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Ascorbic acid (AA) is one of the vital water-soluble antioxidants in blood serum and can function as a key blood serum biomarker for oxidative stress. Therefore, we have developed a highly sensitive and selective AA electrochemical sensor based on novel porous silicon-mesoporous carbon nanocomposites (PSi-MC NCs) modified glassy carbon electrode (GCE). The structural properties and morphological investigation of the PSi-MC NCs were systematically studied by different techniques. This newly designed PSi-MC/GCE-based non-enzymatic electrochemical sensor can measure an extremely wide range of AA (0.5–2473 μM) in phosphate buffer solution (PBS) with a sensitivity 0.1982 μAμM−1cm−2 and a logical limit of detection (LOD) 30.0±0.1 nM. The proposed AA sensor was also applied to detect possible interference from common interfering substances that are present in human blood, showing highly selective performance. The proposed AA sensor also showed highly acceptable results towards the detection of AA levels in human blood serum and vitamin C tablets. This new combination of active material PSi-MC NCs provided steady, excellent reproducibility, repeatability, and long-term stability.

Metal-organic framework (MOF) thin films with flexible nature and prominent qualities have opened doors to new technological applications in different fields. Herein, we propose an electrochemical biosensor for the dual detection of Staphylococcus aureus based on the electrodeposition of Cu metal-organic framework (Cu-MOF) thin films. The promising sensing layer with features of good electronic conductivity and enhanced electron-transfer property can not only identify S. aureus through specific micrococcal nucleases in the supernatant but also detect the pathogen directly via aptamer recognition. The dual analysis design ensures the accuracy of this method for S. aureus detection in the range of 7-7 × 106 cfu/mL with the limits of detection of 1.9 and 5.2 cfu/mL. Moreover, the analytical method validation confirmed that the biosensor could efficiently work in complex biological samples, showing good selectivity and specificity and great potential for clinical diagnosis. More importantly, the current proposed strategy is simple and easy to implement without the need for extra signaling elements, which is convenient for timely clinical detection.

Creation of novel clean light responsive photocatalytic organization requires adequate technical skills and exhaustive efforts. The aim of the current study is to create novel, highly influential photocatalyst frameworks working under visible-light utilizing ZnO/SnO2 nanocomposites in conjugation with biomass originated active carbon (AC) for environmental concerns. The ZnO/SnO2 nanocomposite was created by the sol-gel approach followed by ultra-sonication technique to form trio combination with AC. The XRD investigation displays rutile tetragonal structure of SnO2 and hexagonal wurtzite phase of ZnO in all fabricated nanocomposites. The XPS and FTIR investigations confirmed the elemental composition and successful establishment of trio structure of AC, ZnO and SnO2. Perfect tailoring during the creation process results in achieving band gap values of various AC@ZnO/SnO2 nanocomposites in visible region. The FESEM images of AC@ZnO/SnO2 nanocomposites exhibit particles, rods and sheets like-structures confirming the successful creation of impeccable organization among AC, ZnO and SnO2. The HR-TEM image of 10% AC@ZnO/SnO2 nanocomposite revealed the crystallographic planes (101) and (110) for hexagonal wurtzite ZnO and tetragonal rutile of SnO2. Among various created nanostructures, the 10% AC@ZnO/SnO2 trio organization was found to be the most influential with 94.6 % removal of target linezolid antibiotic and almost complete destruction of insecticide imidacloprid and MB complex structure in just 25 minutes under visible light condition. The 10% AC@ZnO/SnO2 photocatalyst was found to be the most influential candidate giving ⁓ 8.16 times higher detrimental skills than that of pure SnO2. These extraordinary outputs by the newly fabricated 10%AC@ZnO/SnO2 photocatalyst open a new gateway to exploit this promising material towards various environmental issues.

Polyvinyl alcohol (PVA) incorporated with various amounts of ammonium iodide salt (NH4I) composite polymer electrolyte films were prepared via the casting process. The XRD analysis, as a tool for structural investigation, confirms the polymer electrolytes formation. The transmittances of the studied samples are decreased with increasing NH4I fillers. The UV–Vis absorption spectra are shifted to the higher wavelengths, which indicate their importance for light shielding devices. The bandgaps decrease with the increase in NH4I content, attributed to the increase in the crystallite size. The calculated Urbach energy was found to increase with increasing NH4I salt fillers. The samples' optical limiting is carefully investigated using a He–Ne laser beam of wavelength = 632.8 nm. This result enhances light absorption behavior and makes the material suitable for optical UV-protection devices. The correlation between dielectric properties and conductivity is also understood and discussed. The dielectric permittivity e' of the samples is associated with the dipole, and polarization increased with the addition of NH4I salt content as the particle size increased according to XRD analysis. AC impedance spectroscopy was carried out to disclose the PVA doped with NH4I polymer electrolyte films as a function of various NH4I salt fillers. The analysis via complex electric modulus gives abnormal behavior by adding NH4I salt content, where the minimization of the electrode polarization can be achieved. Our results indicate that the newly designed composite polymeric electrolyte films are commonly appropriate for electronic and optoelectronic devices.

Surface and bandgap engineering of graphitic carbon nitride (g-C3N4) could be vital in enhancing photocatalytic performance by suppressing the recombination rate of photogenerated electron-hole pairs. The present report investigated the doping effects of various wt.% (0.2–5.0%) of gold nanoparticles (Au NPs) to g-C3N4 (Au/g-C3N4) for the enhancement of the photocatalytic efficiency of g-C3N4 nanocomposites. A straightforward and cost-effective synthesis methodology has been applied for the desired nanocomposites. Relevant characterization tools such as XRD, XPS, TEM, FTIR, and UV–Vis were utilized to analyze various physicochemical properties. The TEM images clearly show that spherical Au NPs were homogeneously distributed into the thin carbon nitride graphitic layers, confirming the successful doping of Au. The higher-magnification TEM image confirms that the sizes of the Au NPs varied from 15 to 25 nm. The photoactivity of the newly designed Au/g-C3N4 nanocomposites has been evaluated for the degradation of both methylene blue dye and the drug gemifloxacin mesylate, and their efficiencies were compared with that of bare g-C3N4. Our findings revealed that Au/g-C3N4 nanocomposites with various Au contents had superior photocatalytic activity compared to bare g-C3N4. However, the 1%Au/g-C3N4 nanocomposite could be considered the optimum photocatalyst, producing 95.13% destruction of the target dye molecule in 90 min, in contrast to the 69% achieved with bare g-C3N4, under the clean energy of visible light illumination. Additionally, the photodegradation rate of the 1%Au/g-C3N4 nanocomposite is 2.69 times higher than the rate of bare g-C3N4. This report might open a new gateway towards a straightforward and cost-effective synthesis approach for Au/g-C3N4 nanocomposites and provides a smooth and robust platform for the utilization of this new nanocomposite for environmental remediation processes.

