Photocatalyst For Degradation Of Organic Dyes Research Articles

Captivating 2H-MoS2 nanoflowers for efficient NH3 detection and photocatalytic dye degradation

This research unveils the gas sensing and photocatalytic potential of 2H-MoS2 nanoflowers, offering a promising solution for ammonia sensing and wastewater remediation. The 2H phase of MoS2 nanoflowers is synthesized via a simple one-step hydrothermal method using ammonium heptamolybdate and thiourea. The elemental and morphological study confirms the formation of the 2H phase of MoS2 nanoflowers with an average sheet thickness of 14 nm. The XRD and HR-TEM analysis findings are in good accordance with the interlayer spacing of MoS2, calculated to be 0.64 nm. The 2H-MoS2 nanomaterial based chemiresistive sensor is tested for six different targets (NH3, C2H5OH, C3H6O, C3H7OH, HCHO, and C6H5CH3) and shows good selectivity towards ammonia (NH3) with the highest response of 81 %. The response-recovery time, repeatability, concentration, and humidity-based analysis are conducted for the analysis of the sensor. The fabricated 2H-MoS2 based sensor shows a response time of 8.5 s and a recovery time of 4.3 s. Furthermore, three model water contaminated dyes, MB, MO, and RB, are chosen for the photocatalytic experiment under visible light irradiation. The reusability, relative degradation, and pseudo-first-order analysis are used to evaluate the photocatalytic dye degradation properties of 2H-MoS2 nanoflowers. The reaction rate constant of 2H-MoS2 nanomaterials for MB, MO, and RB dyes is calculated to be (0.05010) min−1, (0.03458) min−1, and (0.02516) min−1, respectively. The maximum degradation efficiency of 2H-MoS2 nanoflowers towards MB, MO, and RB dye is 95 %, 86 %, and 76 %, respectively, under visible light irradiation. These findings suggest that the hydrothermally synthesized 2H-MoS2 nanoflowers have multifunctional applications such as effective NH3 sensors as well as photocatalysts for organic dye degradation, paving the way for more efficient and sustainable gas sensing and wastewater treatment technologies.

Easy Scalable Solid-State Synthesis of Highly Efficient Synergetic 2D/1D Micro/Nanostructured g-C3N4/MeS (Me=Cd, Mo) Photocatalysts for Organic Dye Degradation and Hydrogen Evolution

The global reserves of oil, gas, and coal are acknowledged finite, and their consumption rates are increasing each year [1]. Following Fujishima’s groundbreaking discovery of photocatalytic water splitting using TiO2 electrodes in 1972 [2], photocatalysis technology gained recognition as a promising approach for renewable energy and environmental conservation [3]. Since that pivotal moment, significant advancements have been made in developing preparation methods for highly efficient photocatalysts, predominantly centered on semiconductors like metal oxides and sulfides [4].In this study, we introduce effective synergistic photocatalysts, that utilize g-C3N4 and MeS (Me=Cd, Mo) semiconductors featuring a 2D/1D micro/nanostructure. Photocatalysts were successfully produced through solid-state method using planetary ball mill, where reaction of MeS formation occurs on the surface of g-C3N4. A comprehensive analysis of the binding energy of electrons of semiconductors was conducted to understand its impact on the photocatalytic activity of the prepared g-C3N4/MeS. The fabricated materials were used in the photodegradation of organic dyes and demonstrated remarkable efficacy. Regarding photocatalytic hydrogen evolution, the g-C3N4/CdS in conjunction with Pt co-catalyst, achieved a hydrogen evolution rate of up to 2254.54 μmol*h⁻¹ *g⁻¹, accompanied by apparent quantum efficiency of 2.0%. Acknowledgments This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. АР13068426).

