Positive Holes Research Articles

Thermal-Induced Effects on the Structural and Photocatalytic Properties of Nickel Oxide Nanoparticles for Indigo Carmine Dye Removal

Nickel oxide (NiO) nanoparticles were formed using the chemical precipitation method. The effect of the calcination process on the structural parameters, optical bandgap, and photocatalytic performance was investigated. The structural characteristics were carried out using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscope (SEM). The XRD analysis reveals that the formed NiO crystallized in an fcc crystal structure and the calcination process influences the crystallite size, microstrain, dislocation density, and average surface area. For example, the smallest and largest particle sizes (19.13 nm and 27.63 nm) were achieved for the samples prepared at 800 °C for 4 h and 900 °C for 2 h, respectively. Based on the diffuse reflectance spectroscopy analysis, the energy bandgap has the lowest values (3.33 eV) for the prepared NiO that calcinated at 800 °C for 2 h compared with other samples. The formation of a Ni–O stretching vibration mode is revealed by FTIR, and the broadness of the absorption band confirms that the NiO samples are nanocrystals. The morphology of the prepared NiO reveals the formation of spherical nanoparticles for NiO calcinated at 700 °C, while dodecahedron-like shapes were observed for NiO calcinated at 800 and 900 °C. The photocatalytic performance of NiO nanoparticles as catalysts for the degradation of indigo carmine dye was investigated under ultraviolet–visible irradiation up to 3 h. The best degradation efficiency was found to be 76% for NiO calcinated at 800 °C for 4 h, which belonged to the smallest crystallite size of 19.13 nm, and the highest surface area of 47.02 m2 g−1. The superior and excellent performance of this sample compared to other samples was confirmed by achieving the highest reaction rate constant (4.51 × 10−3 min−1). The proposed photodegradation mechanism shows the importance of increasing the time required for the recombination process between the positive holes and the excited electrons, which is the best possible when using the optimum photocatalyst sample that was prepared at 800 °C for 4 h.

Characteristics of spark plasma sintered nanocarbon materials

We prepared binder-free monoliths of carbon nanohorns（CNHs）, hole-opened carbon nanohorns （CNHoxs）, multi-walled carbon nanotube（MWCNT）, and single-walled carbon nanotube（SWCNT）using spark plasma sintering（SPS）method at 1800℃ and 80 MPa in vacuum. The density of the SPS-treated SWCNT is 1.8 g/cm3, which is close to that of graphite, while those of CNHs, CNHoxs, and MWCNT remained 1.1-1.3 g/cm3 even after SPS treatment. We evaluated the monoliths using Raman spectroscopy and scanning electron microscopy observation, which showed a significant defect formation and graphitization of SWCNTs. Moreover, the increase of defects density in CNHs, CNHoxs, and MWCNT was moderate, and sub-micron size structures remained. We observed that the monoliths of CNHs and CNHoxs were highly conductive with a Hall mobility of positive holes of ～50 cm2/Vs and electrical conductivity of ～300 S/cm. These experimental results indicated that the SPS treatment under appropriate conditions could provide a CNHs monolith with nanostructure and good electrical conductivity.

Photocatalytic Degradation Pathways of the Valsartan Drug by TiO2 and g-C3N4 Catalysts

The photocatalytic degradation of the valsartan (VLS) pharmaceutical using TiO2 and g-C3N4 catalysts under simulated solar light is studied in this paper by high-resolution Orbitrap mass spectrometry. •OH radicals were the major oxidant species for the degradation of valsartan using TiO2, while positive holes (h+), followed by a much lesser amount of •OH radicals, were the major species in the case of g-C3N4. Valsartan degradation followed first order kinetics by both catalysts with TiO2 being the catalyst with the better photocatalytic efficiency. The transformation products (TPs) and their evolution profiles are identified and monitored, respectively, by means of LC-HRMS. Based on TPs identification, the degradation mechanisms are discussed. The major degradation pathways for g-C3N4 include decarboxylation and subsequent oxidation, hydroxylation, and cleavage of C–N bond, while for TiO2 cyclization, TPs are abundant and the hydroxylation occurs in the first stage products. The study highlights the complex nature of TPs formed during such processes, the different mechanisms involved and the necessity for the identification of TPs for the assessment of the treatment and the tracking of such TPs in different environmental compartments.

