Minimizing CO2 emissions by photocatalytic CO2 reduction to CH3OH over Li2MnO3/WO3 heterostructures under visible illumination.

Photocatalytic CO2 reduction to valuable fuels has proved to be a favourable process to produce renewable energy and reduce CO2 emissions, which mostly depends on designing effective photocatalysts with the rapid separation rate of charge carriers. In this contribution, mesoporous n-n heterojunction Li2MnO3/WO3 nanocomposites were designed via a simplistic sol-gel process for CO2 reduction utilizing visible illumination (λ > 420 nm). XRD and TEM measurements confirmed the synthesized Li2MnO3/WO3 nanocomposite is a monoclinic structure, and its particle size is 25 ± 5 nm. The obtained Li2MnO3/WO3 exhibited narrower bandgap energy (1.74 eV), larger surface area (212 m2g-1), exceedingly visible absorbing, and lower recombination of electron and hole. The yield of CH3OH was determined about 198, 871, 1140, 1550 and 1570 mmolg-1 for bare WO3 and 5%, 10%, 15% and 20% Li2MnO3/WO3 nanocomposites, respectively. These results evidenced that the 15% Li2MnO3/WO3 photocatalyst exhibited the best reduction ability compared to other nanocomposites. The CO2 reduction over 15% Li2MnO3/WO3 photocatalyst achieved a maximal CO2 conversion with the substantially boosted CH3OH, i.e., 1550 mmolg-1 after 9 h, which was enhanced 7.8 folds great than of WO3 NPs. Mesoporous Li2MnO3/WO3 nanocomposites, in comparison with bare WO3 NPs, created more active sites for facilitating CO2 and had a specific electric field to more effectively separate charge carriers. The Li2MnO3/WO3 photocatalyst has superior photostability during the continuous reduction of CO2 for 45 h with no remarkable decrease. The possible direct S-scheme mechanism for electron transfer over Li2MnO3/WO3 photocatalyst with the enhanced CO2 reduction ability was discussed. The present work demonstrates an avenue for building highly effective heterostructure photocatalysts in solar-energy-induced potential applications.

Synthesis of mesoporous Ag/α-Fe2O3/TiO2 heterostructures with enhanced and accelerated photo/-catalytic reduction of 4-nitrophenol.

4-Nitrophenol (4-NP) is reported to originate disadvantageous effects on the human body collected from industrial pollutants; therefore, the detoxification of 4-NP in aqueous contamination is strongly recommended. In this study, the heterojunction mesoporous α-Fe2O3/TiO2 modulated with diverse Ag percentages has been constructed via a sol-gel route in the occurrence of a soft template P123. The formation of biphasic crystalline TiO2 anatase and brookite phases has been successfully achieved with the average 10 nm particle sizes. The photo/-catalytic reduction of 4-NP has been performed utilizing NaBH4 as a reducing agent with and without visible illumination. All Ag/Fe2O3/TiO2 nanocomposites exhibited significantly higher photo/-catalytic reduction efficiency than pure Fe2O3, TiO2 NPs, and Fe2O3/TiO2 nanocomposite. 2.5% Ag/Fe2O3/TiO2 nanocomposite was considered the highest and superior photocatalytic reduction efficiency, and it almost achieved 98% after 9 min. Interestingly, the photocatalytic reduction of 4-NP was accelerated 9 times higher than the catalytic reduction over 2.5% Ag/Fe2O3/TiO2; its rate constant value was 709 and 706 times larger than pure TiO2 and Fe2O3 NPs, respectively. The enhanced photocatalytic reduction ability of Ag/Fe2O3/TiO2 nanocomposite might be referred to as significantly providing visible light absorption and a large surface area, and it can upgrade the effective separation and mobility of electron holes. The stability of the synthesized catalysts exhibited that the obtained catalysts can undergo a slight decrease in reduction efficiency after five successive cycles. This approach highlights a novel route for constructing ternary nanocomposite systems with high photo/-catalytic ability.

Hierarchical porous TiO2 with a uniform distribution of anchored gold nanoparticles for enhanced photocatalytic efficiency and accelerated charge separation for the degradation of antibiotics.

