UV Vis Light Irradiation Research Articles

Construction of Z-scheme photocatalyst with p-n heterojunction of molecular semiconductors for enhanced photocatalytic water oxidation

Here, the donor-acceptor organic composites of n-type perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and p-type cobalt phthalocyanine (CoPc) semiconductors are firstly synthesized and optimized for photocatalytic oxygen evolution (POE) as catalyst. The POE rate of 12.30 mmol·g−1·h−1 with the apparent quantum yield of 4.00 % at 475 nm can be achieved under visible light (> 420 nm), as compared with 1.58 mmol.g−1.h−1 of PTCDA. Under the full UV-Vis light (> 320 nm), the rate is up to 17.65 mmol·g−1·h−1. The systematical experiments clearly reveal the generation of dual-channel energy transfer of fluorescence resonance from CoPc to PTCDA and electron transfer from oxygen groups in PTCDA to Co atom in CoPc under UV-Vis light irradiation. Consequently, the formation of Z-scheme p/n heterojunction in CoPc/PTCDA composite greatly enhances the POE performance due to the lifetime increase of metal-ligand charge transfer exciton in CoPc (44.83 vs. 2.95 ps) and perylene cationic exciton (20.13 vs. 2.13 ps).

Photo-modulated regeneration of hypercrosslinked polymer adsorbents for water treatment

Hypercrosslinked polymers (HCPs) are highly effective adsorbents for removing dyes from water. However, the regeneration of such adsorbents is typically achieved with energy-intensive thermal methods or with solvents that generate chemical waste. Here in this proof of concept study, we used HCPs loaded with azobenzene molecules (HCPs@Azo) that were developed in our previous work, and four types of dyes – Methyl Orange (MO), Methylene Blue (MB), Rhodamine B (RB), Uniblue A (UA), at concentrations ranging from 10 to 500 mg L−1, to demonstrate the feasibility of photo-modulated regeneration of HCP-based adsorbents. Azobenzene in HCP pores reduced dye adsorption by 4–31 %, but upon photo-isomerisation from trans to cis states, led to the desorption of 1.7–20 % dyes that were previously adsorbed. These desorption capacities were 71–209 % higher than using water for regeneration. Compared to the traditional method using organic solvents such as methanol to regenerate HCP-based adsorbents, our approach of photo-modulated regeneration led to the desorption of 50 % more MO and MB dyes. HCPs@Azo also demonstrated good reusability, showing comparable photo-modulated adsorption and desorption capacities after four cycles of UV–visible light irradiation. Results from this work can potentially pave the way for solvent-less regeneration of adsorbents, creating a waste-less adsorbent regeneration process.

Silver nanoparticle-enhanced photocatalytic CO2 reduction over Ag/Nb2O5 under UV–vis light irradiation

A photocatalyst composed of Ag nanoparticles (NPs) supported on pseudo-hexagonal niobium pentoxide (TT-Nb2O5) was synthesized in this study. This catalyst exhibited an enhanced photocatalytic performance for the reduction of CO2 by H2O under UV–vis light irradiation. A CO yield of up to 66.5 μmol·g−1·h−1 with a selectivity of 92.1% were achieved, and also an excellent stability was observed across four cycles. Characterization studies show that the introduction of Ag NPs onto Nb2O5 was beneficial for the formation of oxygen vacancies (Vos) (which were further regenerated when exposed to UV light), resulting in the enhanced adsorption and activation of CO2. The electron-rich Ag NPs were conducive to the formation of Ag-H bonds after the dissociation of H2O to H+, which promoted the proton-electron coupling process for converting the CO2 absorbed at Vos sites into CO. Moreover, the localized surface plasmon resonance (LSPR) of Ag NPs，which was induced by visible light, playing a role in accelerating the decomposition and desorption of *COOH into CO. This work provides new insight into reduction of CO2 by H2O under UV–vis light irradiation.