Electrochemical biosensing relies on electron transport on the electrode surface. However, the limited functional area of the two-dimensional electrode prevents the qualitative breakthrough in the efficiency of electron transfer. Here, a three-dimensional electron transporter was constructed to improve the efficiency of electron transfer by using an interface-immobilized DNA hydrogel. A three-dimensional pure DNA hydrogel is constructed and used as a scaffold for electron transfer. Then, an electron mediator is embedded in the DNA hydrogel through intercalative binding, and DNAzyme with intrinsic peroxidase-like activity is introduced at the node of the hydrogel scaffold to fabricate an electrochemical biosensor. The conduction of the electron mediator in the scaffold enables the acquisition of long-distance DNAzyme catalytic signals, thereby overcoming the limitation of two-dimensional electrodes. This three-dimensional electron transporter is significant for enriching the toolbox of electrochemical biosensing and can provide potential support for the development of highly sensitive biosensors.

The coupling between inorganic semiconductor metal oxide and nanocarbon material is a proper route to fabricate efficient electrochemical sensors. Herein, the electrocatalytic oxidation, detection of nitrite ions (NO2−) is investigated using reduced graphene oxide/mesoporous zinc oxide (rGO/ZnO) nanocomposite-modified glassy carbon electrode (GCE). The mesoporous ZnO and rGO were prepared via a modified sol-gel in presence of F127 structural template agent and modified Hummers’ methods, respectively. The rGO/ZnO nanocomposite was then produced via a simple ultrasonication and characterized using various analytical techniques to examine the morphology, structure and chemical constituents. The newly-developed rGO/ZnO/Nafion nanocomposite exhibited remarkable sensing response towards NO2− oxidation compared to bare GCE or ZnO/Nafion/GCE. The rGO/ZnO/Nafion/GCE sensor demonstrated a linear dynamic range between 200 and 4000 µM for linear sweep voltammetry (LSV) and 20 to 520 µM (for amperometry). Remarkable sensitivity and low limit of detection (LOD: at S/N = 3) were projected to be 0.3156 μAμM−1cm−2 and 1.18 μM for LSV, whereas values of 0.2754 μAμM−1cm−2 and 1.36 µM were obtained using the amperometric technique. The modified electrocatalyst demonstrated excellent operational stability, reproducibility and anti-interfering ability towards several common active species. The developed rGO/ZnO/GCE electrode represents a favorable strategy for efficient detection and quantification of NO2− by the electrochemical approach.

This study was designed to isolate microalgal species which can tolerate severe environmental stresses and can be used for wastewater treatment and biofuel generation. Three different microalgal strains (including Chlorella sorokiniana GEEL-01, Parachlorella kessleri GEEL-02, and Parachlorella kessleri GEEL-03) were isolated from a wastewater treatment plant and Waterwheel Park. The highest growth rate (1.61 OD680nm) was observed for C. sorokiniana GEEL-01 with highest removal of total nitrogen (1.5 mg L−1 day−1) and total phosphorus (1.82 mg L−1 day−1). The biocomponents of the isolated species ranged from 19.47–29.64%, 39.39–52.51%, and 15.08–22.75% for carbohydrate, protein, and lipid, respectively, based on the dry cell weight (DCW). The function groups in microalgal biocompounds were also confirmed by Fourier-transform infrared radiation (FT-IR) spectra, indicated their ability for biofuel generation. Ultimate and proximate analyses of C. sorokiniana GEEL-01 showed high carbon (54.24% DCW) and volatile content (92.69% DCW), compare to other strains. Moreover, it exhibited a significant accumulation of lipid with an increase in the fractions of saturated fatty acids (64.5%), and the major fatty acids were palmitic acid (11.17%), stearic acid (33.86%), oleic acid (9.84%), and linoleic acid (11.56%). Biodiesel derived from the major fatty acids had optimum engine efficiency properties including iodine value (77.34 g I2/100 g oil) and cetane number (54.83). Cultivation of C. sorokiniana GEEL-01 can serve as a dual function of biodiesel feedstock generation and nutrients removal.

Herein, a simple hydrothermal rout was developed to produce highly efficient yttrium vanadate (YVO4) nanoparticles photocatalyst for catalytic degradation of methylene blue (MB) dye and phenol as color and colorless organics under UV illumination. The XRD results confirmed a crystalline, single phase of YVO4 with a tetragonal structure at either 12 h (sample Y-12) or 24 h (sample Y-24) hydrothermal treatment. The mesoporous character was evaluated using N2 sorption measurement. The TEM investigation revealed self-assembled

Chemical sensors fabricated from porous silicon (PSi) for liquid organic analytes (ethanol, acetonitrile, methanol and acetone) are demonstrated, with an emphasis on the impact of the Ag electrical contact placement on sensor performance. Sensors with front side contact display larger shift in capacitance response (2–3 times more sensitive) compared to the backside sensor design as the solvents immediately interact with the pore openings before infiltration. Much slower response time (7–30 min range) for front side vs. (50–200 s scale range) for backside configuration is observed. Both sensor designs exhibit excellent solvent infiltration-evaporation reversible response, indicating no chemical reaction or surface modification occurred. The response time was in the order of ethanol > acetonitrile > methanol > acetone, which correlates well with the solvent vapor pressure. The capacitance shift in both sensor devices is likely related to the interface interaction, revealing a closer correlation with the dipole moments of solvents. This is supported by the photoluminescence quenching upon exposure to organic solvents, with a relative intensity decrease tracks with the dipole moment. The sensitivity remains sufficiently high during the repeated use, with excellent storage stability for backside contact. This comparative study suggests the viability of the current sensor structure and design particularly with backside contact for sensing of various chemical analytes with notably sensitivity and extremely rapid response. Keywords: Meso-porous silicon, Electrical sensor, Capacitance, Photoluminescence, Organic solvents

Synthesis and characterization of efficient photocatalysts based on novel polyaniline-SrSnO3 (PANI/SrSnO3) nanocomposites at various PANI contents (0-10 wt%) are demonstrated. The X-ray diffraction and FT-IR characterizations exhibit the formation of standard single phase of orthorhombic SrSnO3 and chemical interaction between SrSnO3 and PANI. The TEM image of SrSnO3 shows mixture of irregular shapes of nanoparticles and nanorods with slight agglomeration and sizes ranging from 10 to 50 nm. In addition, SrSnO3 nanostructures intermingled or covered by conducting polymer PANI confirmed the coupling of nanocomposite between PANI and SrSnO3. The newly obtained PANI/SrSnO3 nanocomposites have been evaluated for photodegradation of both methylene blue dye and gemifloxacin mesylate drug and compared with pure PANI and SrSnO3. The findings showed that PANI/SrSnO3 nanocomposites at various PANI contents revealed better photocatalytic efficiency than either pure PANI or SrSnO3. However, 5% PANI/SrSnO3 nanocomposite is considered the optimum photocatalyst with 83% destruction of dye molecule within 4 h under UV illumination compared with 33.8% and 43.7% degradation for pure SrSnO3 and PANI, respectively. In addition, the photodegradation rate of 5% PANI/SrSnO3 nanocomposite is greater 4 and 3 folds than that pure SrSnO3 and PANI, respectively.

