Photocatalytic Dye Degradation Research Articles

Reduced Work Function in Anatase ⟨101⟩ TiO2 Films Self-Doped by O-Vacancy-Dependent Ti3+ Bonds Controlling the Photocatalytic Dye Degradation Performance.

TiO2 has the proven capability of catalytically decomposing pollutants under light illumination, thereby embracing potential applications in wastewater management. The photocatalytic dye degradation activity is largely controlled by the optical band gap that dictates the extent of electron-hole pair generation via photon absorption, and the recombination kinetics of charges. In this context, the material's work function governs how easily the charge carriers can be transferred at the dye-adsorbed photocatalytically active sites. Accordingly, nanocrystalline TiO2 thin films are grown in the anatase phase with ⟨101⟩ orientation, using RF magnetron sputtering at 200 °C. Besides studying the film's structural morphology, optical band gap, and elemental composition, the electronic properties are extensively investigated. The work function of the material was controlled by varying the O-vacancy-dependent Ti3+ bonding configuration in the network. It has been demonstrated how the photocatalytic methylene blue dye degradation activity of the nanocrystalline TiO2 films of predominantly the anatase phase improves on reducing the sputtering pressure during deposition. At a low deposition pressure of 20 mTorr, a low work function of ∼4.2 eV of the film, resulting from the formation of a Ti3+-bond through the O vacancies in the network, potentially increases its carrier lifetime and delivers the superior photocatalytic activity (∼82.7% dye degradation with a rate constant of k ∼ 0.0073 min-1) via silently facilitating fast electron transfer from the photocatalyst to the dye in the aqueous solution. The higher stoichiometric film prepared at p = 40 mTorr exhibits an inferior photocatalytic activity (∼20.4% dye degradation with a rate constant of k ∼ 0.0009 min-1), as retarded by its higher work function of ∼4.62 eV, despite retaining a relatively low band gap. Thus, without using any heterojunction or extrinsically doped photocatalyst, the dye degradation can be controlled simply by reducing the work function of nanocrystalline TiO2 thin films via controlling the O-vacancy-dependent Ti3+ bonding in its self-doped network.

Carbon nitride impregnated non-woven jute post-industrial waste in photocatalytic degradation of textile dyes

Carbon nitride impregnated non-woven jute post-industrial waste in photocatalytic degradation of textile dyes

Photo-catalytic dye degradation potentials of Ag-Pd bimetallic nanoparticles synthesized from Vitex negundo.

Plant extracts are a great alternative to synthesizing nanoparticles of different metals and metal oxides. This green synthesis method has opened up numerous possibilities in various scientific domains. In present study, Leaf extract from Vitex negundo is a non-deciduous, long-lasting shrub from the Verbenaceae family is used as capping and reducing agents for the synthesis of silver and palladium nanoparticles. The characterization study UV-vis spectrophotometer analysis showed absorbance value around 320nm which confirming that Ag-Pd nanoparticles have been successfully obtained. Further, SEM is used to investigate the morphology of Ag-Pd NPs, which revealing their spherical and rod-like configuration, aggregation, and the size of the particles are obtained between 50 and 100nm. The successful synthesis of Ag-Pd NPs was further confirmed by the EDAX chart, which displayed the peak of Ag and Pd at bending energies between 0.5 and 1.5keV. According to the quantitative study, Ag and Pd ions found about 5.24 and 13.28%, respectively. In addition, surface studies with TEM confirming that synthesized Ag-Pd NPs are predominates with spheres structure morphologies, with sizes averaging 11.20nm and ranging from 10 to 20nm. Further, Ag-Pd nanoparticles was applied as potential photocatalyst materials to degrade methylene blue dye and found about 85% of the degradation efficiency within 150min of the sunlight exposure thus could be used as catalyst to removal of hazardous organic dye molecules.

Surface engineered recombinant Escherichia coli for the potential application of the cobalt contaminated wastewater treatment and the photocatalytic dye degradation.

The novel recombinant Escherichia coli strain was construct through cell surface display for the treatment of cobalt contaminated wastewater and dye contaminated wastewater. First, structural analysis of known cobalt binding peptide was conducted and core binding sites were figured out which showing better cobalt binding ability. The cobalt peptides were attached to OmpC to construct cobalt adsorbing recombinant Escherichia coli. The recombinant strain efficiently absorbed and retrieved cobalt from cobalt wastewater by adsorbing 1895 µmol/g DCW of cobalt. Following adsorption, cobalt nanoparticles were synthesized through thermal decomposition of cobalt adsorbed recombinant strain at 500˚C. The nanoparticles exhibited noteworthy photocatalytic properties, demonstrating a substantial capacity for degrading dyes when used as a catalyst at a concentration of 10 mg/dl. These results presenting potential solutions for effective and environmentally friendly approaches to address cobalt and dye contaminated wastewater treatment process.