Microstructural and mechanical properties of photocatalytic cement mortar with g-C3N4/CoAl-LDH nanoflowers

The g-C3N4/CoAl-LDH nanoflowers with a strong photocatalytic activity under UV–visible light irradiation was synthesized and applied with different dosages to prepare photocatalytic cement mortars (PCM). Besides the photocatalytic assessment by NOx degradation, the effect of g-C3N4/CoAl-LDH on the microstructural and mechanical properties of cement mortars were investigated by means of X-ray diffraction (XRD), X-ray computed tomography (X-CT), mercury intrusion porosimetry (MIP), capillary water absorption and strength tests. The results show that in addition to the unique air self-purification characteristics, g-C3N4/CoAl-LDH can promote cement hydration with filling effect and further improve the microstructural and mechanical properties of mortar. Moreover, the ability of g-C3N4/CoAl-LDH to capture CO32− can alleviate the influence of carbonation on photocatalytic performance. Therefore, g-C3N4/CoAl-LDH exhibits lasting photocatalytic performance in cement-based materials. This work is expected to contribute to the effort of searching for new multifunctional nano-additives for improved sustainability of building materials.

Enhanced photocatalytic activity of ZnO microflowers by a trace amount of Ti3C2 MXene

As a novel metal compound with a narrow bandgap and excellent conductivity, two-dimensional (2D) layered Ti3C2 MXene has received growing attention from researchers. In this work, microflower-like ZnO/Ti3C2 composite photocatalysts were prepared by a one-pot method and characterized by XRD, SEM, TEM and XPS techniques. The photocatalytic performances of the ZnO/Ti3C2 photocatalysts were evaluated by the degradation of methyl orange (MO) under UV–visible light irradiation. The photocatalytic activity of ZnO was obviously enhanced with a trace amount of Ti3C2. The pseudo-first-order rate constants of the ZnO/Ti3C2-0.05 and ZnO/Ti3C2-0.5 with Ti3C2 mass percentages of 0.041% and 0.41%, respectively, were 2.9 and 4.2 times higher than that of the ZnO. The enhanced photocatalytic activity of ZnO/Ti3C2 composite was due to the increased transfer of photo-generated charge carriers. Furthermore, the ZnO/Ti3C2-0.5 composite also showed good stability, the degradation efficiency of MO was still maintained 99% even after 10-cycle of reutilization. ZnO/Ti3C2 and other Ti3C2-containing composites may have potiential application in wastewater treatment and environment remediation.

Non-metal doped ZnO photocatalyst prepared by sonication-assisted Sol-gel method and use for dye degradation

SeO2/ZnO (1, 3, 5%) nanopowders were synthesized by a sonication-assisted sol–gel method for the first time. They were characterized by spectroscopic, morphological, and microscopic measurements. To determine the photocatalytic activity of these nanoparticles, methylene blue (MB) was used as the model pollutant under solar light. The capacity of these novel nanopowders to form hydroxyl and superoxide radicals has been demonstrated by using scavengers such as benzoic acid and triphenylphosphine, respectively. The capture experiments were also supported by some spectroscopic analyzes. It was seen that superoxide radical species played an important role. For the dye degradation, 1% SeO2/ZnO among nano samples showed the best photocatalytic performance, achieving approximately 94% decrease after 90 min of UV–visible light irradiation. The reusability of 1% SeO2/ZnO catalyst with the best photocatalytic activity was tested five times. The new catalyst was found to be quite stable without reducing the efficiency.

Synthesis, Structural Characterization, Hirschfeld Surface Analysis and Photocatalytic CO2 Reduction of Yb(III) Complex with 4-Aacetylphenoxyacetic Acid and 1,10-Phenanthroline Ligands

A new nine-coordinated Yb(III) complex [YbL3(Phen)] (1) (HL = 2-(4-acetylphenoxy)acetic acid (APA), Phen = 1,10-phenanthroline) was synthesized with 2-(4-acetylphenoxy)acetic acid, YbCl3.6H2O, NaOH and 1,10-phenanthroline as materials. Complex (1) was characterized by IR and X-ray single-crystal diffraction analysis. The results show that the Yb(III) ion is nine-coordinated with seven carboxylate oxygen atoms from five different deprotonated APA ligands and two nitrogen atoms from one Phen ligand. Complex (1) forms a 3D supramolecular framework through the - stacking interactions between the Phen aromatic rings. The hirschfeld surface analysis of complex (1) was also calculated. The CO2 photoconversion activity of complex (1) has been performed under UV-vis light irradiation. The complex (1) shows good photocatalytic activity with the yield of CO is closed to 146 mmol/g after three hours of UV-vis light irradiation, the CO selectivity has reached to 97.9%. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Glutathione-Mediated Synthesis of Yolk-Shell AuAg Nanostructures Containing a Spherical Core and Cuboctahedral Skeletons and Their Applications in Plasmonic Catalysis.