Solution casting method is used to prepare solid polymer electrolyte films composed of Na2TeO3/PVA (x wt% of Na2TeO3; x = (0.0, 1.1, 3.3, 4.4, 8.9 and 17.8). The description of crystalline nature parameters of the solid polymer electrolyte films has been confirmed by adding salt by XRD analysis. The average inter-crystallite separation and stacking fault is reduced as the dislocation density increments with a rising salt concentration in the polymer matrix. The decrease in the indirect optical energy gap and the observed increase in refractive index (n) of Na2TeO3/PVA samples with the increasing Na2TeO3 salt compared with the pure PVA suggest the possibility of their use in optical device applications. Moreover, the materials' refractive index values were determined from Moss, Reddy, Anani, and Kumar-Singh relationships. In terms of equivalent circuits, the impedance spectra were fitted and explained. The optical limiting of prepared films with different salt content was investigated by continuous laser beam waves operated at 532.8 nm. The findings showed that the films attenuate the laser beam. The obtained dielectric parameters supposed that the Na2TeO3 salt embedded within the PVA as a matrix conveys faster charge transfer and acts as a non-ideal capacitor. The conductivity–frequency dependence was investigated using empirical Jonscher’s power law. The produced polymeric electrolyte films can be widely relevant to electronic and optoelectronic, and biomedical applications.

The slaughterhouse waste (SHW) contains high organics which makes SHW a feasible feedstock for anaerobic digestion (AD). The present study systematically assessed the microbiome response and biomethanation along with the production of volatile fatty acids (VFAs) and ammonia under 2%, 4%, 6%, and 8% (w v−1) loadings of SHW in AD. The optimum loading was 2% SHW which resulted in maximum biomethane production and VFAs consumption. A higher SHW concentration (4% and 6%) resulted in a prolonged lag-phase and decreased biomethane production. High VFAs (28.88 g L−1) and ammonia nitrogen (>4 g L−1) accumulation were observed at 8% SHW leading to permanent inhibition of biomethane and methanogenic archaea. An increase in ammonia and VFAs concentration, at 4% and 6% SHW loadings, shifted the methanogenic pathway from acetoclastic to hydrogenotrophic lead by Methanoculleus. Acetoclastic Methanosaeta (77.15%) dominated the reactors loaded with 2% SHW resulting in the highest biomethane production.

Herein, we demonstrate the effectiveness of surface-enhanced Raman scattering (SERS) to detect trace concentration of potentially harmful imidacloprid pesticide. To achieve this ultimate objective, a rapid and highly effective methodology for the fabrication of active and stable porous silicon (PSi) plated palladium nanoparticles (PdNPs) SERS substrates by an electrochemical anodization and immersion plating routes was applied. The PSi layers were fabricated by the electrochemical anodization of a silicon wafer in ethanoic fluoride solution, followed by uniformly deposition of PdNPs via a simple immersion plating technique. The structural features and morphology of fabricated frameworks of PSi-Pd NPs have been investigated by field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectra. The PSi substrate demonstrates a meso-porous morphology with good distribution, good pore density and average pore sizes around 20 nm. The SERS performance of Si–Pd NPs and PSi–Pd NPs substrates has been examined taking imidacloprid (an insecticide) as a target analyte. The SERS signal of imidacloprid using PSi–Pd NPs substrate exhibited immense enhancement compared to the Si-Pd NPs substrate. The active substrate revealed excellent detectable performance with a concentration as low as 10–9 M imidacloprid and an enhancement factor (EF) of 1.2 × 105. This large EF is fundamentally ascribed to the combined effect of the electromagnetic improvement and charge transfer mechanisms. Additionally, no aging effect was observed for the present substrates kept in air for two weeks. Striking enhancement in Raman spectral signals obtained with the current PSi–Pd NPs substrates can provide a simple and smooth platform towards the sensitive detection of various target analytes.

Efficiently assessing the invasive capability of tumor cells is critical both for the research and treatment of cancer. Here, we report a novel method called the electrochemical trans-channel assay for efficient evaluation of tumor cell invasiveness. A bioinspired extracellular matrix degradation model (EDM) has been first fabricated on a porous anodic alumina (PAA) membrane to construct the electrochemical apparatus. Upon contacting the invasive tumor cells, invasive capability can be sensitively evaluated by the degree of EDM impairment, which is recorded by the electrochemical trans-channel ionic currents in a label-free manner. Compared to the most commonly used trans-well migration method, this assay can be accomplished in an efficient way that is significantly faster (20 min) and more convenient. Besides, quantitation can also be realized for monitoring the invasion process, which cannot be achieved by other currently used methods. Our proposed electrochemical trans-channel assay method has shown a synergistic effect for the evaluation of tumor cell invasiveness, providing a promising method for clinical assessment or prognostic applications of tumor metastasis.

A voltammetric approach was developed for the selective and sensitive determination of hydrogen peroxide using Au plated porous silicon (PSi) nanopowder modified glassy carbon electrode (GCE). The AuNPs-PSi hybrid structure was synthesized via stain etching procedure followed by an immersion plating method to deposit AuNPs onto PSi via a simple galvanic displacement reaction with no external reducing agent to convert Au3+ to Au0. The as-fabricated AuNPs-PSi catalyst was successfully characterized by XRD, Raman, FTIR, XPS, SEM, TEM and EDS techniques. Well crystalline nature of the as-fabricated hybrid structure with AuNPs size ranging from 5 to 40 nm was observed. The specific surface area and total pore volume for both PSi and AuNPs plated PSi were evaluated using N2 adsorption isotherm technique. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were applied to investigate the catalytic efficiency of AuNPs-PSi modified electrode compared to pure PSi/GCE and unmodified GCE. The sensing performance of the active material modified GCE was thoroughly examined with linear sweep voltammetry (LSV) and square wave voltammetry (SWV) techniques. The AuNPs-PSi/GCE exhibited a remarkable linear dynamic range between 2.0 and 13.81 mM (for LSV) and 0.5–6.91 mM for (SWV) with high sensitivity and low detection limit of 10.65 μAmM−1cm−2 and 14.84 μM for LSV, whereas 10.41 μAmM−1cm−2 and 15.16 μM using SWV techniques, respectively. The fabricated sensor electrode showed excellent anti-interfering ability in the presence of several common biomolecules as well as demonstrated good operational stability and reproducibility with low relative standard deviation. Moreover, the modified electrode showed acceptable recovery of H2O2 in a real sample analysis. Thus, the developed AuNPs-PSi hybrid nanomaterial represents an excellent electrocatalyst for the efficient detection and quantification of H2O2 by the electrochemical approach.

The development of a simple, sensitive, and effective method for the analysis of circulating tumor cells (CTCs) is essential for cancer diagnosis and metastasis prediction. In this work, we have proposed an enzyme-free electrochemical method for specific capture, sensitive quantification, and efficient release of CTCs. To achieve this, the specific interaction between CTCs and the corresponding aptamer designed to be located in the identification probe (IP) will unfold the hairpin structure of IP. Consequently, IP will initiate a hybridization reaction to produce a duplex, which will further trigger the hybridization chain reaction (HCR) process to form a composite product of CTCs and double-stranded DNA polymers. Therefore, a significantly amplified signal readout can be obtained. Moreover, the composite product can be brought to the electrode surface by tetrahedral DNA nanostructures to achieve the purpose of capturing and quantifying CTCs. More significantly, these captured CTCs can be controlled released without compromising cell viability via a simple strand displacement reaction. Taking the breast cancer cell MCF-7 as a representative, the newly developed approach led to an ultralow detection limit of 3 cells mL-1, which is superior to several studies previously reported. The current method has also been demonstrated to analyze CTCs in human whole blood and hence revealed a great potential in the future.