A novel approach to synthesize porous Au/TiO2 nanocomposites has been achieved through a pyrolytic strategy by employing NH2-MIL-125(Ti) as a TiO2 precursor, and photo-deposition of Au nanoparticles (NPs) onto porous nanocrystalline TiO2 with varying Au contents (0.05-0.5%). TEM images of Au/TiO2 nanocomposites showed that TiO2 particles were spherical structures, highly dispersed, and homogeneous with diameters of 10-15 nm, and Au NPs (20-30 nm) were anchored onto porous TiO2 matrices with a uniform distribution. The synthesized Au/TiO2 nanocomposites were assessed through the degradation of two antibiotic models, metronidazole (MNZ), and trimethoprim (TMP), under visible light and compared with undoped TiO2 and commercial TiO2 (P-25). The synthesized Au/TiO2 photocatalyst revealed enhanced photocatalytic performance in the mineralization (80%) and degradation (100%) of MNZ and TMP in both water matrices compared to undoped TiO2 (60%, 76%) and commercial P-25 (48%, 65%). The obtained 0.1% Au/TiO2 nanocomposite could complete the mineralization of TMP and MNZ with rate constant values (4.47 × 10-3 min-1 and 5.23 × 10-1 min-1) owing to the large well-developed porosity and high surface area of TiO2 and the small size of Au NPs with high dispersity, surface plasmon resonance, and stability. The recyclability of the 0.1% Au/TiO2 nanocomposite exhibited high durability without the leaching or loss of photocatalytic performance after four cycles. Complete degradation was achieved within 100 min in the water matrix from real wastewater, indicating promising results for the degradation of pharmaceuticals in the different water matrices. The present work opens a new route to synthesize low-cost, effective, and high photocatalytic performance nanocomposites with a small Au content as a cocatalyst onto semiconductor materials.

Mesoporous BiVO4/TiO2 heterojunction: enhanced photoabsorption and photocatalytic ability through promoted charge transfer.

BiVO4 has been constructed into heterojunctions with TiO2 to boost the photocatalytic ability under visible illumination. Here, mesoporous BiVO4/TiO2 nanocomposites have been fabricated by a facile sol-gel approach utilizing nonionic surfactant and addressed for morphological, optical, structural, and degradation of ciprofloxacin (CIP) in water under visible illumination as an antibiotic pollutant model. The TEM images demonstrated that the TiO2 NPs are homogenous in terms of shape and size (15 ± 5 nm). The introduction of BiVO4 into mesoporous TiO2 could effectively enhance the rapid separation efficiency of the photoinduced carriers and optical absorption. The 3%BiVO4/TiO2 photocatalyst possessed the best degradation efficiency (100%) within 60 min which was promoted 20-folds larger than TiO2 NPs (5%). 3%BiVO4/TiO2 nanocomposite exhibited the fastest degradation rate (2.15 × 10-2 min-1), which was 40 times faster than bare TiO2 photocatalyst (0.05 × 10-2 min-1). The enhanced photocatalytic ability originated from superior charge separation characteristics and high solar energy absorption in mesopore structures. The recombination rate and mobility of charge carriers were characterized utilizing photoluminescence (PL) and photoelectrochemical measurements. This work highlights the advantages of mesoporous heterojunction BiVO4/TiO2 nanocomposites for photocatalytic performances and provides a multilateral route to design an effective wide-spectrum response photocatalyst for the development of comparable materials. The photocatalytic mechanism for degradation CIP over BiVO4/TiO2 was discussed in detail..

Impact of reaction parameters for photodegradation pharmaceuticals in wastewater over gold/titania photocatalyst synthesized by pyrolysis of NH2-MIL-125(Ti).