Smart Surfaces: Photocatalytic Degradation of Priority Pollutants on TiO2-Based Coatings in Indoor and Outdoor Environments-Principles and Mechanisms.

Heterogeneous photocatalysis using semiconductor oxides such as TiO2, provides an up-and-coming solution for the degradation of environmental pollutants compared with other technologies. TiO2-containing construction materials and paints activated by UV/solar light destroy the ozone precursors NO and NO2 up to 80% and 30%, respectively. The majority of TiO2 materials developed so far are primarily for outdoor use. In recent years, substantial efforts have been made to investigate further the photocatalytic activity of materials containing TiO2 toward priority air pollutants such as NO, NO2, and volatile organic compounds (VOCs) frequently accumulated at high concentration levels, particularly in indoor spaces. The intention of the investigations was to modify the titanium dioxide (TiO2), so that it may be activated by visible light and subsequently used as additive in building envelop materials and indoor paints. This has been achieved, to a high extent, through doping of TiO2 with transition metals such as V, Cr, Fe, Mn, Ni, Co, Cu, and Zn, which reduce the energy gap of TiO2, facilitating the generation of free electrons and holes, thus, extending the absorption spectral range of modified TiO2 to the area of visible light (bathochromic shift-redshift). A substantial problem using TiO2-containing paints and other building materials in indoor environments is the formation of byproducts, e.g., formaldehyde, through the heterogeneous photocatalytic reaction of TiO2 with organic matrices. This affects the air quality in confined spaces and, thus, becomes a possible risk for human health and wellbeing. This work describes the principles and mechanisms of the photocatalytic reactions at the air/catalyst interface of priority pollutants such as NO, benzene, and toluene as individual compounds or mixtures. Emphasis is placed on the reaction and recombination processes of the charge carriers, valence band positive holes (h+) and free electrons (e−), on the surface of TiO2, and on key factors affecting the photocatalytic processes, such as humidity. A hypothesis on the role of aromatic compounds in suppressing the recombination process (h+ and e−) is formulated and discussed. Furthermore, the results of the photocatalytic degradation of NO under visible light conditions using different admixtures of TiO2 and manganese doped (Mn–TiO2) are presented and discussed.

Study of molar properties of GO after doping with transition metals for photodegradation of fluorescent dyes.

We synthesized graphene oxide (GO) doped with transition metal ions and characterized it using XPS, FT-IR, TGA/DTG, XRD, SEM, AFM, ICP-OES, UV/vis, and Raman spectroscopy. An intrinsic viscosity [η] of 0.002-0.012 g% @ 0.002 aq-GO was determined for viscosity average molecular weight (M v) of GO at 288.15, 298.15, and 308.15 K. Mark-Houwink (M-H) constants k (cm3 g-1) and a (cm3 mol g-2) were calculated for 5-15 mg/100 mL polyvinylpyrrolidone (PVP), using 29, 40, 55 kg mol-1 as markers for calculating M v by fitting the [η] to the Mark-Houwink-Sakurada equation (MHSE). We obtained 48 134.19 g mol-1 M v at 298.15 K, and the apparent molar (V ϕ m , cm3 mol-1), limiting molar volumes (V 0 GO)GO⃑0, enthalpy (ΔH m, J mol-1), entropy (ΔS m, J mol-1 K-1), viscosity (η m, mPa s mol-1), surface tension (γ m, mN m-1 mol-1), friccohesity (σ m, scm-1 mol-1), fractional volume (ϕ m, cm3 mol-1), isentropic compressibility (K sϕ,m, 10-4 cm s2 g-1 mol), infer GO molar consistency throughout the chemical processes. Molar properties (MPs) infer a GO monodispersion producing negative electrons (e-) and positive holes (h+) under sunlight. The transition metal ions (Fe2+, Mn2+, Ni2+, Cr3+, TMI) doped onto GO (TMI-GO), can photodegrade methylene blue (MB) in 60 min compared with 120 min using GO alone. The 4011 C atoms, 688 hexagonal sheets, 222 π-conjugations, and 4011 FE were calculated from the 48 134.19 g mol-1. The functional edges are the negative and positive holes generating centres of the GO 2D sheets.

