2D g-C3N4 nanosheets functionalized with nickel-doped ZrO2 nanoparticles for synergistic photodegradation of toxic chemical pollutants.

The photocatalytic removal of toxic chemical pollutants from wastewater has garnered significant attention in recent times owing to its notable removal efficiency, cost-effectiveness, and eco-friendly characteristics. Nonetheless, this catalytic process necessitates augmented charge separation and distinctive interface properties to facilitate catalytic reactions for water treatment applications. Therefore, in the current study, novel g-C3N4/Ni-doped ZrO2 heterostructured hybrid catalysts have been synthesized via a hydrothermal approach. Microscopic studies reveal that ZrO2 nanospheres were distributed on the layered-like 2D structure of g-C3N4 nanosheets. Electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), UV-Vis diffuse reflectance spectroscopy (UV-DRS), and photoluminescence (PL) characterizations were employed to investigate the impact of bandgap, electron-hole recombination, charge transfer, and interface properties on the catalytic performance of g-C3N4/ZrO2 hybrids. XRD analysis confirmed that the Ni-ions do not disturb the host lattice crystal structure and heterostructure development between g-C3N4 and doped ZrO2 sample. Structurally, Ni-doped nanoparticles were found to be equally superficially dispersed on g-C3N4 sheets. Optical analysis results suggest that the hybrid catalyst possesses a narrow bandgap of 2.56 eV. The synthesized photocatalyst degraded rhodamine B (RhB) and tetracycline (TC) with ∼92% and ∼89% degradation efficiency, respectively. Heterostructured hybrid catalysts showed superior degradation rate constants than other catalysts. This might be attributed to the sufficient separation of electron-hole due to the development of a heterojunction. The radical scavenging experiments suggested that O2●- and ●OH radicals contributed substantially to the dye elimination activity of the composite. Therefore, the synthesized novel nanohybrid catalysts in this study present an efficient and straightforward synthesis method for the efficient removal of toxins from wastewater under visible light irradiation.

Novel g-C3N4/BiVO4 heterostructured nanohybrids for high efficiency photocatalytic degradation of toxic chemical pollutants.

Novel heterostructured hybrid catalysts are essential for the efficient photocatalytic removal of organic pollutants from wastewater generated by the pharmaceutical and textile industries. In this study, novel g-C3N4/BiVO4 nanohybrid catalysts were prepared using a solvothermal technique, and examined their structural and optical properties using different characterizations. The X-ray diffraction analysis confirmed the monoclinic crystal phase of BiVO4. Field emission scanning electron microscopy (FESEM) images revealed that g-C3N4 sheets anchored on the surface of BiVO4 nanospheres. X-ray photoelectron spectroscopy (XPS) analysis confirmed the oxidation states of g-C3N4/BiVO4 composite sample. UV-Vis DRS spectroscopy analysis revealed that the composite (2.08 eV) sample had a reduced bandgap compared to other samples. The photocatalytic properties of the prepared samples were tested in the presence of organic methylene blue (MB) and antibiotic tetracycline (TC) pollutants under visible light illumination. The hybrid composite catalyst exhibited enhanced photocatalytic degradation efficiency of MB (88%) and TC (89%) pollutants at elevated rate constants of 0.0128 and 0.01174 min-1, respectively. The improved catalytic performance of the composite catalyst is due to the heterojunctions between g-C3N4 and BiVO4 that successfully reduced the rate of charge carrier recombination in the catalyst system. Scavenger experiments revealed that O2●- and h+ radicals played a main role in the degradation of the chemical pollutants. The developed g-C3N4/BiVO4 heterostructured catalyst is a suitable candidate for removing contaminants from industrial wastewater because of its facile fabrication and exceptional photocatalytic activity under visible light irradiation.

Heterostructured 2D/2D ZnIn2S4/g-C3N4 nanohybrids for photocatalytic degradation of antibiotic sulfamethoxazole and photoelectrochemical properties.

