantum dots (GQDs). The coverage includes the principal components of ETLs, which are compact and mesoporous TiO2, SnO2, ZnO and the fullerene derivative PCBM. Basic considerations of solar cell design are provided and the effects of the different ETL materials on the power conversion efficiency (PCE) have been surveyed. The strategy of adding GBMs is based on a range of phenomenological outcomes, including enhanced electron transport, enhanced current density-voltage (J-V) characteristics and parameters, potential for band gap (Eg) tuning, and enhanced device stability (chemical and environmental). These characteristics are made complicated by the variable effects of GBM size, amount, morphology, and distribution on the nanostructure, the resultant performance, and the associated effects on the potential for charge recombination. A further complication is the uncertain nature of the interfaces between the ETL and perovskite as well as between phases within the ETL. [ABSTRACT FROM AUTHOR]

The effects of curing temperature, blast furnace slag content, and Ms on the initial and final setting times, and compressive strengths of geopolymer paste and mortars are examined. The present work demonstrates that ambient-cured geopolymer pastes and mortars can be fabricated without requiring high alkalinity activators or thermal curing, provided that the ratios of Class F fly ash (40–90 wt%), blast furnace slag (10–60 wt%), and low alkalinity sodium silicate (Ms = 1.5, 1.7, 2.0) are appropriately balanced. Eighteen mix designs were assessed against the criteria for setting time and compressive strength according to ASTM C150 and AS 3972. Using these data, flexible and reproducible mix designs in terms of the fly ash/slag ratio and Ms were mapped and categorised. The optimal mix designs are 30–40 wt% slag with silicate modulus (Ms) = 1.5–1.7. These data were used to generate predictive models for initial and final setting times and for ultimate curing times and ultimate compressive strengths. These projected data indicate that compressive strengths >100 MPa can be achieved after ambient curing for >56 days of mixes of ≥40 wt% slag. [ABSTRACT FROM AUTHOR]

The lead-free piezoelectric material sodium bismuth titanate (NBT, Na 0.5 Bi 0.5 TiO 3) has attracted considerable attention owing to its promising dielectric, piezoelectric, and electrical properties. However, the literature on the binary subsystems is contradictory and there are only limited data for the ternary system. The present work surveys all of the reports of the binary subsystems Bi 2 O 3 – TiO 2 and Na 2 O – TiO 2 and synthesizes these data into inclusive revised versions. The compatibilities for the ternary system Na 2 O – Bi 2 O 3 – TiO 2 were determined experimentally, thus enabling the construction of a complete isothermal section at 800 °C. The compatibilities associated with the problematic binary subsystem Na 2 O – Bi 2 O 3 , which experiences extreme volatilisation, were determined through the generation of the absent standard-state thermodynamic functions for the relevant binary and ternary phases, thus providing a full suite of thermodynamic data for this system. The thermodynamic stability diagrams for Na 2 O, Bi 2 O 3 , and TiO 2 thus were calculated. The isothermal section also addresses the contradictions in the literature concerning the formation of solid solutions of Bi 12 TiO 20-x / Bi 12-x Ti 1+x O 20+0.5x , pyrochlore (Bi 2 Ti 2 O 7 / Na w Bi 2-x Ti 2-y O 7-z), BTO (Bi 4 Ti 3 O 12 / Na x Bi 4 Ti 3 O 12+0.5x), and NBT (Na 0.5 Bi 0.5 TiO 3 / Bi 1±x Na x TiO 3.5±x). Further, it was observed that the congruent melting point of NBT, which was determined to be 1225 °C, was preceded by the onset of gradual structural destabilization at 940 °C. Also, the NBT rhombohedral → tetragonal phase transformation was observed at an onset temperature of ∼250 °C. The present work thus provides platform data for the fabrication and reactivities of materials in the ternary system Na 2 O – Bi 2 O 3 · TiO 2 and its binary subsystems. [ABSTRACT FROM AUTHOR]

Synroc, a candidate nuclear wasteform and Synroc technology, a waste treatment solution utilizing hot‐isostatic pressing (HIPing) have significant potential for the immobilisation of challenging nuclear wastes from both current and innovative reactors and fuel cycles. Hot isostatic press (HIP) consolidation is undertaken within sealed metal HIP canisters, where metal buffers (e.g., Ti, Fe and Ni) can be incorporated to control the redox environment within the canister. This study, for the first time, reports the effect of varying Ti‐metal addition (0, 2, 4, and 8 wt.%) on phase formation, microstructural characteristics, and wasteform performance for HIP consolidated Synroc‐C containing 20 wt.% simulated PUREX type (PW‐4b) high level waste. Quantitative X‐ray diffraction analysis, scanning electron microscopy‐energy dispersive X‐ray spectroscopy (EDS) and transmission electron microscopy‐EDS analyses were undertaken for analytical investigations. The chemical durability of the samples was assessed using ASTM C1220‐21 standard test. Hot‐isostatically pressed (HIPed) samples with 0 and 8 wt.% Ti added for redox control produced unfavourable phase formation. However, the HIPed samples with Ti additions of 2 and 4 wt.% as a redox buffer showed the desired phase formation of Synroc‐C without any significant change to the partitioning of waste elements among the phases along with compatible durability results, when compared to previous literature for hot uniaxial pressing (HUPed) or sintered materials. [ABSTRACT FROM AUTHOR]