High Resolution 3-D Simulations of Venting in 18650 Lithium-Ion Cells

High temperature gases released through the safety vent of a lithium-ion cell during a thermal runaway event contain flammable components that, if ignited, can increase the risk of thermal runaway propagation to other cells in a multi-cell pack configuration. Computational fluid dynamics (CFD) simulations of flow through detailed geometric models of four vent-activated commercial 18650 lithium-ion cell caps were conducted using two turbulence modeling approaches: Reynolds-averaged Navier-Stokes (RANS) and scale-resolving simulations (SRS). The RANS method was compared with independent experiments of discharge coefficient through the cap across a range of pressure ratios and then used to investigate the ensemble-averaged flow field for the four caps. At high pressure ratios, choked flow occurs either at the current collector plate when flow through the current collector plate is more restrictive or the positive terminal vent holes when flow through the current collector plate is less restrictive. Turbulent mixing occurred within the vent cap assembly, in the jets emerging from the vent holes, and in recirculating zones directly above the vent cap assembly. The global maximum turbulent viscosity ratio (μT/μ) of the MTI, LG MJ1, K2, and LG M36 caps at pressure ratio ofP1/P2= 7 were 4,575, 3,360, 3,855, and 2,993, respectively. SRS and RANS simulations showed that both velocity magnitude and fluctuating velocity magnitude were lower for vent holes which are obstructed by the burst disk. SRS showed high levels of fluctuating velocity in the jets, up to 48.5% of the global maximum velocity. The present CFD models and the resulting insights provide the groundwork for future studies to investigate how jet structure and turbulence levels influence combustion and heat transfer in propagating thermal runaway scenarios.

Enhanced bezafibrate degradation and power generation via the simultaneous PMS activation in visible light photocatalytic fuel cell

A collaborative system including peroxymonosulfate (PMS) activation in a photocatalytic fuel cell (PFC) with an BiOI/TiO2 nanotube arrays p-n type heterojunction as photoanode under visible light (PFC(BiOI/TNA)/PMS/vis system) was established. Xenon lamp was used as the light source of visible light. A 4.6 times higher pseudo-first-order bezafibrate (BZF) degradation rate constant was achieved in this system compared with the single PFC(BiOI/TNA)/vis system. The radical quenching experiments revealed that the contribution of reactive oxidative species (ROS) followed the order of 1O2 ≈ h+ >> •OH > SO4•− >>O2•−. The EPR tests demonstrated that PMS addition enlarged the formation of 1O2, •OH and SO4•−, but suppressed O2•− yield. Interestingly, 1O2 was further proved to dominantly originated from the priority reaction between positive photoinduced holes (h+) and negatively charged PMS. Besides, N2-purging tests and density functional theory calculation indicated that PMS probably reacted with residual photoinduced electron (e−) on the more negative conduction band (CB) of BiOI to form •OH and SO4•−, but competed with dissolved oxygen. Other e− transferred to the less negative CB of TNA through p-n junction will efficiently move to cathode through the external circuit. The greatly promoted power generation of PFC system was observed after PMS addition due to extra h+ consumption and efficient e− separation and transfer. Besides, three possible pathways for BZF degradation were proposed including hydroxylation, fibrate chain substituent and amino bond fracture. This study can provide new insights into the mechanisms of PMS assisted photocatalysis and accompanying energy recovery.

Photocatalytic ozonation in water treatment: Is there really a synergy between systems?

