Nano-sized TiO2 Research Articles

Direct TiH2 powder production by the reduction of TiO2 using Mg in Ar and H2 mixed gas atmosphere

To develop a direct production process for TiH2 powder from TiO2, the reduction of TiO2 using Mg in molten MgCl2 – KCl salt under a high hydrogen chemical potential was investigated. The reduction of nano-sized TiO2 powder was conducted at 973 – 1073 K under an Ar or Ar and 10% H2 mixed gas atmosphere when the mass ratios of Mg to feed and salt to feed were 1.14 – 2.86 and 0.87 – 3.48, respectively. The results showed that the oxygen concentration in the Ti product decreased as the mass ratio of salt to feed and temperature decreased. Furthermore, according to the variation in Mg amounts, the oxygen concentration was 0.350 – 0.441 mass%. In addition, employing hydrogen during the reduction enhances the capability to decrease the oxygen concentration in the Ti product. Moreover, the hydrogen concentration in the Ti product increased as the amount of molten salt decreased, thereby enabling pure TiH2 production. As a result, TiH2 powder with an oxygen concentration of 0.350 mass% was obtained under a certain condition. These results demonstrate the feasibility of the direct production of low-oxygen TiH2 powder from TiO2 via reduction at 973 K using Mg in an Ar and H2 mixed gas atmosphere.

Effect of Microsize and Nanosize TiO2 on Porous Mullite-Alumina Ceramic Prepared by Slip Casting.

Sintered porous mullite-alumina ceramics are obtained from the concentrated suspension of powdered raw materials such as kaolin, gamma and alpha Al2O3, and amorphous SiO2, mainly by a solid-state reaction with the presence of a liquid phase. The modification of mullite ceramic is achieved by the use of micro- and nanosize TiO2 powders. The phase compositions were measured using an X-ray powder diffraction (XRD) Rigaku Ultima+ (Tokyo, Japan) and microstructures of the sintered specimens were analysed using scanning electron microscopy (SEM) Hitachi TM3000-TableTop (Tokyo, Japan). The shrinkage, bulk density, apparent porosity, and water uptake of the specimens was determined after firing using Archimedes' principle. The apparent porosity of the modified mullite ceramic is 52-69 ± 1%, water uptake is 33-40 ± 1%, pore size distributions are 0.05-0.8 μm, 0.8-10 μm and 10-1000 μm, and bulk density are variated from 1.15 ± 0.05 to 1.4 ± 0.05 g/cm3. The microsize TiO2 and nanosize TiO2 speed up the mullitisation process and allow the decrease in the quantity used as raw material amorphous SiO2, which was the purpose of the study. The use of nanosize TiO2 additive increases the porosity of such a ceramic, decreasing the bulk density and linear thermal expansion.

Size-dependent anatase to rutile phase transition under acoustic shocked conditions – A case study of TiO2 bulk and nanoparticles

In the present work, we attempt to explore the size-dependent structural stability of bulk (0.28 µm) and nano-sized (25 nm) anatase TiO2 particles under acoustic shocked conditions. Based on the observed X-ray diffractometric, Raman spectroscopic and transmission electron microscopic results with respect to the number of shock pulses, at the 90-shocked condition, the nano-size particles undergo the anatase to the rutile phase transition, whereas the bulk size TiO2 particles remain to be in the anatase phase. From the comprehensive assessment, it is demonstrated that the bulk TiO2 samples have higher structural stability compared to the nano-size samples. The nano-sized anatase-TiO2particles have values of lower thermal conductivity compared to the bulk-sized particles such that the value of lower thermal conductivity is a prominent crucial factor in initiating the dynamic recrystallization which results in the anatase-to-rutile phase transition. Based on the observed present experimental results and previous reports, it has been authenticated that, while increasing the particle size from nano-scale to micro-scale, the critical shock number for the anatase to rutile phase transition is significantly increased.