Frame/skeleton-like nanostructures are of great value in plasmonic catalysis as a result of the synergetic structural advantages arising from both maximized surface atomic exposure and efficient incident light absorptions. Herein, we report the size-tunable fabrication of yolk-shell AuAg nanoparticles containing a spherical core and cuboctahedral skeletons (AuAg YSCNSs), together with the exploration of their applications for assisting the reduction of 4-nitrophenol (4-NP) under ultraviolet-visible (UV-vis) light irradiation. The use of glutathione (GSH) at an appropriate amount to mediate the galvanic replacement reaction between Au@Ag core-shell nanocubes and HAuCl4 is found to be crucial in regulating the shape evolution. Their sizes could be readily tuned by altering the edge lengths of Au@Ag core-shell nanocubes. When working as the photocatalyst assisting the reduction of 4-NP, the AuAg YSCNSs exhibit a higher apparent rate constant under UV-vis light irradiation. The current work demonstrates the feasibility to create skeleton-like noble metal nanocrystals with the shape largely deviated from that of the original template via the "top-down" carving strategy by introducing non-metallic surface doping, which could be potentially extended to other noble metals or alloys.

Revealing the critical roles of silver species on TNT film for photocatalytic decomposition of volatile organic pollutants under UV or visible light irradiation: From mechanism study to scaled-up test

Ag nanoparticles are commonly employed as co-catalysts to promote photocatalytic reactions. In addition to their apparent roles as electron traps and catalytic active sites, nanoparticulate Ag can also generate hot electrons under visible light irradiation, which endows visible light photocatalytic activity to its supporting material. On the other hand, Ag0 can be easily converted to Ag2O, however, few studies focus on its formation and roles during the photocatalytic process. In this work, we have successfully fabricated and optimized the preparation procedures of titania nanotube (TNT) and Ag species deposited TNT to get the optimum photochemical activities of Ag modified TNT. Specifically, the roles of Ag species on TNT film have been investigated by photoelectrochemical (PEC) measurements and photocatalytic decomposition of volatile organic pollutants under UV or visible light irradiation. Toluene (30 ppm) can be effectively decomposed (∼83.3%) and mineralized (∼70.7%) by Ag species modified TNT in 3 h under UV–visible light irradiation, while the degradation and mineralization ratios are only about 60.0% and 33.3% under visible light irradiation. The results demonstrate that appropriate Ag/Ag2O ratio on TNT film are crucial for improving PEC and photocatalytic performance, and the interconversion between Ag and Ag2O influences the photochemical stability of Ag/TNT film. The scaled-up tests (∼1.0 m3 reactor) on the degradation of low concentration of toluene and formaldehyde prove that the optimized Ag/TNT film can be considered as a promising photocatalyst for indoor air purification.

Facile synthesis of visible-responsive photocatalytic Eu-doped layered double hydroxide for selective removal of NOx pollutant

Efficient nitrogen oxides (NOx) removal from the urban atmosphere is still a target for the researchers. Herein, a Zn2Al-CO3 based layered double hydroxide (LDH) was doped with increasing amounts of Eu3+ (0.01–0.04) and the photocatalytic oxidation of NOx gases was investigated. The LDHs were synthesized by a facile coprecipitation method at room temperature and ambient pressure. The successful Eu3+ substitution in the LDH layers induces a shift in the M−O bonds that modifies the electronic band structure of the doped photocatalysts. Compared to the undoped LDH, the NOx removal efficiency was enhanced by ∼ 17–25 % under UV–Vis light irradiation. Remarkably, a NOx removal efficiency of ∼ 47 % was attained by the optimally doped LDH under Visible irradiation (420 nm), surpassing raw LDH (∼ 9 %). Moreover, the Eu3+ doped LDHs retained its photocatalytic efficiency during long periods of irradiation during consecutive tests with high selectivity (>90 %). Photoluminescence studies indicated that Eu3+ was located in a non-centrosymmetric position, thereby producing structural disorder within the lattice. Eu doping promoted charge separation and a higher production of ⋅OH radicals as verified by time-resolved photoluminescence and electron paramagnetic resonance, respectively. We believe this work reports unprecedent results obtained by Eu-doping of Zn2Al-based LDHs under visible light for NOx photooxidation and serves as a new strategy to prepare functional LDHs for other photocatalytic applications.