Mo-doped TiO2 [≤ 0.20 wt% Mo; ≤ 0.10 mol% (metal basis)] with conjugated polyvinyl alcohol (TiO2/C-PVA) composite thin films was prepared by sol-gel dip coating on polished fused SiO2 substrates, followed by annealing at 180 °C for 4 h. These conditions were sufficient for solid solubility, despite the unusually low annealing temperature. The annealed thin films consisted of homogeneously distributed individual and slightly agglomerated anatase grains in a continuous C-PVA matrix characterized by the carbon double bond formed upon conjugation. The films exhibited drying shrinkage cracks, which increased consistently in extent with increasing Mo-doping concentration, effectively increasing the number of exposed TiO2 particles. Mo addition enhanced anatase nucleation, recrystallization, and growth at lower doping concentrations (up to ≤ 0.10 wt%), thereby increasing crystallinity. However, increasing doping levels (> 0.10 wt%) appeared to exceed the solubility limit, resulting in supersaturation and significant lattice destabilization. Mo-doping also caused the Ti2p XPS peaks to shift to lower binding energies and the Mo3d peaks to shift to higher binding energies. These data are consistent with thermodynamically unstable Ti4+ → Ti3+ conversion and thermodynamically stable Mo5+ → Mo6+ conversion, which are interpreted in terms of intervalence charge transfer (IVCT), in which charge compensation is achieved through majority Ti4+ → Ti3+ reduction plus Mo5+ → Mo6+ oxidation. Ti3+ concentration also reflects a direct correlation with the Mo-doping concentration and resultant IVCT within the Mo solubility limit and a reverse effect upon supersaturation. There is a correlation with the Eg but this can be attributed to recrystallization rather than a semiconducting effect. No effect of midgap state formation from enhancement of the VO·· concentration is expected because IVCT is a redox effect only and dissolution of Mo5+ or Mo6+ would generate Ti vacancies. The methylene blue dye degradation data exhibited the same trend but at a significant level (90.6% degradation), thus indicating that the mechanism dominating the photocatalytic performance is the recrystallization of the anatase and/or the modification of the semiconducting properties induced by Mo-doping, as indicated by the trends in band gap. [ABSTRACT FROM AUTHOR]

Indium tin oxide (ITO) coatings have been proposed to reduce thermal emission losses for solar thermal applications. Unfortunately, ITO also has a large amount of free charge carriers (∼1 × 1020 per cm3), which absorb sunlight. To address this issue, we propose a nano-patterned ITO-coated quartz exhibiting both anti-reflectivity (to maximize solar transmission) and low emissivity (to minimize long wavelengths radiative losses). A record small-size nanosphere (∼60 nm) etch mask was prepared via double self-assembly, followed by dry etching and characterisation. In parallel, alternative nanopattern geometries were modelled using the Lumerical FDTD software to optimise short wavelength transmission without diminishing the inherently low emissivity of unetched ITO. It was found that an inverted moth's eye pattern (height = 250 nm and spacing = 80 nm) gave the best results at various solar concentrations (1 sun @ 100 °C, 10 suns @ 400 °C, and 100 suns @ 600 °C), resulting in ∼7% improvement in the solar weighted transmission as well as a similar boost in the overall efficiency factor for selectivity. It was concluded that if the proposed deposition/etching processes can be cost-effectively scaled in a continuous process, it would provide a net performance boost for most solar thermal technologies. [Display omitted] [ABSTRACT FROM AUTHOR]

The present work provides guidelines for the engineering of oxygen vacancy concentrations using morphology-maps based on the characteristics of nanoceria (CeO2−x) nanocubes, nanorods, and truncated nanooctahedra. These were characterised by XRD, TEM, BET, DLS, and XPS. The morphology maps reveal that the redox performance, particle size, and surface roughness (apparent porosity) can be optimised by engineering the oxygen vacancy concentrations, but the morphology is dominated by the reaction temperature. However, the oxygen vacancy concentration is controlled by the concentration of the NaOH precipitant/oxidant. These vacancies can be potentially located at the surface, subsurface, and bulk regions, but the subsurface vacancies provide the principal redox activity. The biological effects of nanoceria in terms of oxygen vacancies were analysed in normal and cancer cells. Nanoceria particles exhibit antioxidant and cytoprotective effects at physiological pH 7.4 but prooxidant and cytotoxic effects at tumour microenvironment pH 6.4. The relative redox performances and cytotoxicities are in the order nanocubes ＜ nanorods ＜ truncated nanooctahedra, which is a direct reflection of the relative oxygen vacancy concentrations. The redox performance of nanoceria has been contextualised by cellular uptake and its quantification in osteosarcoma cells. [ABSTRACT FROM AUTHOR]

TiO 2 thin films of varying Co and Mo individual doping levels (0.00–1.00 mol% metal basis) were fabricated on soda-lime-silica glass substrates by spin coating, followed by annealing at 450 °C for 2 h. Mineralogical analyses showed that all of the films were comprised only of anatase and suggested that both Co and Mo formed interstitial solid solutions. For the Co-doped films, the variation in anatase XRD peak intensities indicated three discrete stages of structural and nanostructural development: recrystallization (≤0.05 mol% Co), lattice distortion (0.05–0.60 mol% Co), and precipitation (≥0.60 mol% Co). For the Mo-doped films, Mo consistently enhanced nucleation, recrystallization, and lattice distortion within the solubility limit, which was not reached at 1.00 mol% Mo. Chemical analyses showed that Ti 4+ /Ti 3+ , Co 3+ /Co 2+ , and Mo 5+ /Mo 4+ (and possibly Mo 6+ ) were present in the films. The formation of non-equilibrium valences was considered in terms of the effects of crystal field stabilization energy (CFSE), intervalence charge transfer (IVCT), and electronegativity. Nanostructural analyses of the Co-doped films showed that, with increasing doping level, the grain size increased at the lowest level, followed by a decrease owing to changes in the structure (lattice destabilization) and nanostructure (localized liquid formation). In contrast, the grain size of the Mo-doped films increased with increasing doping level due to the maintenance of solid solubility, defect formation (and associated enhanced nucleation and recrystallization), and grain growth. Defect formation and charge compensation resulted in lattice contraction, which was confirmed by laser Raman microspectroscopy and resultant destabilization. Optical analyses showed that all of the thin films were flat, smooth, and nanostructurally homogeneous. The band gap data suggested that the governing effect derived from the lattice distortion associated with the lattice incorporation of both dopants. Photocatalytic testing showed that the lowest level of doping for both dopants (0.01 mol%) yielded maximal photocatalytic activity and that the performance decreased with increasing doping levels. This was attributed to the effects of nucleation and recrystallization, semiconducting effect, dopant size effect, and minimal lattice distortion. [ABSTRACT FROM AUTHOR]

