Methylene Blue Aqueous Solution Research Articles

Synthesis and Characterization of Low-Dimensional Quaternary Sulfides of Thallium, Tl2Cu2GeS4, Tl2Ag2GeS4, and Tl2Ag2SnS4.

Three new low-dimensional quaternary sulfides, namely, Tl2Cu2GeS4(1), Tl2Ag2GeS4(2), and Tl2Ag2SnS4(3) were synthesized by solid-state reactions and characterized by single-crystal X-ray diffraction, spectroscopic, thermal, and photocatalytic studies. The compounds 1, 2, and 3, respectively, have centrosymmetric layered, noncentrosymmetric layered, and noncentrosymmetric one-dimensional structures, in which Cu+, Ge4+, and Sn4+ ions have tetrahedral coordination and Ag+ ion has linear, trigonal planar and tetrahedral coordinations. The monovalent thallium cations have TlS8 dodecahedral coordination and TlS7 and TlS6 coordination polyhedra of irregular shape. The compounds 1, 2, and 3 are semiconductors with the respective energy band gap values of 1.68, 2.02, and 1.90 eV. Compared to compounds 1 and 2, compound 3 has a higher efficiency value of 22.9% for the photodegradation of aqueous solution of methylene blue. Band structures and projected density of states of all three compounds were computed using density functional theory, and these results are in good agreement with experiments.

Fennel Seed Biochar: A Sustainable Approach for Methylene Blue Removal from Aqueous Solutions.

In this study, biochars were produced from by-products of the herbal industry, specifically fennel seeds (Foeniculum vulgare), through direct activation by carbon dioxide at two different temperatures. The biochar samples were comprehensively analysed. Additionally, adsorption studies were conducted for methylene blue. The resulting adsorbents exhibited a specific surface area ranging from 2.29 to 14.60 m2/g. The resulting materials displayed a basic character on their surface. The constants for adsorption models were determined for each dye as well as thermodynamic parameters and the kinetics of the process. The sorption capacities of methylene blue for the samples exhibited a range of 22 to 43 mg/g. The adsorption kinetics of the dye on the biochar materials were found to follow a pseudo-second-order model, with the adsorption process best described by the Langmuir isotherm for the DA-800 sample and the Freundlich isotherm for the DA-750 sample. This indicates the development of a monolayer adsorbate on the biochar surfaces. The efficacy of the adsorption process in aqueous solutions of methylene blue was found to increase with rising temperature. Furthermore, based on thermodynamic studies, the adsorption process was found to be spontaneous and endothermic.

A CuBTC/CuS Photocatalyst for Organic Dyes: Degradation Kinetics and Mechanistic Insights

AbstractOrganic dyes derived from industrial processes have harmful potential to aquatic systems and require novel oxidative treatment. Metal‐organic frameworks (MOF) couple high adsorption capacity and photocatalytic action, which can be improved through heterojunctions. In this work, CuBTC (MOF) photocatalyst was synthesized by an electrochemical methodology, and the in situ CuS templated formation by addition of Na2S solution, giving CuBTC/CuS composites. The synthesized CuBTC MOF and CuBTC/CuS composites were characterized by XRD, FTIR, TGA, and EDX. The adsorptive capacity and photocatalytic properties were evaluated by the photocatalytic performance against methylene blue (MB) aqueous solution, under dark and simulated solar irradiation. Under simulated solar irradiation, the CuBTC/CuS achieved 87 % dye photodegradation after 120 min, 1.7 times higher than CuBTC. The photocatalytic action mechanisms were investigated by free‐radical capture experiments. At the equilibrium, the photocatalytic process presented pseudo‐first‐order (PFO) and pseudo‐second‐order (PSO) non‐linear kinetic models, showing a higher correlation with the PFO model, with a rate constant of 94.3×10−3 min−1. The photocatalytic performance of the composite was also evaluated over five cycles, decreasing to 68 %. The proposed strategy showed promise for the developing of highly effective materials to combat water pollution.