Nickel phosphide nanoparticles as a noble-metal-free co-catalyst for the selective photocatalytic aerobic oxidation of CH4 into CO and H2

In this study, we report the use of NiP2/TiO2 as a photocatalyst for the transformation of methane (CH4) to carbon monoxide (CO) and hydrogen (H2) under UV–visible light irradiation. As a co-catalyst, NiP2 can promote the charge separation of TiO2 on the one hand, and can effectively promote the activation of O2 to generate superoxide ions (O2–) on the other hand. O2–, as the main active species, cleaves CH4 molecules to form methoxyl radical (•CH3O). Under the influence of photogenerated holes, •CH3O gradually undergoes oxidation to form an intermediate *COOH, which is subsequently converted to CO. Meantime, H+ is reduced to form H2. Therefore, the production of CO and H2 attained 267.5 and 72.4 μmol g–1h−1 for the NiP2/TiO2-2 photocatalyst with the optimal ratio, respectively. In fact, this research showcases the capability of NiP2/TiO2 as a remarkably effective and specific photocatalyst for transforming CH4 into high-value commodities.

A photochemical approach to the synthesis of ZnO/CuO films and their application to the photocatalytic degradation of rhodamines (Rh-B and Rh-6G) under UV–Vis light irradiation

A photochemical approach to the synthesis of ZnO/CuO films and their application to the photocatalytic degradation of rhodamines (Rh-B and Rh-6G) under UV–Vis light irradiation

Photo-assisted Zn-air battery-driven self-powered aptasensor based on the 2D/2D Schottky heterojunction of cadmium-doped molybdenum disulfide and Ti3C2Tx nanosheets for the sensitive detection of penicillin G

A novel photocatalyzed Zn-air battery-driven (ZAB)-based aptasensor has been manufactured using the two dimensional (2D)/2D Schottky heterojunction as photocathode and Zn plate as photoanode. It was then employed to sensitively and selectively detect penicillin G (PG) in the complex environment. The 2D/2D Schottky heterojunction was established by the in situ growth of cadmium-doped molybdenum disulfide nanosheets (Cd–MoS2 NSs) around Ti3C2Tx NSs (denoted as Cd–MoS2@Ti3C2Tx) by using phosphomolybdic acid (PMo12) as precursor, thioacetamide as sulfur source, and Cd(NO3)2 as a doping agent through the hydrothermal method. The gained Cd–MoS2@Ti3C2Tx heterojunction possessed contact interface, hierarchical structure, and plenty of sulfur and oxygen vacancies, thus showing the enhanced separation ability of photocarriers and electron transfer. Due to the enhanced UV–vis light adsorption ability, high photoelectric conversion efficiency, and exposed catalytic active sites, the constructed photocatalyzed ZAB displayed a boosted output voltage of 1.43 V under UV–vis light irradiation. The developed ZAB-driven self-powered aptasensor demonstrated an ultralow detection limit of 0.06 fg mL−1 within a PG concentration ranged from 1.0 fg mL−1 to 0.1 ng mL−1, as deduced from the power density-current curves, along with high specificity, good stability and promising reproducibility, as well as excellent regeneration ability and wide applicability. The present work provided an alternative analysis method for the sensitive analysis of antibiotics based on the portable photocatalyzed ZAB-driven self-powered aptasensor.

Deep Eutectic Solvent-Assisted Synthesis of a Strontium Tungstate Bifunctional Catalyst: Investigation on the Electrocatalytic Determination and Photocatalytic Degradation of Acetaminophen and Metformin Drugs

In this work, we propose a modified solid-state approach for the sustainable preparation of a SrWO4 bifunctional catalyst using thymol-menthol-based natural deep eutectic green solvents (NADESs). Various spectroscopic and morphological techniques analyzed the as-synthesized SrWO4 particles. Acetaminophen (ATP) and metformin (MTF) were selected as the model drug compounds. The electrochemical detection and photocatalytic degradation of ATP and MTF upon ultraviolet-visible (UV-vis) light irradiation in the presence of as-prepared SrWO4 particles as an active catalyst are examined. The present study displayed that the proposed catalyst SrWO4 has enhanced catalytic activity in achieving the optimum experimental conditions, and linear ranges of ATP = 0.01-25.90 μM and MTF = 0.01-25.90 μM, a lower limit of detection (LOD) value (ATP = 0.0031 μM and MTF = 0.008 μM), and higher sensitivity toward ATP and MTF determination were obtained. Similarly, the rate constant was found to be k = ATP = 0.0082 min-1 and MTF = 0.0296 min-1 according to the Langmuir-Hinshelwood model, benefitting from the excellent synergistic impact of the SrWO4 catalyst toward the photocatalytic degradation of the drug molecule. Hence, this work offers innovative insights into the applicability of the as-prepared SrWO4 bifunctional catalyst as an excellent functional material for the remediation of emerging pollutants in water bodies with a recovery range of 98.2-99.75%.