In recent years, antibiotic drugs have been extensively used owing to increased industrial growth, and this has created issues related to drinking water and a green environment. Different techniques have been used to resolve these issues, among which heterogeneous photocatalysis has been widely explored for the elimination of toxic compounds from wastewater resources. In this study, ZnIn2S4, g-C3N4, and ZnIn2S4/g-C3N4 hybrid heterostructured composites are synthesized via hydrothermal method and used these (i) for the removal of antibiotic sulfamethoxazole pollutant and (ii) photoelectrochemical water oxidation. The nanomaterials were characterized using X-ray diffraction, Scanning electron microscopy, transmission electron microscopy, and UV-vis spectroscopy. The developed hybrid heterostructured composites were able to degrade sulfamethoxazole pollutants as well as offer improved photoelectrochemical properties compared to pristine samples. The catalytic performance of the materials developed under visible light irradiation was greatly improved for the degradation of the antibiotic drug up to 89.4% in 2 h. Moreover, the hybrid heterostructured photoelectrode showed a better photocurrent density (8.68 mA/cm2) and exhibited ∼19.2 and 29.9 times greater photocurrent density than the pristine photoelectrodes. Such a considerably increased catalytic activity was attributed to the active separation of charge carriers and transmission. The study offers an innovative approach to develop effective catalysts, and for the degradation of sulfamethoxazole as well as the PEC properties for hydrogen production.

Hydrothermally derived Cr-doped SnO2 nanoflakes for enhanced photocatalytic and photoelectrochemical water oxidation performance under visible light irradiation.

Photocatalytic dye degradation is a method of environmental degradation that is commonly used to eliminate various pollutants produced by pharmaceutical and textile industries. Herein, pure and chromium (Cr)-doped SnO2 nanoflakes were synthesized using a simple facile hydrothermal method and photocatalytic properties were studied under visible light illumination. In addition, photoelectrochemical (PEC) water oxidation properties were also studied using the prepared samples. Doping of transition metal ions introduces structural defects, which narrow the band gap of host sample, resulting in high catalytic activity. The synthesized doped SnO2 displayed a rutile tetragonal crystal phase with a nanoflakes-like surface morphology having no other contaminations. The optical band gap of Cr-doped SnO2 nanoflakes was significantly reduced (2.48 eV) over the pure sample (3.32 eV), due to successful incorporation of Cr ions into the host lattice. Furthermore, the dye removal efficiency of these nanoflakes was investigated for methyl orange (MO) and tetracycline (TC) organic contaminations. The Cr-doped SnO2 nanoflakes exhibited superior photodegradation with 87.8% and 90.6% dye removal efficiency, within 90 min of light illumination. PEC water oxidation analysis showed that the doped photoelectrode achieved enhanced photocurrent density and showed a higher photocurrent density (1.08 mA cm-2) over that of the undoped electrode (0.60 mA cm-2). Electrochemical impedance spectroscopy (EIS) showed that doped electrodes exhibited lesser charge resistance than the pure electrode. The synthesized Cr-doped SnO2 nanoflakes are suitable for water oxidation and photodegradation of organic pollutants. Thus, we strongly believe that the obtained results in this report will continue to provide new opportunities for the improvement of effective visible light photocatalysts for industrial wastewater treatment and water splitting for H2 generation.

Highly efficient photodegradation of toxic organic pollutants using Cu-doped V2O5 nanosheets under visible light.

Photodegradation of organic pollutants using metal oxides has shown extraordinary promise owing to the catalytic efficacy, low cost, less noxiousness, and good chemical constancy. In this research, pure and transition metal ions (Cu)-doped V2O5 nanosheets were synthesized and investigated for their photocatalytic efficiency using methyl blue (MB) and rhodamine B (RhB) organic dye pollutants under visible light irradiation. The orthorhombic crystal phase was confirmed by XRD analysis, which exhibited a stable phase upon incorporating Cu dopant ions. Optical properties were examined using optical absorption spectroscopy, while a reduced band gap was observed in the doped V2O5 nanosheets over the undoped sample. EIS analysis confirmed lower charge resistance in doped V2O5 nanosheets. The Cu dopant incorporation into the host matrix considerably enhanced photodegradation efficiency for MB and RhB impurities under light illumination. The improvement in catalytic efficacy is attributed to dopant ions that can separate photoinduced charge carriers and the quick movement of the charge. Moreover, comparatively lesser crystalline size, improved specific surface area, and hydroxyl group onto the catalyst surface are quite advantageous to offer better photocatalytic activity of Cu-doped V2O5 nanosheets.

Synthesis of transition metal ions doped-ZrO2 nanoparticles supported g-C3N4 hybrids for solar light-induced photocatalytic removal of methyl orange and tetracycline pollutants.