Flat TiO 2 thin films were dip coated on contact lens polymer substrates (fluorinated ethylene propylene copolymer, FEP) using a hybrid sol-gel and annealed for 12 h at ≤200 °C. The grain sizes were in the range 10–20 nm but extensive shrinkage cracking was present. The crystallinities of the films annealed at ≤150 °C increased with increasing temperature gradually but only to a limited extent, although the crystallinity at 200 °C was significant. Recrystallisation resulted in decreased transparency, increased reflectivity, and a red shift to lower band gap. The methylene blue (MB) degradation was in the order 25 °C < 200 °C < 100 °C < 150 °C, indicating that the photocatalytic performance was dominated by crystallinity and exposed surface area, the latter of which decreased at 200 °C owing to partial submergence in the softened polymeric substrate. The films indicated antimicrobial capacity since they exhibited a maximal level of S. aureus destruction (85%) following 5 h of UV irradiation. The films also appeared to be microstructurally stable following wash testing in contact lens washing solution. [ABSTRACT FROM AUTHOR]

The properties of mullite-glass and mullite-mullite interfaces have been investigated at 1800 K by molecular dynamics ( MD) simulation and high-resolution TEM. The simulation showed that mullite-glass interfaces typically have much lower interfacial energies than mullite-mullite interfaces, which results from the structural flexibility of the glass and associated accommodation of interfacial mismatch. The (110)-glass interface has the lowest energy of all interfaces studied, which is consistent with the observed dominance of this interface in experimental mullite-glass samples examined by TEM. The simulation shows that the interfacial energies of the (100)-glass and (010)-glass interfaces are higher than that those of the (001)-glass interface, so [100] and [010] would be expected to be the dominant growth directions. However, the growth of mullite in glass occurs predominantly in the [001] direction. This apparent discrepancy can be explained by the fact that growth in the [100] and [010] directions is limited by the slow growth of (110) plane (i.e., [110] direction), which facilitates [001] growth, which is confirmed by the TEM data. [ABSTRACT FROM AUTHOR]

Ce-doped TiO 2 thin films were prepared by sol-gel, spin coated on glass substrates, and annealed at 450 °C for 2 h. Solid solubility of Ce in anatase at the lowest doping level (≤0.25 mol% Ce) generated point defects that enhanced nucleation and recrystallization, resulting in relatively uniform grain sizes. In contrast, at ≥0.50 mol% Ce, overdoping, precipitation at grain boundaries, and liquid formation resulted in bimodal nanostructures with decreasing sizes of both the matrix grains and agglomerates owing to the progressive hindrance of Ti diffusion. The optimal photocatalytic performance at 0.25 mol% Ce was associated with a less densely packed array of fine matrix grains, while the performance at higher doping levels was dominated by liquid formation, greater packing densities, and blockage of active sites. The occurrence of Ce ↔ Ti intervalence charge transfer and associated oxygen vacancy formation are likely causes for the observed lowering of the band gap, reduction in the recombination rate, and enhancement of radiation absorption at longer wavelengths (red shift). [ABSTRACT FROM AUTHOR]

[Display omitted] • Superior results are found when conventional therapeutic approaches are combined with inorganic nanoparticle (INP) strategies. • INPs possess intrinsic anticancer and gene silencing properties, which make them advantageous in cancer therapy when used in combination with other agents. • INPs are highly customized, safe and effective RNA delivery vehicles that overcome the challenges associated with employing RNA as a therapeutic candidate owing to concerns about in vivo stability. • Signaling pathway targeting is challenging, hence a more efficient strategy is required. • Efficient delivery carriers, such as INP, are necessary to increase the selectivity of target CSCs or CSC signaling pathways. Inorganic nanoparticles for drug delivery in cancer treatment offer many potential advantages because they can maximize therapeutic effect through targeting ligands while minimizing off-target side-effects through drug adsorption and infiltration. Although inorganic nanoparticles were introduced as drug carriers, they have emerged as having the capacity for combined therapeutic capabilities, including anticancer effects through cytotoxicity, suppression of oncogenes and cancer cell signaling pathway inhibition. The most promising advanced strategies for cancer therapy are as synergistic platforms for RNA interference (siRNA, miRNA, shRNA) and as synergistic drug delivery agents for the inhibition of cancer cell signaling pathways. The present work summarizes relevant current work, the promise of which is suggested by a projected compound annual growth rate of ∼ 20% for drug delivery alone. [ABSTRACT FROM AUTHOR]

In nature, snowflake ice crystals arrange themselves into diverse symmetrical six-sided structures. We show an analogy of this when zinc (Zn) dissolves and crystallizes in liquid gallium (Ga). The lowmelting-temperature Ga is used as a “metallic solvent” to synthesize a range of flake-like Zn crystals. We extract these metallic crystals from the liquid metal solvent by reducing its surface tension using a combination of electrocapillary modulation and vacuum filtration. The liquid metal–grown crystals feature high morphological diversity and persistent symmetry. The concept is expanded to other single and binary metal solutes and Ga-based solvents, with the growth mechanisms elucidated through ab initio simulation of interfacial stability. This strategy offers general routes for creating highly crystalline, shape-controlled metallic or multimetallic fine structures from liquid metal solvents. [ABSTRACT FROM AUTHOR]