Metal chalcogenides (CuS or MoS2)-modified TiO2 as highly efficient bifunctional photocatalyst nanocomposites for green H2 generation and dye degradation

Herein, we report the modification of TiO2 nanostructures with two different metal chalcogenides (CuS or MoS2). The effect of the preparation scheme (hydrothermal and coprecipitation methods) and the mass ratio of metal chalcogenides were investigated. The as-synthesized photocatalyst nanocomposites were fully characterized by various techniques. Moreover, the photo/electrochemical analysis were performed to investigate the photoelectric properties and photocatalytic mechanism. The photocatalytic performance was evaluated using two test reactions. In the case of H2 generation via water splitting, it was found that 0.5 wt% CuS-TiO2 synthesized via the coprecipitation method exhibited an initial hydrogen evolution rate (HER) of 2.95 mmol h−1 g−1. While, the optimized 3 wt% MoS2-TiO2 synthesized by the hydrothermal method, showed an HER of 1.7 mmol h−1 g−1. Moreover, the degradation efficiency of methylene blue dye was 98% under UV–Vis light irradiation within 2 h over 0.5 CT_PP and 3MT_HT. Under visible irradiation, the degradation efficiency was 100% and 96% for 3MT_PP and 0.5CT_HT in the presence of H2O2, respectively. This study has proven that metal chalcogenides can act as effective, stable, and low-cost bifunctional co-catalysts to enhance the overall photocatalytic performance.

Porous Hybrid PVDF/BiFeO3 Smart Composite with Magnetic, Piezophotocatalytic, and Light-Emission Properties

The creation of multi-stimuli-sensitive composite polymer–inorganic materials is a practical scientific task. The combination of photoactive magneto-piezoelectric nanomaterials and ferroelectric polymers offers new properties that can help solve environmental and energy problems. Using the doctor blade casting method with the thermally induced phase separation (TIPS) technique, we synthesized a hybrid polymer–inorganic nanocomposite porous membrane based on polyvinylidene fluoride (PVDF) and bismuth ferrite (BiFeO3/BFO). We studied the samples using transmission and scanning electron microscopy (TEM/SEM), infrared Fourier spectroscopy (FTIR), total transmission and diffuse reflection, fluorescence microscopy, photoluminescence (PL), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), vibrating-sample magnetometer (VSM), and piezopotential measurements. Our results demonstrate that the addition of BFO increases the proportion of the polar phase from 76.2% to 93.8% due to surface ion–dipole interaction. We also found that the sample exhibits laser-induced fluorescence, with maxima at 475 and 665 nm depending on the presence of nanoparticles in the polymer matrix. Furthermore, our piezo-photocatalytic experiments showed that under the combined actions of ultrasonic treatment and UV–visible light irradiation, the reaction rate increased by factors of 68, 13, 4.2, and 1.6 compared to sonolysis, photolysis, piezocatalysis, and photocatalysis, respectively. This behavior is explained by the piezoelectric potential and the narrowing of the band gap of the composite due to the mechanical stress caused by ultrasound.