Ac/dc conductivity and ML-based evaluation of electric characteristics of methylene blue solution

Utilizing a precision LCR meter, the complex permittivity ε*(f) of methylene blue (MB) solutions in distilled water (DW) was determined at various temperatures and concentrations in the lower frequency range from 20 Hz to 2 MHz. The complex ac conductivity σ*(f) of the liquid samples was calculated using ε*(f). DC conductivity, σdc of the samples was also calculated. The effect of changes in temperature and concentration on the σ*(f) and ε*(f) of solutions are examined. A solution of MB in DW, ranging from diluted to concentrated, greatly enhances the electrical conductivity σdc. The empirical Casteel-Amis (CA) formula was employed to fit the experimental σdc values at different concentrations. Accurate measurement of complex permittivity of liquid solutions over wide range of concentration at broad range of frequencies and temperature is laborious and uneconomical. Therefore, we performed the complex permittivity measurement of the aqueous solution of MB over a limited concentration and temperature range over 201 frequency point. Then we used this experimental data in CatBoost regression model to predict the dielectric properties at intermediate frequencies and various concentrations. This model was employed to assess the performance of material characteristics using R-squared score. The study demonstrated that the CatBoost regression model can predict material performance at intermediate frequencies and concentrations while decreasing measurement resource needs by 60 %.

Synthesis of biomass-based BiOI@Hydrochar heterogeneous catalyst and investigation of its activity in sonocatalytic process

Innovative studies in recent years to remove pollutants discharged into water resources through various means are critically important for protecting existing water resources. An important part of these studies is heterogeneous catalysis-based AOPs, where new generation composite materials are used and high organic pollutant degradation has been achieved. This study used the solvothermal approach to produce a BiOI@BH sonocatalyst doped with hydrochar (BH). A variety of analysis techniques, including XRD, FESEM, EDS, FTIR, DRS, and BET surface analysis, were used to assess changes in the physico-chemical properties of the BiOI@BH structure in comparison to BiOI. Both the adsorption and sonocatalytic degradation processes for the methylene blue aqueous solution were found to be more successful with the BiOI@BH structure. The following order of oxidative species activity was observed in sonocatalytic degradation: •OH > h+ > O2•–. Recovery studies showed that the decrease in the efficiency of the catalyst after 5 cycles in MB degradation was 10 %. It was determined that the MB degradation efficiency increased significantly with the use of persulfate oxidant at pH> 5. Finally, MB solution (20 mg L−1) was degraded by 99 % in the presence of 5 mM persulfate and 0.5 g L−1 BiOI@BH at 90 min

Enhanced visible-light photocatalytic activity of N-doped C/Na2Ti6O13/TiO2 hollow spheres for efficient dye degradation

Doping and hybridization with other semiconductors are highly effective ways to address the limitations, including their weak response to visible light and significant recombination of photogenerated carriers. In addition, the assisted carbon on the catalyst surface and the structural design have the advantage of being catalytically active. Herein, visible-light-active N-doped C/Na2Ti6O13/TiO2 hollow spheres (denoted as N–C/NTO/TiO2 HS) were successfully prepared using a facile two-step method and evaluated for methylene blue (MB) aqueous solution degradation under visible-light irradiation.The as-obtained N–C/NTO/TiO2 HS demonstrated improved photocatalytic efficiency (94 %) and pseudo-first-order kinetic degradation rate (0.023 min−1). Moreover, after three cycles of testing, N–C/NTO/TiO2 HS showed a 91 % degradation rate in its photostability. The enhanced photocatalytic performance was attributed to the combined effects of N-doping, carbon species on the surface, and the coupling of TiO2 and Na2Ti6O13 using morphology engineering. Finally, based on the experimental results, a possible photocatalytic mechanism was proposed. This study provides a rational approach toward the development of high-performance titanate-based photocatalysts for solar energy-assisted wastewater treatment.