In sensor research community, the advances in materials are main strategy for driving developments in the field, with an ultimate objective to enhance three interrelated analytical parameters that are sensor sensitivity, selectivity and response time. Herein, we demonstrate the design and fabrication of highly sensitive and selective amperometric sensor to detect ascorbic acid (AA) with rapid and reproducible response behavior. The sensor based on glassy carbon electrode (GCE) that initially modified with novel TiO2/reduced graphene oxide (rGO) nanocomposites synthesized by simple chemical and calcination processes. The as-synthesized nanocomposite was fully characterized by XRD, FTIR-Raman, SEM-EDS and TEM, which revealed wrinkled wave like 2-D graphene nano-sheets with crystalline anatase phase of TiO2 nanoparticles anchored on the surface. Cyclic voltammetry and electrochemical impedance spectroscopy showed enhanced electrochemical activity of TiO2/rGO nanocomposite modified GCE compared to either bare GCE or TiO2 modified electrode. Sensor analytical parameters derived from amperometric measurements indicated outstanding sensing performance, giving a superior sensitivity 1.061 μA μM−1 cm−2, low limit of detection (LOD) 1.19 μM at (S/N = 3) within a linear range of AA concentration (25 to 725 μM) with a correlation coefficient R2 = 0.9888 and a rapid response time

Novel silver nanoparticles decorated porous silicon (AgNPs-PSi) was fabricated via stain etching of Si, followed by simple immersion plating of Ag and applied successfully for enhanced electro-oxidation and quantification of ascorbic acid (AA). The newly developed nanocomposite consists of mesoporous Si (

Mesoporous TiO2/g-C3N4 nanocomposites with different TiO2 weight percentages have been synthesized using template as structure directing agent under mild hydrothermal conditions. XRD diffraction patterns exhibited the crystalline anatase phase of TiO2 along with distinguished peak for g-C3N4. Raman spectroscopy and FT-IR indicated the presence of TiO2 and g-C3N4 in designed heterojunctions. TEM images showed high crystallinity of TiO2 nanoparticles (size ∼15–20 nm) with porous network dispersed on 2D layered g-C3N4 sheets. N2 sorption analysis revealed large pore volume and high surface area of TiO2/g-C3N4 nanocomposites along with the mesoporous nature of TiO2. The photocatalytic efficiency of designed photocatalysts was assessed by photodegradation of methylene blue through visible light illumination. All TiO2/g-C3N4 nanocomposites revealed superior photocatalytic performance than both pure g-C3N4 and mesoporous TiO2. 10%TiO2/g-C3N4 nanocomposites revealed the highest photocatalytic performance among all prepared samples owing to its large surface area, extended visible light utilization, perfectly formed heterojunction and excellent mobility of charge carriers within the mesoporous framework. A mechanism for the destruction of MB has also been proposed. Continuous efforts for designing “smart” photocatalytic material showing wide spectral response in visible region is the present desire for the destruction of harmful pollutants.

An electrochemical approach was developed for rapid and effective detection of hydrazine using polythiophene (PTh)/ZnO nanocomposite modified glassy carbon electrode (GCE). The PTh/ZnO nanocomposite was synthesized by a modified sol-gel procedure using F127 structure directing mediator, followed by a chemical oxidative polymerization process. Cyclic voltammetry measurements using the PTh/ZnO modified GCEs revealed remarkable sensing response toward hydrazine compared to either bare GCE or pure ZnO, with diffusion-controlled electrode kinetics. Effective amperometric (i-t) response was achieved for the current modified electrodes, yielding a very rapid response time of

The development of active semiconductor photocatalysts with desirable material properties and efficient carrier transformation is indispensable for better photocatalyst utilization and performance optimization. Here, we demonstrate the synthesis of novel mesoporous NiO-TiO 2 nanocomposites at different NiO contents through a modified sol–gel method in the presence of triblock copolymer as a structure directing agent, followed by a simple ultrasonication process for enhancement of the photocatalytic properties under visible light illumination. The results indicated that XRD patterns of the NiO/m-TiO 2 nanocomposites at different NiO contents show a biphasic anatase-rutile structure. TEM images of the NiO/m-TiO 2 nanocomposites showed the formation of very fine TiO 2 nanoparticles and NiO sheet-like structure with particle sizes ranging between 10 and 15 nm and 30–50 nm, respectively. The mesoporous NiO/TiO 2 nanocomposites have large surface areas of 111.3 m 2 /g and wide pore volumes of 0.376 cc/g. NiO/m-TiO 2 nanocomposites exhibit highly enhanced photocatalytic performance for Methylene Blue (MB) decomposition under visible light illumination, compared with either pure mesoporous TiO 2 or pure NiO nanoparticles. The optimum NiO loading content was amounted to be 0.5 wt%, giving a photodegradation rate of 3.3 × 10 −7 mol L −1 min −1 with a photocatalytic efficiency of 90%, exceeding that of pure NiO and pure mesoporous TiO 2 by more than 10 and 1.5 times, respectively. Additionally, the optimal photocatalyst exhibited extremely high degradation ability towards the gemifloxacin mesylate (GFM: antibiotic drug), complete degradation of molecule was obtained after 180 min. The enhancement of the photocatalytic performance of prepared photocatalysts is explained by the synergistic effect, high surface area, low bandgap values, meso-structure and the formation of p-n junction at the interface of NiO and TiO 2 . The facile synthesis route, along with superior photocatalytic activity and proper reusability make the current mesoporous NiO/TiO 2 nanocomposite a potential candidate in photocatalysis related fields.

In this contribution, a facile synthesis of polythiophene (PTh), using various ratios of thiophene (Th) monomers, mesoporous SrTiO 3 nanocomposites has been achieved through in-situ oxidative polymerization method. XRD patterns exhibit well-defined, sharp crystalline SrTiO 3 structure. XPS, FTIR and Raman spectra clearly revealed the formation of PTh-SrTiO 3 nanocomposites. HRTEM and FESEM images confirmed that the PTh-SrTiO 3 structure is quite similar to the undoped SrTiO 3 with fine nanoparticles size in the range of 10–20 nm. PTh-SrTiO 3 nanocomposites possessed type IV isotherm that is characteristic for mesoporous materials. BET surface area values of 0.5, 1 and 10 wt% PTh doped SrTiO 3 are 118.00 m 2 /g, 126.66 m 2 /g and 72.36 m 2 /g, respectively. The photocatalytic performance of PTh-SrTiO 3 nanocomposites for MB photodegradation was performed and compared with either pure PTh or undoped SrTiO 3 under visible light illumination. The photocatalytic efficiency of the PTh-doped SrTiO 3 nanocomposites is superior to that of either pure PTh or undoped SrTiO 3 . 1% PTh-SrTiO 3 nanocomposite exhibits the highest photocatalytic performance with more than 90% MB photodegradation. The photodegradation rate of 1% PTh-SrTiO 3 nanocomposite is greater 4.75 times than that of pure PTh or undoped SrTiO 3 . This is explained by its large surface area, synergetic effect that led to efficient separation of the photogenerated charge carriers, low band gap energy and mesoporous structure.