Novel green synthesis approach of eco-friendly magnetic/semiconductor nanocomposites as magnetically separable and reusable photocatalyst for organic dye degradation

Eco-friendly and effective separation of photocatalytic nanoparticles from the reaction mixture is crucial to facilitate their repeated use in photocatalysis. The development of magnetic/semiconductor nanocomposites with high catalytic performance and easy separation is an efficient strategy for wastewater treatments. In this study, we explore the potential of combination of magnetic (CoFe2O4) and semiconductor (ZnS) synthesized via a green approach using Moringa oleifera leaf extract as magnetically separable photocatalysts for dye degradation. X-ray diffraction analysis confirmed the presence of the cubic spinel ferrite phase of CoFe2O4 and the cubic zinc blend phase of ZnS within the nanocomposites. The micrographs illustrated nearly spherical nanoparticles with average particle sizes of 12 nm for CoFe2O4 and 26 nm for CoFe2O4/ZnS, respectively. The presence of SO suggested the incorporation of ZnS on the surface of CoFe2O4/ZnS nanocomposites. The UV–visible spectra revealed an increase in the band gap energy from 3.7 to 4.5 eV with increasing ZnS concentrations. Magnetic properties analysis signified that the CoFe2O4/ZnS nanocomposites exhibited ferromagnetic characteristics. The optimal degradation efficiency of photodegradation methylene blue was observed for CoFe2O4/ZnS 50 %, achieving 78.3 % degradation within 80 min with intervals 20 min. The magnetically separable capability allows for the recycling of nanocomposites after three consecutive cycles. Therefore, CoFe2O4/ZnS nanocomposites emerge as promising candidates as separable photocatalysts for the removal of organic pollutants in environments.

Harnessing a Ti-based MOF for selective adsorption and visible-light-driven water remediation.

In pursuit of universal access to clean water, photocatalytic water remediation using metal-organic frameworks (MOFs) emerges as a strong alternative to the current wastewater treatment methods. In this study, we explore a unique Ti-based MOF comprised of 2D secondary-building units (SBUs) connected via biphenyl dicarboxylic acid (H2bpdc) ligands - denoted as COK-47 - as a visible-light-driven photocatalyst for organic dye degradation. Synthesized via a recently developed microwave-assisted method, COK-47 exhibits high hydrolytic stability, demonstrates a strong dye uptake, and shows noteworthy dye-degradation performance under UV, visible, and solar light, outperforming benchmark TiO2 and MIL-125-Ti photocatalysts. Due to its nanocrystalline structure and surface termination with organic linkers, COK-47 exhibits selective degradation of cationic pollutants while remaining inert towards anionic dyes, thus highlighting its potential for selective oxidation reactions. Mechanistic studies reveal the involvement of superoxide radicals in the degradation process and emphasize the need to minimize the recombination of photogenerated electron-hole pairs to achieve optimal performance. Post-catalytic studies further confirm the high stability and reusability of COK-47, making it a promising photocatalyst for water purification, organic transformation, and water splitting reactions under visible light.

Synthesis of SmMnO3/Sm2O3 nanocomposites as efficient photocatalysts for organic dye degradation by sol gel pechini method

In this research, we present SmMnO3/Sm2O3 nanocomposites as a novel ferromagnetic photocatalyst, synthesized through a straightforward sol-gel Pechini method utilizing citric acid and oxalic acid as fuels. Achieving the desired morphology involved varying the fuel type and calcination temperature. Comprehensive physicochemical characterizations were conducted using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller BET. With a band gap of 2.1 eV in the visible range, the SmMnO3/Sm2O3 nanocomposites exhibit promising optical properties. The photocatalytic prowess of these nanocomposites was systematically assessed against Malachite Green and Acid Red, with optimization of key parameters such as light source, pollutant concentration, and catalyst dosage. Notably, the peak photocatalytic activity was observed for Malachite Green, achieving an impressive 96% degradation under visible light within 120 min. The elucidation of the photocatalytic mechanism employed scavengers, revealing the pivotal role of OH• in the photodegradation process. Recycling experiments demonstrated consistent and acceptable results over five cycles, affirming the recyclability and durability of the SmMnO3/Sm2O3 nanocomposites. This study introduces a novel ferromagnetic photocatalyst with notable photocatalytic efficiency, emphasizing its potential applications in environmental remediation. The novelty of this work lies in the introduction of a new nanocomposite for photocatalysis in visible light, achieving high efficiency within a short time frame of 120 min.