Photocatalytic Bleaching Process of Cotton Fabric with H2O2 and H2O2 /n-TiO2

This study delves into the exploration of an alternative bleaching method as a substitute for hydrogen peroxide, addressing concerns related to its excessive chemical usage, high waste load, and elevated energy and water consumption. Photocatalytic bleaching was implemented on 100% cotton fabrics. Initially, hydrogen peroxide served as a catalyst, and the photocatalytic effect was meticulously examined. Subsequently, nano-sized TiO2 was introduced into the photocatalytic recipe, and operational conditions were fine-tuned to determine the optimal bleaching process for cotton fabrics. All photocatalytic experiments were systematically compared with conventional hydrojen peroxide bleaching method. A comprehensive analysis, encompassing color spectrum values, SEM, SEM-EDX, XRD, and FTIR-ATR tests, was conducted. The results revealed a notable 13.36% enhancement in whiteness performance during bleaching when subjected to photocatalytic treatment with nano TiO2 and H2O2 in tandem. This study posits itself as an environmentally conscious alternative to the long-standing conventional bleaching processes prevalent in the textile industry.

Characterisation of titanium dioxide (nano)particles in foodstuffs and E171 additives by single particle inductively coupled plasma-tandem mass spectrometry using a highly efficient sample introduction system

This study addressed primarily the characterisation and quantification of titanium dioxide (TiO2) (nano)particles (NPs) in a large variety of commercial foodstuffs. The samples were purchased from local markets in Spain before the ban of TiO2 food additive (E171) in the EU. The analyses were carried out by single particle inductively coupled plasma-tandem mass spectrometry (spICP-MS/MS) in mass shift mode (oxidation of 48Ti to 48Ti16O (m/z = 64)) and using a highly efficient sample introduction system (APEX™ Ω). This novel analytical approach allowed accurate characterisation of a large panel of TiO2 NPs sizes ranging from ∼12 to ∼800 nm without isobaric interferences from 48Ca isotope, which is highly abundant in most of the analysed foodstuffs. TiO2 NPs were extracted from foodstuffs using sodium dodecyl sulphate (0.1%, w/v) and diluted with ultra-pure water to reach ∼ 1000 particles signals per acquisition. All the analysed samples contained TiO2 NPs with concentrations ranging from 1010 to 1014 particles kg−1, but with significant low recoveries compared to the total Ti determination. A selection of samples was also analysed using a similar spICP-MS/MS approach with a conventional sample introduction system. The comparison of results highlighted the improvement of the limit of detection in size (12 nm) by the APEX™ Ω system, providing nanoparticulate fractions ranging from ∼4% (cheddar sauce) up to ∼87% (chewing gum), which is among the highest nanoparticulate fractions reported in literature using a spICP-MS approach. In addition, two commercially available E171 additives were analysed using the previous approaches and other techniques in different European laboratories with the aim of methods inter-comparison. This study provides occurrence data related to TiO2 NPs in common commercial foodstuffs but it also demonstrates the potential of the novel analytical approach based on APEX™-ICP-MS/MS to characterise nano-size TiO2 particles in complex matrices such as foodstuffs.

Thermo-mechanical behaviours investigation of Nano-Sized Al2O3, TiO2, and Graphene Nanoplatelet Reinforced Epoxy Composites