Numerous studies report on the synergy between ozonation and photocatalytic oxidation (TiO2/UVA), which could open the way to the application of photocatalytic ozonation (PCOz) in water treatment. With the aim of establishing the existence of this synergy and its origin, in this work, using TiO2 P25, 365 nm UVA LEDs and ozone transferred doses up to 5 mg (mg DOC0)−1 (DOC0 7 – 10 mg L−1), a systematic study has been carried out featuring the effect of pH, alkalinity and water matrix in each of the systems involved in PCOz, with special attention to the role of organics adsorption onto TiO2. In ultrapure water, an increase in pH and carbonates content exerted a slight negative effect on the photocatalytic degradation of primidone (low adsorption onto TiO2 and mainly abated by free HO•), this effect being higher on its mineralization. The negative effect of pH and alkalinity was much stronger for oxalic acid (high tendency to adsorb and mainly oxidized by positive holes). Accordingly, the results obtained at pH < pHpzc (point of zero charge of the catalyst) in ultrapure water cannot at all be extrapolated to secondary effluents, since their composition negatively affects the photocatalytic performance. At the experimental conditions applied, only for the secondary effluent a synergy between O3/UVA and TiO2/UVA systems was observed. This synergy would be related, on the one hand, to the generation, from the matrix itself, of reactive entities or intermediates that promote the decomposition of ozone into HO•; and, on the other hand, to an increase in catalyst activity as the matrix UVA absorption decreases, rather than from direct interactions between both systems. Despite de above, ozone requirement to achieve a significant reduction of DOC is high and would only be an interesting strategy for the elimination of ozone-refractory micropollutants.

A novel heterogeneous photo-Fenton Fe/Al2O3 catalyst for dye degradation

The activity of heterogeneous photo-Fenton catalysts based on iron and supported on commercial alumina was studied for the degradation of rhodamine B, methyl orange and methylene blue under UV irradiation. The catalysts were prepared by impregnation, drying, and calcination or omitting this last step and referred to as dried or calcined samples. All samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption, diffuse reflectance UV–vis absorption spectroscopy and X-ray photoelectron spectroscopy (XPS). The XRD results revealed that all catalysts showed peaks of α-Al2O3 and FeSO4. The band gap of the catalysts compared with alumina decreased, due to the presences of Fe species which functioned as traps inhibiting the electron-hole recombination. The XPS results revealed the presence hydroxyl groups on the surface and the presence of both Fe3+ and Fe2+ in both catalysts. The photodegradation experiments showed that the heterogeneous photo-Fenton process was much faster compared with the heterogenous photocatalyst on all the tested dyes. The dried Fe/Al2O3 with the presence of H2O2 under UV irradiation showed the best degradation of rhodamine B, methyl orange, and methylene blue at 99.6, 100, and 99.1% at 5, 10, and 5 min, respectively. This could probably be ascribed to a good dispersion of Fe particle species on Al2O3, a low band gap and a proper concentration of hydroxyl groups and sulfate groups on the surface. The scavenger test revealed that the hydroxyl radicals played the main role in the photodegradation of dyes in this process compared with the superoxide radicals and positive holes.

Behavior of graphene under glow discharge plasma

The following paper describes performance of CVD graphene under influence of a glow discharge plasma of very low energy. The presented experimental results show changes in graphene resistance followed by alternations of magnitude and polarity of Hall voltage, that are controlled via the ignition of plasma. The Hall voltage polarity reversal represents changes in the nature of electrical conductivity, distinguishing between positive (holes) or negative (electrons) charges carrying the current in the graphene sample under the given conditions.

Balancing static vacuum black holes with signed masses in four and five dimensions

We construct a new set of asymptotically flat, static vacuum solutions to the Einstein equations in dimensions 4 and 5, which may be interpreted as a superposition of positive and negative mass black holes. The resulting spacetimes are axisymmetric in 4-dimensions and bi-axisymmetric in 5-dimensions, and are regular away from the negative mass singularities, for instance conical singularities are absent along the axes. In 5-dimensions, the topologies of signed mass black holes used in the construction may be either spheres $S^3$ or rings $S^1 \times S^2$; in particular, the negative mass static black ring solution is introduced. A primary observation that facilitates the superposition is the fact that, in Weyl-Papapetrou coordinates, negative mass singularities arise as overlapping singular support for a particular type of Green's function. Furthermore, a careful analysis of conical singularities along axes is performed, and formulas are obtained for their propagation across horizons, negative mass singularities, and corners. The methods are robust, and may be used to construct a multitude of further examples. Lastly, we show that balancing does not occur between any two signed mass black holes of the type studied here in 4 dimensions, while in 5 dimensions two-body balancing is possible.