Novel interface engineering of LDH-based materials on Mg alloy for efficient photocatalytic systems considering the geometrical linearity of condensed phosphates

This study presents a facile and rapid method for synthesizing novel Layered Double Hydroxide (LDH) nanoflakes, exploring their application as a photocatalyst, and investigating the influence of condensed phosphates’ geometric linearity on their photocatalytic properties. Herein, the MgO film, obtained by plasma electrolysis of AZ31 Mg alloys, was modified by growing an LDH film, which was further functionalized using cyclic sodium hexametaphosphate (CP) and linear sodium tripolyphosphate (LP). CP acted as an enhancer for flake spacing within the LDH structure, while LP changed flake dispersion and orientation. Consequently, CP@LDH demonstrated exceptional efficiency in heterogeneous photocatalysis, effectively degrading organic dyes like Methylene blue (MB), Congo red (CR), and Methyl orange (MO). The unique cyclic structure of CP likely enhances surface reactions and improves the catalyst's interaction with dye molecules. Furthermore, the condensed phosphate structure contributes to a higher surface area and reactivity in CP@LDH, leading to its superior photocatalytic performance compared to LP@LDH. Specifically, LP@LDH demonstrated notable degradation efficiencies of 93.02%, 92.89%, and 88.81% for MB, MO, and CR respectively, over a 40 min duration. The highest degradation efficiencies were observed in the case of the CP@LDH sample, reporting 99.99% for MB, 98.88% for CR, and 99.70% for MO. This underscores the potential of CP@LDH as a highly effective photocatalyst for organic dye degradation, offering promising prospects for environmental remediation and water detoxification applications.

Copper Selenide (CuSe) Monolith Fabricated by Facile Copper Foam Selenization for Efficient Photocatalytic Degradation of Methylene Blue

A critical challenge that impedes the application of photocatalytic techniques for organic dye degradation from polluted industrial effluents is that traditional powdery photocatalysts exposed limited photo-absorption sites and exhibited inefficient recyclability. To overcome these challenges, this study designed a one-step process to synthesize a monolithic copper selenide (CuSe)-based photocatalyst. The characterization results fully supported that the maintenance of the copper foam during the selenization process was the prerequisite for the monolithic photocatalyst to keep its structural integrity in photocatalytic reactions. The surface of the monolithic photocatalyst fully covered by active CuSe is crucial for the exposure of photocatalytically active sites and the efficient degradation of methylene blue (MB). It was found that the CuSe-based monolithic photocatalyst exhibited excellent MB degradation performances under harsh pH conditions and high MB concentrations. From these perspectives, it is reasonable to conclude that the CuSe-based monolithic photocatalyst as prepared is a promising alternative to traditional powdery photocatalysts for organic dye degradation and industrial effluent cleaning.

Synthesis of highly fluorescent carbon quantum dots from rubber seed shells for the adsorption and photocatalytic degradation of dyes

The potentials of biomass-based carbon quantum dot (CQD) as an adsorbent for batch adsorption of dyes and its photocatalytic degradation capacity for dyes which are congo red (CR) and methylene blue (MB) have been conducted in this study. The CQDs properties, performance, behaviour, and photoluminescence characteristics were assessed using batch adsorption experiments which were carried out under operating conditions including, temperature, pH and dosage. The morphological analysis revealed that CQDs are highly porous, uniform, closely aligned and multi-layered. The presence of hydroxyl, carboxyl and carbonyl functional groups indicated the significance of the oxygenated functional groups. Spectral analysis of photoluminescence for CQDs confirmed their photoluminescent quality by exhibiting high excitation intensity and possessing greenish-blue fluorescence under UV radiation. The removal percentage of the dyes adsorbed for both CR and MB dyes was 77% and 75%. Langmuir isotherm and pseudo-second-order models closely fitted the adsorption results. Thermodynamics analysis indicated that the adsorption process was exothermic and spontaneous, with excellent reusability and stability. The degradation efficiency of CQDs on both dyes was more than 90% under sunlight irradiation and obeyed the first-order kinetic model. These results demonstrated CQDs to be an excellent adsorbent and outstanding photocatalyst for organic dye degradation.