Polyvinyl alcohols (PVAs) are used commonly in polymer-modified mortars to manipulate their properties. The present work reports the kinetics of hydration of off-white Portland cement pastes modified by PVA (PVA/cement = 0.5 mass%) as a function of the degree of hydrolysis ( DH) and the degree of polymerisation ( DP). To this end, the hydrolysis of PVAs in extracted cement pore water and in cement paste was analysed using titration method, the heat flow from the hydration of unmodified and PVA-modified cement pastes were monitored over the first 24 h following mixing using isothermal calorimetry, and the Ca(OH) (CH) contents of these cement pastes were calculated from thermogravimetric analysis. The results show that PVAs underwent near-complete hydrolysis within the first hour following the mixing of the aqueous PVA solution with cement, i.e., the original PVA was present in the pore solution as fully hydrolysed PVA chains and released acetate groups. Addition of PVA retarded the hydration of CS to form C-S-H and CH and also the hydration reaction of CA and gypsum to form ettringite; however, the addition of PVA had no effect on the formation of monosulphate except for the case of samples with high DP and fully hydrolysed PVA was added which resulted in the accelerated formation of monosulphate. The DH and DP of PVA have an important effect on the hydration of Portland cement. The effects of DH resulted from the variations in the amounts of fully hydrolysed PVA and the released acetate groups. [ABSTRACT FROM AUTHOR]

Partially hydrolysed polyvinyl alcohols (PVAs) are used commonly in polymer-modified mortars to manipulate their properties. These PVAs undergo hydrolysis in wet cement which results in the release of acetate groups into the pore water. To evaluate their contribution to cement hydration, the present work investigates the impact of acetic acid on the early hydration of off-white Portland cement using glacial acetic acid concentrations of up to 0.20 mass% (cement basis). To this end, the heat flow of the hydration of unmodified and acetic acid-modified cement pastes was monitored over the first 24 h following mixing using isothermal calorimetry, and the mineralogical compositions of these cement pastes were determined using quantitative X-ray diffraction analysis. Acetic acid addition showed a mixed effect. The slow reaction period was extended; in the acceleration period, the hydration of CS to form calcium silicate hydrate (C-S-H) and Ca(OH) (CH) and the hydration reaction of CA and gypsum to form ettringite were retarded; in the deceleration period, the exsolution of CaSO and renewed formation of ettringite were delayed, while the formation of monosulphate was accelerated. These effects were enhanced with increasing acetic acid concentration up to a surface adsorption acetate saturation level that could be identified from the curves of heat flow. [ABSTRACT FROM AUTHOR]

The corrosion of duplex stainless steel 2205 was investigated both under service conditions and via an electrochemical study in chlorinated media. The steel sample surfaces showed pitting, crevice and selective dissolution, with the ferrite phase being more susceptible to dissolution in this media. The dissolution of MnS was identified to be a contributing factor for pitting corrosion, while electrochemical investigations revealed that the presence of hypochlorite ions caused a switching from a general corrosion phenomenon to a localized one. [ABSTRACT FROM AUTHOR]

• Hollandite wasteform fabricated by HIP to immobilise Cs/Sr separated waste. • Phase formation and microstructures were identified at the interaction zone. • Hollandite incorporated minor HIP-canister chemistry at the interaction zone. • No deleterious phases were observed that would reduce wasteform performance. A potential hollandite wasteform for immobilising waste containing Cs, Ba, Sr, and Rb, projected from a solvent extraction process that separates Cs/Sr from spent nuclear fuel, was fabricated via hot isostatic pressing (HIPing) within a stainless-steel (SS) canister at 1250 °C / 30 MPa / 2 h. Before HIPing, 2 wt.% Ti metal was added to the precursor, as a redox control additive. Detailed elemental profiling and microstructural analysis at the interaction zone between the wasteform and the SS HIP canister were thoroughly investigated with transmission electron microscopy (TEM) using a lamella extracted by focused ion beam (FIB) milling, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The interaction zone towards the wasteform was ∼20–30 µm in distance and in this region, a hollandite composition with varying chemistry was observed relative to the bulk wasteform. Moreover, the regular Cr-oxide layer, often observed previously for HIPed Synroc-type materials, was not present due to the achievement of reducing condition by adding Ti-metal as redox additive and simultaneous diffusion of canister material towards the ceramic. Predominant Cr-diffusion was observed with incorporation in the hollandite phase along with minor Fe, Mn and Co from the SS canister. This study provides a detailed understanding of the HIP canister – wasteform interaction zone for a hollandite-rich wasteform design for the first time. Importantly, no deleterious phases were formed that may otherwise reduce the performance of the wasteform. This study further demonstrates the flexibility of HIPing as a consolidation process for the treatment of radioactive wastes. [ABSTRACT FROM AUTHOR]

[Display omitted] The air-solution interface of supersaturated calcium hydrogen carbonate (Ca(HCO 3) 2) represents the highest saturation state due to evaporation/CO 2 -degassing, where calcite crystals are expected to nucleate and grow along the interface. Hence, it should be possible to form a free-standing mineral-only calcium carbonate (CaCO 3) microfilm at the air-solution interface of Ca(HCO 3) 2. The air-solution interface of phosphate buffered saline (PBS) could represent a phase boundary to introduce a hybrid microstructure of CaCO 3 and carbonate-rich dicalcium hydroxide phosphate (carbonate-rich hydroxylapatite). Supersaturated Ca(HCO 3) 2 was prepared at high pressure and heated to form CaCO 3 microfilms, which were converted to bone-like microfilms at the air-solution interface of PBS by dissolution-recrystallisation. The microfilms were characterised by scanning electron microscopy, 3D confocal microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, laser Raman microspectroscopy, and X-ray photoelectron spectroscopy. An in situ X-ray diffraction (XRD) system that simulates the aforementioned interfacial techniques was developed to elucidate the microfilms formation mechanisms. The CaCO 3 and bone-like microfilms were free-standing, contiguous, and crystalline. The bone-like microfilms exhibited a hybrid structure consisting of a surface layer of remnant calcite and a carbonate-rich hydroxylapatite core of plates. The present work shows that the air-solution interface can be used to introduce hybrid microstructures to mineral microfilms. [ABSTRACT FROM AUTHOR]