Photodegradation is an eco-friendly degradation process routinely employed for the removal of various pollutants produced by pharmaceutical and textile industries. In this work, g-C3N4 sheets (g-CN) supported with Fe-doped ZrO2 nanoparticles have been prepared via a facile hydrothermal method as photocatalysts for the effective photodegradation of methyl orange (MO) and tetracycline (TC). The as-prepared photocatalysts were characterized by using a wide range of techniques to understand the origin of their superior photodegradation performance. Structurally, Fe-doped ZrO2 nanoparticles were found to be uniformly superficially distributed on g-C3N4. The addition of Fe-doped ZrO2 nanoparticles was also found to improve the surface area and light absorption capacity of pure g-CN. It was further revealed that the development of heterojunctions between g-C3N4 and Fe-doped ZrO2 nanoparticles effectively reduced the recombination rate of electron and hole pairs within the photocatalyst system, resulting in improved photocatalytic activity. Previous studies have pointed at the superoxide radical anions (˙O2-) and (OH·) as being primarily responsible for the degradation of MO and TC species, leading us to hypothesize that the g-FZ composite works via a possible free-radical based catalytic mechanism to support the photodegradation process.

Novel g-C3N4/Cu-doped ZrO2 hybrid heterostructures for efficient photocatalytic Cr(VI) photoreduction and electrochemical energy storage applications.

Pure ZrO2, graphitic carbon nitride, Cu-doped ZrO2 nanoparticles (Cu-Zr), and doped Cu-Zr nanoparticles decorated on the g-C3N4 surface (g-CuZr nanohybrids) were successfully prepared by a hydrothermal technique. Synthesized catalysts were examined by XRD, FE-SEM, TEM, UV-Vis spectroscopy, photoluminescence (PL), and BET surface measurements, respectively. The photocatalytic reduction of Cr(VI) photoreduction as well as energy storage supercapacitor applications were thoroughly investigated. The g-CuZr hybrid photocatalyst outperformed other pristine photocatalysts in terms of light absorption and catalytic Cr(VI) reduction performance under stimulated solar light irradiation. Furthermore, methylene blue (MB) was used as a photosensitizer to further improve the Cr(VI) photoreduction performance. In precise, the heterostructured hybrid catalyst exhibited improved photocatalytic Cr(VI) photoreduction activity (∼88.1%) in 5 mg/L MB solution over other catalysts. Moreover, the decoration of Cu-Zr on the surface of g-C3N4 enhanced the absorption ability of light and catalytic Cr(VI) photoreduction performance. The PL, EIS, and transient photocurrent analysis demonstrated that the efficiency of the charge carrier's separation in the nanohybrid catalyst was superior over other catalysts. Furthermore, heterostructured g-CuZr nanohybrid electrode exhibited superior specific capacitance (297.2 F/g) over other electrodes, which are 5.5 folds (54.01 F/g), ∼2 folds (144.01 F/g) better than pure ZrO2 and g-C3N4 electrodes. Likewise, the nanohybrid electrode retained about 90% of the capacitive value after 2500 cycles over its initial capacitance.

Water Mediated One-Pot, Stepwise Green Synthesis, Anti-Inflammatory and Analgesic Activities of (3-Amino-1-Phenyl-1H-Benzo[f]Chromen-2-yl) (1H-Indol-3-yl) Methanone Catalysed by L-Proline.