The efficient remediation of pharmaceuticals, including wastewater, remains a remarkably challenging issue for water regeneration. Herein, porous Au/TiO2 synthesized by pyrolysis of NH2-MIL-125(Ti) was utilized to be an efficient photocatalyst for mineralization of trimethoprim (TMP) and Metronidazole (MNZ) as the parent compound. The effects of different factors, including TMP and MNZ concentrations, light intensity, H2O2 concentration, Au/TiO2 dosage, and pH value of reaction solution on the degradation and mineralization performances during UV and visible light (VIS), were addressed. The porous Au/TiO2 photocatalyst exhibited superior photocatalytic degradation of TMP and MNZ under UV and VIS illumination. The optimum pH values were 4; the optimum dosage of Au/TiO2 was 1.5 g/L, H2O2 concentration was 9.8 mM, TMP and MNZ concentrations was 10 ppm, and their photodegradation efficiency was 100% after 30 min illumination time and mineralization efficiency 98.2% after 3 h illumination for TMP and MNZ, respectively under UV illumination, however, the photodegradation efficiency was 100% after 50 min illumination and mineralization efficiency 96.3% after 4.5 h illumination time for TMP and MNZ, respectively under VIS illumination. The real wastewater matrix with 10 mg/L of TMP and MNZ were subjected to 60 min of illumination under similar optimum conditions of synthetic solution. The results indicated that photodegradation efficiency was determined to be 100% after 70 min illumination time for removal of both TMP (k = 3.4 × 10-2 min-1) and MNZ (k = 2.87 × 10-2 min-1). This is ascribed to the incorporation of Au NPs onto TiO2, reducing the photoinduced electron-hole recombination, thus promoting the photocatalytic performance. The possible mechanism for photodegradation of antibiotics was also discussed. The demonstration of photocatalysis mechanism over Au/TiO2 photocatalyst can provide some directing in the enhancement of novel photocatalysts based on MOFs doped by noble metal.

S-scheme mesoporous Li2MnO3/g-C3N4 heterojunctions as efficient photocatalysts for the mineralization of trichloroethylene in aqueous media.

Novel mesoporous Li2MnO3/g-C3N4 heterostructures were prepared for the first time by utilizing the sol-gel route in the presence of a nonionic surfactant. TEM and XRD measurements showed that Li2MnO3 (5-10 nm) with monoclinic structures was uniformly distributed onto porous g-C3N4 for the construction of Li2MnO3/g-C3N4 heterojunctions. The obtained photocatalysts were assessed for mineralization and removal of trichloroethylene (TCE) in aqueous media under visible light exposure. Complete degradation of TCE over a 3 %Li2MnO3/g-C3N4 heterostructure within 120 min was achieved. The degradation rate over Li2MnO3/g-C3N4 heterostructures was significantly enhanced, and the 3% Li2MnO3/g-C3N4 heterostructure exhibited a large degradation rate of 7.04 µmolL-1 min-1, which was enhanced by 5 and 3.8 fold compared to those of pristine g-C3N4 (1.39 µmolL-1 min-1) and Li2MnO3 (1.85 µmolL-1 min-1), respectively. The photocatalytic efficiency of the Li2MnO3/g-C3N4 heterojunction was outstandingly promoted because integrating Li2MnO3 with g-C3N4 could create close interfaces with well-matched band potentials for easy mobility and low recombination of photoinduced carriers. The coexistence of Li2MnO3/g-C3N4 interfaces led to a synergic effect, which is considered the key factor in photoinduced electron-hole separation. The synthesis procedure that was employed here is a promising process for the preparation of effective g-C3N4-based photocatalyst systems for photocatalysis applications.

Highly Dispersed Pt Nanoparticle-Doped Mesoporous ZnO Photocatalysts for Promoting Photoconversion of CO2 to Methanol.

Photoreduction of CO2 is considered a challenge due to the lack of effective photocatalysts with wide-spectrum absorption, active charge separation dynamically, and CO2 adsorption. Herein, mesoporous Pt/ZnO nanocomposites with different Pt percentages (0.5-2%) have been fabricated using the sol-gel process in the presence of a template for CO2 photoreduction during visible-light exposure. Pt nanoparticles (NPs) deposited onto mesoporous ZnO with a considerable surface area can effectively promote charge mobility. The mesoporous 1.5% Pt/ZnO nanocomposite exhibits an optimal CH3OH yield (668 µmol g-1), which is 18.5-fold larger than that of mesoporous ZnO (36 µmol g-1). The most photoactive material was the 1.5% Pt/ZnO nanocomposite, producing CH3OH of 668 µmol g-1, and the production rate of CH3OH over the 1.5% Pt/ZnO nanocomposite (74.11 µmol g-1 h-1) was increased 20 times in comparison with ZnO NPs (3.72 µmol g-1 h-1). The enhancement of CO2 photoreduction efficiency over Pt/ZnO nanocomposites was attributed to the formation of the heterojunction at the Pt/ZnO interface, promoting a lower resistance to charge transfer and a larger electron transfer to the conduction band. Mesoporous Pt/ZnO nanocomposites offer enhanced accessibility and a larger surface area. Such an unparalleled mesostructure provides a new framework for the construction and design of photoactive materials with high-efficiency photocatalysts.

