High TiO2 Research Articles

Photocatalytic degradation of methylene blue by efficient TiO2‐partially reduced graphene oxide composites

The effect of graphene oxide with different reduction degrees on the photocatalytic efficiency of titanium dioxide‐graphene (TiO2‐G) composites has not been systematically studied. In this paper, titanium dioxide‐partially reduced graphene oxide (TiO2‐PRGO) nanocomposites were prepared by a modified one‐step solvent‐thermal method and further reduced with ascorbic acid to obtain TiO2‐PRGO(xh) with a higher degree of reduction (ascorbic acid 80° reduced TiO2‐PRGO x h, x = 1, 2, 3, 4). The composites were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and ultraviolet–visible diffuse reflectance spectroscopy (DRS). The transient photocurrent response and electrochemical impedance results show that TiO2‐PRGO has the most outstanding photoelectrochemical properties. Compared with pure TiO2 and other samples, the TiO2‐PRGO nanocomposites exhibited excellent photocatalytic properties, and their photocatalytic efficiencies for the degradation of methylene blue (MB) were up to seven times higher than those of the pure TiO2 nanomaterials, and twice that of TiO2‐PRGO(4h). The photodegradation of methylene blue by the composites decreased as the degree of PRGO reduction increased. The efficient photocatalytic performance of TiO2‐PRGO can be attributed to the high TiO2 loading and good electrical conductivity. Notably, TiO2‐PRGO photocatalysis for 90 min resulted in 100% degradation of MB. Meanwhile, TiO2‐PRGO has good reusability, and the degradation rate of TiO2‐PRGO remained at 95% after four times of degradation in MB solution.

Engineered nanomaterials display a variable interaction with anoxygenic photoelectrogenic biofilm for pharmaceutical pollutants degradation

Engineered nanomaterials (ENMs) have been reported to facilitate extracellular electron transfer (EET) by increasing the electrical conductivity of electroactive biofilms. However, the mechanisms between different ENMs and anoxygenic photoelectrogenic bacteria for degrading organic pollutants remain unclear. In this study, we investigated the mechanism of metronidazole (MNZ) degradation by different concentrations of carbon nanotubes (CNTs), Iron (III) oxide (Fe3O4) NPs, and titanium dioxide (TiO2) NPs in Rhodopseudomonas palustris based photoelectrogenic biofilms. At low concentrations, CNTs enhanced the electrochemical activity and EET capacity of the biofilm, possibly by increasing the DNA concentration and cellular activity in the cathodic biofilm. However, the ecological toxicity of CNTs at high concentrations damaged the activity of R. palustris, resulting in a decline in the MNZ degradation rate (0.29179 h−1 at 185 μg/L and 0.27801 h−1 at 370 μg/L). A high TiO2 NPs concentration (370 μg/L) significantly boosted the MNZ degradation rate (133 % increase) via photocatalytic activity. But it affected the biofilm activity and EET. Overall, Fe3O4 NPs demonstrated superior performance. At 185 μg/L, the photosynthetic current and MNZ degradation rate increased by 138 % and 142 %, respectively. Despite a slowdown in the utilization rate of Fe (III) and EET at high concentrations, the biofilm exhibited sustained high activity, indicating that Fe3O4 NPs can significantly enhance the metabolism of R. palustris. These findings were not only important for optimizing the performance of anoxygenic photoelectrogenic biofilms but also for regulating the ecological impact of ENMs in natural environments.

Compositionally variable basement and tectonic affinity of the Bainaimiao arc belt: Implications for crustal growth of the Central Asian Orogenic Belt