Synthesis of Cu doped NiO for their antioxidant and photocatalytic properties: Green synthesis using Lycopodium Linn

Metal oxide nanoparticles produced by plant extracts are more stable and biocompatible in comparison with those produced by physical and chemical methods. This research focuses on the synthesis of pure and Cu doped NiO nanoparticles (NPs) using Phytolacca dodecandra L'Herit (P.d) leaf extract and evaluation of their antioxidant and photocatalytic activities. The obtained Cu-doped NiONPs have been characterized through X-ray diffraction (XRD), Transmission electron microscope (TEM), Fourier transform infrared (FT-IR), Ultraviolet-visible (UV–Vis), N2 adsorption-desorption and X-ray photoelectron spectra (XPS) analyses in different concentrations (1, 3, and 5 %) of copper at an optimum temperature of 400 °C. The photocatalytic activity of prepared samples was studied by degradation of Rose Bengal (RB) and Methylene Blue (MB) dye aqueous solutions. Under UV radiation for 60 min. 5-Cu-NiO nanophotocatalyst showed degradation efficiency of 98.7 % (0.5 mol/L), high apparent constant (0.9871 min−1) and long term stability towards MB dye. In the antioxidant test, NiO NPs and Cu−NiO NPs prevented the oxidation of 50 % of the H2O2 molecules at a concentration of 363.96 and 350.29 μg/mL, respectively. Moreover, the enhancement of the antioxidant activity of the biosynthesized NiO NPs might be an effect of copper ions present in the particles. Facile and green synthesis process with the excellent degradation performance demonstrates that the Cu doped NiO NPs have a great potential for wastewater treatment applications.

Boosting the photocatalytic activity of bismuth vanadate (BiVO4) via optimization of the internal polarization

Photocatalytic performance can be improved by optimizing the morphology and surface texture of the photocatalyst or forming different p-n and/or n-n heterojunctions. Although the heterojunction system enhances photocatalytic property; however, an internal spontaneous polarization electric field may be much more effective due to the separation of electron-hole pairs when the polarization field forces them to move in different directions. The present study demonstrated this insight where the BiVO4 synthesis condition and polarization field forces were controlled via homogeneous precipitation in the presence of polyvinylpyrrolidone (PVP). The as-synthesized BiVO4 photocatalysts' structure and morphology were investigated using XRD, SEM, Raman, DRS, and PL. The result revealed that the increase of PVP concentration reformed the shaping to the truncated bipyramid-like shape and creates a spontaneous internal polarization that enhanced BiVO4 photocatalytic performance. The photocatalytic activity of BiVO4 was evaluated by monitoring the photocurrent enhancement using chronoamperometry, electrochemical impedance spectra and the photodegrading of methylene blue (MB) aqueous solution to harmless compounds in the presence of light. The spontaneous polarization between the different facets of BiVO4 crystal enhances the e−/h+ separation during internal facets homojunction and leads to four times photocurrent enhancement and the MB photocatalytic degradation rate increased from 0.43 to 1.92 min−1.

Synthesis of stannite Cu2CoSnS4 and its use as photocatalyst for degradation of pollutants

We report the synthesis of p-type stannite Cu2CoSnS4 (CCTS) powder by direct fusion, and its use as a photocatalyst for the degradation of methylene blue (MB) under solar irradiation. Structural analysis by X-ray diffraction and Raman spectroscopy revealed that the prepared powder is polycrystalline and has preferential orientation along the (112) plane, characteristic of the stannite phase. Scanning electron microscopy (SEM) images show agglomerated nanoparticles. Compositional analysis by energy dispersive spectroscopy shows that the composition of the prepared CCTS powder approaches the theoretical 2:1:1:4 stoichiometry. The oxidation state of the constituent elements in CCTS powder were investigated by X-ray photoelectron microscopy (XPS), which reveals that the valence states of the constituent elements present in the CCTS sample are: Cu+, Co2+, Sn4+and S2−. Optical analysis through diffusion reflectance and photoluminescence (PL) spectroscopy were used to estimate the bandgap, which was found to be about 1.4 eV. Upon visible light illumination, CCTS powder exhibits an excellent photocatalytic performance. The apparent reaction rate constant k found to be k = 13.10−3 min−1, which suggests that the p-type stannite CCTS powder would be a promising candidate of photocatalyst for the degradation of MB in aqueous solution.