Composite materials find extensive applications in various industries, thanks to their remarkable properties. These sectors include energy, maritime, motor sports, aviation, space and defense. The materials commonly used in these sectors are fiber reinforced plastic (FRP) composite materials. Epoxy materials are commonly used as matrix in the production of FRP materials. This study delves into the enhancement of epoxy-based nanocomposites by using graphene nanoplatelets (GNP-5nm), TiO2 (13nm), and Al2O3 (8nm) nanoparticles. These nanoparticles were added at varying mass ratios into a commercial epoxy to investigate their effects on some chemical, thermal and mechanical properties. Meticulous mixing methodologies were used to reduce clumping effects and ensure even distribution during the process. The curing process was carried out in a PLC (Programmable Logic Controller) controlled hot air oven under isothermal conditions under the influence of 100 °C for 30 minutes. Tensile strength, elongation at break, toughness, resilience modulus, elasticity modulus, hardness, FTIR analysis and thermal conductivity properties were characterized to assess the nanoparticle influence on the epoxy matrix. The results showed that there were remarkable improvements in mechanical properties with nanoparticle reinforcement. Especially, 1.25% Al2O3 inclusion exhibited a substantial increase of 140.32% in tensile strength and a 7% rise in shore D hardness compared to pure epoxy. This enhancement was attributed to enhanced O-H bonding between 'O' atoms in Al2O3 nanoparticles and epoxy polymer chains, enhancing matrix-filler interactions. Additionally, the effect of 1.0% TiO2 led to plasticity, displaying a 32% rise in elongation at break, signifying improved deformation energy absorption compared to neat epoxy. In thermal conductivity measurements, the highest thermal conductivity was observed in the sample with 1.25% GNP added and it increased by 123.5% compared to neat epoxy. In TiO2 and Al2O3 added samples, an increase of 69% and 47%, respectively, was observed at 1.25% additive rates compared to neat epoxy. According to the results, thanks to the nanoparticle reinforcement added into the epoxy matrix, composite structures can be given new and superior properties specific to the applications.

Regulating interfaces of composite polymer electrolyte via surface charge on fillers for stable solid-state lithium battery

The commercial potential of composite polymer electrolytes (CPEs) is significant due to their ability to combine the advantages of both inorganic and polymer solid electrolytes. However, the unstable interface and insufficient ionic conductivity remain important challenges in practical applications of CPEs for achieving high-performance solid-state lithium batteries (SLBs). Herein, we construct a double-layer composite polymer electrolyte (D-CPE) by incorporating nanosized TiO2 fillers with adjustable concentrations of oxygen vacancies into poly (ethylene oxide) (PEO)-based electrolyte composites. In the D-CPE structure, one CPE layer containing TiO2 fillers with oxygen vacancies exclusively interfaces with the LiFePO4 cathode, while the other CPE layer consisting of pristine TiO2 fillers (with negatively charged surfaces) solely contacts the lithium anode. This design of D-CPE achieves high ionic conductivity, a broad electrochemical window, and interfacial stability without additional resistance at the electrolyte-electrolyte interface simultaneously. The LiFePO4/D-CPEs/Li battery exhibits excellent cycling stability at 0.1 C, maintaining a capacity of 157.2 mAh g−1 with a capacity retention rate of 99.1% after 100 cycles. Furthermore, even at 0 °C, it delivers an impressive discharge capacity of 133.1 mAh g−1 at 0.1 C. This work presents a simple and effective approach to achieving superior polymer-based electrolytes for high-performance solid-state lithium batteries.

The Influence of Titanium Dioxide (TiO2) Particle Size and Crystalline Form on the Microstructure and UV Protection Factor of Polyester Substrates.

The inclusion of particles in a polymeric substrate to achieve certain properties is a well-known practice. In the case of textile substrates, this practice may deeply affect the structure of the produced yarns, as even a filament with no textile applications can be obtained. In this manuscript, titanium dioxide (TiO2) particles were incorporated into polyester (PET) chips and the influence of these fillers on the properties of yarn and fabric, and the ultraviolet protection factor (UPF) was assessed. For this purpose, rutile and anatase crystalline forms of TiO2, as well as the size of the particles, were evaluated. Moreover, parameters such as mechanical properties, orientation of the macromolecules and thermal behavior were analyzed to ensure that the textile grade is maintained throughout the production process. The results showed that the inclusion of micro- and nanoparticles of TiO2 decreases the molecular weight and tenacity of PET. Also, although orientation and crystallinity varied during the textile process, the resulting heatset fabrics did not present important differences in those parameters. Finally, the attainment of textile-grade PET-TiO2 fabrics with UPF indexes of 50+ with both rutile and anatase and micro- and nano-sized TiO2 forms was demonstrated.