Bakelite is a thermoset plastic commonly found in electronic and automobile components. CaCO3 is generally found in the polymer as a filler material. Since it cannot be remelted, the disposal of this material has become an environmental issue. The present study investigates a new route to utilize waste bakelite as a source of carbon in EAF steelmaking process. This paper reports the carbon dissolution behaviour of bakelite/coke blends into liquid steel at 1550 °C. The carbon pick up in the liquid steel after reaction with varying blends of bakelite/coke for 30 minutes ranged between 0.13 wt% to 0.17 wt%; these were generally higher than that observed from coke alone (0.1 wt%). The dissolution rate (K) was also found to improve and the observed trend was BK2 (0.045 × 10−3 s−1) > BK3 (0.023 × 10−3 s−1) > BK1 (0.005 × 10−3 s−1) > coke (0.003 × 10−3 s−1). The reaction products formed at the interface after 30 minutes of contact between liquid steel and bakelite/coke blends were observed to be a CaS-Al2O3 complex. The presence of CaS in the interfacial layer due to the CaO in the ash, lowered melting temperature of the layer, thereby allowing for increased removal of the ash layer and greater carbon pick-up. The CaO is formed from the decomposition of CaCO3, and its presence was found to have a positive effect on modifying the properties of the coke, and thereby enhancing the carbon dissolution behaviour. [ABSTRACT FROM AUTHOR]

Critical catalysis studies often lack elucidation of the mechanistic role of defect equilibria in solid solubility and charge compensation. This approach is applied to interpret the physicochemical properties and catalytic performance of a free‐standing 2D–3D CeO2−x scaffold, which is comprised of holey 2D nanosheets, and its heterojunctions with MoO3−x and RuO2. The band gap alignment and structural defects are engineered using density functional theory (DFT) simulations and atomic characterization. Further, the heterojunctions are used in hydrogen evolution reaction (HER) and catalytic ozonation applications, and the impacts of the metal oxide heteroatoms are analyzed. A key outcome is that the principal regulator of the ozonation performance is not oxygen vacancies but the concentration of Ce3+ and Ce vacancies. Cation vacancy defects are measured to be as high as 8.1 at% for Ru‐CeO2−x. The homogeneous distribution of chemisorbed, Mo‐oxide, heterojunction nanoparticles on the CeO2−x holey nanosheets facilitates intervalence charge transfer, resulting in the dominant effect and resultant ≈50% decrease in overpotential for HER. The heterojunctions are tested for aqueous‐catalytic ozonation of salicylic acid, revealing excellent catalytic performance from Mo doping despite the adverse impact of Ce vacancies. The present study highlights the use of defect engineering to leverage experimental and DFT results for band alignment. [ABSTRACT FROM AUTHOR]

Uniformly codoped anatase TiO 2 thin films of varying (equal) Mo and Cr concentrations (≤1.00 mol% for each dopant) were fabricated using sol-gel spin coating and deposited on fused silica substrates. All films were annealed at 450 °C for 2 h to recrystallise anatase. Undoped anatase films have been subjected to dual ion implantation for the first time, using Mo, Cr, and sequential Mo + Cr at 1 × 1014 atoms/cm2. The films were characterised by GAXRD, AFM, SIMS, XPS, and UV–Vis and the performance was assessed by dye degradation. Despite the volumetric doping by sol-gel and the directional doping by ion implantation, neither method resulted in homogeneous dopant distributions. Both methods caused decreasing crystallinities and associated partial amorphisation. The XPS signal of the uniformly codoped films is dominated by undissolved dopant ions, which is not the case for the ion-implanted films. Increasing Ti valences are attributed to the fully oxidised condition of the Ti4+ ions that diffuse to the surface from Ti vacancy formation compared to the Ti valence of the bulk lattice, which contains Ti3+. Increasing O valence is attributed to the electronegativity of O2−, which is higher than that of Ti4+. Detailed structural mechanisms for the solubility and energetics mechanisms involve the initial formation of Mo and Cr interstitials that fill the two voids adjacent to the central Ti ion in the TiO 6 octahedron, followed by integrated solid solubility (ISS) and intervalence/multivalence charge transfer (IVCT/MVCT). The sequential order of the last two is reversed for the two different doping methods. These two effects are likely to be the source of synergy, if any, between the two dopant ions. The photocatalytic performances of the uniformly codoped films are relatively poor and correlate well with the band gap (E g). The performances of the ion - implanted films do not correlate with the E g , where TiO 2 –Mo performs poorly but TiO 2 –Cr and TiO 2 –Mo–Cr outperform the undoped film. These results are interpreted in terms of the competition between the effects of Mo doping, which causes partial amorphisation and/or blockage of active sites, and Cr doping, which may cause Mo–Cr synergism, Cr-based heterojunction formation, and/or improved charge-carrier separation owing to the surface-deposition nature of ion implantation. •Mo-Cr synergism responsible for improved catalytic behaviour of implanted films. •Mo implantation caused blockage of active sites. •Cr implantation formed heterojunction and improved charge-carrier separation. •Mo-Cr codoped films showed lower performance from band gap increase. •Structural models explained varying dopant solubility scenarios. [ABSTRACT FROM AUTHOR]