As an important part of the southeastern boundary of the Central Asian Orogenic Belt (CAOB), the Bainaimiao arc belt, particularly its tectonic affinity and Precambrian basement composition, is an important element to provide new insights about the crustal growth of the CAOB. However, these remain poorly understood. This paper presents new geochronological, whole-rock geochemical and zircon Hf isotope data on early Paleozoic intrusive rocks from the Bainaimiao arc belt in the southeastern CAOB. The Ordovician gabbroic diorites in the Zhengxiangbaiqi area of the western Bainaimiao arc belt have low SiO2 contents (51.73–54.82 wt%), high TiO2 (0.99–1.07 wt%) and TFe2O3 contents (9.68–9.89 wt%), depletions in Nb, Ta and Ti, and positive εHf(t) values (6.8–11.3). These rocks generated from partial melting of a mantle wedge that has been metasomatized by subducted-derived fluids. The Silurian monzogranites in the Zhengxiangbaiqi area have high contents of SiO2 (72.61–75.12 wt%) and K2O (2.75–4.12 wt%), positive εHf(t) values (0.7–9.3) and abundant Precambrian inherited zircons. These monzogranites originated from partial melting of the thickened juvenile crustal components with significant ancient crustal contamination. The Silurian granites and granodiorites in the Faku area of the eastern Bainaimiao arc belt are characterized by high Na2O contents (4.00–4.52 wt%), high Sr/Y ratios, low MgO (1.15–1.74 wt%) and K2O contents (0.52–1.42 wt%), low K2O/Na2O ratios, and positive εHf(t) values ranging from 0.6 to 8.1. These rocks were derived from partial melting of a subducted slab interacted with mantle peridotite. New zircon U-Pb-Hf isotope data from these early Paleozoic intrusive rocks combined with previous results indicate that the Precambrian basement of the Bainaimiao arc belt is laterally heterogeneous, with Neoarchean-Paleoproterozoic basement beneath the western Bainaimiao arc belt and Paleo-Mesoproterozoic basement beneath the central Jilin area in the eastern Bainaimiao arc belt. The Bainaimiao arc belt has a tectonic affinity different from the North China Craton (NCC) and represents a composite arc system consisting of an ensialic island arc with a basement composition similar to that of the Precambrian microcontinents in the CAOB in the Bayan Obo-Damaoqi-Bainaimiao-Zhengxiangbaiqi and central Jilin areas and an oceanic island arc in the Ongniud-Faku and southern Jilin areas. The involvement of composite arc systems in the amalgamation of the accretionary orogenic belt could be an important mechanism for crustal growth in the CAOB.

Stool titanium dioxide is positively associated with stool alpha-1 antitrypsin and calprotectin in young healthy adults

Titanium dioxide (TiO2/E171) is used widely in foods, primarily as a food additive. Animal models have shown that chronic TiO2 exposure may disturb homeostasis of the gastrointestinal tract by increasing gut permeability, inducing gut inflammation, and increasing the likelihood of microbial infection. Adults have a wide range of ingested TiO2,which span two to three orders of magnitude, with a small portion of individuals consuming near gram quantities of TiO2/day. However, research on the health effects of chronic ingestion of TiO2/E171 in humans is limited. We hypothesized that regularly ingested TiO2/E171 is associated with increased gut inflammation and gut permeability in healthy adults. We tested this hypothesis in a cross-sectional design by measuring clinically established stool markers of gut inflammation (calprotectin, lactoferrin) and gut permeability (alpha-1 antitrypsin; A1AT) in 35 healthy adults, and comparing these markers between relatively high and low TiO2 exposure groups. Participants were stratified by TiO2 stool content (high dry stool TiO2 content: 0.95–9.92 μg/mg, n = 20; low content: 0.01–0.04 μg/mg; n = 15). Differences in gut health markers were tested between high and low exposure groups by independent samples t-test or Mann-Whitney U test. Multivariable linear regression was used to assess the association between TiO2 in dry stool and measured stool alpha-1 antitrypsin (A1AT). Participants in the high stool TiO2 group had greater stool A1AT (42.7 ± 21.6 mg/dL; median: 38.3; range: 1.0–49.2 mg/dL), compared to the low TiO2 group (22.8 ± 13.6 mg/dL; median: 20.9; range: 8.7–93.0 mg/dL), P = 0.003. There was also greater stool calprotectin in the high TiO2 group (51.4 ± 48.6 μg/g; median 29.2 μg/g; range: 15.3–199.0 μg/g) than in the low group (47.5 ± 63.3 μg/g; median 18.8 μg/g; range: 1.6–198.1 μg/g), P = 0.04. No clear difference was observed for lactoferrin (high TiO2 group 1.6 ± 2.1 μg/g; median: 0.68 μg/g; range: 0.01–7.7 μg/g, low TiO2 group: 1.3 ± 2.6 μg/g; median: 0.2; range: 0.01–7.6 μg/g) (P = 0.15). A1AT concentration was positively associated with stool TiO2, after adjusting for confounders (β ± SE: 19.6 ± 7.2; P = 0.01) R2 = 0.38). Community dwelling, healthy adults with the highest TiO2 stool content had higher stool A1AT and calprotectin, compared to those with the lowest TiO2 stool content. Ongoing research is needed to validate these observations in larger groups, and to determine the long-term effects of ingested TiO2 on human gut health, using these and additional health endpoints.