Eutrophication is a global concern that has severely deteriorated aquatic ecosystems. This phenomenon has impacted the freshwater bodies (such as lakes and rivers) across the world due to the nutrients (mainly N and P) arising from point and non-point pollution sources. Nutrient enrichment induces cyanobacteria formation, hypoxia, and release of bloom toxins, causing their accumulation in aquatic organisms and humans. Preventing the use of chemicals (such as fertilizers) at the source can avoid nutrient release in the run-off streams, thus controlling non-point pollution. While point source pollutants can be effectively controlled at the sewage treatment plants. Although freshwater eutrophication managements have been widely discussed, a systematic eutrophication characterization of lakes and rivers worldwide, with their effective, economically feasible, eco-friendly, and beneficial bio-treatments is still scarce. Hence, in this review, a complete eutrophication-based characterization of lakes and rivers all over the world is provided. Different cost-effective and efficient bio-remediations to control point and non-point pollution are discussed, additionally with a comparative account for the selection of a suitable microbe and remediation approach. A combined point and non-point pollution management can eradicate eutrophication.

In this work, we demonstrate the use of annealed sol-gel derived ZnO nanoparticles acting as electron transport layer (ETL) in inverted bulk heterojunction (BHJ) polymer solar cells (PSCs). We have examined the photovoltaic performance of devices based on poly(2-methoxy-5-(2-ethylhexyloxy)- p -phenylenevinylene) (MEH-PPV):(6,6)-phenyl-C61-butyric acid methyl ester (PC 61 BM) blend system employing the ZnO nanoparticles as an ETL with CuI as hole transport layer (HTL) in comparison to the case of using the conventional HTL of poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) sulfonic acid (PEDOT:PSS). The effect of the presence of another layer of ZnO macrospheres attached to the ZnO nanoparticles is also investigated. The highest power conversion efficiency (PCE) value of 1.35% was achieved for device: ITO/ZnO nanoparticles/MEH-PPV:PC 61 BM/CuI/Ag, which is 275% more the value obtained when CuI was replaced by PEDOT:PSS. The comprehensive analyses on structural and optical characteristics including SEM, XRD, FTIR, PL and UV–vis spectroscopy indicated that the use of the ZnO nanoparticles alone as ETL, together with the CuI as HTL could effectively reduce trap-assisted recombination and charge accumulation at the interface, which is beneficial for the enhanced device performance.

The development of efficient visible-light photocatalyst heterostructures remains a major concern for obtaining desirable material properties and effective carrier transformation. Here, we demonstrate, for the first time, the synthesis of novel heterostructures of Fe2O3/Bi2S3 nanorods via a one-step hydrothermal route and employed effectively as visible-light-driven photocatalysts for the degradation of organic pollutants of methylene blue dye (MB) and phenol. TEM and FE-SEM images displayed that Fe2O3/Bi2S3 heterostructure is nanorods with ∼30–60 nm diameter and 0.5–1 μm length. The newly prepared Fe2O3/Bi2S3 nanorods exhibit greatly enhanced photocatalytic activity toward both MB and phenol compared to pure Bi2S3 and the heterostructure with low molar ratio of 0.06 Fe2O3/Bi2S3 exhibits the best photocatalytic activity under visible light irradiation. A maximum degradation efficiency of MB and phenol ∼90% and 96% was accomplished using Fe2O3/Bi2S3 nanorods compared to only 60% and 69% using pure Bi2S3, respectively. The photodegradation rates for MB and phenol are promoted respectively as ∼2.6 and 3 times using Fe2O3/Bi2S3 heterostructure higher than pure Bi2S3. Photoluminescence spectra measurement along with the calculation of relative band alignment indicated that Fe2O3/Bi2S3 heterostructure significantly suppress the recombination of photogenerated charge carriers, which is beneficial to improve the photocatalytic activity. The facile synthesis approach, unique photocatalytic activity and excellent reusability of the current Fe2O3 modified Bi2S3 nanostructure make it a promising photocatalyst for the environmental remediation related fields.

Enhancing the efficiency of solar cells via quantum dots (QDs) as an energy-down-shift (EDS) layer is a new approach to utilize the wasted energy in the ultra-violet (UV)-light, but the smaller Stokes shift in QDs leads towards partial self-re-absorption losses among QDs due to which the overall enhancement is limited. Here, Mn 2+ -doped Cd 0.5 Zn 0.5 S/ZnS core/shell QDs were deposited as an EDS with a higher Stokes shift on the front surface of monocrystalline p -type silicon (mc- p -Si) solar cells through straightforward and cost-effective spin-coating technique. The Mn 2+ :Cd 0.5 Zn 0.5 S/ZnS QDs confirmed a typical EDS (2.76–4.96 eV → 2.13 eV), which absorb UV light in the range of 250–450 nm and emit visible yellow-orange light at 583 nm. Application of these QDs into the mc- p -Si solar cells clearly exhibited a larger Stokes shift (>200 nm), generated through a functional energy tuning effect (ETE) of Mn 2+ dopant. Through this EDS having an ETE (EDS/ETE) QDs, a remarkable enhancement of the external-quantum-efficiency (EQE) in the UV region was observed. The EQE was improved by ~22.5% in the wavelength range of 300–450 nm and the short-circuit-current-density was enhanced about 1.42 mA/cm 2 (+4.02%), which are the highest records reported so far. In particular, the power-conversion-efficiency was improved by ~3.22%, compared to its reference value recorded in the absence of an EDS/ETE QD layer. These results suggested that the Mn 2+ -doped QDs played a significant role in improving the efficiency and current density of solar cells.

The development and designing of self-testing blood-glucose electrochemical biosensor is an effective approach for diabetic patients to overcome and control this high health concerning issue. Herein, we successfully designed novel single-walled carbon nanotubes-porous silicon nanocomposites framework (SWCNTs-PSi NCs) via simple stain etching and ultrasonication techniques. X-ray Diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), Energy-Dispersive Spectroscopy (EDS), and X-ray Photoelectron Spectroscopy (XPS) were employed to study the porous morphology with ~30 nm pore size and overall structural characterization of the SWCNTs-PSi NCs. This newly fabricated SWCNTs-PSi modified glassy carbon electrode (GCE) biosensor can measure an extremely wide range of glucose (0.5–28.5 mM) in phosphate buffer solution (PBS) compared to the regular glucose concentration level in human blood serum (3.9–7.1 mM) with a sensitivity 0.0614 μAmM−1 cm−2 and detection limit 9.6 ± 0.1 μM. This non-enzymatic glucose biosensor demonstrated excellent selectivity during the investigation of the possible impact of common interfering substances that are present in human blood. This proposed non-enzymatic glucose biosensor has also been tested for real human blood serum analysis to determine blood glucose levels showing highly motivated results. The newly designed SWCNTs-PSi/GCE biosensor exhibits excellent reproducibility and repeatability, along with long-term stability.