Rich oxygen vacancies in confined heterostructured TiO2@In2S3 hybrid for boosting solar-driven CO2 reduction

Solar energy driving CO2 reduction is a potential strategy that not only mitigates the greenhouse effect caused by high CO2 level in atmosphere, but also yields carbon chemicals/fuels at the same time. Herein, a facile way to design the heterogeneous TiO2@In2S3 hollow structures possessing robust light harvesting in both ultraviolet and visible regions is proposed and exhibits a higher generation rate of 25.35 and 1.24 μmol·g−1·h−1 for photocatalytic CO2 reduction to CO and CH4, respectively. The excellent photocatalytic catalytic performance comes from i) the confined heterostructured TiO2@In2S3 possesses a suitable band structure and a broadband-light absorbing capacity for CO2 photoreduction, ii) the rich interfaces between nanosized TiO2 and In2S3 on the shell can significantly reduce the diffusion length of carriers and enhance the utilization efficiency of photogenerated electron-hole pairs, and iii) enriched surface oxygen vacancies can provide more active sites for CO2 adsorption.

Laser powder bed fusion of crack-free 6061Al alloy using nano-sized TiO2 modified powders

Growth of coarse columnar grains during solidification easily leads to hot cracking during laser powder bed fusion (LPBF) of Al alloys. This work offers an alternative route to inhibit the formation of coarse columnar grains during LPBF process. The crack-free 6061Al alloy with a refined microstructure was obtained using nano-sized TiO2 modified feedstock powders. After HIPPing, a nearly defect-free sample was obtained with a fracture elongation of 19.5 ± 0.14%. After artificially peak ageing treatment, the TiO2 modified 6061Al alloy fabricated by LPBF exhibits a tensile strength of 336.1 ± 3.5 MPa and the fracture elongation is still 8.1 ± 0.92%. It is believed that the approaches used in this work are also effective for other LPBF fabrication of low-printability Al alloys.

Effect of nanosized titanium dioxide and zinc oxide as antimicrobial agents on early compressive strength of high-performance concrete

Incorporation of antimicrobial agents in concrete can enhance the resistance of the concrete to biodeterioration. However, there is lack of adequate knowledge on the effect of antimicrobial agents on performance measures of high-performance concrete (HPC), particularly during early strength development, when the hydration reaction is ongoing, is not well understood. Therefore, the effect of antimicrobial agents on early compressive strength (CS) of HPC was investigated. The cement in HPC samples was partially replaced with nanosized titanium dioxide (TiO2) and zinc oxide (ZnO) by up to 2% by weight of the cement. Using response surface methodology, 21 combinations of TiO2 and ZnO contents were generated. The combinations were adopted for preparation of the samples. Individual and combined effects of TiO2 and ZnO on 7-day CS of the samples were evaluated. The standard form of the second-order response surface model is adopted to develop a model to fit the strength data. Statistics of the data verify that the model can be employed to predict the 7-day CS of HPC that employs nanosized TiO2 and ZnO as antimicrobial agents.

Constructing cell-membrane-mimic grain boundaries for high-performance n-type Ag2Se using high-dielectric-constant TiO2

The coupling of charge carrier and phonon transport limits the application of Ag2Se as a low-toxic near-room-temperature thermoelectric material. Strategies that reduce the thermal conductivity via enhancing the phonon scattering usually lead to reduced carrier mobility due to high grain boundary potential barrier. In this study, we developed a cell-membrane-mimic grain boundary engineering strategy for decoupling the charge carrier and phonon scattering through decorating high-dielectric-constant rutile TiO2 at Ag2Se grain boundaries to enable the charge carrier/phonon selective permeability. The nano-sized TiO2 with high dielectric permittivity can secure the charge carrier transport by shielding the interfacial Coulomb potential to lower the energy barrier of grain boundaries, rendering an enhanced power factor. Additionally, benefited from the enhanced phonon scattering by TiO2 nanoparticles, a significantly decreased lattice thermal conductivity of ∼0.20 W m−1 K−1 and a high zT of ∼0.97 at 390 K are obtained in the Ag2Se-based nanocomposites. This work demonstrates that such cell-membrane-mimic grain boundary engineering strategy may shed light on developing high-performance thermoelectric materials.