Intense Visible-Light Absorption in SrRuO3/C3N4 Heterostructures for the Highly Efficient Reduction of Hg(II).

Strontium ruthenium oxide (SrRuO3) is recognized as a metallic itinerant ferromagnet and utilized as a conducting electrode in heterostructure oxides with unforeseen optical characteristics, including remarkably low-reflection and high-absorption visible-light spectrum compared to classical metals. By coupling mesoporous SrRuO3 nanoparticles (NPs) with porous g-C3N4 nanosheets for the first time, we evidence remarkably promoted visible light absorption and superior photocatalytic performances for Hg(II) reduction under illumination with visible light. The photocatalytic performance of g-C3N4 increased upon boosting the SrRuO3 percentage to 1.5%, and this (1.5% SrRuO3/g-C3N4 heterostructure) is considered the optimum condition to obtain a high photocatalytic efficiency of about 100% within 50 min. It was promoted 3.68 and 5.75 times compared to SrRuO3 and g-C3N4, respectively. Also, a Hg(II) reduction rate of 1.5% SrRuO3/g-C3N4 was enhanced3.84- and 6.28-fold than those of pure SrRuO3 NPs and g-C3N4, respectively. Such a high photocatalytic performance over SrRuO3/g-C3N4 photocatalysts was explained by the characteristics of SrRuO3 NPs incorporated on porous g-C3N4 layers, which demonstrate strong absorption of visible light with a narrow band gap, a large photocurrent density of ∼9.07 mA/cm2, well-dispersed and small particle sizes, and cause facile diffusion of HCOOH and Hg(II) ions and electrons. The present work provides a dramatic novel approach to the challenge of constructing visible-light photosensitive photocatalysts for wastewater remediation.

Hydrogen Generation over RuO2 Nanoparticle-Decorated LaNaTaO3 Perovskite Photocatalysts under UV Exposure.

The efficacy of LaNaTaO3 perovskites decoration RuO2 at diverse contents for the photocatalytic H2 generation has been explored in this study. The photocatalytic performance of RuO2 co-catalyst onto mesoporous LaNaTaO3 was evaluated for H2 under UV illumination. 3%RuO2/LaNaTaO3 perovskite photocatalyst revealed the highest photocatalytic H2 generation performance, indicating that RuO2 nanoparticles could promote the photocatalytic efficiency of LaNaTaO3 perovskite significantly. The H2 evolution rate of 3%RuO2/LaNaTaO3 perovskite is 11.6 and 1.3 times greater than that of bare LaNaTaO3 perovskite employing either 10% CH3OH or pure H2O, respectively. Interestingly, the photonic efficiency of 3%RuO2/LaNaTaO3 perovskite was enhanced 10 times than LaNaTaO3 perovskite in the presence of aqueous CH3OH solutions as a hole sacrificial agent. The high separation of charge carriers is interpreted by the efficient hole capture using CH3OH, hence leading to greater H2 generation over RuO2/LaNaTaO3 perovskites. This is attributed to an adjustment position between recombination electron-hole pairs and also the reduction of potential conduction alignment as a result of RuO2 incorporation. The suggested mechanisms of RuO2/LaNaTaO3 perovskites for H2 generation employing either CH3OH or pure H2O were discussed. The photocatalytic performances of the perovskite photocatalyst were elucidated according to the PL intensity and the photocurrent response investigations.

Fabrication of Mesoporous PtO-ZnO Nanocomposites with Promoted Photocatalytic Performance for Degradation of Tetracycline.