Synthesis and characterization of ZnO, ZnO Doped Ag2O Nanoparticles and its Photocatalytic Activity

Aim: Zinc oxide (ZnO) nanomaterials play an important role in many industries because of their amazing optical, electrical, mechanical, thermal, and structural capabilities. Introduction: The current study focuses on the production of ZnO nanoparticles for photocatalytic dye degradation activities, and three types of ZnO nanoparticles are prepared: pure ZnO nanocrystals extracted through chemical and biological route and Ag2O doped ZnO nanoparticles. Methods: The average particle size of chemically produced ZnO nanocrystals was predicted to be 34 nm, and SEM examination validated the creation of ZnO nanorods-like structure from chemical technique, which exhibits enhanced photocatalytic activity. X-ray diffraction study of Ag2O/ZnO nanoparticles revealed a hexagonal shape. Results: The average particle size was determined to be between 16 and 17 nm. The findings of the SEM examination also revealed that the produced Ag2O doped ZnO nanoparticles agglomerated in hexagonal forms and adhered as bulks and rods that increased with the amount of Ag nanofluids. As a result, it is determined that agglomerated Ag2O/ZnO nanoparticles with hexagonal and rod structures operate as an efficient photocatalytic agent. Conclusion: It is obvious that 25 ml of Ag2O nanofluid doped with ZnO produces an excellent photocatalyst for organic dye degradation and is appropriate for large-scale applications.

Visible-light-responsive hydrogen-reduced CoOx loaded Rh/Sb:SrTiO3 nanocubic photocatalyst for degradation of organic pollutants and inactivation of bacteria

In this work, we synthesized cobalt oxide loaded Rh/Sb:SrTiO3-nanocube (NC) photocatalysts for organic dye degradation and bacterial inactivation. Firstly, we synthesized Rh/Sb-doped SrTiO3 NC nanocomposite and further loaded cobalt oxide (2 wt%) via wet impregnation and followed by hydrogen-reduction treatments. Interestingly, after hydrogen heat treatment cobalt oxide-loaded photocatalysts convert into metallic Co/CoOx-Rh/Sb:SrTiO3 NCs. The hydrogen-treated Co/CoOx-Rh/Sb:SrTiO3 NCs (red) photocatalyst shows significantly high degradation efficiencies and good recyclability for Orange II dye (90.1%) and bisphenol A (99.1%) under visible-light irradiation (λ ≥ 420 nm) within 30 min. Additionally, the bacterial inactivation efficiency of Co/CoOx-Rh/Sb:SrTiO3 NCs (red) photocatalyst reaches about ∼97% for both Staphylococcus aureus and Escherichia coli under visible light. The enhanced photocatalytic dye degradation and bacterial inactivation activity of Co/CoOx-Rh/Sb:SrTiO3 NCs (red) photocatalyst was due to the delayed photogenerated charge-recombination process, generation of oxygen vacancies, and the synergistic effect of a metallic Co/CoOx phase. Further, radical trapping experiments confirmed that the degradation of Orange II was governed by the major species, •O−2 and h+. In last, the possible charge-transfer mechanisms of the photocatalytic degradation of organic pollutants, as well as the inactivation of bacteria over the Co-Rh/Sb: SrTiO3 (red) NC photocatalyst, are presented in detail.

The flexibility of CuI chains and the functionality of pyrazine-2-thiocarboxamide keys to obtaining new Cu(I)-I coordination polymers with potential use as photocatalysts for organic dye degradation

This research focuses on two interesting aspects in the synthesis of new coordination polymers (CPs) taking advantage of the lability of coordination bonds. The first is the use of multifunctional and flexible building blocks, such as pyrazine-2-thiocarboxamide (Pyrtca) and CuI, and the second is the modification of the synthetic conditions to expand the amount of different crystalline phases. This means that starting from the same building blocks, we can increase the number of compounds obtained and diversify their final properties, as well as their possible applications. Furthermore, Cu(I)-halogen coordination polymers have been extensively studied for a long time due to their interesting optoelectronic properties. However, despite being usually semiconductors, research related to their possible behavior as photocatalysts is almost non-existent. In this work, we present five compounds, four coordination compounds with formulas [CuI(Pyrtca)]n (CP1), [Cu3I3(Pyrtca)7] (2) [Cu2I2(Pyrtca)]n(CP4 and CP4′) and a transformation of the starting ligand to a cationic imidazole derivative (compound 3) where copper iodine serves as a catalyst. All the compounds have been characterized by different techniques including single-crystal X-ray diffraction. The antibacterial behavior of CP1 against E. Coli DH5, E. Coli BL21, and C. glabrata (CECT 1448), as well as their optoelectronic properties, are also discussed in the work. The value of the band gap obtained (1.91 eV) for the two-dimensional coordination polymer of formula [Cu2I2(Pyrtca)]n(CP4) allows us to study its behavior as a photocatalyst in the degradation of persistent dyes in water with interesting results, achieving a total degradation of Methylene Blue and Rhodamine B in 40 min under UV–visible light.