Broadband and strong visible-light driven photocatalytic enhancement utilizing two-dimensional plasmonics of Au/Cu-modified SrTiO3 perovskite nanostructures

Addressing limited access to clean drinking water demands innovative solutions to energy and environmental crises. Photocatalysis offers promise without eliciting secondary pollution, yet traditional metal oxide semiconductor photocatalysts encounter impediments in solar energy utilization and charge carrier recombination rates. To overcome these limitations, we present for the first time, a novel design, fabrication, and characterization of two-dimensional plasmonic noble metal/perovskite nanostructure hybrids for photocatalysis, combining Au as the plasmonic material with Cu-modified SrTiO3 as the semiconductor, fabricated on elastomeric polydimethylsiloxane substrates. Integrating localized surface plasmon resonance and Schottky junction-related band-bending significantly extends optical absorption into the ultraviolet-visible-infrared bands and enhances the effective carrier lifetimes, ensuring state-of-the-art photocatalytic efficiency. Exceptional photocatalytic performance in a 5-ppm aqueous methylene blue solution can be attained with 72.69-wt% Cu incorporation in the perovskite oxide, reaching a visible light-mediated photodegradation efficiency of 26% - an astounding 62.5-% efficiency increase compared to previous experiments without Cu modification. This advancement underscores the synergistic potential of noble metals and photocatalytic semiconductors in managing water purification challenges.

Efficient Adsorption of Methylene Blue Using a Hierarchically Structured Metal-Organic Framework Derived from Layered Double Hydroxide.

The growing concerns about environmental pollution, particularly water pollution, are causing an increasing alarm in modern society. One promising approach to address this issue involves engineering existing materials to enhance their effectiveness. A one-step solvothermal reconstruction approach was used to build an eco-friendly two-dimensional (2D) AlNiZn-LDH/BDC MOF composite. The characterizations confirm the formation of a metal-organic framework (MOF) at the layered double hydroxide (LDH) surface. The resulting synthesized material, 2D AlNiZn-LDH/BDC MOF, demonstrated remarkable efficacy in decontaminating methylene blue (MB), a model cationic dye found in water systems. The removal performance of 2D AlNiZn-LDH/BDC MOF was significantly higher than that of pristine 2D AlNiZn-LDH. This improvement shows the potential to increase the adsorption capabilities of nanoporous LDH materials by incorporating organic ligands and integrating meso-/microporosity through MOF formation on their surfaces. Furthermore, their kinetic, isothermal, and thermodynamic studies elucidated the adsorption behavior of this composite material. The results of synthesized MOF showed excellent removal efficiency (92.27%) of 10 ppm of MB aqueous solution as compared to pristine LDH. Additionally, the as-synthesized adsorbent could be regenerated for six successive cycles. This method holds promise for the synthesis of novel and highly effective materials to combat water pollution, laying the groundwork for potential advancements in diverse applications.

High-performance of ZnO/TiO2 heterostructured thin-film photocatalyst fabricated via atomic layer deposition