Optical bistability in topological layered structure and its application in photonic neural network

Optical bistable state exhibits its great potential applications in photonic integrated circuit and photonic neural network. However, the traditional optical bistable state will be influenced by the system disorders, which are not suitable for application. In this work, we investigate the topological bistable states in a layered structure with center inversion symmetry consisting of alternating layers of high index material TiO<sub>2</sub> and low index material SiO<sub>2</sub>. In the topological mode, the electric field is highly localized in the inversion center of the layered structure (also known as the interface) and exponentially decays into the bulk. Thus, when the nonlinear permittivity is strategically introduced into those layers, nonlinear phenomena such as the bistable state appears. The finite element numerical simulations reveal that the optimal bistable state appears when the layer period is 5 with a threshold power around 1.2 W/m. Benefiting from the topological characteristics, such a bistable state persists when random perturbations are introduced into the layer thickness and refractive index. Finally, we apply the bistable states to a photonic neural network. The bistable function shows prediction accuracy similar to the classic activation function ReLu and sigmoid in various learning tasks. These results provide a novel method for inserting highly robust optical bistable states from topological layered structure into photonic neural network.

Amphiboles of Alkaline-Ultrabasic Rocks from North-Western Part of the Ukrainian Shield

Different magnesian amphiboles — pargasites, Ca-Na- and alkaline ones (richterites, Mg-kathophorites, Mg-taramites, Mg-riebeckites, Mg-arfvedsonites and intermediate varieties) of alkaline-ultrabasic rocks (hypabyssal intrusions and dikes) from North-Western part of the Ukrainian Shield are studied and analyzed (mainly microbe method). Some pargasites and richterites are characterized by increased or high TiO2 contents (2.9-3.2%). In studied region more enriched in iron and titanium amphiboles (ferri-kaersutites) rarely occur too in veins rocks of essexite composition. Chemistry of amphiboles depends on types of rocks and erosion of their intrusions. Low aluminian and alkaline amphiboles are characteristic for at least eroded intrusions (dikes) whereas in more eroded and more crystallized hypabysal intrusions amphiboles with higher aluminium of pargasite composition form. Such diversity of studied amphiboles is caused by composition of alkaline-ultrabasic melts and some different depth of their crystallization.

Linking kimberlite magmatism in the Brazilian Platform with Pangea break-up events using in situ Rb-Sr in phlogopite