Effect of operational parameters on photocatalytic degradation of ethylparaben using rGO/TiO2 composite under UV radiation

The objective of this study was to analyze the influence of different operational variables (catalyst loading, initial EtP concentration, medium pH, the presence of anions and radical scavengers) on the performance of ethylparaben (EtP) photodegradation catalyzed with an rGO/TiO2 composite. EtP was selected for study after analyzing the effect of paraben chain length on its catalytic photodegradation, finding that the photodegradation rate constant values of methyl-, ethyl-, and butyl-paraben are 0.050, 0.096, and 0.136 min−1, respectively. This indicates that the photodegradation rate constant of parabens is higher with longer alkyl chain, which augments its oxidation capacity. The percentage removal of EtP at 40 min increases from 66.3 to 98.6 % when the composite dose rises from 100 to 700 mg/L; however, an additional increase in the composite dose to 1000 mg/L does not substantively improve the photodegradation rate or percentage EtP removal (98.9 %). A rise in the initial EtP concentration from 15 to 100 mg/L reduces the percentage of degradation from 100 to 76.4 %. The percentage EtP degradation is lower with higher solution pH. The presence of HCO3− or Cl− anions in the medium reduces the degradation performance. Results obtained using positive hole and hydroxyl radical scavengers demonstrate that positive holes play an important role in EtP degradation. No degradation product evidences toxicity against the cultured human embryonic kidney cell line HEK-293.

Ruppeiner curvature along a renormalization group flow

We report on an investigation of Ruppeiner curvature RU for (d+1)-dimensional hyperbolic black holes in anti-de Sitter spacetimes and its connection with Renormalization Group (RG) flows in the dual d-dimensional conformal field theories (CFTs) in Minkowski spacetimes. A repulsive type interaction among microstructures is found, which is weaker for positive mass black holes and grows stronger for negative mass black holes at low temperatures. In particular, we show that RU evaluated along a zero mass curve is a universal constant, depending only on the dimension of space-time. The extremal black holes are pointed out to have a positive Ruppeiner curvature irrespective of their horizon topology.

Visible Light-Driven Photocatalytic Activity and Kinetics of Fe-Doped TiO2 Prepared by a Three-Block Copolymer Templating Approach.

Fe-doped titania photocatalysts (with 1, 2.5, and 3.5 wt. % Fe nominal content), showing photocatalytic activity under visible light, were prepared by a soft-template assisted sol–gel approach in the presence of the triblock copolymer Pluronic P123. An undoped TiO2 photocatalyst was also prepared for comparison. The photocatalysts were characterized by means of X-ray powder Diffraction (XRPD), Quantitative Phase Analysis as obtained by Rietveld refinement, Diffuse Reflectance (DR) UV−Vis spectroscopy, N2 adsorption/desorption at −196 °C, electrophoretic mobility in water (ζ-potential), and X-ray photoelectron spectroscopy (XPS). The physico-chemical characterization showed that all the samples were 100% anatase phase and that iron was present both in the bulk and at the surface of the Fe-doped TiO2. Indeed, the band gap energy (Eg) decreases with the Fe content, with Tauc’s plot determined values ranging from 3.35 (undoped TiO2) to 2.70 eV (3.5 wt. % Fe). Notwithstanding the obtained Eg values, the photocatalytic activity results under visible light highlighted that the optimal Fe content was equal to 2.5 wt. % (Tauc’s plot determined Eg = 2.74 eV). With the optimized photocatalyst and in selected operating conditions, under visible light it was possible to achieve 90% AO7 discoloration together with a TOC removal of 40% after 180 min. The kinetic behavior of the photocatalyst was also analyzed. Moreover, the tests in the presence of three different scavengers revealed that the main reactive species are (positive) holes and superoxide species. Finally, the optimized photocatalyst was also able to degrade phenol under visible light.