Oxide semiconductor is one of the most promising candidates for photocatalysts due to its light absorption ability, electronic properties, and stability. It is used in various applications such as solar-energy conversion, CO2 reduction, and water splitting. In this research, ZnO, TiO2, and ZnO/TiO2 heterostructured thin films are fabricated via atomic layer deposition (ALD), and their photocatalytic performances are evaluated. The film thickness can be controlled using ALD, and surface reactions can easily occur in thin films owing to the short distances between the active sites and charge carriers. In addition, unlike a powder catalyst, the bilayer photocatalyst is fixed in the solution; therefore, it does not make the solution turbid or disturb the light penetration. Diethylzinc and titanium tetraisopropoxide are used as precursors for Zn and Ti, and the thin films are deposited on soda-lime glass substrates at 150 °C using H2O as the reactant gas. The photocatalytic activity and stability are evaluated through photodegradation tests using methylene blue aqueous solution. The ZnO single-substance thin film exhibits a high degradation rate, but its performance significantly decreases after three consecutive experiments. The TiO2 single-substance thin film exhibits a relatively low degradation rate, but high reusability, exhibiting characteristics opposite to that of ZnO. Therefore, a TiO2 thin film is coated on ZnO to leverage both these advantages. The thin films are heat-treated at 400 °C for 10 min after deposition in a vacuum atmosphere. The surface morphology, crystal structure, and electrical characteristics of the photocatalyst specimens are analyzed through high-resolution scanning electron microscopy, Cs-corrected scanning transmission electron microscopy, and x-ray diffraction analysis. Their photocatalytic performances under ultraviolet (UV) irradiation are measured through UV–visible spectroscopy. The heat-treated ZnO/TiO2 heterostructured thin film exhibits a photodegradation rate exceeding 80%, with little degeneration after three cycles, indicating enhanced photodegradation performance and stability.

Fabrication and Characterization of Electrospun Cu-Doped TiO2 Nanofibers and Enhancement of Photocatalytic Performance Depending on Cu Content and Electron Beam Irradiation.

Titanium dioxide (TiO₂) is a widely studied material with many attractive properties such as its photocatalytic features. However, its commercial use is limited due to issues such as deactivation in the visible spectrum caused by its wide bandgap and the short lifetime of photo-excited charge carriers. To overcome these challenges, various modifications could be considered. In this study, we investigated copper doping and electron beam treatment. As-spun TiO2 nanofibers were fabricated by electrospinning a TiO2 sol, which obtained viscosity through a polyvinylpyrrolidone (PVP) matrix. Cu-doped TiO2 nanofibers with varying dopant concentrations were synthesized by adding copper salts. Then, the as-spun nanofibers were calcined for crystallization. To evaluate photocatalytic performance, a photodegradation test of methylene blue aqueous solution was performed for 6 h. Methylene blue concentration was measured over time using UV-Vis spectroscopy. The results showed that Cu doping at an appropriate concentration and electron-beam irradiation showed improved photocatalytic efficiency compared to bare TiO2 nanofibers. When the molar ratio of Cu/Ti was 0.05%, photodegradation rate was highest, which was 10.39% higher than that of bare TiO2. As a result of additional electron-beam treatment of this sample, photocatalytic efficiency improved up to 8.93% compared to samples without electron-beam treatment.

Facile construction of robust superhydrophobic ZIF‐8@pulp/cellulose nanofiber (CNF) membrane for multifunctional applications

Given the increasing contamination of freshwater supplies, it is essential to effectively treat industrial wastewater. However, treating industrial wastewater using a single method is challenging due to the presence of complex contaminants like petroleum, organic dyes, bacteria, and other complex contaminants. In this study, we present a straightforward and scalable approach to prepare multifunctional nanocellulose-based membranes (NM) that exhibit superhydrophobicity, self-cleaning, oil/water separation, photocatalysis, and anti-bioadhesion properties. To begin with, we created NM by extruding fiber slurry onto a stencil and drying it. Next, we built a polyurethane (PU)/ZIF‐8/1H, 1H, 2H, 2H‐perfluorooctyltriethoxysilane (POTS)-based superhydrophobic layer by spraying it over the NM's surface. By employing the aforementioned processes, we successfully integrated multiple functions into a single superhydrophobic NM. Our results demonstrate that the NM-PU/ZIF-8/POTS membrane exhibits superior hydrophobicity performance, with a high-water contact angle (166.8 ± 0.8°) and a low rolling angle (5 ± 0.3°). Moreover, these samples retain high-water contact angles and low rolling angles even in harsh environments such as acid and alkali solutions, high temperatures, abrasion resistance, UV aging resistance, bending and folding, tape peeling, and self-cleaning. The NM-PU/ZIF-8/POTS membrane also exhibits high and stable oil-water separation performance, with a separation efficiency of 94.6% and a relatively high separation flux (133.2 L·m−2·h−1). At the same time, the NM-PU/ZIF-8/POTS membrane exhibits water-in-oil emulsion separation ability. The membrane’s stability, effectiveness, and reusability were demonstrated through ten repetitions of degradation experiments using aqueous methylene blue solution, with the NM-PU/ZIF-8/POTS membrane exhibiting an excellent degradation rate (>94%). Finally, the bioadhesion resistance test indicated a reduction of 69.1% in the adhesion rate of the NM-PU/ZIF-8/POTS membrane. Overall, the creation of the NM-PU/ZIF-8/POTS membrane serves as a useful inspiration for the practical application of superhydrophobic NM in multifunctional integration, while also broadening the scope of membrane applications.