Kimberlite magmatism provides insights into periodic tectonothermal processes linked to the evolution of supercontinents. Paleozoic and Mesozoic kimberlites overlapping with the Pangea cycle are exposed in the Amazonian Craton (Pimenta Bueno field) and the Neoproterozoic Brasília Belt. Phlogopite in mantle xenoliths in kimberlites from the Amazonian Craton are characterized by low Cr2O3 (< 1 wt%) and an enrichment in TiO2 (> 2 wt%), akin to secondary phlogopite formed by kimberlite magma infiltration in the mantle. Low Ti-Cr (< 1 wt%) and high #Mg (91–92) grains are linked to extensive metasomatism of garnet peridotites resulting in clinopyroxene-phlogopite rocks. In situ phlogopite Rb-Sr isochron ages of 250–220 Ma constrain the emplacement of pipes in the Amazonian Craton with no age difference between distinct phlogopite compositions (higher and lower TiO2 phlogopite) and microstructures (porphyroclasts, neoblasts, reaction rims). Mantle xenoliths in kimberlite pipes from the Brasília Belt present high TiO2 (> 2 wt%) akin to secondary phlogopite formed by magma infiltration, and low Ti-Cr (1 wt%), and high #Mg (> 92) phlogopite akin to primary grains in equilibrium with garnet. In situ phlogopite Rb-Sr isochron ages from all Brasília Belt phlogopite types span 90–80 Ma, constraining the emplacement of diamondiferous and barren pipes, with no relic of older metasomatic events. The kimberlites from the Pimenta Bueno field (Amazonian Craton) are coeval with the beginning of the extension within Pangea that culminated with the Central Atlantic rifting. In fact, the Permian-Triassic kimberlites occur close to intracratonic basins that are crosscut by ca. 200 Ma dykes and sills of the Central Atlantic Magmatic Province. In situ phlogopite Rb-Sr isochron ages spanning 90–80 Ma in the pipes from central and southeastern Brazil (Brasília Belt) may be associated with propagation of far-field stresses linked to opening of the South Atlantic Ocean during the Pangea break-up.

High energy facet-dominated TiO2−X facet heterojunction with excellent carrier utilization for ultrasensitive SERS sensing and efficient degradation of antibiotic residues

Realizing efficient utilization of photogenerated carriers is crucial to boosting the photophysical and photochemical performances of semiconductors. Herein, (101) and (001) facets co-exposed anatase TiO2−X facet heterojunction with abundant oxygen vacancies was developed as a new surface-enhanced Raman scattering (SERS) substrate and also as an excellent photocatalyst for synchronous detection and degradation of antibiotic residues in actual water system. Due to the efficient carrier separation induced by facet heterojunction and the efficient charge migration derived from exposure of more high energy (001) facets, the TiO2−X facet heterojunction exhibits an ultrahigh SERS enhancement factor of 1.07 × 107 for non-resonant Raman probe, with excellent spectral reproducibility and stability. More meaningfully, the developed substrate can realize an ultrasensitive detection for different kinds of antibiotic residues in real river water, even a comprehensive identification for multicomponent residues. Moreover, TiO2−X facet heterojunction can also execute an efficient photocatalytic degradation for residue pollutants in actual water system. And, the developed multi-function substrate possesses an excellent recyclability not only in SERS detection but also in photocatalysis.

Development of High Electrochemical Performance-Reliability TiO2 Nanoparticle-Mulberry Paper Based Supercapacitor

The paper-based energy storage systems with lightweight, thin and large scalability have been attracted much attention in the field of next generation research. Along with the advantages of these papers, they have excellent flexibility and wettability, so they have high power density even under mechanical bending and twisting deformation, making them suitable for wearable devices. However, conventional paper has limited electrochemical stability due to its low chemical resistance and decomposition in organic or acidic electrolytes.Mulberry paper can be an outstanding alternative for overcoming the limitations of conventional paper-based energy storage systems. Mulberry fibers form a stronger mechanical network and are longer than conventional paper fibers, so they have excellent chemical strength. Therefore, in this study, a supercapacitor with high electrochemical performance and reliability was produced based on mulberry paper.As high electrochemical performance active materials, TiO2 nanoparticle and graphene oxide nanocomposites were used. A TiO2 nanoparticle was coated on a mulberry paper substate, graphene oxide was coated, and heat treatment was performed at 700℃ under nitrogen atmosphere for 3 hours. Mulberry paper was carbonized to increase areal energy density. It was strongly fixed by the reduced graphene oxide to maintain the flexibility of carbonized mulberry paper and prevent the delamination of the TiO2 nanotube without protection layer.Therefore, it is suitable for wearable energy storage systems because it can maintain excellent charge-discharge cycle reliability and flexibility carbonized mulberry paper by improving areal energy density from carbonized mulberry paper and metal oxides and preventing the delamination of the metal oxide.