Electrochemical Response of Sr(Ce0.9Zr0.1)0.95Yb0.05O3-α high-Temperature Hydrogen Sensors

In future fusion reactors, tritium and deuterium will be used as a primary fuel. Currently, the most important research and development project about nuclear fusion energy is ITER (International Thermonuclear Experimental Reactor). To produce the fusion reaction, tritium will be generated inside the core using a breeding blanket. One of the suggested blankets is based on the use of molten lithium–lead eutectic alloy (Pb-15.7Li) [1]. This blanket will be flowing around the reactor core and while the fusion reaction occurs, energy is released and collected with an external heat exchanger system.Due to its short half-life (12.3 years), there are not natural tritium sources. Therefore, it must be obtained in situ and continuously in the breeding blanket. This hydrogen isotope can be produced by bombarding lithium with fast neutrons, which escape from the generated and confined plasma in the toroid-shaped vacuum chamber of a tokamak, to yield tritium and helium (6Li + n → 4He + 3H + 4.8MeV) [2]. Hence, dynamic tritium concentration measurement is of major interest for nuclear fusion reaction engineering and experimental proof of tritium self-sufficiency in liquid metal breeding systems. Consequently, it is necessary a measuring system that allows determining tritium concentration in high-temperature conditions.Electrochemical sensors based on solid-state proton conductor ceramics can be used for that purpose. These materials have attracted significant interest because of their chemical and physical durability, especially at elevated temperatures. These electrolytes are perovskite-type materials with electrical carriers, positive holes, excess electrons, oxide ion vacancies, and interstitial protons, which interact with oxide ions. Under this approach, new methods of synthesis are being studied in order to obtain ceramic materials of higher quality and purity able to offer better measurement signals.In the present work, the proton-conducting perovskite Sr(Ce0,9-Zr0,1)0,95Yb0,05O3-α was synthesized by two different methods. On one side, a conventional sol-gel method, using citric acid as a complexing agent, was employed [3]. On the other hand, the second method used was the glycine method, which is based on the combustion of glycine with the precursor's nitrates. Using the glycine method, it could be obtained a ceramic porous foam that improved the sintering process. Both synthesized materials were characterized using X-Ray Diffraction and SEM-EDS analysis.Finally, the obtained ceramic materials were properly sintered and shaped in order to construct electrochemical hydrogen sensors. Amperometric measurements were performed at 500°C and 600°C using different hydrogen concentrations and the response of the two sensors was compared.

Visible light active Fe-Pr co-doped TiO2 for water pollutants degradation

Fe–Pr co-doped TiO2 photocatalysts are synthetized by sol–gel method using titanium tetraisopropoxide, praseodymium nitrate and iron acetylacetonate as precursors of titania, praseodymium and iron, respectively. The chemical-physical properties of all prepared samples are analysed by X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy (UV–vis DRS), photoluminescence (PL) spectroscopy and N2 adsorption at −196 °C. XRD patterns show the main peaks of anatase phase in all photocatalysts and evidence that Fe and Pr ions are effectively introduced into the TiO2 lattice. UV–vis DRS spectra indicate the reduction of the band gap value of Fe-Pr co-doped TiO2 with respect to TiO2 and Pr-doped TiO2 thank to co-doping of TiO2 with Pr and Fe ions. The photocatalytic performances of all prepared samples are investigated for the degradation of Acid Orange 7 azo dye (AO7) and also of phenol under visible light irradiation. Photocatalytic efficiency obtained using Fe–Pr co-doped TiO2 markedly increases compared to un-doped TiO2, Pr-doped TiO2 and Fe-doped TiO2 photocatalysts. Fe-Pr co-doped TiO2 prepared with 8.5 mg of praseodymium nitrate gave the best photocatalytic activity. The enhanced photocatalytic activity should be associated with the simultaneous doping of TiO2 with Pr3+ and Fe3+ ions that induces a marked decrease of band gap value together with an enhanced generation of oxygen vacancies, which can trap electrons, and therefore reducing their recombination with photogenerated positive holes. Indeed, using the optimized Fe-Pr co-doped TiO2, the dye discoloration and mineralization is about 87 and 80 %, respectively, after 60 min of LEDs visible light irradiation, underlining the best performances of the optimized Fe–Pr co-doped TiO2 in terms of treatment time. Finally, the optimized Fe-Pr co-doped TiO2 is tested for visible light degradation of phenol in aqueous solution, confirming the absence of possible sensitization phenomena of photocatalyst surface by the AO7 dye.