The spread of injectate after deep serratus anterior plane and superficial parasternal intercostal plane blocks: a cadaveric dye study.

We investigated the distribution of injected dye after deep serratus anterior plane and superficial parasternal intercostal plane blocks in 15 Thiel embalmed cadavers. We injected 0.4 ml.kg-1 of 0.25% aqueous methylene blue solution into the deep serratus anterior and superficial parasternal intercostal planes using real-time ultrasound needle visualisation followed by posterior dissection to observe the distribution of the injected dye in the chest wall. The two blocks were performed bilaterally in 15 cadavers at the T5/T6 level, comprising 60 blocks in 30 hemithoraces in total. At dissection, the intercostal nerve territories were observed to be dyed completely from T2 to T6 in 28 of 30 hemithoraces, and extending caudal to T6 in 10 hemithoraces. Following the deep serratus anterior plane blocks in all cadavers, the dye was found to have spread to the axillae. Following the superficial parasternal intercostal plane blocks, the dye reached T7 in four cadaver dissections. We concluded that the territories innervated by the intercostal nerves (T2-T6 dermatomes) are dyed following the combination of the two blocks when performed at the T5-T6 intercostal space level. These techniques might provide an effective option for anaesthesia in breast surgery.

The Development and Synthesis of a CdZnS @Metal–Organic Framework ZIF-8 for the Highly Efficient Photocatalytic Degradation of Organic Dyes

The development of photocatalysts for organic degradation is a hot research topic. In this study, CdZnS was selected as the carrier, and ZIF-8 was combined with it to explore the photocatalytic performance of the composite. In addition, the compound material, CdZnS@ZIF-8, was used as a photocatalyst for the decomposition of methylene blue dye, and the performance of pure CdZnS and pure ZIF-8 was compared. The photocatalytic efficiency of CdZnS@ZIF-8 was significantly higher than that of the other two. In the experimental reaction, the amount of catalyst was 0.04 g, the pH value was 7, the initial concentration of methylene blue aqueous solution was 20 mg/L, and the degradation of methylene blue in 50 mL aqueous solution could reach 99.5% under visible light irradiation for 90 min, showing excellent photocatalytic efficiency in the visible light range. It demonstrated excellent photocatalytic function in the visible light region, and the electron transfer phenomenon at the interface occurred in the het-junction and the separation of the photo-generating electron–hole as an electron acceptor of ZIF-8 further promoted the photocatalytic effect.

A Fresh Perspective on the Impact of ZnTiO3 Coupling on the Microstructure and Photocatalytic Properties of TiO2 Fabricated at Varied Temperatures.