Facile preparation of ZnO/TiO2 nanocomposite photocatalysts and study of their photocatalytic performance

Due to its strong photocatalytic activity, chemical stability, resistance to chemical and optical corrosion, and non-toxic qualities, TiO2 has received a lot of attention as a significant semiconductor material. One of the main areas of research in the field of photocatalysis has always been the system made of ZnO, another significant semiconductor, which has stronger physical and chemical characteristics and photocatalytic activity than TiO2 and ZnO alone.The performance of the photocatalysts can be optimized by adjusting the ratio of the components in the complexes. It was found that the catalytic activity of the particulate ZnO nano photocatalysts could be improved by trace TiO2 addition and high TiO2 concentration in the complex, with higher degradation efficiency for methyl orange under simulated solar illumination. The enhanced performance was attributed to the high photogenerated electron-hole separation rate caused by the increased surface oxygen vacancy defects and the enhanced interfacial charge transfer of the pluralistic heterojunction structure. In addition, there is a certain selectivity of ZnO and TiO2 for the photocatalytic degradation of methylene blue and methyl orange, which is related to the charged nature of the catalyst surface and the ionic nature of the pollutant molecules. The inhibitor studies revealed that the degradation reactions of methylene blue and methyl orange involved the active species hydroxyl radicals, superoxide radicals, and photogenerated holes formed on the catalyst surface, with superoxide radicals dominating the methyl orange reaction. The produced photocatalysts' great stability was validated by cycling experiments. Further research on the impact of catalyst dosage and pH of the contaminant solution on the photocatalytic performance of the catalysts revealed that an increase in catalyst dosage resulted in a greater number of active sites for contaminant molecules and incident light, which increased the efficiency of contaminant degradation. In an alkaline environment, the efficiency of the catalyst for photodegradation of pollutants was significantly increased due to the high concentration of strongly oxidizing hydroxyl radicals contained in the alkaline solution.

Preparation of synthetic rutile from Rosetta ilmenite concentrate

The hydrometallurgical procedure is suggested in this work to upgrade the ilmenite mineral which is separated from black sand at Rosetta, Egypt, to obtain high TiO2. The ilmenite concentrate is subjected to a digestion process using sulfuric acid solution in the presence of date molasses. Date molasses is chosen as new, cheap, eco-friendly and effective reductant. The relevant factors for titanium and iron dissolution from ilmenite concentrate include: the acid concentration, sample/acid ratio, reaction time, temperature in addition reductant percentage. These factors are studied and optimized. The optimum conditions are realized at 10 M H2SO4 acid with a solid/liquid ratio of 1/10 at 120 °C for 2 h in the presence of a definite amount of date molasses. Under these conditions, titanium and iron leaching efficiencies are attained at 98.4% and 92.8%, respectively. The resultant leach liquor is then subjected to a hydrolysis step for titanium separation as Ti(OH)2, dried at 110 °C and ignited at 850 °C to obtain high-grade titanium oxide (93.5%) TiO2.

ِA new occurrence of rift-related damtjernite (ultramafic) lamprophyre, Gebel Anweiyib area, Arabian Nubian shield: Insights from bulk rock geochemistry and remote sensing data analysis