AIM: The reactions were carried out by one pot three-component synthesis, 3- cyanoacetylindole (1) on reaction with aromatic aldehydes (2) and ß-naphthol (3) in an aqueous medium in the presence of L-proline as a catalyst under reflux for 30 min, resulting in (3-amino-1- phenyl-1H-benzo[f]chromen-2-yl) (1H-indol-3-yl)methanone (4). The method has many advantages like short reaction times, good yields, and simple workup procedure, besides being green in nature. Pharmacological evaluation of title compounds was done for anti-inflammatory and analgesic activities. Anti-inflammatory activity was carried carrageenan-induced paw edema model in which indomethacin was used as standard and analgesic activity was evaluated by eddy's hot plate method using diclofenac as standard drug. BACKGROUND: Benzopyrans or chromenes are an important class of heterocyclic compounds due to their broad spectrum of biological activity and a wide range of applications in medicinal chemistry. The chromene moiety is found in various natural products with interesting biological properties. Chromenes constitute the basic backbone of various types of polyphenols and are widely found in alkaloids, tocopherols, flavonoids, and anthocyanins. Indoles are omnipresent in various bioactive compounds like alkaloids, agrochemicals, and pharmaceuticals. OBJECTIVE: The objective of this study is to synthesize one-pot stepwise Green synthesis, antiinflammatory and analgesic activities of 3-amino-1-phenyl-1H-benzo[f]chromen-2-yl) (1H-indol-3- yl) methanones. METHODS: The acute anti-inflammatory effect was evaluated by carrageenan-induced mice paw edema (Ma Rachchh et al., 2011). Edema was induced by injecting carrageenan (1% w/v, 0.1 ml) in the right hind paw of mice. The test compounds 1-12, indomethacin (10 mg/kg), and the vehicle were administered orally one hour before injection of carrageenan. Paw volume was measured with a digital plethysmometer at 0, 30, 60, 90, 120 min after injection. Percentage increase =A-B/ A *100. RESULTS: Carrageenan induced paw edema model was used for anti-inflammatory activity in which animals treated with standard (indomethacin) and test compounds showed a significant decrease in the paw edema. Analgesic activity was estimated using Eddy's hot plate method; animals were treated with standard (diclofenac) and test compounds showed a significant increase in the reaction time. CONCLUSION: A green, one-pot, step-wise and three-component synthesis of 3-amino-1-phenyl-1Hbenzo[ f]chromen-2-yl) (1H-indol-3-yl) methanone was achieved by using water as a solvent, Lproline as catalyst under reflux conditions. The reactions were carried out in eco-friendly conditions with shorter reaction times, easier workup, and high yields. Anti-inflammatory activity was evaluated by carrageenan-induced paw edema model, where significant anti-inflammatory activity is shown by all the test compounds 4(a-l) compared to standard drug. Analgesic activity was studied by Eddy's Hot plate method and Test compounds 4e, 4f, 4h, 4i, 4j, 4k, 4l showed significant activities compared to the reference drug.

Novel Z-scheme binary zinc tungsten oxide/nickel ferrite nanohybrids for photocatalytic reduction of chromium (Cr (VI)), photoelectrochemical water splitting and degradation of toxic organic pollutants.

A simple hydrothermal approach was demonstrated for synthesizing a coupled NiFe2O4-ZnWO4 nanocomposite, wherein one-dimensional ZnWO4 nanorods were inserted into two-dimensional NiFe2O4 nanoplates. Herein, we evaluated the photocatalytic removal of Cr(VI), and degradation of tetracycline (TC) and methylene blue (MB) by the nanocomposite, as well as its ability to split water. The ZnWO4 nanorods enriched the synergistic interactions, upgraded the solar light fascination proficiency, and demonstrated outstanding detachment and migration of the photogenerated charges, as confirmed by a transient photocurrent study and electrochemical impedance spectroscopy measurements. Compared to pristine NiFe2O4 and ZnWO4, the NiFe2O4-ZnWO4 nanocomposite exhibited a higher Cr(VI) reduction (93.5%) and removal of TC (97.9%) and MB (99.6%). Radical trapping results suggested that hydroxyl and superoxide species are dominant reactive species, thereby facilitating the Z-scheme mechanism. Furthermore, a probable photocatalytic mechanism was projected based on the experimental results. The photoelectrochemical analysis confirmed that NiFe2O4-ZnWO4 exhibited minor charge-transfer resistance and large photocurrents. We propose a novel and efficient approach for designing a coupled heterostructured nanocomposites with a significant solar light ability for ecological conservation and water splitting.

Green synthesis of Cu-doped ZnO nanoparticles and its application for the photocatalytic degradation of hazardous organic pollutants.