ZnTiO3/TiO2 composite photocatalysts were synthesized via the sol-gel technique, and the impact of varying heat treatment temperatures (470, 570, 670 °C) on their crystalline arrangement, surface morphology, elemental composition, chemical state, specific surface area, optical characteristics, and photocatalytic efficacy was systematically investigated. The outcomes revealed that, as the temperature ascends, pure TiO2 undergoes a transition from anatase to rutile, ultimately forming a hybrid crystal structure at 670 °C. The incorporation of ZnTiO3 engenders a reduction in the TiO2 grain dimensions and retards the anatase-to-rutile phase transition. Consequently, the specimens manifest a composite constitution of anatase and ZnTiO3. In contrast, for pure TiO2, the specimen subjected to 670 °C annealing demonstrates superior photocatalytic performance due to its amalgamated crystal arrangement. The degradation efficacy of methylene blue (MB) aqueous solution attains 91% within a 60-min interval, with a calculated first-order reaction rate constant of 0.039 min-1. Interestingly, the ZnTiO3/TiO2 composite photocatalysts exhibit diminished photocatalytic activity in comparison to pristine TiO2 across all three temperature variations. Elucidation of the photocatalytic mechanism underscores that ZnTiO3 coupling augments the generation of photogenerated charge carriers. Nonetheless, concurrently, it undermines the crystalline integrity of the composite, yielding an excess of amorphous constituents that impede the mobility of photoinduced carriers. This dual effect also fosters escalated recombination of photogenerated charges, culminating in diminished quantum efficiency and reduced photocatalytic performance.

Nanocomposites of Nb2O5 and ZnO with reduced graphene oxide for heterogeneous photocatalysis of dyes

Nanocomposites of Nb2O5 and ZnO with reduced graphene oxide for heterogeneous photocatalysis of dyes

Enhancing photocatalysis through annealing: Unveiling the role of physical properties in photocatalytic behavior

Using spray pyrolysis, silver-doped In2S3 thin films were deposited on pre-heated glass substrates, with varying doping concentrations. Subsequently, these films underwent vacuum annealing at 400 °C for a duration of 2 h. A comprehensive study of their structural, morphological, and optical properties was conducted, revealing homogeneous, compact, crack-free films with polycrystalline tetragonal-phase of In2S3. Among the set of the analyzed films the best parameter values, including crystallite size, dislocation density, micro-strain, grain size, and root mean square (RMS) roughness, were achieved when maintaining a Silver-to-indium (|Ag|/|In|) ratio of 4 % in the precursors for both as-deposited and annealed samples. The annealing process had a discernible impact on the grain size distribution, resulting in a significant increase in crystallite and grain size, along with RMS roughness, for most doped films. The optical analysis of these films unveiled their transparency in the visible and near-infrared regions, coupled with substantial absorption in the UV region. Higher Ag concentration in the as-deposited films led to an increased band gap energy in the annealed samples. The roughness peaked at |Ag|/|In| = 4 %, resulting in a noteworthy enhancement of photocatalytic activity, achieving 95 % photodegradation of a methylene blue aqueous solution. This underscores the critical role of surface properties in determining performance. Future research intends to explore other applications for these thin films, including potential usage in gas sensors, capitalizing these films' promising characteristics.

Integrated adsorption and photocatalytic removal of methylene blue dye from aqueous solution by hierarchical Nb2O5@PAN/PVDF/ANO composite nanofibers

This work presents the development of hierarchical niobium pentoxide (Nb2O5)-based composite nanofiber membranes for integrated adsorption and photocatalytic degradation of methylene blue (MB) pollutants from aqueous solutions. The Nb2O5 nanorods were vertically grown using a hydrothermal process on a base electrospun nanofibrous membrane made of polyacrylonitrile/polyvinylidene fluoride/ammonium niobate (V) oxalate hydrate (Nb2O5@PAN/PVDF/ANO). They were characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) analysis, and Fourier transform infrared (FTIR) spectroscopy. These composite nanofibers possessed a narrow optical bandgap energy of 3.31 ​eV and demonstrated an MB degradation efficiency of 96 ​% after 480 ​min contact time. The pseudo-first-order kinetic study was also conducted, in which Nb2O5@PAN/PVDF/ANO nanofibers have kinetic constant values of 1.29 ​× ​10−2 ​min−1 and 0.30 ​× ​10−2 ​min−1 for adsorption and photocatalytic degradation of MB aqueous solutions, respectively. These values are 17.7 and 7.8 times greater than those of PAN/PVDF/ANO nanofibers without Nb2O5 nanostructures. Besides their outstanding photocatalytic performance, the developed membrane materials exhibit advantageous characteristics in recycling, which subsequently widen their practical use in environmental remediation applications.