It has been demonstrated in previous experimental and computational work that doping CeO 2 with transition metals is an effective way of tuning its properties. However, each previous study on CeO 2 doping has been limited to a single or a few dopants, making it difficult to establish a definitive strategy to modify the properties of CeO 2 through doping. In this paper, we systematically study the formation energies, structural stability and electronic properties of CeO 2 doped with the entire range of the ten 3d transition metals using density functional theory (DFT) calculations at the hybrid level. Particularly, the formation energies of oxygen vacancies, and their effects on electronic properties, are also considered. These results could provide a meaningful guide for the design of CeO 2 -based materials with improved visible-light photocatalytic and catalytic performance. [Display omitted] • Formation energies, structural stability and electronic properties of CeO 2 doped with the entire range of the ten 3 d transition metals have been systematically studied by DFT at the hybrid level. • Most of the 3d TMs can potentially increase the oxygen vacancy concentration compared with undoped CeO2 by decreasing the vacancy formation energy. • Most of the 3d TMs can increase visible-light absorption of CeO2 by introducing mid-gap states. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) are a new type of ultra-high surface area porous materials with applications in catalysis, energy storage, and gas adsorption. Compared to other MOFs, Zirconium-based MOFs (Zr-MOFs) demonstrate improved stability due to strong bonds between tetravalent zirconium and carboxylate ligands, making them applicable in real world conditions. This study aims to investigate optimal synthesis conditions for the solvothermal fabrication of Zr-MOFs by looking at two promising tetratopic ligand-based MOFs, Zr-TCPP and Zr-TPTC. By systematically investigating the impact of synthesis parameters on yield, crystallinity, and morphological characteristics, both general and specific trends were determined. The present work demonstrated that the ideal reactant ratio was twice the actual Zr:ligand ratio in the final structure. Stronger acid modulators were found to produce more crystalline samples for MOFs with flexible ligands (Zr-TPTC), where formic acid use resulted in more crystalline samples compared to acetic acid; however, this lowered the yield. The effect of temperature on yield was non-linearly dependent on the reactant ratio used for synthesising flexible Zr-TPTC. For MOFs with rigid ligands (Zr-TCPP), increasing synthesis temperature did not affect yield but decreased crystallite size and improved phase selectivity. Stability tests in water and acid were performed on both MOFs to assess the effect on crystallinity and morphology and the results showed expected trends for Zr-MOFs. The optimized synthesis parameters for Zr-TCPP resulted in a superior method of producing PCN-222 with higher yield and crystallinity. On the other hand, a new Zr-TPTC MOF with high yield and crystallinity was synthesised using the optimized parameters. This study thus elucidates the role of synthesis parameters on Zr-MOF properties and yield and furthers the understanding of MOF synthesis mechanisms, expanding the potential for their applicability in industry. • The ideal reactant ratio was twice the actual Zr:ligand ratio found in the MOFs. • Stronger acid modulators produced lower yield and more crystalline samples. • The effect of temperature on yield was non-linearly dependent on the ligand used. • Optimized synthesis of PCN-222 MOF (Zr-TCPP) and a new Zr-TPTC MOF was produced. [ABSTRACT FROM AUTHOR]

TiO 2 coatings were fabricated by anodization of Ti6Al4V in 1 M H 3 PO 4 or H 2 SO 4 , at room temperature at 120 V for 10 min, and followed by annealing at 300° or 500 °C for 8 h. Analyses include mineralogy (GAXRD, Raman), chemistry (XPS), morphology and microstructure (FESEM, FIB, 3D confocal microscopy), thermodynamic, optical (UV–Vis), and photocatalytic performance (MB degradation). The present work highlights factors that govern the nature of the materials and their performance. The influence of the oxidation strength of the acid is pervasive in that it impacts on the crystallinity, microstructural homogeneity, coating thickness, Ti3+ concentration, gas generation during arcing to form pores, and resultant pore size and distribution density. A key observation is that the pores form a subsurface network of variable continuity, which has a significant impact on the surface area and associated density of photocatalytically active sites, access by liquids and gases inside the coating, penetration depth of incident radiation, gas condensation, and residual liquid trapping. These data and the related thermodynamic analyses of the acids, anodization processes, and oxidation processes facilitate the generation of schematic models for the anodization mechanisms and the resultant surface, bulk, and microstructural effects that dominate the photocatalytic performance. [ABSTRACT FROM AUTHOR]

Thin films of anatase codoped with 0.01 mol% Co and 0.01 mol% Mo up to 5.00 mol% Co and 5.00 mol% Mo were fabricated by spin coating on soda-lime-silica glass substrates. The films subsequently were calcined in air at 450 °C for 2 h. The mineralogical, chemical, morphological, topographical, optical, and photocatalytic properties of the films were investigated in order to assess the factors and mechanisms affecting the photocatalytic properties. The analytical techniques included glancing angle X-ray diffraction, X-ray photoelectron spectrometry, atomic force microscopy, UV–Vis spectrophotometry, and methylene blue photodegradation. A key determinant of the data was the solubility limit of the dopants, particularly Co. When this was exceeded (≥0.30 mol%), the formation of undetectable precipitates commenced blockage of the active sites, thereby reducing the photocatalytic performance. The initial precursor cation valences altered from Co2+ and Mo5+ to Co2+/Co3+ and Mo4+/Mo5+ upon interstitial solid solution. The absence of charge-compensating Ti3+/Ti4+ redox indicates that charge compensation for the codoping was by IVCT through the reaction Co2+ + Mo5+ ↔ Co3+ + Mo4+. While the three dominant factors affecting the band gap were crystallinity, grain size, and precipitation, the band gap did not dominate the photocatalytic performance or its kinetics. These were reduced by blockage of the active sites by dopant precipitates and, to a lesser extent, from contamination from the cations from the substrate. These phases were the dominant factor in decreasing the optical transmission and thus increasing the band gap through the absorption, reflection, and scattering mechanisms of these grains; the crystallinity and grain size were of secondary importance. • Two dominant effects influenced the photocatalytic properties of codoped TiO 2 films. • Decreased transmittance resulted from increased diffuse scattering and reflectivity. • Dopant precipitation resulted in the greatest extent of blockage of active sites. [ABSTRACT FROM AUTHOR]