Herein, we report a simple incorporation of PtO NPs at diverse percentages (0.2-0.8 wt %) onto a highly crystalline and mesoporous ZnO matrix by the wet-impregnation approach for degradation of tetracycline (TC) upon visible light exposure. These well-dispersed and small-sized PtO NPs provide the mesoporous PtO-ZnO nanocomposites with outstanding photocatalytic performance for complete TC degradation. The optimized 0.6% PtO-ZnO photocatalyst exhibits excellent TC degradation, and its degradation efficiency reached ∼99% within 120 min. The photocatalytic performance of the 0.6% PtO-ZnO nanocomposite is 20 and 10 times higher than that of pristine ZnO and commercial P-25, respectively. The photodegradation rate of TC over the 0.6% PtO-ZnO nanocomposite is 34 and 12.5 times greater than that of pristine ZnO and commercial P-25, respectively. This is because of the large surface area, unique porous structure, synergistic effect, and broad visible light absorption of the PtO-ZnO nanocomposite. Moreover, mesoporous PtO-ZnO nanocomposites showed a high stability and recyclability over five iterations. This work demonstrates the remarkable role of combining PtO and ZnO photocatalysts in providing nanocomposites with significant potential for the preservation of human health through wastewater remediation.

Soft and hard templates assisted synthesis mesoporous CuO/g-C3N4 heterostructures for highly enhanced and accelerated Hg(II) photoreduction under visible light.

Herein, triblock copolymer surfactant (F127) and mesoporous silica (MCM-41) as soft and hard templates were employed to synthesize of mesoporous CuO/g-C3N4 heterostructures with large surface areas for Hg(II) photoreduction in existence of formic acid as a holes sacrificial. TEM image for mesoporous CuO/g-C3N4 indicated that CuO NPs are homogeneously distributed with spherical shape in particle size ~5 nm onto the surface of g-C3N4. Mesoporous 2%CuO/g-C3N4 heterostructure was achieved a high Hg(II) photoreduction rate of 628.74 µmolg-1h-1 and high photoreduction efficiency of ~100% within 50 min compared with the pure either mesoporous CuO NPs (130.11 µmolg-1h-1, 21%) and g-C3N4 (88.54 µmolg-1h-1, 14%). The highest Hg(II) photoreduction rate achieved was 628.74 µmolg-1h-1, which is 4.83 and 7.1 magnitudes stronger than mesoporous CuO NPs and g-C3N4. The excellent photocatalytic performance of mesoporous CuO/g-C3N4 heterostructures for Hg(II) photoreduction is referred to highly dispersed mesoporous CuO NPs with small particle size onto g-C3N4, narrow bandgap, large surface area, a rapid transfer of Hg(II) ions and HCOOH to easily reach the active sites due to the facile penetration through the mesostructure, thus promoting the utilization of porous structure of CuO/g-C3N4 heterostructures for efficient diffusion of Hg(II) ions. The intense interaction between mesoporous CuO NPs and porous g-C3N4 confirms the durability of the CuO/g-C3N4 heterostructures during recyclability for five times.

Facile Synthesis of Mesoporous Ag2O-ZnO Heterojunctions for Efficient Promotion of Visible Light Photodegradation of Tetracycline.

Fabrication of 3D mesoporous Ag2O-ZnO heterojunctions at varying Ag2O contents has been achieved through poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic F-108) as the structure-directing agent for the first time. The mesoporous Ag2O-ZnO nanocomposites exhibited a mesoporous structure, which revealed a large pore volume and high surface area. The photocatalytic efficiency over mesoporous Ag2O-ZnO nanocomposites for tetracycline (TC) compared with that over commercial P-25 and pristine ZnO NPs through the visible light exposure was studied. Mesoporous 1.5% Ag2O-ZnO nanocomposites indicated the highest degradation efficiency of 100% of TC during 120 min of the visible light exposure compared with 5% and 10% for pristine ZnO NPs and commercial P-25, respectively. The TC degradation rate took place much rapidly over 1.5% Ag2O-ZnO nanocomposites (0.798 µmol L-1 min-1) as compared to either commercial P-25 (0.097 µmol L-1 min-1) or ZnO NPs (0.035 µmol L-1 min-1). The mesoporous 1.5% Ag2O-ZnO nanocomposite revealed the highest degradation rate among all synthesized samples, and it was 23 and 8 orders of magnitudes greater than those of pristine ZnO NPs and P-25, respectively. The photoluminescence and transient photocurrent intensity behaviors have been discussed to explore photocatalysis mechanisms. It is anticipated that the present work will contribute some suggestions for understanding other heterojunctions with outstanding behaviors.