Anaerobic digestion, a promising technology for waste utilization and bioenergy generation, is a suitable approach to convert the shrimp waste to biomethane, reducing its environmental impact. In this study, shrimp chaff (SC) was co-digested corn straw (CS), wheat straw (WS), and sugarcane bagasse (SB). In co-digestion, SC enhanced biomethane production of CS by 8.47-fold, followed by SC + WS (5.67-folds), and SC + SB (3.37-folds). SC addition to agricultural biomass digestion also promoted the volatile solids removal up to 85%. Microbial community analysis of SC and CS co-digestion presented the dominance of phylum Bacteroidetes, Firmicutes, Proteobacteria, and Euryarchaeota. Proteolytic bacteria were dominant (18.02%) during co-digestion of SC and CS, with Proteiniphilum as major bacterial genera (14%) that converts complex proteinaceous substrates to organic acids. Among the archaeal community, Methanosarcina responsible for conversion of acetate and hydrogen to biomethane, increased up to 70.77% in SC and CS digestion. Addition of SC to the digestion of agricultural wastes can significantly improve the biomethane production along with its effective management to reduce environmental risks.

Catechol reacts with a variety of biomolecules including DNA, proteins, membranes, etc. and thus causes irreparable damage to human health. Therefore, herein a highly sensitive and selective electrochemical catechol (CC) sensor based on a novel polypyrrole/carbon black doped α-Fe2O3 nanocomposite (PPy/CB/α-Fe2O3 NCs) modified glassy carbon electrode (GCE) is developed and demonstrated. The structural and morphological properties of the PPy/CB/α-Fe2O3 NCs were investigated by FESEM, TEM, EDS, XPS, XRD, FTIR, and Raman spectroscopy. This newly designed highly-sensitive PPy/CB/α-Fe2O3/GCE-based electrochemical sensor can measure a wide range of CC (0.5–1188 μM) in phosphate buffer solution (PBS) with a sensitivity of 0.3521 μAμM−1cm−2 and a logical limit of detection (LOD) 52.8 ± 0.1 nM. The selectivity of the proposed CC sensor was also examined in the presence of common interfering substances. Furthermore, the CC sensor electrode showed highly acceptable results towards the detection of CC level in real samples analysis by the standard addition method. This new combination of active materials, PPy/CB/α-Fe2O3 modified GCE exhibited excellent reproducibility, repeatability, and long-term stability during the electrochemical detection of catechol. Therefore, this approach will emerge as an effective technique in developing efficient electrochemical sensors to detect phenolic compounds for environmental safety.

Designing and fabrication of novel visible light active photocatalysts is still a challenging task, which requires highly dedicative efforts and professional skills. The current work focused to design distinct visible-light responsive photocatalysts based on Bi2S3 in combination with Pt nanoparticles for environmental remediation. The Pt/Bi2S3 frameworks were developed by a simple one-pot hydrothermal methodology followed by a photo-deposition technique. The XRD analysis confirmed the orthorhombic Bi2S3 with high degree of crystallinity whereas the FTIR and XPS investigations further confirmed the successful creation of hybrid nanostructures between Pt and Bi2S3 nanomaterials. FESEM analysis showed the flakes like appearance of Bi2S3 arranged in stacking or piling pattern. TEM analysis revealed that the Pt nanoparticles (varied from 8 to 15 nm) were evenly distributed onto Bi2S3 nanoflakes ranging from 50−150 nm in size. The UV–vis spectroscopic analysis showed the lowering of energy bandgap upon addition of Pt into Bi2S3 nanoflakes. The newly designed Pt/Bi2S3 photocatalysts were tested for their photocatalytic skills on gemifloxacin mesylate drug under visible light illumination. The 1% Pt/Bi2S3 displayed an exceptional performance with 93.0 % drug removal after 25 min and complete destruction of methylene blue (MB) dye in just 30 min under visible-light source. The newly fabricated 1% Pt/Bi2S3 photocatalyst was found to be an extraordinary candidate among all samples, giving 1.9 times higher degradation skills than that of bare Bi2S3. These promising features of the 1% Pt/Bi2S3 framework might be beneficial for its utilization in various environment related challenging tasks.

Ochratoxin A (OTA) is a toxic metabolite that is widely distributed in food products. Herein, we proposed a new fluorescent aptasensor for OTA detection by using cascade strand displacement reaction. The binding of OTA and OTA aptamer on magnetic beads surface inhibited its hybridization with complementary DNA, and subsequently initiated the strand displacement reaction that induced amplified fluorescence signal. By tracing fluorescence response, our method demonstrated an improved detection limit of 0.63 ng/mL, a short assay time of 110 min, and a satisfactory detection specificity by using ochratoxin B, aflatoxin B1, and zearalenone as control toxins. Recovery studies were conducted by spiking OTA in real food samples, including white wine, red wine, cereal drink, coffee beverage and tea beverage, and confirmed desirable accuracy and practical applicability of our method. Therefore, our method may have a great potential use in the food quality control in the future.

Rapid and efficient identification of pathogen is indispensable in clinical diagnosis because of the extremely severe consequence induced by pathogens infection. Taking advantages of the various compositions of pathogen surfaces, in this work we have proposed a simple and rapid sensor array for different pathogens identification and discrimination based on two-dimensional metal–organic frameworks (2D-MOFs) conjugated with functional peptide. Owing to the outstanding physical and chemical properties, ultrathin 2D-MOFs can adsorb dye-labeled peptides and consequently quench the fluorescence quickly and efficiently. Nevertheless, in the presence of pathogens, the anionic surface and different bimolecular composition of pathogens will endow them to interact with the 2D-MOFs or peptides through the diverse non-specific interactions. Subsequently, the dye-labeled peptides can be released with a recovery of fluorescence intensity. Consequently, the sensor array can identify various pathogens rapidly and efficiently based on the distinct fluorescence response patterns. Moreover, experimental results reveal that this approach can discriminate different pathogens with 100% accuracy, even in urine or mixed samples, demonstrating its reliability and effectiveness in the complex biological samples. More importantly, the procedure of pathogens identification by using this sensor array is very fast with only ~ 15 min, indicating the great potential applications in the timely clinical treatments and reliable monitoring of infectious disease trends.

1 T phase of MoS2 has been recently established as a high photo and electro active catalyst for hydrogen generation and energy storage applications. The present study explores the possibility of utilizing its enhanced features for photovoltaic applications with a detailed analogy of the two phases of MoS2 for counter electrode applications in Quantum dot sensitizes solar cells (QDSSCs). The two phases namely 2H and 1 T phase of MoS2 have been synthesized by two different approaches namely bottom up and top down methods. The functionalized (stabilized) 1 T phase shows a significant improvement in its photovoltaic performance over 2H phase as a composite counter electrode (CE) material used with CuS in QDSSCs. The study is supported by material characterization via microscopy, spectroscopy and electrochemical characterization through impedance studies. The metallic 1 T phase with its bandgap less than 1 eV significantly improves the electron life time, charge transfer, charge separation and hence the overall performance of the QDSSCs thus offering itself as a new stable photovoltaic CE material.

We propose herein initial results to develop optimum redox mediators by the combination of computational simulation and catalytic functionalization of the core structure of vitamin K3. We aim to correlate the calculated energy value of the LUMO of different vitamin K3 derivatives with their actual redox potential. For this, we optimized the catalytic alkylation of 1,4-naphthoquinones with a designed Ag(i)/GO catalyst and synthesized a series of molecules.