CeO 2 , TiO 2 , and CeO 2 –TiO 2 layered thin films of different compositions were deposited on polished fused silica glass substrates using spin coating and then annealed at 550 °C for 1 h. Poorly crystalline fluorite-type CeO 2 and anatase-type TiO 2 were the only phases detected. The valence effects for Ce are attributed to intervalence charge transfer (IVCT) while those for TiO 2 are attributed to simultaneous Ti4+ → Ti3+ redox and IVCT. Contamination of the grain boundaries by Si from the substrate is likely to have contributed to blockage of surface-active sites. While the roughnesses of the former thin films exhibited the expected direct correlation with the grain size, those of the latter two types of thin films showed a converse relation, suggesting that the grain boundaries of the layered TiO 2 thin films included a recrystallized CeO 2 –TiO 2 invariant point liquid and/or a CeO 2 –TiO 2 –SiO 2 glass. These would have derived from the other sources of grain boundary contamination, which are Si contamination from the substrate and/or exsolved CeO 2 beyond the solubility limit of TiO 2. The UV–Vis spectra demonstrated two principal types of curves, with the CeO 2 and higher TiO 2 concentration giving typical spectra with sharp absorption edges while those of the lower TiO 2 concentration indicated highly defective nanostructures with diffuse absorption edges. These data support the conclusion that CeO 2 initially decreases the E g by enhancing nucleation and recrystallization through defect formation but subsequently increases the E g through supersaturation and consequent lattice distortion. The CeO 2 thin films exhibited much worse photocatalytic performances than those of the TiO 2 thin films, although no significant differences between the TiO 2 thin films and the CeO 2 –TiO 2 layered thin films were apparent, which probably resulted from the competing effects of blockage of the active sites on the grain boundaries and the extent of recrystallization of the thin film phases, the latter of which is more significant. [ABSTRACT FROM AUTHOR]

Hydrogen production from water by piezocatalysis is very attractive owing to its high energy efficiency and novelty. BaTiO 3 , a highly piezoelectric material, is particularly suitable for this application due to its high piezoelectric potential, non-toxic nature, and physicochemical stability. Owing to the critical role of morphology on properties, one-dimensional (1D) materials are expected to exhibit superior water-splitting performance and thus there is a need to optimise the processing conditions to develop outstanding piezocatalysts. In the present work, piezoelectric BaTiO 3 nanowires (NWs) were hydrothermally synthesised with precursor Ba:Ti molar ratios of 1:1, 2:1, and 4:1. The morphology, defect chemistry, and hydrogen evolution reaction (HER) efficiency of the as-synthesised BaTiO 3 NWs were systematically investigated. The results showed that the morphological features, aspect ratio, structural stability and defect contents of the 1D morphologies collectively have a significant impact on the HER efficiency. The morphological evolution mechanism of the 1D structures were described in terms of ion exchange and dissolution-growth processes of template-grown BaTiO 3 NWs for different Ba:Ti molar ratios. Notably, the BaTiO 3 NWs synthesised with Ba:Ti molar ratio of 2:1 displayed high crystallinity, good defect concentrations, and good structural integrity under ultrasonication, resulting in an outstanding HER efficiency of 149.24 μmol h−1g−1 which is the highest obtained for nanowire morphologies. These results highlight the importance of synthesis conditions for BaTiO 3 NWs for generating excellent piezocatalytic water splitting performance. Additionally, post-ultrasonication tested BaTiO 3 NWs demonstrated unexpected photocatalytic activity, with the BTO-1 sample (1:1 Ba:Ti) exhibiting 56% photodegradation of RhB in 2 h of UV irradiation. [Display omitted] • The 1D materials BaTiO 3 NWs were successfully synthesised with hydrothermal method. • The morphological evolution of BaTiO 3 NWs was studied with changing Ba:Ti ratios. • The BaTiO 3 NWs (Ba:Ti = 2:1) showed an outstanding piezocatalytic HER efficiency. • The post-tested BaTiO 3 NWs revealed photocatalytic activity caused by NWs breakage. [ABSTRACT FROM AUTHOR]

A simple template-free method was used to fabricate unique undoped, Cr-doped, and S-doped mesoporous 2D-3D ceria (CeO 2-x) nanostructures by using triethanolamine (TEA) to exfoliate electrodeposited cerium coordination polymer (Ce-CP), followed by heat treatment at 450 °C. For undoped CeO 2-x fabrication, varying the amount of TEA impacted the exfoliation extent and the resultant microstructural and defect characteristics, with the optimal Ce-CP to TEA ratio determined to be 30 mg:0.35 mL. For doped CeO 2-x , the introduction of dopants (substitutionally and/or interstitially) and heterojunction formation resulted in the creation of defects from charge compensation (ionic, electronic, and redox) which influenced charge carrier concentrations for reactions. The precipitation of excess dopants on the surface to create heterojunctions allowed for reduced crystallite sizes, lowering of the optical band gaps, and increased charge carrier separation, which in turn minimised charge carrier diffusion distance, ultimately increasing photocatalytic efficiency. Dye degradation tests showed that 10 mol% Cr-doped CeO 2-x revealed superior photocatalytic performance with a reaction rate of 15.88 × 10−3 min−1 (87% degradation after 160 min) compared to both 2.5 mol% S-doped CeO 2-x and undoped CeO 2-x (68% and 57% after 160 min, respectively). With sulphur addition, although the defect concentration increased and the crystallite sizes and band gaps were lowered, the degradation performance declined with increasing dopant amount owing to the reduced porosity from liquid-phase microstructural densification. Thus, the positive changes to the electronic and microstructural features from dopant-related heterojunction formations were observed to be the most critical factors impacting the photocatalytic performance of these unique nanostructures. [Display omitted] • Exfoliation with TEA and annealing generates 2D-3D ceria nanostructures. • Defect creation by doping and charge compensation mechanisms. • Cr-doping induces heterojunction formation, enhancing photocatalytic efficiency. • S-doping cause microstructural densification and reduces active sites. [ABSTRACT FROM AUTHOR]