Doping Strontium into Neodymium Manganites Nanocomposites for Enhanced Visible light Driven Photocatalysis.

Nd1-xSrxMnO3 nanocomposites perovskites were synthesized using sol gel method at different Sr content x = 0.3, 0.5, 0.7, and 0.9. The photocatalytic performance of the Nd1-xSrxMnO3 nanocomposites for photodegradation of Acridine orange dye (AO) was evaluated over visible light illumination. The single phase of orthorhombic pbnm was formed for x = 0.3 and 0.5; however monoclinic and orthorhombic were observed at x = 0.7 and 0.9. The Energy gap of the Nd1-xSrxMnO3 nanocomposites were estimated for all concentrations to be in the range of 3 ± 0.05 eV. The photocatalytic efficiency of Nd0.3Sr0.7MnO3 nanocomposite was 95% of the initial AO dye concentration within 3 h illumination time. The linear increase of the photodegradation rate was found in our samples as a result of the increase of Sr contents from 0.3 to 0.7wt %. Interestingly, the Nd0.3Sr0.7MnO3 content has the highest degradation rate of AO which is two times faster than undoped NdMnO3. This superior behavior in photocatalytic activity of Nd0.3Sr0.7MnO3 nanocomposite emerges from large surface area, structural anisotropy, and small particle size. These findings shows convincingly that the Nd1-xSrxMnO3 photocatalysts possess great promise for visible light driven photodegradation of AO dye.

Photodegradation of Microcystin-LR Using Visible Light-Activated C/N-co-Modified Mesoporous TiO2 Photocatalyst.

Microcystin-LR (MC-LR), a potent hepatotoxin produced by the cyanobacteria, is of increasing concern worldwide because of severe and persistent impacts on humans and animals by inhalation and consumption of contaminated waters and food. In this work, MC-LR was removed completely from aqueous solution using visible-light-active C/N-co-modified mesoporous anatase/brookite TiO2 photocatalyst. The co-modified TiO2 nanoparticles were synthesized by a one-pot hydrothermal process, and then calcined at different temperatures (300, 400, and 500 °C). All the obtained TiO2 powders were analyzed by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM), specific surface area (SSA) measurements, ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL) analysis. It was found that all samples contained mixed-phase TiO2 (anatase and brookite), and the content of brookite decreased with an increase in calcination temperature, as well as the specific surface area and the content of non-metal elements. The effects of initial pH value, the TiO2 content, and MC-LR concentration on the photocatalytic activity were also studied. It was found that the photocatalytic activity of the obtained TiO2 photocatalysts declined with increasing temperature. The complete degradation (100%) of MC-LR (10 mg L-1) was observed within 3 h, using as-synthesized co-modified TiO2 (0.4 g L-1) at pH 4 under visible light. Based on the obtained results, the mechanism of MC-LR degradation has been proposed.

Highly Sensitive Ethanol Chemical Sensor Based on Novel Ag-Doped Mesoporous α-Fe2O3 Prepared by Modified Sol-Gel Process.

Mesoporous α-Fe2O3 has been synthesized via a simple sol-gel procedure in the presence of Pluronic (F-127) triblock copolymer as structure directing agent. Silver (Ag) nanoparticles were deposited onto α-Fe2O3 matrix by the photochemical reduction approach. Morphological analysis revealed the formation of Ag nanoparticles with small sizes < 20 nm onto the mesoporous structure of α-Fe2O3 possessing < 50 nm semi-spherical shape. The XRD, FTIR, Raman, UV-vis, PL, and N2 sorption isotherm studies confirmed the high crystallinity, mesoporosity, and optical characteristics of the synthesized product. The electrochemical sensing toward liquid ethanol has been performed using the current devolved Ag/α-Fe2O3-modified glassy carbon electrode (GCE) by cyclic voltammetry (CV) and current potential (I-V) techniques, and the obtained results were compared with bare GCE or pure α-Fe2O3. Mesoporous Ag/α-Fe2O3 was found to largely enhance the sensor sensitivity and it exhibited excellent sensing characteristics during the precision detection of low concentrations of ethanol. High and reproducible sensitivity of 41.27 µAmM- 1 cm- 2 at lower ethanol concentration region (0.05 to 0.8 mM) and 2.93 µAmM- 1 cm- 2 at higher concentration zone (0.8 to 15 mM), with a limit of detection (LOD) of 15.4 µM have been achieved. Investigation on reaction kinetics revealed a characteristic behavior of mixed surface and diffusion-controlled processes. Detailed sensing studies revealed also that the sensitivity toward ethanol was higher than that of methanol or isopropanol. With further effort in developing the synthesis and fabrication approaches, a proper utility for the current proposed protocol for fabricating a better sensor device performance is possible.