The Removal of Sulfamonomethoxine (SMM) with Copper Oxide/Zirconium Dioxide (CuO/ZrO2) Nanocomposites by Photocatalytic Degradation in Pharmaceutical Industry Wastewaters and the Evaluation of Microtox (Aliivibrio fischeri) and Daphnia magna Acute Toxicity Assays

In this study, Copper oxide/zirconium dioxide (CuO/ZrO2) nanocomposites (NCs) as a photocatalys was examined during photocatalytic degradation process (PDP) in the efficient removal of Sulfamonomethoxine (SMM) from pharmaceutical industry wastewater (PI ww) plant, İzmir, Turkey. Different pH values (3.0, 4.0, 7.0, 9.0, 10.0 and 12.0), increasing SMM concentrations (5, 10, 20 and 40 mg/l), increasing CuO/ZrO2 NCs concentrations (100, 200, 400, 800 and 1000 mg/l), different CuO/ZrO2 NCs mass ratios (1/2, 2/3, 3/4, 4/4, 4/3, 3/2, 2/1), increasing recycle times (1., 2., 3., 4., 5., 6. and 7.) was operated during PDP in the efficient removal of SMM in PI ww. The characteristics of the synthesized nanoparticles (NPs) were assessed using XRD, DRS, FESEM, EDX, FTIR, TEM and XPS analyses, respectively. The acute toxicity assays were operated with Microtox (Aliivibrio fischeri also called Vibrio fischeri) and Daphnia magna acute toxicity tests. The photocatalytic degradation mechanisms of CuO/ZrO2 NCs and the reaction kinetics of SMM were evaluated in PI ww during PDP. Cost analysis was evaluated for SMM removal with CuO/ZrO2 NCs by PDP in PI ww. ANOVA statistical analysis was used for all experimental samples. Maximum 99.6% SMM removal was obtained during PDP in PI ww, at 350 W UV-vis light irradiation power, at 147 mW/cm2 light intensity, after 120 min, at pH=12.0 and at 25oC, respectively. Maximum 99.2% SMM removal was found with PDP in PI ww, at 5 mg/l SMM, at 350 W UV-vis, at 147 mW/cm2, after 120 min, at pH=12.0 and at 25oC, respectively. Maximum 99.5% SMM removal was measured to 800 mg/l CuO/ZrO2 NCs with PDP in PI ww, at 5 mg/l SMM, at 350 W UV-vis, at 147 mW/cm2, after 120 min, at pH=12.0 and at 25oC, respectively. Maximum 99.4% SMM removal was measured at 4/3wt CuO/ZrO2 NCs mass ratios, at 5 mg/l SMM, at 800 mg/l CuO/ZrO2 NCs, at 350 W UV-vis, at 147 mW/cm2, after 120 min, at pH=12.0 and at 25oC, respectively. Maximum 99.5% SMM recovery was measured in PI ww during PDP, after 1. recycle time, at 5 mg/l SMM, at 800 mg/l CuO/ZrO2 NCs, at 4/3wt CuO/ZrO2 NCs mass rartio, at 350 W UV-vis, at 147 mW/cm2, after 120 min, at pH=12.0 and at 25oC, respectively. 97.31% maximum Microtox acute toxicity removal was found in SMM=20 mg/l after 180 min, and at 60oC. It was observed an inhibition effect of SMM=40 mg/l to Microtox after 180 min, and at 60oC. 93.27% maximum Daphnia magna acute toxicity removal was obtained in SMM=20 mg/l after 180 min, and at 60oC, respectively. It was obtained an inhibition effect of SMM=40 mg/l to Daphnia magna after 180 min and at 60oC. As a result, the CuO/ZrO2 NCs during PDP in PI ww was stable in harsh environments such as acidic, alkaline, saline and then was still effective process. Finally, the combination of a simple, easy operation preparation process, excellent performance and cost effective, makes this CuO/ZrO2 NCs a promising option during PDP in PI ww treatment.

The Use of a Novel Graphitic Carbon Nitride/Cobalt Molybdate (G-C3 n4 /ComoO4 ) Nanocomposites for the Doxycycline Removal by Photocatalytic Degradation in Pharmaceutical Industry Wastewaters and the Evaluation of Microtox (Aliivibrio Fischeri) and Daphnia Magna Acute Toxicity Assays