Heterostructured α-Bi2O3/BiOCl Nanosheet for Photocatalytic Applications.

Photocatalytic degradation of organic pollutants in wastewater is recognized as a promising technology. However, photocatalyst Bi2O3 responds to visible light and suffers from low quantum yield. In this study, the α-Bi2O3 was synthetized and used for removing Cl− in acidic solutions to transform BiOCl. A heterostructured α-Bi2O3/BiOCl nanosheet can be fabricated by coupling Bi2O3 (narrow band gap) with layered BiOCl (rapid photoelectron transmission). During the degradation of Rhodamine B (RhB), the Bi2O3/BiOCl composite material presented excellent photocatalytic activity. Under visible light irradiation for 60 min, the Bi2O3/BiOCl photocatalyst delivered a superior removal rate of 99.9%, which was much higher than pristine Bi2O3 (36.0%) and BiOCl (74.4%). Radical quenching experiments and electron spin resonance spectra further confirmed the dominant effect of electron holes h+ and superoxide radical anions ·O2− for the photodegradation process. This work develops a green strategy to synthesize a high-performance photocatalyst for organic dye degradation.

Insight into Potassium Vanadates as Visible-Light-Driven Photocatalysts: Synthesis of V(IV)-Rich Nano/Microstructures for the Photodegradation of Methylene Blue.

Photocatalysis is regarded as a promising tool for wastewater remediation. In recent years, many studies have focused on investigating novel photocatalysts driven by visible light. In this study, K2V6O16·nH2O nanobelts and KV3O8 microplatelets were synthesized and investigated as photocatalysts. Samples were obtained via the facile method based on liquid-phase exfoliation with ion exchange. By changing the synthesis temperature (20–80 °C), different compositions, morphologies, and V4+/V5+ ratios were obtained and investigated as photocatalysts for organic dye degradation. Potassium vanadates’ structural, morphological, and optical properties were characterized using X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Physical Property Measurement System (PPMS), thermogravimetric analysis (TGA) with mass spectrometry (MS), N2 adsorption, scanning electron microscopy (SEM), photoluminescence (PL), and UV–vis diffuse reflectance spectroscopy (DRS). Synthesized K2V6O16·nH2O and KV3O8 showed an efficient absorption in the visible wavelength region with a narrow band gap energy of 1.80 and 1.91 eV, respectively. Their photocatalytic activity was evaluated by the degradation of methylene blue (MB) under simulated solar light illumination. The KV3O8 microplatelets exhibited the greatest photocatalytic activity, resulting in more than 90% degradation of the dye within the first 30 min. It is suggested that the observed excellent photocatalytic performance is attributed to the high content of V4+ species. Furthermore, the influence of active species was investigated, and the mechanism responsible for the photodegradation of the MB dye was discussed for the first time for potassium vanadates.

1D copper (II) based coordination polymer/PANI composite fabrication for enhanced photocatalytic activity

One-dimensional Copper (II) Coordination polymer with pyridine-2-carboxylic acid ligand (CP1) was loaded on PANI through in situ chemical oxidative polymerization of aniline to form 1 wt%, 2 wt%, 5 wt%, 10 wt%, and 12 wt% CP1/PANI composites and study their photcatalytic activities. The photocatalytic efficiencies of CP1 and CP1/PANI composite materials were studied for degradation of methylene blue (MB) under ultraviolet (UV) light irradiation. Results reveal that CP1/PANI composite materials exhibit higher photocatalytic performances in comparison with that of CP1. The 10 wt %CP1/PANI composite exhibits the highest efficiency of about 88.31 % for the degradation in 210 min. The higher photocatalytic activity of CP1/PANI composite can be credited to the synergistic effect between CP1 and PANI that accelerates the separation efficiency of photogenerated electrons (e-) and holes (h+) at the interface between CP1 and PANI. Thus, CP1/PANI composites can be suitably used as an efficient photocatalysts for organic dye degradation.