Mesoporous WO3-graphene photocatalyst for photocatalytic degradation of Methylene Blue dye under visible light illumination.

Advanced oxidation technologies are a friendly environmental approach for the remediation of industrial wastewaters. Here, one pot synthesis of mesoporous WO3 and WO3-graphene oxide (GO) nanocomposites has been performed through the sol-gel method. Then, platinum (Pt) nanoparticles were deposited onto the WO3 and WO3-GO nanocomposite through photochemical reduction to produce mesoporous Pt/WO3 and Pt/WO3-GO nanocomposites. X-ray diffraction (XRD) findings exhibit a formation of monoclinic and triclinic WO3 phases. Transmission Electron Microscope (TEM) images of Pt/WO3-GO nanocomposites exhibited that WO3 nanoparticles are obviously agglomerated and the particle sizes of Pt and WO3 are ~10nm and 20-50nm, respectively. The mesoporous Pt/WO3 and Pt/WO3-GO nanocomposites were assessed for photocatalytic degradation of Methylene Blue (MB) as a probe molecule under visible light illumination. The findings showed that mesoporous Pt/WO3, WO3-GO and Pt/WO3-GO nanocomposites exhibited much higher photocatalytic efficiencies than the pure WO3. The photodegradation rates by mesoporous Pt/WO3-GO nanocomposites are 3, 2 and 1.15 times greater than those by mesoporous WO3, WO3-GO, and Pt/WO3, respectively. The key factors of the enhanced photocatalytic performance of Pt/WO3-GO nanocomposites could be explained by the highly freedom electron transfer through the synergetic effect between WO3 and GO sheets, in addition to the Pt nanoparticles that act as active sites for O2 reduction, which suppresses the electron hole pair recombination in the Pt/WO3-GO nanocomposites.

Efficient photodecomposition of herbicide imazapyr over mesoporous Ga2O3-TiO2 nanocomposites.

The unabated release of herbicide imazapyr into the soil and groundwater led to crop destruction and several pollution-related concerns. In this contribution, heterogeneous photocatalytic technique was employed utilizing mesoporous Ga2O3-TiO2 nanocomposites for degrading imazapyr herbicide as a model pollutant molecule. Mesoporous Ga2O3-TiO2 nanocomposites with varied Ga2O3 contents (0-5wt%) were synthesized through sol-gel process. XRD and Raman spectra exhibited extremely crystalline anatase TiO2 phase at low Ga2O3 content which gradually reduced with the increase of Ga2O3 content. TEM images display uniform TiO2 particles (10±2nm) with mesoporous structure. The mesoporous TiO2 exhibits large surface areas of 167m2g-1, diminished to 108m2g-1 upon 5% Ga2O3 incorporation, with tunable mesopore diameter in the range of 3-9nm. The photocatalytic efficiency of synthesized Ga2O3-TiO2 nanocomposites was assessed by degrading imazapyr herbicide and comparing with commercial photocatalyst UV-100 and mesoporous Ga2O3 under UV illumination. 0.1% Ga2O3-TiO2 nanocomposite is considered the optimum photocatalyst, which degrades 98% of imazapyr herbicide within 180min. Also, the photodegradation rate of imazapyr using 0.1% Ga2O3-TiO2 nanocomposite is nearly 10 and 3-fold higher than that of mesoporous Ga2O3 and UV-100, respectively. The high photonic efficiency and long-term stability of the mesoporous Ga2O3-TiO2 nanocomposites are ascribed to its stronger oxidative capability in comparison with either mesoporous TiO2, Ga2O3 or commercial UV-100.