Structural, Magnetic, Optical Properties and Photocatalytic Activity of Nanocrystalline Cobalt Ferrite Prepared by Three Different Methods

Cobalt ferrite (CoFe2O4) is an interesting material due to its rich physical properties. In order to study the influence of synthetic methods on the crystalline and morphological structure, optical and magnetic properties of the CoFe2O4, we synthesized here the CoFe2O4 by three different methods, including the chemical co-precipitation method, sol-gel method, and ceramic method. The resulting powders were characterized by different analyses: XRD, SEM, TEM, BET, FTIR, UV-Vis, PL, XPS, and surface acidity. The characterization results showed a significant variation in the structural, particle size, surface area, and optical properties of pure cobalt ferrite with changing the synthetic method. Both XRD and FTIR analyses confirm the formation of the cubic spinel phase, where the crystallite size changes from 21 to 36 nm. XPS analyses demonstrated the effect of the synthetic method on the cation distribution at the tetrahedral and octahedral sites in the spinel ferrite lattice. The magnetic properties of the prepared samples were studied at room temperature using the vibrating sample magnetometer (VSM) and found to be strongly dependent on the synthetic method and showed either ferromagnetic or super-paramagnetic character. The cobalt ferrite samples showed high photocatalytic activity against Basic Red 18 (BR 18) dye under visible light irradiation. The effects of particle size, surface areas, and morphology on the photocatalytic activity were discussed and the positive holes are suggested to be the major active species of the dye dissociation.

Scleral Perforation Secondary to Cyclophotocoagulation

A 66-year-old man with ectodermal dysplasia syndrome, right eye Type 1 Boston Keratoprosthesis (K-Pro), and chronic angle-closure glaucoma underwent cyclophotocoagulation diode in the right eye (2500 mW, 2-4 seconds), which resulted in scleral perforation with 3 Seidel positive holes along the inferotemporal limbus (Fig A). LiquiBand glue was applied and the perforations were covered with a Tutoplast scleral patch graft followed by amniotic membrane (Fig B). Two weeks later, the graft had fallen off (Fig C), and the large perforations coalesced.

Unique Z-scheme carbonized polymer dots/Bi4O5Br2 hybrids for efficiently boosting photocatalytic CO2 reduction

Constructing heterojunctions with matched band semiconductor is regarded as effective strategy to promote high-efficiency photocatalytic CO2 reduction. Herein, 0D/2D direct Z-scheme heterojunction involving carbonized polymer dots and Bi4O5Br2 nanosheets (CPDs/Bi4O5Br2) is designed and fabricated, which effectively facilitate migration and separation efficiency of photogenerated carriers and retain more negative electron reduction potential of CPDs and more positive hole oxidation potential of Bi4O5Br2. Moreover, CPDs promote adsorption of CO2 and intermediate COOH* as well as desorption of product CO. The direct Z-scheme mechanism of CPDs/Bi4O5Br2 is collaboratively confirmed by theory calculation, X-ray photoelectron spectroscopy and time-resolved transient absorption spectroscopy. The 8 wt% CPDs/Bi4O5Br2 exhibits the maximal CO production of 132.42 μmol h−1g−1 under Xe lamp irradiation, 5.43 fold higher than that of Bi4O5Br2 nanosheets. The CPDs with up-conversion properties can broaden light utilization range, so that composite material also show better CO2 conversion performance when excitation wavelength is greater than 580 nm.

Degradation of phenol in batik industry wastewater using thin layer TiO2 photocatalyst

The synthesis of thin layer TiO2 photocatalyst has been performed and its performance was tested to the degradation of phenol in wastewater of batik industry. The powder of anatase TiO2 was impregnated in glass plate, so that thin layer TiO2 photocatalyst was obtained. The performance test of thin-layer TiO2 photocatalyst in the degradation of phenol was performed in a batch photoreactor equipped with six types of black light UV lamp (@10 watts) and a magnetic stirrer. This research has been performed at pH variation and UV radiation time. The result of this research showed that the initial concentration of phenol in batik wastewater was 3,3684 ppm. The optimum pH was obtained at pH 11 with percent degradation of 40.41%. The optimum UV radiation was obtained at 8 hours with percent degradation of 41.72%. The longer the irradiation time the more photon energy is absorbed by TiO2 causes more positive holes to be formed. The positive holes will react with H2O or hydroxyl ions to form OH radicals that further break down organic compounds in waste.