Evaluation of possible cytotoxic, genotoxic and epigenotoxic effects of titanium dioxide nanoparticles and possible protective effect of melatonin

Nanoparticles (NPs) are particles of matter that are between 1 to 100 nm in diameter. They are suggested to cause toxic effects in both humans and environment thorough different mechanisms. However, their toxicity profile may be different from the parent material. Titanium dioxide (TiO2) NPs are widely used in cosmetic, pharmaceutical and food industries. As a white pigment, the use of TiO2 is used in food coloring, industrial paints, clothing and UV filters has increased tremendously in recent years. Melatonin, on the other hand, is a well-known antioxidant and may prevent oxidative stress caused by a variety of different substances, including NPs. In the current study, we aimed to comparatively investigate the effects of normal-sized TiO2 (220 nm) and nano-sized TiO2 (21 nm) on cytopathology, cytotoxicity, oxidative damage (lipid peroxidation, protein oxidation and glutathione), genotoxicity (8-hydroxydeoxyguanosine), apoptosis (caspase 3, 8 and 9) and epigenetic alterations (global DNA methylation, H3 acetylation) on 3T3 fibroblast cells. In addition, the possible protective effects of melatonin, which is known to have strong antioxidant effects, against the toxicity of TiO2 were also evaluated. Study groups were: a. the control group; b. melatonin group; c. TiO2 group; d. nano-sized TiO2 group; e. TiO2 + melatonin group and f. nano-sized TiO2 + melatonin group. We observed that both normal-sized and nano-sized TiO2 NPs showed significant toxic effects. However, TiO2 NPs caused higher DNA damage and global DNA methylation compared to normal-sized TiO2 whereas normal-sized TiO2 led to lower H3 acetylation vs. TiO2 NPs. Melatonin showed partial protective effect against the toxicity caused by TiO2 NPs.

Color Stability, Physical Properties and Antifungal Effects of ZrO2 Additions to Experimental Maxillofacial Silicones: Comparisons with TiO2

(1) Background: Color changes, physical degradation, and fungal infections are challenges to the longevity of maxillofacial polydimethylsiloxane (PDMS) elastomers. This study aimed to evaluate color changes, physical properties, and antifungal properties of PDMS loaded with ZrO2 and TiO2 submicron- and nano-sized particles. (2) Methods: A 1% weight of 40 nm or 200 nm diameter ZrO2 or TiO2 nanoparticles was mixed into PDMS with 2% functional intrinsic yellow pigment and polymerized. Control materials contained 13% weight 200 nm silica. Samples were exposed to 3000 h of UVB radiation (200 µW/cm2) or darkness. Color parameters L*a*b* and ∆Eab*, ultimate tensile strength, strain, elastic modulus, and Shore A hardness were measured. Candida albicans growth was measured using XTT and confocal microscopy, and data were analyzed with the Dunnett test (p < 0.01). (3) Results: TiO2 200 nm showed the least color change after 3000 h of UVB radiation, followed by TiO2 40 nm (p < 0.05). The silica-containing control group was superior in all physical property measurements due to higher additive content (p < 0.05). TiO2-containing materials exhibited significantly lower C. albicans growth (p < 0.01) than those loaded with ZrO2 or SiO2. (4) Conclusions: TiO2 nanoparticles of 40 nm and 200 nm, when added to pigmented PDMS at 1% weight, provided the best resistance to color change and significantly lowered C. albicans activity compared to silica- and zirconia-filled elastomers. Particle size differences rendered minor differences for most properties. The incorporation of low-level submicron- and nano-sized TiO2 particles has the potential to improve color stability and antifungal activity in silicones designated for maxillofacial prostheses and may be extended to denture reline applications.