The occurrence of lamprophyre dikes is being reported first time in the Gebel Anweiyib area, south Eastern Desert, Egypt. The investigation of the ultramafic lamprophyre (damtjernite) dikes intruded into the crustal younger granites and metasediments based on their spectral characteristics, mineralogical and geochemical compositions. Three multispectral sensors of Landsat-8, ASTER and S2 have been used to detect and characterize the lithologic units and the lamprophyre dikes. The reflectance and absorption signatures of the granitic rocks and lamprophyre dikes were the basis for detecting them from the remotely sensed data using the application of advanced image processing algorithms including FCC, BR, PCA, MNF, and DS. Geochemical studies inferred that the damtjernite dikes are under-saturated with SiO2 (<38.89 wt%), alkaline with total alkalis (avg. 4 wt%), metaluminous with A/CNK (0.22–0.51), and ultramafic with MgO (13.88–19.23 wt%). They exhibit unique geochemical characteristics of mantle (with high MgO, Ni, Cr, and Mg#) coupled with crustal (high Sr, Ba, Zr, Ga and REEs) sources, similar to global ultramafic lamprophyres. High TiO2 and highly fractionated REEs with low HREEs (avg. 23 ppm) relative to LREEs (avg. 354 ppm) contents, yielding residual garnet in melts. Low partial melting of primitive garnet lherzolite can account the obtained REEs in the ultramafic lamprophyres. These features signify their derivation from a deeper enriched asthenospheric (plume-type) magma like OIB, which is attested by the high Nb/La (avg. 1.32), Nb/U (avg. 102), La/Yb (avg. 43), and low Y/Nb < 0.52, Rb/Sr < 1, Rb/Ba (<0.14), and Sr/Ba (<0.9), suggesting their derivation from a mantle-derived source rather than crustal rocks. High concentrations of TiO2 and Fe2O3 in the ultramafic lamprophyres, reflecting their formation from a fertile peridotite by mantle plume-derived melts with K-residual phlogopite rather than amphibole as obtained by low Ba/Rb and high Rb/Sr ratios. The Anweiyib lamprophyres are anorogenic and confined to being derived from rifting regions, and their magma is not contaminated with crustal sources during emplacement.

Record of an oceanic island in the Neo-Tethys Ocean (lowermost Cretaceous Xiazha Formation, Yarlung-Zangbo suture zone, South Tibet)

The Xiazha Formation recently identified in the Yarlung-Zangbo suture zone of southern Tibet has been considered as crucial evidence for early (pre-Cretaceous) subduction of Neo-Tethyan oceanic lithosphere. In this study, we carried out an integrated stratigraphic, petrographic, and geochemical study of the Xiazha Formation, which consists of abyssal chert, siliceous mudrocks, and calcareous turbidites deposited onto basaltic basement. Basalt geochemistry indicates alkali to tholeiitic magmas generated in a within-plate oceanic setting. The siliciclastic fraction contained in calcareous turbidites consists of plagioclase and mafic-rock fragments derived from the underlying basalts, and includes Cr-spinel grains with relatively high TiO2 and moderate Al2O3 concentrations pointing to an OIB source. Based on these data, and virtual lack of detritus of continental origin, we infer that the Xiazha Formation was deposited in oceanic island/plateau within the Neo-Tethyan domain. Its stratigraphy records an evolution from basaltic eruptions to the development of a carbonate platform surrounding the basaltic island, and finally to drowning of the atoll. The Xiazha Formation was not deposited in a subduction-related basin and, therefore, cannot be used as evidence for pre-Cretaceous initiation of the Yarlung subduction zone.

Lithospheric mantle heterogeneity beneath the Siberian craton: Evidence from garnet xenocryst database with implications for kimberlite compositions

This contribution reports some 16,000 major and minor element analyses of garnet xenocrysts derived from 18 (out of the 21 known) kimberlite fields of the Yakutian Kimberlite Province (YaKP) on the Siberian craton in Russia. Using TiO2–in–garnet as an indicator of heterogeneity within the subcontinental lithospheric mantle (SCLM), as well as garnet mg# (mg#=Mg2+/(Mg2++Fe2+)*100), we distinguish three subpopulations of garnet: 1) high content of TiO2 (0.26–0.50 wt%) and high mg# (80.6–82.6) garnet xenocrysts are common in the southern diamondiferous kimberlite fields; 2) garnet xenocrysts with low content of TiO2 (0.06–0.26 wt%) and relatively high values of mg# (78.8–81.7), which prevail in the northern ‘barren’ kimberlite fields; and 3) three anomalous northern kimberlite fields (Chomurdakh, Ogoner-Yuryakh, Toluopka) characterized by the predominance of garnet xenocrysts with high TiO2 content (0.53–0.78 wt%) at relatively low mg# (76.9–78.3).It is reasonable to assume that relatively thin cratonic mantle lithosphere beneath the three anomalous kimberlite fields underwent intense metasomatic overprinting by melts and fluids injected from the underlying asthenosphere, which changed the compositions of peridotitic garnets significantly. An interpretation of the data presented in this study is that the generally high TiO2 contents of kimberlites in the northern YaKP (>1.5 wt% TiO2) are a primary magmatic feature of asthenospheric origin because the lithospheric mantle traversed by these kimberlite magmas is TiO2 depleted. We propose a model in which the relatively thin SCLM of the northern Siberian craton provided less opportunity for high-TiO2 asthenospheric kimberlite melts to interact and change compositions on their way to the Earth’s surface. The high-TiO2 kimberlites of the northern YaKP may thus represent a good approximation of the primary compositions of natural kimberlite melts.