A capacitive detection of liquid ethanol using reactive, thermally oxidized films constructed from electrochemically synthesized porous silicon (PSi) is demonstrated. The sensor elements are fabricated as meso-PSi (pore sizes

Herein, a facile synthesis of mesoporous Au/ZnO nanocomposite using photochemical reduction approach is demonstrated. The findings indicated that Au nanoparticles with size ranging from 4 to 10 nm were homogenously distributed on the surface of mesoporous ZnO. The synthesized mesoporous Au/ZnO nanocomposite as efficient electrochemical sensor towards hydrazine detection was assessed using different electrochemical techniques including cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometric i-t response. The results showed that the mesoporous Au/ZnO modified GCE (glassy carbon electrode) yields an enhanced hydrazine oxidation peak at a relatively lower potential of ~0.45 V vs. Ag/AgCl (Ipa = 2.6 μA, 150% higher than pure mesoporous ZnO). The amperometric detection of hydrazine at the mesoporous Au/ZnO sensor exhibits a rapid increase in the oxidation current upon the successive additions of hydrazine. The relation between the current vs. hydrazine concentration is linear (R2 = 0.9973) over the concentration range of 0.2–14.2 μM, with a diffusion-controlled kinetic process. The sensitivity and limit of detection (LOD) of the sensor was estimated to be 0.873 μA μM−1 cm−2 and 0.242 μM, respectively. The key result in our synthesized mesoporous Au/ZnO nanocomposite showed significant selectivity for hydrazine detection in the presence of different interferences. Moreover, the mesoporous Au/ZnO sensor demonstrated long-term stability that exhibited high selectivity, sensitivity, repeatability, reproducibility, and fast kinetic detection within 10 s. Keywords: Mesoporous, Au/ZnO, Electrochemical sensor, Amperometric, Hydrazine

Fabrication of efficient chemical sensors is a prime strategy for detecting trace levels of environmental species, but predominantly limited by slow response time, relatively low sensitivity and poor selectivity. Here, we demonstrate, for the first time, the synthesis of a novel nanocomposite of α-Fe2O3/crosslinked polyaniline (α-Fe2O3/CPANI) via a simultaneous gelation and polymerization process. The newly prepared α-Fe2O3/CPANI nanocomposite was employed as an efficient hydrazine chemical sensor with high sensitivity and selectivity. The XRD, XPS and HR-TEM results confirmed the presence of PANI and revealed a well-crystalline, structurally uniform crystals of rhombohedral α-Fe2O3 phase with particle sizes

The photoluminescence (PL) and UV–vis spectral analysis of DAM-ADC (diallyl maleate: DAM, polyallyl diglycol carbonate: ADC) nuclear detector are demonstrated for the first time. The DAM-ADC surfaces were exposed to thin 241 Am disk source that emits alpha particles with activity 333 kBq. It is found that the track density of the irradiated samples remarkably influences the PL characteristics of the DAM-ADC detector. The spectral peak heights and the integrated intensities under the peaks exhibit linear correlations with correlation coefficient R 2 =0.9636 and 0.9806, respectively for different alpha particle fluences ranging from 8.16–40.82×10 7 particles/cm 2 . Additionally, a correlation coefficient R 2 =0.9734 was achieved for the UV–vis spectral analysis. The linear fitting functions, along with the corresponding fitting parameters were evaluated in each case. Both the PL and the UV–vis data of the irradiated DAM-ADC samples showed considerable spectral differences, and hence they would be used to offer sensitive approaches for alpha particle detection.

Bi2S3 nanorods with orthorhombic structure were successfully synthesized through hydrothermal method. Systematic experiments were accomplished to study the variable factors such as the Bi/S molar ratio, reaction time and reaction temperature, which have great impact on the structural morphologies of Bi2S3 and the photocatalytic performance. TEM and FE-SEM images reveal that the prepared Bi2S3 is flower-like built up from many nanorods with average 30–50 nm in diameter and 0.5–1 μm length. The optimal conditions for the preparation of Bi2S3 nanorods were Bi/S molar ratio 1/2 for 20 h at 180 °C to obtain the highest photocatalytic activity of ~98% towards methylene blue (MB) degradation. It is also found that the determined k values for Bi2S3 nanorods prepared at Bi/S molar ratio 1/2 was higher 40 and 5.5 times than that the samples prepared at either low or high Bi/S molar ratios 1/0.5 and 1/5, respectively. Keywords: Bi2S3 nanorods, Hydrothermal method, Photocatalyst, MB photodegradation, UV illumination

Mesoporous ZnO was synthesized through the sol-gel method in the presence of triblock co-polymer Pluronic (F-127) template as the structure directing agent. Palladium nanoparticles were photochemically reduced and deposited onto mesoporous ZnO to obtain 1 wt.% Pd/ZnO nanocomposite. Structural and morphological analysis revealed high homogeneity and monodispersity of Pd nanoclusters with small particle sizes ∼ 2–5 nm onto mesoporous ZnO. The electrochemical detection of ethanol in aqueous solutions was conducted at the newly developed Pd/ZnO modified glassy carbon electrode (GCE) by the current-potential (IV) and cyclic voltammetry (CV) techniques and compared with bare GCE or pure ZnO. The presence of Pd dopant greatly enhances the sensitivity of ZnO, and the obtained mesoporous Pd/ZnO sensor has an excellent performance for precision detection of ethanol in aqueous solution with low concentration. The sensitivity was found to be 33.08 μAcm−2 mM−1 at lower concentration zone (0.05–0.8 mM) and 2.13 μAcm−2 mM−1 at higher concentration zone (0.8–12 mM), with a limit of detection (LOD) 19.2 μM. The kinetics study of ethanol oxidation revealed a characteristic feature for a mixed surface and diffusion-controlled process. These excellent sensing characteristics make the mesoporous Pd/ZnO nanocomposite a good candidate for the production of high-performance electrochemical sensors at low ethanol concentration in aqueous solution.

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.

In present work, Ag nanoparticles were homogeneously dispersed on g-C3N4 utilizing photo-deposition technique to synthesize Ag/g-C3N4 nanocomposites having different percentages of Ag contents (0–5%). XRD and FT-IR confirmed the graphitic structures of g-C3N4 and Ag/g-C3N4. Results of XPS studies revealed the presence of metallic Ag on g-C3N4. TEM images reflect the homogeneous dispersion of Ag nanoparticles (~15 ± 5) on the surface of g-C3N4.·The photocatalytic activities were evaluated by photocatalytic oxidation of methylene blue (MB) under visible light illumination. 0.5% Ag/g-C3N4 exhibited the highest photodegradation rate which was almost two times higher than that of pure g-C3N4. Photodegradation performance for exploiting MB was slightly decreased after five repeated cycles under visible light showing the highly stable nature of designed nanocomposites. Keywords: Ag doped g-C3N4, Nanocomposites, Photocatalyst, Visible-light, Photodegradation

Amorphous zinc oxide–silica ( a -ZnO–SiO 2 ) nanocomposite has been synthesized using a sol–gel process. X-ray diffraction patterns show a broad diffraction peak of amorphous SiO 2 with no peaks related to ZnO wurtzite structure. ZnO–SiO 2 nanocomposite posses uniformly spherical particles and large surface area 462 m 2 /g. The prepared a -ZnO–SiO 2 nanocomposite was used as a chemical sensor to detect phenyl hydrazine via a simple electrochemical technique by measuring the current–potential ( I – V ) characteristics. The calibration curve exhibits good linearity over all concentration range from 390 μM to 50 mM (r 2 = 0.9986) and the limit of detection was estimated to be 1.42 μM. The sensitivity was calculated to be 10.80 μA cm − 2 mM − 1 as a result of good adsorption ability and large surface area of the prepared sensor. Interestingly, the modified ZnO–SiO 2 nanocomposite sensor electrode was extremely stable during the sensing runs, since no significant sensitivity decrease was observed after being re-used for five times. Furthermore, no deterioration in the I – V characteristics was detected after being stored in ambient conditions for three months, indicating the fabricated sensor exhibited long term stability.