Degradation of rhodamine B dye under visible and solar light on zinc oxide and nickel-doped zinc oxide thin films

The kinetic investigation of rhodamine B dye's photocatalytic degradation, chosen as a model pollutant, was conducted at room temperature using Zinc oxide (ZnO) and nickel-doped zinc oxide (Zn0.97Ni0.03O) photocatalysts synthesized through the spray pyrolysis method. XRD analysis confirmed the formation of hexagonal ZnO and Zn0.97Ni0.03O films, with crystallite sizes ranging from 19 to 29 nm and varying in mean average grain size from 72 nm to 88 nm. The surface morphology of the Ni-doped ZnO films was influenced by nickel doping, observed through SEM and TEM micrographs, revealing a dense structure of spherical-shaped crystals. Light transmission and optical band gap energy of the films ranged between specified values, ranging from 3.27 to 3.24 eV. The degradation process was assessed under various conditions, including different light sources (UV lamp and solar irradiation), pH levels, and substrate concentrations. Degradation followed a pseudo-first-order kinetic model, with rate constants (k) and half-life times (t1/2) calculated accordingly. The degradation efficiency of undoped ZnO and ZnO doped with nickel decreased with increasing concentration under UV irradiation from (0.1–0.5 M) under UV irradiation decreased from (34.29–45.02) (49.61–56.61), while under visible light are (40–45.07 %) (58.46–60.24 %), removal rates ranged within specific percentages. The porous Zn0.97Ni0.03O synthesized at 0.5 M exhibited the highest photocatalytic efficiency due to its enhanced crystallinity, resulting in degradation rates of 9.22 and 11.22 × 10−3 min−1 and half-life times of 75.18 and 61.77 min at 90 min specified for both UV and solar light irradiations, respectively. Acidification of the reaction medium accelerated the photocatalytic degradation kinetics, while alkalization slowed it down. These findings mark a significant advancement in the utilization of oxide semiconductors for water pollutant degradation under natural sunlight.

Retraction Note: Visible light-enhanced photocatalytic dye degradation and hydrogen evolution performance of BiVO4 thin films prepared at various annealing temperatures

Retraction Note: Visible light-enhanced photocatalytic dye degradation and hydrogen evolution performance of BiVO4 thin films prepared at various annealing temperatures

Tailoring MOF-5 Photocatalysts: Low-Temperature Synthesis and Solvent Variations for Enhanced Performance in Dye Degradation

Metal-organic frameworks (MOFs) are emerging as pivotal porous crystalline materials with diverse applications. Typically, MOFs are synthesized using solvothermal techniques at high temperatures and pressures. In this study, a novel approach was employed to synthesize zinc-based MOFs, specifically MOF-5, at low temperatures (up to 50 °C) via chemical mixing at standard pressures. Varying the temperature and solvents, N-methyl-2-pyrrolidone (NMP) and N,N-dimethylformamide (DMF), in the chemical mixing process, the highest yield of the material was observed with DMF at 50 °C (M1). Two additional samples, M2 and M3, are synthesized at room temperature using DMF and NMP, respectively. Despite similarities in XRD, Raman, and FTIR analyses confirming successful MOF-5 formation, noticeable differences in sample morphology arise due to distinct synthesis conditions, particularly solvent and temperature variations. The MOF-5 samples exhibit UV absorption with varying band gaps. Notably, when employed as photocatalysts for organic dye (methylene blue) degradation, M2 outperforms others, achieving an impressive 85% degradation under simulated solar light irradiation. This work underscores the significance of tuning MOF photocatalyst properties through tailored synthesis routes, recognizing the profound impact of morphology and elemental composition on enhancing photocatalytic dye degradation performance. Copyright © 2024 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). 

Tinospora cordifolia-assisted synthesis of silver ferrite nanoparticles: a multifunctional approach to photocatalytic degradation of reactive blue-13 dye, anti-bacterial efficacy, and antioxidant properties