The insulin autoimmune syndrome (IAS) as a cause of hypoglycaemia: an update on the pathophysiology, biochemical investigations and diagnosis.

Insulin autoimmune syndrome (IAS) is considered to be very rare in Caucasians. Understanding its pathophysiology is paramount in (a) appreciating its potential impact on analyses of pancreatic hormones and (b) explaining its highly variable clinical manifestations in non-diabetic, non-acutely ill patients with indeterminate hypoglycaemia. The underlying aetiology of IAS is the presence of variable affinity/avidity endogenous insulin antibodies in significant amounts. The two types of insulin antibodies namely antibodies which bind insulin and/or proinsulin(s) and receptor antibodies (insulin mimetic) will be discussed. Their biochemical and immunological roles in causing hypoglycaemia will be highlighted. Clinical manifestations of IAS can vary from mild and transient to spontaneous, severe and protracted hypoglycaemia necessitating in extreme cases plasmapheresis for glycaemic control. Antibodies of IAS can interfere in pancreatic immunoassay tests causing erroneous and potentially misleading results. Thorough testing for endogenous insulin antibodies must be considered in the investigations of non-diabetic, non-acutely ill patients with indeterminate and/or unexplained hypoglycaemia.

Synthesis of mesoporous sulfur-doped Ta2O5 nanocomposites and their photocatalytic activities.

Mesoporous sulfur (S)-doped Ta2O5 nanocomposites have been synthesized for the first time through the sol-gel reaction of tantalum chloride and thiourea in the presence of a F127 triblock copolymer as structure directing agent. The as-formed mesophase S-doped Ta2O5 hybrid gels were calcined at 700°C for 4h to obtain mesoporous S-Ta2O5 nanocomposites. The experimental results indicated that the surface area of the S-doped Ta2O5 was up to 50m(2)g(-1) and the pore diameter was controllable in the range of 3-7.7nm. The S-doped Ta2O5 nanocomposites behave as superior visible light-sensitive photocatalysts and the 1.5at.% S-doped Ta2O5 (S1.5) photocatalyst exhibited excellent photocatalytic activity of ∼92% for the photodegradation of methylene blue, identical to 80% TOC removal after three hours illumination under visible light. The photodegradation rate of S1.5 photocatalyst showed 3.4 times higher than the undoped Ta2O5 due to their narrow bandgap, large surface area, mesostructure and well crystalline state. The S1.5 photocatalyst could be recycled at least five times without an apparent decrease in its photocatalytic efficiency, indicating its high stability for practical applications. To the best of our knowledge, this is the first report that demonstrates one-step synthesis of mesoporous S-doped Ta2O5 nanocomposites as an efficient photocatalysts under visible light illumination.

Ease synthesis of mesoporous WO3-TiO2 nanocomposites with enhanced photocatalytic performance for photodegradation of herbicide imazapyr under visible light and UV illumination.

Herein, we report the ease synthesis of mesoporous WO3-TiO2 nanocomposites at different WO3 contents (0-5wt%) together with their photocatalytic performance for the degradation of the imazapyr herbicide under visible light and UV illumination. XRD and Raman spectra indicated that the highly crystalline anatase TiO2 phase and monoclinic and triclinic of WO3 were formed. The mesoporous TiO2 exhibits large pore volumes of 0.267cm(3)g-1 and high surface areas of 180m(2)g(-1) but they become reduced to 0.221cm(3)g(-1) and 113m(2)g(-1), respectively upon WO3 incorporation, with tunable mesopore diameter in the range of 5-6.5nm. TEM images show WO3-TiO2 nanocomposites are quite uniform with 10-15nm of TiO2 and 5-10nm of WO3 sizes. Under UV illumination, the overall photocatalytic efficiency of the 3% WO3-TiO2 nanocomposite is 3.5 and 6.6 times higher than that of mesoporous TiO2 and commercial UV-100 photocatalyst, respectively. The 3% WO3-TiO2 nanocomposite is considered to be the optimum photocatalyst which is able to degrade completely (100% conversion) of imazapyr herbicide along 120min with high photonic efficiency ∼8%. While under visible light illumination, the 0.5% WO3-TiO2 nanocomposite is the optimum photocatalyst which achieves 46% photocatalytic efficiency.