Graphitization modified three-dimensional fully interconnected high porous TiO2 ceramics: A promising carrier material for thermal storage and thermal conductivity enhancement

In this work, porous TiO2 ceramics (PTC) and the graphitization modification of PTC (GPTC) with three-dimensional fully interconnected and uniform pore structure as a carrier for PCM was prepared by the Pickering emulsion method. Compared with PTC, the thermal conductivity and porosity of GPTCs were further improved and the specific surface area of GPTCs was increased by 5.7 times. The results of DSC curves showed that the melting and solidification enthalpy of PEG-GPTC20 were 143.8 J/g and 139.0 J/g, respectively, which only decrease by 0.68 % and 0.35 % after 100 phase change cycles. The experimental thermal conductivity of PEG-GPTC20 composites improved by 3.2 times. The results of non-isothermal crystallization kinetics revealed that the nucleation activation energy: PEG>PEG-PTC > PEG-GPTC, which indicated that GPTCs porous carrier encapsulation was beneficial to the nucleation process of PEG. The PEG-GPTCs composite phase change material designed in this paper has significant advantages in maintaining high thermal conductivity and heat storage performance at the same time while comparing other composites. Therefore, GPTCs are a promising carrier material for thermal storage and thermal conductivity enhancement.

Supported MOCVD TiO2 Thin Films Grown on Modified Stainless Steel Mesh for Sensing Applications.

Among semiconductor metal oxides, that are an important class of sensing materials, titanium dioxide (TiO2) thin films are widely employed as sensors because of their high chemical and mechanical stability in harsh environments, non-toxicity, eco-compatibility, and photocatalytic properties. TiO2-based chemical oxygen demand (COD) sensors exploit the photocatalytic properties of TiO2 in inducing the oxidation of organic compounds to CO2. In this work, we discuss nanostructured TiO2 thin films grown via low-pressure metal organic chemical vapor deposition (MOCVD) on metallic AISI 316 mesh. To increase the surface sensing area, different inorganic acid-based chemical etching protocols have been developed, determining the optimal experimental conditions for adequate substrate roughness. Both chemically etched pristine meshes and the MOCVD-coated ones have been studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) microanalysis, and X-ray photoelectron spectroscopy (XPS). We demonstrate that etching by HCl/H2SO4 at 55 °C provides the most suitable surface morphology. To investigate the behavior of the developed high surface area TiO2 thin films as COD sensors, photocatalytic degradation of functional model pollutants based on ISO 10678:2010 has been tested, showing for the best performing acid-etched mesh coated with polycrystalline TiO2 an increase of 60% in activity, and degrading 66 µmol of MB per square meter per hour.

Chemical composition optimization of Al2O3-TiO2 composite coatings for enhanced wear and corrosion resistance

This study aimed to optimize the chemical composition of wear- and corrosion-resistant Al2O3-TiO2 composite coatings. 2-layered and 4-layered Al2O3-TiO2 coatings were fabricated on a 316L substrate with various Al2O3 and TiO2 content (20 %, 35 %, 50 %, 65 %, and 80 % in weight) at 900 °C by sol-gel technique. Wear properties were measured by dry sliding tests against an Al2O3 ball, and corrosion behavior was determined through potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests. All Al2O3-TiO2 composite coatings consisted of α-Al2O3 and rutile phases, regardless of the chemical composition. Increasing TiO2 content significantly increased coating thickness at the same number of layers. The 2-layered configurations resulted in lower wear rates in low-TiO2 compositions, whereas the 4-layered configurations provided higher wear resistance in high TiO2-containing coatings. The high Al2O3 concentration caused extremely high corrosion rates compared to those consisting of high TiO2. Wear and corrosion losses were decreased with increasing TiO2 content due to its nanosized structure, allowing well-adhered, continuous, and less porous coating morphology. The maximum improvement in wear and corrosion resistance was obtained in the 4-layered 65 % TiO2-containing composite coating.