In recent times, the synthesis of metal nanoparticles (NPs) using plant extracts has recently emerged as an intriguing issue in the field of nanoscience and nanobiotechnology, with numerous advantages over conventional physicochemical approaches. In the current study, ZnO NPs were synthesized from Synadium grantii leaf extricate with varying Cu-dopant concentrations. In order to the synthesis of the pure and Cu-doped ZnO NPs, zinc nitrate hexahydrate and copper nitrate trihydrate were used as a precursor in leaf extracts of the plant. XRD, TEM, FTIR, XPS, and PL measurements were carried out to examine the physical and optical properties of the synthesized samples. The photocatalytic studies of the prepared samples were studied using Methylene blue (MB), Indigo Carmine (IC), and Rhodamine B (RhB) organic pollutants. The wurtzite crystal structure of synthesized samples was confirmed by XRD and TEM analysis. Further, the presence of functional groups in the prepared samples was confirmed by FTIR analysis. XPS analysis confirmed that the binding energies of a host material and dopant ions. The emission peaks identified at 424, 446 and 573 nm are associated with the electron movement from the deep donor level, zinc interstitial to the zinc vacancy and oxygen vacancy. 3% and 5% Cu-doped samples exhibited superior photocatalytic activity for MB, IC, and RhB dyes. The green synthesized ZnO NPs showed enriched photocatalytic performance, signifying that bio-synthesis can be an outstanding approach to develop versatile and environmental products.

Synthesis, spectroscopic and biological activity evaluation of Ni(II), Cu(II) and Zn(II) complexes of schiff base derived from pyridoxal and 4-fluorobenzohydrazide.

A novel Schiff base ligand, 4-fluoro-N-((3-hydroxy-5-(hydroxymethyl)-2-methylpyridin-4-yl)methylene)benzohydrazide (PLFBH) was synthesized by condensationof pyridoxal and 4-fluorobenzohydrazide. Its complexes with Ni(II), Cu(II), and Zn(II) metal ionswere prepared and characterized by spectroscopic IR, 1H-NMR, UV, LC-MS, ESR, and powder XRD studies and by elemental analysis and thermal analysis, molar conductance, and magnetic susceptibility measurements. The results indicate the geometry of the complexes to be hexa coordinate distorted octahedral. Based on the electronic absorption and fluorescence emission spectra and viscosity studies, an intercalative mode of binding of the complexes with CT-DNA was suggested, which was also supported by DNA docking studies. The docking studies of metal complexes with DNA were carried out using Autodock 4.2. The in vitro anticancer assay for the Cu(II)-PLFBH complex was performed to assess the ability of the complex to inhibit human cell proliferation on HeLa human cervical carcinoma cells, MCF-7 human breast carcinoma cells, and A549 human lung carcinoma cells. The Cu(II)-PLFBH complex exhibited moderate to good inhibitory effect on the cancer cell lines studied. The complexes showed good cleavageability toward plasmid pBR322 DNA. The metal complexes were found to show good antibacterial activity against gram positive bacteria, Staphylococcus aureus and Bacillus cereus and gram negative bacteria Escherichia coli and Pseudomonas aeruginosa cultures,while the ligand showed marginal activity.Supplemental data for this article is available online at https://doi.org/10.1080/15257770.2021.1961271 .

Ultra-small zinc oxide nanosheets anchored onto sodium bismuth sulfide nanoribbons as solar-driven photocatalysts for removal of toxic pollutants and phtotoelectrocatalytic water oxidation.

Heterostructured nanohybrids were prepared from sodium bismuth sulfide (NaBiS2) and zinc oxide (ZnO) through hydrothermal process. The nanocomposite was used for tetracycline (TC) degradation as well as photoelectrochemical (PEC) water oxidation. Morphology and structural analyses were performed to confirm the dispersion of ultra-small ZnO nanosheets into the NaBiS2 nanoribbons. By tuning the band gap, it was possible to degrade tetracycline toxic pollutant within 90 min under the simulated solar light irradiation, while PEC suggested a lower charge-transfer resistance, high photocurrent response, and exceptionally good stability. The highest photocurrent density of 0.751 mAcm-2 vs. Ag/AgCl in 0.1 M Na2SO3 solution was observed under solar-light illumination. Detailed photocatalytic mechanisms for the degradation of TC and PEC water oxidation are discussed.

Vanadium-doped graphitic carbon nitride for multifunctional applications: Photoelectrochemical water splitting and antibacterial activities.