Photocatalytic Oxidation of Benzene to Phenol and Dye Over N and S Doped Ferromagnetic Nanosize TiO2

Photocatalytic Oxidation of Benzene to Phenol and Dye Over N and S Doped Ferromagnetic Nanosize TiO2

Pressure Drop and Heat Transfer Characteristics of TiO2/R1234yf Nanorefrigerant: A Numerical Approach

Global warming is one of the most dangerous ecological issues facing the globe. Refrigerants are a major contributor to global warming. This investigation mainly focuses on the analysis of a greener nanorefrigerant. Nanorefrigerant can improve the efficiency of refrigeration and air conditioning systems that use vapor compression. In the present investigation, mathematical and computational methods are used to assess the heat transfer and pressure drop properties of TiO2/R1234yf. In order to analyze the heat transfer characteristics and the transport features of the innovative nanorefrigerant, appropriate mathematical predictive models were adapted from earlier investigations. The models are validated by the experiments using TiO2/POE nanolubricant as a test fluid. The investigation was conducted with a temperature range of 10 °C to 40 °C and a volume percentage of nano-sized TiO2 particles in R1234yf refrigerant ranging from 0.2 to 1%. According to the research, the introduction of nanoparticles increases viscosity, thermal conductivity, and density. However, as the amount of nanoparticles rises, the specific heat capacity of the nano-enhanced refrigerant decreases. The nanorefrigerant’s heat transfer coefficient and pressure drop are improved by 134.03% and 80.77%, respectively. The outcomes observed from the predictive technique and the simulation approach had an average absolute variation of 9.91%.

Magnetic and ultrasonic integrated photocatalytic hydrogen evolution effects with Nanosize CoOCu2OZnO and TiO2 decorated on reduced graphene oxide

In this study, metal oxide composite (CoOCu2OZnO) and TiO2 on graphene oxide composite (CCZ−G−T) were synthesized to improve visible light-driven H2 evolution through the addition of a cation scavenger, ultrasonic effect, and magnetic field effect. The synthesized nanocomposites were characterized through structural, surface, and electrochemical analyses with band structure. The photocatalyst showed hydrogen production of 792 μmol·g−1 for 4 hours. Moreover, this CCZ−G−T photocatalyst exhibits relatively high photocatalytic activity at (530−810) μmol·g−1 when using a scavenger, 1,190 μmol·g−1 when using a magnetic field of 0.14 T, and 1,230 μmol·g−1 when using ultrasonic waves. The CCZ−G−T composite exhibited 630 μmol·g−1 under a magnetic field condition of 0.14 T for 1 hour, which was significantly higher than the hydrogen production rate of 510 μmol·g−1 under ultrasonic conditions. The current study provides new insights into the magnetic field effect on the hydrogen evolution reaction (HER) of graphene-based photocatalysts.

Photoadsorption of Cr(VI) on titanium dioxide modified by high-energy milling

Microcrystalline powders of rutile and anatase were milled in a high-energy planetary mill down to obtain nanosized TiO2 powders (the size of coherent scattering region (CSR) about 30 nm and 60 nm, respectively). The resulting powders were characterized by HRTEM, Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and the ξ-potential of the aqueous suspensions was determined. High-energy milling made it possible to significantly increase the ability of TiO2 to remove chromium from aqueous solutions. The effectiveness of the powders for not only Cr(VI) removing but also total chromium adsorption under UV-irradiation and short wavelength visible light has been shown. This is important, since Cr(III) does not remain in the aqueous medium and cannot be oxidized back to Cr(VI) under the influence of some environmental factors. It is possible to remove more than 99.9% of total chromium and 100 % of chromium hexavalent from a 50 mg·L-1 solution of Cr(VI) using milled anatase. XPS showed that, upon the photoadsorption, Cr(VI) is reduced to Cr(III). The presence of an acetate buffer in the solution promotes the most efficient removal of chromium. This work shows a simple way to obtain a highly effective material with potential applications for the removal of high toxic hexavalent chromium from industrial wastewater. The milled anatase sample was successfully tested to remove Cr (VI) from a real wastewater sample.