The origin of Ni and Mn variations in Hawaiian and MORB olivines and associated basalts

The origins of differences in the Mn and Ni contents of olivine phenocrysts from ocean island basalts (OIB) and mid-ocean ridge basalts (MORB) are disputed. One prevalent hypothesis is mixing between peridotite melts and melts of an olivine-free pyroxenite that forms by reaction between large extents of melting of recycled ocean crust and peridotite. A second is peridotite melting at various pressures without contributions from recycled materials, and a third is mixing of recycled crust into peridotite sources. All models purport to account for olivine data, but an additional requirement is that the models account for corresponding liquid compositions. Here we demonstrate that none of the proposed models alone are able to account for both olivine and liquid data. The pyroxenite model predicts variations in liquid Mn to account for high Fe/Mn ratios, in contrast to the data where the high ratios result primarily from Fe variations. Using an updated model of Ni partitioning, combined with quantitative modeling of polybaric melting, confirms the important role of pressure on olivine compositions, and in addition shows that extent of melting and mantle fertility are also important. Most MORB are consistent with ∼10% -15% melting of peridotite at lower pressures, but low Ni olivines found on ridges adjacent to hot spots require a depleted mantle source. High Ni olivines can be produced by low degree melting of peridotite at high pressure, but such models do not produce the high Ni liquids that are also observed, nor the trace element abundances such as high TiO2. Mixing basalt and peridotite sources is not successful because it fails to account for the low Na/Ti ratios of OIB. A successful model for OIB involves adding ∼3–5% of a low degree eclogite melt with high trace element abundances and low Na/Ti to mantle peridotite, and then melting this source to small extents at high pressure. The need for a low degree melt of eclogite also rules out models that call upon high degrees of melting of eclogite that react with peridotite to produce OIB sources, and shows that this melting does not occur during upwelling beneath hot spots, where high degree melts of eclogite would occur. A firm conclusion of this work is that olivine compositions cannot be used to calculate the amount of recycled crust in mantle sources. Further work to explore variations within OIB and MORB will benefit from the realization that olivine compositions alone cannot be interpreted reliably without quantitative polybaric melting models and attention to co-existing liquids and trace element abundances.

A high performance TiO2 anode modified by germanium and oxygen vacancies for lithium-ion batteries

A TiO2 anode modified by germanium and oxygen vacancies was fabricated using a hydrothermal method with an autoclave at 180 °C, followed by reduction sintering at 600 °C for 5 h in a reducing atmosphere. Germanium was obtained and distributed uniformly on the surface of the anatase TiO2 particles. Oxygen vacancies were identified on the TiO2 surface by electron paramagnetic resonance and X-ray photoelectron spectroscopy. The specific capacity of the Ge@TiO2−x anode was 510 mAh g−1 after 550 charge-discharge cycles. The charge transfer and electrolyte impedance of Ge@TiO2−x were smaller than those of the initial TiO2. The lithium-ion diffusion coefficient in Ge@TiO2−x was 7.87 × 10−13 cm2·s−1, which was significantly higher than that of a commercial TiO2 anode. The germanium and oxygen vacancies in TiO2 provided more active sites for the transport of lithium ions and electrons, thereby reducing the energy barrier, accelerating the charge transfer of lithium ions and enhancing the conductivity and capacity of the Ge@TiO2−x anode.

High strength Ni matrix TiO2 composites by supercritical CO2 assisted Co-electrodeposition with different sizes of TiO2 particle

High strength Ni matrix TiO2 composites by supercritical CO2 assisted Co-electrodeposition with different sizes of TiO2 particle