Abstract Mo3+- or Mo5+-doped TiO 2 sol-gel thin films (≤0.100 mol%) were spin coated on fused silica glass substrates and annealed at 450 °C for 2 h. The effect of the valence of the dopant precursor is significant to the nanostructural development and resultant properties. Mo3+ or Mo5+ doping yields converse trends with doping level, thus reflecting the competing influences of lattice distortion and destabilization (dominating Mo3+ doping) and nucleation and recrystallization (dominating Mo5+ doping). Mo doping results in oxidation of Mo3+ and reduction of Mo5+, both of which alter to Mo(5−x)+, as well as oxidation of Ti3+ to Ti(4+x)+; all of these result in V O • • annihilation. Although the absorption edges were largely indistinguishable, Mo3+ doping causes a red shift and Mo5+ doping causes a blue shift. These data suggest that the performances are controlled by the synergistic effects of crystallinity, surface area, and band gap, with the latter's exhibiting the dominant effect. This suggests that the defect structure governs the photocatalytic performance but also that the defect chemistry at these low annealing temperatures is indicative of nonequilibrium conditions, thereby explaining the significance of the dopant valence. Highlights • The dominant effects are lattice distortion (Mo3+) and recrystallization (Mo5+). • Charge transfer causes Mo3+ and Ti3+ oxidation, Mo5+ reduction and V O • • removal. • Synergistic effect of crystallinity, surface area, and band gap improved efficiency. [ABSTRACT FROM AUTHOR]

The present work reports data for the mineralogical, nanostructural, optical, and photocatalytic properties of Cr-doped, V-doped, and Cr/V-codoped TiO2 nanoparticles in terms of the effects of doping level and associated particle size on their photocatalytic performance. The photocatalytic performance of doped TiO2 is dependent not only on the particle size at low-doping levels but also on both the type and amount of dopant(s) at high-doping levels. These data illustrate the existence of two clear regimes in behaviour and enable the introduction of a new interpretation of the causes of these effects. At ultralow and low-doping levels, extrinsic effects (viz., particulate characteristics) determine the performance. At high-doping levels, intrinsic effects (viz., dopant-controlled chemical and electrical characteristics) determine the performance. In the intermediate range of medium-doping levels, the performance shows the mixed effects of these two factors. A schematic model comprehensively summarizing the role of doping in these extrinsic and intrinsic effects on the photocatalytic process is presented. Further, a phenomenological model that identifies the regions of dominance of these effects as a function of particle size and doping level on the photocatalytic performance is proposed. These generic models assist in both understanding the systematic effects of doping on photocatalysts and identifying approaches for modification. [ABSTRACT FROM AUTHOR]

• Impact of microalgae blending on coking behaviour and coke quality is study. • Microalgae addition of up to 10% did not adversely influence coal thermoplasticity. • Microalgae addition lowered the activation energy of carbonization in the plastic range. • Porous biochar structures, typical of conventional biomass, were not detected for microalgae. • Cokes made from blends of microalgae and coal outperformed those of conventional biomass. The steel industry is responsible for approximately 7% of global greenhouse gas emissions, mainly in the form of CO 2 from the blast furnace ironmaking process. Among several strategies proposed to reduce CO 2 emission, the partial replacement of coal with biomass during the cokemaking process has gained increasing interest. However, such replacement with lignocellulosic biomass species demonstrates a detrimental effect on coke quality. In this work, as an alternative to lignocellulosic biomass, the use of microalgae biomass (Chlorella vulgaris) is discussed for coal blending and bio-coke production. Three Australian metallurgical coal samples, varying in rank and fluidity, were blended with microalgae at up to 10 wt% to evaluate the impact of biomass addition rate on coking behaviour and coke quality. The work evaluates the impact of microalgae on coal blend properties, coking performance, and coke quality and strength (CSR/CRI, microtexture, and coke reactivity). The results demonstrated that microalgae blending with high-rank premium metallurgical coals did not adversely affect thermoplastic properties during coking or resultant bio-coke quality. Furthermore, the reactivity under simulated blast furnace conditions showed that microalgae addition led to a slight increase of up to 4.4% in coke gasification reactivity, which was attributed to the higher alkali content and isotropic textures in coke. Unlike lignocellulosic biomass, in bio-cokes produced by blending microalgae no porous and fibrous structures related to the biochar structure were identified. It was postulated that this non-fibrous nature of microalgae allows cokes to maintain their strength even for blending up to 10 wt%. [ABSTRACT FROM AUTHOR]

Sn-doped anatase hollow spheres were fabricated using a template method involving polystyrene spheres as core and anatase coating as shell. The synthesis route included the preparation of PS spheres, followed by their coating by Sn-doped TiO 2 sol-gel precursor and subsequent removal of the PS cores by pyrolysis and recrystallization at 500 °C for 2 h. The observation of minor amounts of rutile suggests that Sn promotes the anatase → rutile phase transformation. At doping levels of ≤ 1.0 mol% Sn, the unsaturated solubility and increasing defect densities enhanced nucleation. At 1.0–2.0 mol% Sn, the solubility remained unsaturated but increasing Sn incorporation reduced crystallinity owing to lattice deformation and partial amorphization. At 2.0–3.0 mol% Sn, solid solution saturation occurred, resulting in excess dopant precipitation, leading to grain boundary pinning and partial blockage of surface-active sites. Ionic radii, thermodynamic, phase equilibria, intervalence charge transfer, and defect chemistry considerations suggest that Sn 4+ exhibits substitutional solid solubility in the TiO 2 lattice. The photocatalytic performance was in the order 1.0 > 1.2 > 1.5 ≈ 0.7 > 2.0 > 0.0 > 3.0 mol% Sn. This ranking is consistent with the dominant role of crystallinity such that, at ≤ 1.0 mol% Sn, the performance increased owing to enhanced nucleation from low defect density and increasing crystallinity while, at 1.0–2.0 mol% Sn, the performance decreased from increased lattice strain and effective partial amorphization, and, at 2.0–3.0 mol% Sn, it decreased from maximal lattice strain and blockage of active sites. [ABSTRACT FROM AUTHOR]