ABSTRACT Tinospora cordifolia plant extract was used for the green synthesis of AgFeO2 NPs, which were then characterised using FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), UV-vis spectroscopy, VSM (vibrating sample magnetometry), zeta potential, BET (Brunauer-Emmett-Teller), and XRD (X-ray diffraction) analysis. The notable XRD peaks observed at 550–600 cm−1 in the hybrid NPs can be attributed to the presence of iron oxide skeleton (-O-Fe), indicating the presence of AgFeO2 nanocrystals. Additionally, two peaks at approximately 526 and 486 cm−1 indicate the stretching vibrations of the Ag-O and Fe-O bonds within the AgFeO2 NPs, respectively. SEM analysis showed spherical nanoparticles forming irregular clusters with an average size of 19.43 nm. Vibrating Sample Magnetometer (VSM) analysis demonstrated that the AgFeO2 NPs exhibited superparamagnetic behaviour. This is characterised by an effective magnetisation of 61.57 emu/g, with low saturation magnetisation, magnetic remanence and non-zero coercivity making them suitable for magnetic applications. The zeta potential of −23.16 mV suggested NP stability due to electrostatic repulsion. UV-vis spectroscopy verified the existence of AgFeO2 NPs with an absorbance peak at 246 nm. BET analysis indicated that nanoparticles exhibited a large surface area of 3.4027 m2 g−1 and a nanoporous structure with an average pore size diameter of 3.1436 Å. 96% degradation of RB-13 dye was observed at pH 2 within contact time of 60 min, 50 mg concentration of catalyst and 10 ppm dye solution. The values of R2 = 0.96 and 0.94 confirm the validity of Pseudo’s first order and Langmuir-Hinshelwood’s kinetic models, respectively, for dye degradation. Anti-bacterial activity indicated that with increasing concentration of AgFeO2 NPs, the antibacterial activity becomes less because the time needed to detect bacteria was increased due to less active site availability for AgFeO2 NPs. The ascorbic acid consistently exhibits higher antioxidant activity at 82.25, 84.67, and 88.66% than Tinospora cordifolia leaf extract 51.34, 60.91, 74.02, and AgFeO2 NPs 61.54, 70.81, and 80.22 at 50, 75 and 100 μg/mL concentrations, respectively.

Graphene-based Semiconductors for Photocatalytic Degradation of Organic Dye from Wastewater: A Comprehensive Review

Graphene-based Semiconductors for Photocatalytic Degradation of Organic Dye from Wastewater: A Comprehensive Review

β-Ga2O3 nanostructures for photocatalytic degradation of red amaranth toxic dye

Beta gallium oxide (β-Ga2O3) microstructures composed of ∼50 nm nanoparticles were synthesized by the hydrothermal method. Using the Tauc plot method a value of ∼4.9 eV was obtained for the optical band gap of β-Ga2O3. TEM and XRD analyses revealed high crystallinity of the β-phase of gallium oxide nanostructures. Since there are few publications for the photocatalytic properties of β-Ga2O3 the obtained results contribute to better understanding of the photocatalytic effect of this material on toxic dye red amaranth. Moreover, it is shown that β-Ga2O3 is a very efficient photocatalyst leading to high percentage degradation of dyes for relatively short periods. For example, the degradation of red amaranth and rhodamine B toxic dyes under UV light irradiation reached 97% and 100% after 165 and 120 min, respectively.

Green and cost-effective photocatalytic degradation of murexide dye with acid catalyst

Green and cost-effective photocatalytic degradation of murexide dye with acid catalyst

Optimization and modelling of magnesium oxide (MgO) photocatalytic degradation of binary dyes using response surface methodology

Textile industry dye effluent contains a mixture of different kinds of dyes. Many times, photocatalysis is targeted as a solution for the treatment of dye effluent from the textile industry. Many researches have been published related to the photocatalysis of single textile dyes but in the real-world scenario, effluent is a mixture of dyes. Magnesium oxide (MgO) is used as a photocatalyst to treat a mixture (binary solution) of Methylene blue (MB) and Methylene violet (MV) along with individual MB and MV dyes in this article. MgO shows remarkable photocatalytic activity at about 93 and 88% for MB and MV dye in binary solution within 135 min. Furthermore, to study the influence of process parameters, experiments are designed with the help of the central composite design (CCD), and Response surface methodology (RSM) is used to study the interactions between parameters. For this study, five parameters are selected i.e., Photocatalyst dosage, initial concentration of both dyes, time of exposure to the light source, and pH of the binary solution. The photocatalytic process is also optimized and finally optimization of process parameters is validated with an experiment. The result of the validation experiment is very close to the predicted photocatalytic activity.

Natural sunlight energy harvesting using NiAl2O4@N-rGO hetero-junction for photocatalytic degradation of crystal violet dye: Kinetic and mechanistic insights