Bioremediation of mercury pollution by mercury-resistant bacteria requires the key steps of mercury ions (Hg2+) capture and transportation. Inspired by the functions of mercury transporters in mercury-resistant bacteria, we have fabricated an artificial ionic gate, which may further behave as an Hg2+ biosensor. The gate is constructed by using the asymmetrically modified porous anodic alumina (PAA) film capable of forming Hg2+-activated complexes to control ionic current, while the gate works due to the changes between graphene oxide (GO) and different DNA structures. Specifically, single strand poly(T)n DNA on PAA film may transform into duplex structure through T-Hg2+-T coordination chemistry when Hg2+ exists. Compared with the ring by ring delivery via S-Hg intermediates in bacteria, this artificial gate may show better flexibility for Hg2+ transport, because the poly(T)n-Hg2+ complex can be wrapped in a chain structure with controllable DNA length. Furthermore, with the advantages of simple structure, convenient operation and good practicality, the constructed artificial Hg2+-activated ionic gate has been developed as a biosensor for sensitive detection of Hg2+, with the limit of detection (LOD) down to 0.07 fM. The fabricated ionic gate may be used for building an instrument that can absorb and detect Hg2+ from wastewater in the future.

The main concern of lignocellulosic biomass utilization for biofuel production is the presence of lignin which hinder the hemicellulose and cellulose accessibility. In this study, chemical and biological pretreatments have been used for decomposition of the lignocellulosic cotton stalk (CS) into monosaccharides. Long-term fermentation/co-fermentation (upto 5 cycles) of pretreated CS by immobilized yeasts (Saccharomyces cerevisiae YPH499 and Pachysolen tannophilus 32691) for bioethanol was investigated. Spectroscopic analysis (including FTIR, XRD, SEM, and TGA) showed the disintegration and abrasion in CS structure after application of both the pretreatments. The maximum sugar utilization efficiency in 1st cycle of co-fermentation by immobilized yeasts was 94.1 and 90.4% with 0.46 and 0.44 g/g bioethanol production in chemical and biological pretreatment, respectively. Moreover, bioethanol yield was slightly sustained till 2nd cycle (0.38−0.40 g/g). However, bioethanol production steadily declined at 3rd cycle and reached to the lowest value at 5th cycle. These results demonstrated that co-fermentation with immobilization approach might significantly improve the bioethanol production from pretreated lignocellulosic biomass (including CS).

Herein, an electrochemical approach was developed for the rapid and selective determination of hydrazine using 5% polyaniline (PANI)-doped mesoporous SrTiO3 nanocomposite modified glassy carbon electrode (GCE). The nanocomposite was synthesized by a modified sol-gel procedure using F127 structure mediator agent to obtain mesoporous SrTiO3 followed by an ultra-sonication technique to produce the final PANI doped SrTiO3. Various characterization tools, namely, XRD, XPS, FE-SEM and HR-TEM confirmed the successful formation of the nanocomposite and revealed cubic perovskite structure with d-spacing value 2.70 A for mesoporous SrTiO3. Cyclic voltammetry and electrochemical impedance spectroscopy measurements exhibited higher electrocatalytic performance of the PANI/SrTiO3 nanocomposite compared to either pure SrTiO3 or unmodified GCE. The hydrazine oxidation reaction follows the first-order diffusion-controlled kinetics with a transfer coefficient value 0.65 obtained from Tafel plot analysis. Linear sweep voltammetry (LSV) and amperometric (i-t) techniques revealed that the PANI/SrTiO3 nanocomposite modified GCE exhibited remarkable sensitivity; 0.2128 μAμM−1 cm−2 over the concentration range 0.2–3.56 mM (LSV) and 0.2438 μAμM−1 cm−2 over the concentration range 16–58 μM (amperometry) with a rapid response time

The present work aims to enhance the photocatalytic performance of mesoporous ZnO by doping with polythiophene (PTh) for the treatment of toxic pollutants. Polythiophene doped ZnO (PTh/ZnO) photocatalysts with various weight percentages of PTh (1–10%) were synthesized via modified sol-gel and oxidative polymerization techniques. The XRD patterns revealed a well-crystalline hexagonal wurtzite phase of ZnO, whereas the XPS, FTIR and Raman spectra confirmed the successful coupling between PTh and ZnO nanostructures. TEM results illustrate the uniform distribution of PTh onto the mesoporous ZnO. UV–vis spectroscopy revealed a small lowering in bandgap energies upon PTh incorporation. The prepared PTh/ZnO nanostructures have been successfully exploited for the photocatalytic degradation of methylene blue dye (MB) and gemifloxacin mesylate (GFM) antibiotic. All doped samples exhibited superior performances in comparison to either pure PTh or undoped ZnO. The 5% PTh/ZnO showed the highest activity with 95 % degradation efficiency of MB dye in 180 min of irradiation with rate constant value 0.0156 min−1 which is almost 2.6 higher than pure ZnO. In addition to this, 5% PTh/ZnO proven to be highly active towards the degradation of gemifloxacin mesylate antibiotic after 180 min of irradiation time, yielding ∼80 % degradation efficiency. Repeated cyclic use of the current photocatalyst indicated excellent reusability and operational stability. The reaction mechanism involved during the photocatalytic degradation is also proposed.

The combination of inorganic semiconductor metal oxides and organic conducting polymers is a favorable strategy in fabricating electrochemical sensors due to their outstanding electrocatalytic performance. Herein, a novel electrochemical sensor for detection of liquid methanol is fabricated using a modified glassy carbon electrode (GCE) with Nafion binder. The active sensing material is composed of a conductive polythiophene (PTh) doped iron oxide (α-Fe2O3) that simply synthesized by a facile sol-gel route in presence of a structure directing agent F127 followed by an oxidative polymerization process. Cyclic voltammetry and electrochemical impedance measurements revealed enhanced electrocatalytic response at the PTh/α-Fe2O3/Nafion modified GCE compared to either α-Fe2O3/GCE or bare GCE with a diffusion-controlled kinetics in ferro/ferricyanide redox couple. Material characterization using various analytical techniques confirmed the formation of PTh sheets onto highly crystalline rhombohedral structure of α-Fe2O3 with distinctly lattice fringes 0.37 nm. Outstanding sensing parameters are achieved with a sensor sensitivity of 0.793 μAmM−1cm−2, limit of detection LOD at (S/N = 3) = 1.59 mM, a wide range of methanol concentration from 5 to 1000 mM with a correlation coefficient R2 = 0.9483. Furthermore, the current proposed sensor electrode showed adequate operational stability and acceptable reproducibility and repeatability.