In this study, a novel graphitic carbon nitride/cobalt molybdate (g-C3 N4 /CoMoO4 ) nanocomposites (NCs) as a photocatalys was examined during photocatalytic degradation process in the efficient removal of Doxycycline (DOX) from pharmaceutical industry wastewater plant, İzmir, Turkey. Different pH values (3.0, 4.0, 6.0, 7.0, 9.0 and 11.0), increasing DOX concentrations (5 mg/l, 15 mg/l, 30 mg/l and 45 mg/l), increasing g-C3 N4 /CoMoO4 NCs concentrations (1 mg/l, 2 mg/l, 3 mg/l, 4 mg/l, 6 mg/l, 8 mg/l and 10 mg/l), different g-C3 N4 /CoMoO4 NCs mass ratios (5/5, 6/4, 7/3, 8/2, 9/1, 1/9, 2/8, 3/7 and 4/6), increasing recycle times (1., 2., 3., 4., 5., 6. and 7.) was operated during photocatalytic degradation process in the efficient removal of DOX in pharmaceutical industry wastewater. The characteristics of the synthesized nanoparticles (NPs) were assessed using X-Ray Difraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-Ray (EDX), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), and Diffuse reflectance UV-Vis spectra (DRS) analyses, respectively. The acute toxicity assays were operated with Microtox (Aliivibrio fischeri also called Vibrio fischeri) and Daphnia magna acute toxicity tests. ANOVA statistical analysis was used for all experimental samples. The maximum 99% DOX removal efficiency was obtained during photocatalytic degradation process in pharmaceutical industry wastewater, at 150 W UV-vis light irradiation power, after 180 min photocatalytic degradation time, at pH=9.0 and at 25°C, respectively

Tuning the Optical Properties of ZnO by Co and Gd Doping for Water Pollutant Elimination

In the present study, pure, Co, Gd, and Co/Gd di-doped ZnO nanoparticles were synthesized via the co-precipitation synthesis route. The prepared samples were characterized through different techniques such as the X-ray diffraction method (XRD), scanning electron microscopy (SEM), UV-Vis spectroscopy, photoluminescence (PL)spectroscopy, and an impedance analyzer and vibrating sample magnetometer (VSM). The XRD pattern shows ZnO’s wurtzite hexagonal crystal structure; moreover, the shifting of characteristic peaks toward the lower angle indicates the inclusion of Co and Co/Gd in the ZnO host lattice. SEM micrographs show various morphologies such as rods, the agglomeration of particles, and spherical nanoparticles. The UV-Vis spectroscopy reveals that the absorption increased in the visible region and there was a substantial redshift for the doped samples. The bandgap decreased from 3.34 to 3.18 eV for the doped samples. The PL spectra show near-edge and inter-band transitions; the origin of inter-band transitions is attributed to the defect states present within the bands. The dielectric constant is strongly frequency dependent and decreases with Co and Co/Gd doping, while the electrical conductivity increases. A VSM study indicates that pure ZnO is diamagnetic, while the Co and Co/Gd doped ZnO nanoparticles showed ferromagnetic behavior. Under UV-visible light irradiation, the Co/Gd-ZnO nanoparticles showed higher photocatalytic activity than the ZnO nanoparticles. The enhanced photocatalytic activity may be attributed to a decreased bandgap with doping.

Helianthus-annuus assisted synthesis of ZrO2 nanoparticles: Enhanced electrochemical, photoluminescent, and optical properties

Cubic-phase ZrO2 nanoparticle (NPs) were synthesized using a cost-effective single-pot green combustion method and Helianthus annuus extract, and their properties were evaluated. Powder X-ray diffraction was used to investigate the purity, crystal structure, and size of the NPs, and the average size of the NPs was determined to be ∼ 25 nm. The internal surface morphology of the NPs with distinct voids and pores were observed using scanning electron microscopy (SEM) Ultraviolet–visible (UV-vis) absorption spectroscopy was used to analyze the optical properties of the as-synthesized ZrO2 NPs, and their energy bandgap was determined to be 4.5 eV. The photoluminescence (PL) spectrum of the cubic-phase ZrO2 NPs presented a broad band in the UV-vis region. The PL emission properties of the ZrO2 NPs were studied by analyzing their emission wavelength at ∼490 nm, and the results revealed that the NPs can be efficiently used for display applications. The electrochemical properties of a graphite–ZrO2 NP electrode was qualitatively analyzed by performing cyclic voltammetry (CV) and electrochemical impedance spectroscopy experiments in a three–electrode system with a 0.1 M KCl solution as the electrolyte. Our results suggested that the NPs can be used to evaluate the thermodynamics of the redox reaction, and their capacitance was determined using the CV curves of a graphite–ZrO2 working electrode at different scan rates in the range of 0.01 ∼ 0.05 V/s at room temperature. Furthermore, the photodegradation rate of Reactive Blue 4 textile dye over the as-prepared ZrO2 NPs reached 97% under UV-vis light irradiation.