Bulk graphitic carbon nitride (g-C3N4) exhibits limited water splitting efficiency due todrawbacks including high charge recombination rate, low electrical conductivity, poor quantum efficiency, and few adsorption and active catalytic sites. Herein, we report V-doped g-C3N4 nanoarchitectures prepared via direct calcination of urea and ammonium metavanadate. The obtained V-doped g-C3N4 nanostructures not only improved the visible light absorption property but also increased the charge separation and transportation, resulting in extremely enhanced water splitting activity. The structural, morphological, and optical analysis results confirmed the successful incorporation of V into the host g-C3N4 material, and electrochemical impedance spectroscopy measurements revealed the charge carrier dynamics. Compared to the pristine g-C3N4 photoelectrode, the optimized 0.3 mol% V-doped g-C3N4 photoelectrode showed a considerably higher photocurrent density (0.80 mA cm-2). The enhancement of the catalytic performance could be attributed to the synergistic effects of prolonged light absorption, improved transfer of electrons and holes, and extra active catalytic sites for water splitting. Further, the optimized 0.3 mol% V-doped g-C3N4 sample showed an antibacterial activity higher than that of the undoped photocatalyst.

Green Synthesis of Silver Nanoparticles and Evaluation of Their Antibacterial Activity against Multidrug-Resistant Bacteria and Wound Healing Efficacy Using a Murine Model.

Green nanotechnology has significant applications in various biomedical science fields. In this study, green-synthesized silver nanoparticles, prepared by using Catharanthus roseus and Azadirachta indica extracts, were characterized using UV-Vis spectroscopy, dynamic light scattering, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Silver nanoparticles (Ag NPs) synthesized from leaf extracts of C. roseus and A. indica effectively inhibited the growth of multidrug-resistant (MDR) bacteria isolated from patients with septic wound infections. The maximum bacteriolytic activity of the green-synthesized Ag NPs of C. roseus and A. indica against the MDR bacterium K. Pneumoniae was shown by a zone of inhibition of 19 and 16 mm, respectively. C. roseus Ag NPs exhibited more bacteriolytic activity than A. indica Ag NPs in terms of the zone of inhibition. Moreover, these particles were effective in healing wounds in BALB/c mice. Ag NPs of C. roseus and A. indica enhanced wound healing by 94% ± 1% and 87% ± 1%, respectively. Our data suggest that Ag NPs from C. roseus and A. indicia ameliorate excision wounds, and wound healing could be due to their effective antimicrobial activity against MDR bacteria. Hence, these Ag NPs could be potential therapeutic agents for the treatment of wounds.

Z-scheme binary 1D ZnWO4 nanorods decorated 2D NiFe2O4 nanoplates as photocatalysts for high efficiency photocatalytic degradation of toxic organic pollutants from wastewater.

In this study, dimensionally coupled Z-scheme binary nanocomposites from two-dimensional (2D) NiFe2O4 nanoplates and one-dimensional (1D) ZnWO4 nanorods are prepared for efficient degradation of an antibiotic tetracycline (TC) and organic dye rhodamine B (RhB) under solar illumination. NiFe2O4/ZnWO4 nanocomposites were synthesized by a simple and ecological in-situ hydrothermal method without the use of surfactants. Structural and morphological studies revealed the formation of heterostructure and 1D ZnWO4 nanorods were uniformly distributed over the surface of NiFe2O4 nanoplates. Light-harvesting capability was improved and optimized by loading with different amounts of ZnWO4. Photoluminescence analysis demonstrated inhibited nature of the recombination of photo-excited charge carriers in the nanocomposites. Photocatalytic experiments revealed that the nanocomposite exhibited improved Z-scheme electron-transfer for the degradation of TC under solar illumination. In particular, NFZW-20 nanocomposite demonstrated superior photocatalytic degradation of TC of approximately 98% within 105 min. Furthermore, their photocatalytic performance was investigated by RhB dye under the solar irradiation to achieve 98% of degradation of RhB in 70 min. Improved photocatalytic activities are attributed to the Z-scheme electron-transfer mechanism, which could enhance the superior ability of light absorption and reduced recombination rate of the photogenerated charge carriers.

ZnO nanosheets-decorated Bi2WO6 nanolayers as efficient photocatalysts for the removal of toxic environmental pollutants and photoelectrochemical solar water oxidation.