Construction of magnetically recoverable novel Z-scheme La(OH)3/α-MnO2/MnFe2O4 photocatalyst for organic dye degradation under UV–visible light illumination

Researchers have been fascinated to the field of photocatalysis by the creation of innovative composite photocatalysts to enhance the performance of the catalyst. The novel magnetically recoverable La(OH)3/α-MnO2/MnFe2O4 nanocomposite have been successfully prepared via a simple wet impregnation process. The as-synthesized photocatalysts were characterized by multiple analytical techniques. The photocatalytic performance of the as-prepared materials was examined based on Rhodamine B (Rh B) dye under UV–visible light illumination. The obtained Z-scheme magnetically recoverable La(OH)3/α-MnO2/MnFe2O4 nanocomposite exhibited remarkably photocatalytic activity (94.69%), 4.04 and 2.33 times higher than the La(OH)3 and α-MnO2/MnFe2O4 nanocomposite, respectively. The ferromagnetic behavior of MnFe2O4 nanoparticles (NPs) and the high light absorption capacity of α-MnO2 nanorods improve the photocatalytic performance of La(OH)3/α-MnO2/MnFe2O4 nanocomposite. La(OH)3/α-MnO2/MnFe2O4 nanocomposite was able to help ease the recovery by its ferromagnetic behavior. This enriched photocatalytic performance could be caused by the formation of Z-scheme junctions between La(OH)3 and α-MnO2/MnFe2O4 nanocomposite, which helps effectual charge separation and keeps a high redox potential. Magnetically recoverable La(OH)3/α-MnO2/MnFe2O4 nanocomposite offers potential for photocatalysis and has probable applications in the energy and environmental sectors.

Dewetted Silver Nanoparticle-Dispersed WO3 Heterojunction Nanostructures on Glass Fibers for Efficient Visible-Light-Active Photocatalysis by Magnetron Sputtering.

Fabrication of hybrid-heterojunction nanostructures comprising the Z-scheme and localized surface plasmon resonance is essential for enhancing the photocatalytic degradation of organic compounds to enable environmental remediation. This study focuses on the dispersion of dewetted Ag nanoparticles over the 3D network-like silica glass fibers (SGFs) coated with a Cu-doped WO3 heterojunction system by a high-throughput and cost-effective method using magnetron sputtering, followed by solid-state dewetting. The influence of Cu doping on the crystal structure, growth direction, and morphology of WO3 and the effect of localized surface diffusion-driven dewetted Ag nanoparticles on the photocatalytic performance were investigated. The Cu doping changed the optical band gap, and the 2Cu–WO3/SGF exhibited excellent photocatalytic activity. The surface dispersion of dewetted Ag nanoparticles over Cu–WO3/SGFs exhibited lowest photoluminescence intensity, indicating the effective separation of photogenerated electrons–holes, which led to highest efficiency (∼98%) in photocatalytic degradation of methylene blue among all the fibers with a degradation rate constant (k = 0.0205 min–1) that was ∼18.6 times higher than that of pure WO3 (k = 0.0011 min–1). The findings of this study can provide insights for designing low-cost and efficient visible-light-active photocatalysts for organic dye degradation, enabling environmental remediation.