Corrensite and associated smectites in the Teschenite Association Rocks from the Podbeskydí Area (Czech Republic and Poland)

This study reports on the relatively common presence of the clay mineral corrensite in Teschenite Association Rocks of Early Cretaceous age. Significant quantities of corrensite were noted in monchiquite dikes and pillow lavas, pyroxene-rich rocks (teschenites), picrites, and also in the associated tuffs and tuffites including hyaloclastite breccias, and in strongly albitised calcareous shale enveloping small volcanic bodies. In addition to the transformation of primary mafic minerals such as forsteritic olivine, Ca-Fe-Mg clinopyroxenes, and amphiboles into clay associations, secondary zeolitisation (analcimisation), carbonatisation, silicification, and serpentinisation were also observed. The main clay mineral within the investigated rocks was smectite close to montmorillonite and saponite, but chlorite and serpentinite subgroup minerals were also present. The corrensite-bearing rocks were macroscopically indistinguishable from their smectitised or chloritised equivalents. Corrensite itself formed extremely thin (<1 μm) wrinkled sheets, present both in the rock matrix and the amygdaloid cavities, where it was younger than albite but older than calcite. The presence of corrensite was proven through powder X-ray diffraction analyses; a sequence of basal reflections at 28–29 Å, 14.25 Å, 7.15 Å, etc., were recorded, which after the application of ethylene glycol slightly expanded to 31 Å, 15.5 Å, 7.83 Å, etc. According to the interlayer distances, behaviour of corrensite after ethylene glycolation, the chemical classification criteria, and geological setting the analysed mineral was a HC-type corrensite of hydrothermal origin. The results of wavelength dispersive spectroscopy (WDS) microanalyses yielded an empirical average formula (K0.12Na0.01Ca0.15)Σ0.28(Mg4.84Fe2+1.65Fe3+1.34Mn2+0.02Al0.82)Σ8.95(Si5.86Ti0.10Al2.03P0.01)Σ8.00O20(OH9.89,F0.11) Σ10.00 . nH2O. Elevated Ti content can be explained either by presentce of nanosize TiO2 particles or a substitution of Ti (up to 0.33 apfu) for tetravalent silicon. The abundance of clay minerals in the Teschenite Association Rocks revealed that they were overprinted by several metamorphic events. Corrensite occurrences narrowed the metamorphic conditions to a temperature interval of 60 to 300 °C, which overlaps both zeolite and prehnite-pumpellyite metamorphic facies. The presence of smectites and corrensite in contact and hydrothermally altered sediments, as well as potassium metasomatites, proved that significant hydrothermal activity took place at the contact zones of magmatic/volcanic bodies.

Construction of Co9Se8/TiO2 S‐scheme heterojunction photocatalyst for efficient hydrogen production

Construction of S-scheme heterostructure is the focus of catalyst modification in the field of photocatalysis. In this work, the nanosized Co9Se8 and TiO2 particles were fabricated via a simple hydrothermal process. A series of Co9Se8/TiO2 heterojunctions were subsequently constructed through a physical solvent evaporation strategy. The photocatalytic H2 evolution experiment shows that the H2 evolution rate can reach 8282.7 μmol·g−1·h−1 over 15 %-Co9Se8/TiO2 under 300 W Xe lamp irradiation using 20 % triethanolamine (TEOA) as the sacrifice agent, which is 29.9-fold and 95.8-fold higher than that of pristine TiO2 (277.3 μmol·g−1·h−1) and Co9Se8 (86.5 μmol·g−1·h−1), respectively. The enhanced photocatalytic performance is primarily attributed to the improved light absorption ability and the formed S-scheme heterojunctions between TiO2 and Co9Se8, which could efficiently accelerate the separation and migration of photo-induced charges. Furthermore, the powerful electrons and holes are preserved, thereby earned robust redox ability to prompt H2 evolution reaction. This work affords a feasible approach to obtain S-scheme photocatalysts for effectively converting solar energy to H2.