Herein we report the fabrication of novel Bi2WO6/ZnO heterostructured hybrids for organic contaminant degradation from wastewater and photoelectrochemical (PEC) water splitting upon solar illumination. The Bi2WO6/ZnO photocatalysts were synthesized using a simple and eco-friendly hydrothermal process without the support of any surfactants. From the photocatalytic experiments, heterostructured Bi2WO6/ZnO nanohybrid catalysts exhibited considerably better photocatalytic performance for rhodamine B (RhB) degradation under solar illumination. The BWZ-20 nanocomposite demonstrated superior photodegradation of RhB dye up to 99% in about 50 min. Furthermore, BWZ-20 photoelectrode showeda lower charge-transfer resistance than other samples prepared, suggesting its suitability for PEC water splitting. The photocurrent densities of Bi2WO6/ZnO photoelectrodes were evaluated under the solar irradiation. The BWZ-20 photoelectrode exhibited a significant photocurrent density (0.45 × 10-3A/cm2) at +0.3 V vs. Ag/AgCl, which was~1036-times higher than that of pure Bi2WO6, and ~4.8-times greater than the pure ZnO. Such improved photocatalytic and PEC activities are mainly attributed to the formation of an interface between ZnO and Bi2WO6, superior light absorption ability, low charge-transfer resistance, remarkable production of charge carriers, easy migration of charges, and suppression of the recombination of photogenerated charge carriers.

Copper-doped ZrO2 nanoparticles as high-performance catalysts for efficient removal of toxic organic pollutants and stable solar water oxidation.

Doping effect on the photoelectrochemical (PEC) water splitting efficiency and photocatalytic activities of ZrO2 under visible light are reported. The XRD analysis revealed that pure, 0.1 and 0.3 mol% doped samples showed mixed crystal phases (tetragonal and monoclinic) and 0.5 mol% doped sample showed a pure tetragonal phase. Under visible light, 90% of methyl orange dye degradation was achieved with in 100 min. Moreover, the optimal doped sample showed a significant degradation rate constant over other samples. The doped photoelectrodes display a better PEC water oxidation performance over pure photoelectrode. Furthermore, the optimal doped (0.3 mol %) electrode shows 0.644 mAcm-2 photocurrent density, corresponding to an approximate 50-fold enhancement over pure electrode (0.013 mAcm-2). The optimized doped sample achieved 98% degradation of methyl orange within 100 min of light irradiation. The superior PEC water oxidation and photocatalytic activity of optimal doped samples under visible light are credited to suitable doping content, crystalline size, greater surface area, suitable bandgap, a lower charge carrying resistance, surface properties and the ability for decreasing the charge carrier's recombination rate.

Efficient removal of toxic organic dyes and photoelectrochemical properties of iron-doped zirconia nanoparticles.

Iron (Fe)-doped ZrO2 tetragonal nanoparticles were synthesized by a facile and inexpensive hydrothermal technique, that were doped with Fe3+ ions (0.1, 0.3, and 0.5 mol%) into the host lattice without altering the morphology and crystal structure of the nanoparticles. SEM and TEM investigations indicated that the morphology of ZrO2 nanoparticles did not change even after incorporation of Fe, while the band gap of semiconducting ZrO2 nanoparticles was reduced from 4.97 to 1.77 eV. Such a in band gap was responsible to harvest more photons to stimulate the generation of more electrons in the valence band, thereby enhancing the photoelectrochemical (PEC) water splitting as well as photocatalytic and photoelectrocatalytic activities in the photodegradation of Rhodamine B. The 0.3 mol%-doped ZrO2 electrode showed enhanced photocurrent density (0.07 × 10-3 A/cm2), that was 45-times greater than the pure sample. The electrochemical impedance spectroscopy (EIS) confirmed that 0.3 mol%-doped ZrO2 exhibited the best charge transfer characteristics, which increased with PEC water splitting activity. The maximum photocurrent density and long-term photo-stability were achieved in the light on-off states.

ZnO-based nanostructured electrodes for electrochemical sensors and biosensors in biomedical applications.

Fascinating properties of ZnO nanostructures have created much interest due to their importance in health care and environmental monitoring. Current worldwide production and their wide range of applications signify ZnO to be a representative of multi-functional oxide material. Recent nanotechnological developments have stimulated the production of various forms of ZnO nanostructures such as nano-layers, nanoparticles, nanowires, etc. Due to their enhanced sensing properties, improved binding ability with biomolecules as well as biological activities have enabled them as suitable candidates for the fabrication of biosensor devices in the biomedical arena. In this review, the synthesis of ZnO nanostructures, mechanism of their interaction with biomolecules and their applications as sensors in health care area are discussed considering the biosensors for molecules with small molecular weight, infectious diseases, and pharmaceutical compounds.