Facile production of three-dimensional chitosan fiber embedded with zinc oxide as recoverable photocatalyst for organic dye degradation

Herein we report on a facile and green strategy for continuous production of chitosan-zinc oxide fibers and then compare their photodegradation performance against three organic dyes (i.e., methylene blue (MB), methyl orange (MO) and Rhodamine B, respectively) under different lights. Chitosan-zinc hydrogel fibers (CS/Zn) with different zinc loadings are obtained by direct mixing of chitosan and zinc acetate solutions using a double-syringe injection device. The as-prepared CS/Zn fibers are then immersed into glutaraldehyde (GA) and sodium hydroxide solutions, respectively, and dried at T = 50 °C. The resultant CS/ZnO/GA fibers of ca. 617 μm in diameter are characterized using X-ray diffraction (XRD), thermogravimetric analysis and field emission scanning electron microscope (FE-SEM). XRD and FE-SEM data confirm that the CS/ZnO/GA fibers consist of a large amount of hexagonal wurtzite ZnO nanorods up to 550 nm in length, and exhibit three-dimensional interconnected macroporous architecture. Photodegradation results clearly show that the CS/ZnO/GA fibers are effective for the removal of organic dyes upon UV irradiation and can be easily recovered and reused for at least 6 consecutive cycles. Unlike most reported CS/ZnO nanocomposites, the current CS/ZnO/GA fiber shows a higher adsorption of cationic MB rather than anionic MO, the mechanism of which is proposed.

In-situ development of metal organic frameworks assisted ZnMgAl layered triple hydroxide 2D/2D hybrid as an efficient photocatalyst for organic dye degradation

Metal organic framework (MOF) supported layered triple hydroxide (LTH) 2D/2D hybrid material was prepared by a simple hydrothermal method. The photophysical properties of the prepared samples were investigated through a set of analytical methods such as X-ray diffraction, Fourier-transform infrared spectroscopy, field emission scanning electron microscope, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and mapping. The photocatalytic degradation activity of as prepared 2D/2D MOF-5/LTH hybrid sample was investigated against methylene blue (MB) dye under the UV–visible light irradiation. The degradation efficiency of the MOF-5/LTH hybrid sample was twice a time greater than that of pristine MOF-5, particularly degradation efficiency of the MOF-5, LTH and MOF-5/LTH hybrid samples are 43.3, 57.7 and 98.1% respectively. The Pseudo first order rate and the reusing investigation was further used to study the catalytic activity and stability of the as-synthesized 2D/2D photocatalyst. The observed improvement in the photocatalytic activity of the hybrid samples were owed to enhance visible light absorption, efficient separation and transportation of photoinduced electrons and holes.

CdS@MoS2 Hetero-structured Nanocomposites Are Highly Effective Photo-Catalysts for Organic Dye Degradation.

CdS@MoS2 hetero-structured nanocomposites (HSNPs) were successfully synthesized via a hydrothermal approach. The morphology and crystal structure of these composites as well as their ability to act as photocatalysts for the degradation of methylene blue were investigated using scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and UV–vis absorption spectroscopy. The developed CdS@MoS2 nanocomposites exhibited an 80% degradation rate with 30 min of visible light irradiation. To characterize the basis of the photocatalytic properties of these materials, the transient photocurrent densities were determined for the CdS@MoS2 HSNPs and pure dendritic CdS nanotrees. The results suggest that the photocatalytic activity may reflect electron transfer between the conduction band maximum of CdS and MoS2. Additionally, the improved visible light absorption, decreased electron–hole pair recombination, and enhanced surface area for more effective dye absorption likely contribute to improved photocatalytic performance.

Tightly-coated and easily recyclable Ag@AgBr-cotton hybrid photocatalyst for organic dye degradation under visible light

Immobilization of photocatalysts on substrates is an important factor for water purification in practical applications. In this study, an efficient Ag@AgBr photocatalytic coating was attached onto the surface of cotton fabric via radiation-induced graft polymerization and subsequent chemical reactions, and the resultant product was denoted as Cot-Ag@AgBr. The graft chains acted not only as a source of bromine, but also as an intermediate layer to anchor the Ag@AgBr photocatalytic coating via strong electrostatic interactions. The immobilized Ag@AgBr photocatalytic coating exhibited outstanding photocatalytic properties for organic dye degradation under visible light irradiation. Furthermore, Cot-Ag@AgBr presented high stability and robust durability, which conferred its excellent visible-light-driven photocatalytic activity after five rounds of photodegradation. After 10 min of ultrasonication, the amount of Ag@AgBr precipitate that leached from the Cot-Ag@AgBr was < 2%. Therefore, the as-synthesized cotton fabric offered good insight into the functionalization of polymer substrates with photocatalysts and could be useful for advanced wastewater treatment under the cyclic operations.