In this study, NiAl2O4 (NA) was synthesized by the co-precipitation route and its hetero-junctions were fabricated with N-doped reduced graphene oxide (N-rGO) through the ultra-sonication method. The structural, morphological, magnetic, optical and photocatalytic properties of synthesized NA, N-rGO, and the NA@N-rGO 1–4 hetero-junctions characterized by XRD, FTIR, SEM, VSM, PL and UV–visible spectroscopy, respectively. XRD results showed that crystallite size decreases from 25.01 nm (NA) to 15.20 nm for NA@N-rGO-4 and porosity increases up to 77.7 % for NA@N-rGO-4 making it remarkable for photocatalytic applications and FTIR results confirmed the formation of N-rGO as well as its successful integration into NA matrix, resulting in the formation of hetero-junctions. Magnetic properties were investigated using a vibrating sample magnetometer (VSM), revealing distinctive S-shaped hysteresis loops at 25 °C for both NA and N-rGO, as well as the NA@N-rGO 1–4 hetero-junctions and magnetic saturation decreases with an increase in N-rGO content as for NA@N-rGO-4 Ms drops to 0.0038 emu/g. Notably, the bandgap of NA@N-rGO-4 hetero-junction was effectively reduced from 3.0 eV (in the case of NA) to 2.1 eV, resulting in a discernible decrease in photoluminescence (PL) intensity and increase in e--h+ pair separation. Under visible light, NA@N-rGO-4 exhibited a remarkable 94.68 % efficiency in crystal violet (CV) dye degradation within just 90 min, outperforming NA's 59.05 % degradation efficiency and OH. Radicals play a major contribution to the degradation of dye. The optimization of degradation capabilities was achieved through the manipulation of catalyst dosage, dye concentration and varying pH values for the degradation of CV dye. NA@N-rGO-4 hetero-junction demonstrates the considerable potential for efficient dye degradation in wastewater under visible light, owing to its exceptional catalytic performance.

Investigating dual-functional Al-doped stannic oxide nanorods towards photodegradation of real industry wastes and dye-sensitized solar cell application: An experimental and theoretical interpretation

In this work, we demonstrate a uniquely designed Tin (IV) Oxide (SnO2)-based nanomaterials for energy and environmental applications. Here, the Al-doped SnO2 nanorods (NR) at various concentrations ranging from 3 wt% to 9 wt% carried out following facile co-precipitation technique which induced synergic structural, optical and electrical properties in resulting products. Further, the Al-incorporation induced considerable changes to the structural, optical, and electrical characteristics turning SnO2 nanorods to Al-SnO2 nanocubes (NCs). Resulting changes from nanorod to nanocubes were closely monitored using various characterization techniques, which were then effectively utilized for photocatalytic degradation of important textile industry dyes, encompassing both cationic (MB, CV) and anionic (EBT) types. Optimal Al-doped SnO2 NC (6 wt%) demonstrated significant degradation efficiencies for organic pollutant and textile industry effluents under direct sunlight exposure. On the other hand, combination of optical and electrical properties was utilized in dye-sensitive solar cells (DSSCs) to achieve noteworthy efficiency of 6.33%, surpassing that of previous reported SnO2-based nanostructures. These exceptional performance nanomaterials can be attributed to the optimized morphology of the nanocubes and the reduction of the band gap from 3.24 eV to 2.75 eV facilitated by the introduction of aluminum dopant. Furthermore, synergic combination has also improved visible light excitation, substantially decreased resistance to charge carrier transfer phenomenon, improved the charge carrier concentration, as well as considerably decreased the electron/hole recombination rate. Therefore, presence of Al in SnO2 nanostructure has considerably improved the opto-electrical properties that were interpreted following theoretical studies. Therefore, study gives simple nanomaterials having both the photodegradation and dye-sensitive solar cell (DSSC) performance of the SnO2 nanostructure, as a cost-effective energy conversion and water pollution remediation tool for the near future.

Novel existence of Mn and Cu in WO3 nanostructures for promising photocatalytic activity against MB dye and Levofloxacin antibiotic

To enhance photocatalytic degradation of MB dye and Levofloxacin antibiotic, facile coprecipitation strategy was used to synthesize pure WO3 and novel Mn-Cu codoped WO3 nanostructures. The synthesized nanostructures were probed by XRD, SEM, EDX, FTIR, XPS, BET, TEM, PL and UV–vis spectra to analyze optical and morphological properties. Pure WO3, Mn2%-Cu1%-WO3, Mn2%-Cu3%-WO3, Mn2%-Cu5%-WO3 and Mn2%-Cu7%-WO3 were optimized novel materials that were used for water treatment against model impurities. Optical properties of pure WO3 were enhanced to successfully increase the photocatalytic degradation of principal water pollutants. Over a time span of 175 minutes, 86.7% of MB dye was degraded and 75.9% Levofloxacin was degraded by an average of 49 nm and 2.16 eV bandgap Mn2%-Cu5%-WO3 optimal sample. Due to smaller particle size, surface to volume ratio gave more active sites to the photocatalysts for pollutants degradations. Interestingly, just 15% degradation loss was observed after consecutive 6 cycles against the degradation of MB dye and 9.1% loss against Levofloxacin medicine after 6 photocatalytic runs. XPS spectra offered crucial insights into the elemental composition and chemical states of the Mn-Cu-WO3 nanostructures. According to these findings, Mn-Cu-WO3 can be used as a good candidate with long time stability against pollutants degradations.

Catalysing a sustainable future: Harnessing solar energy with novel Co3O4@VO2 nanocomposites for enhanced photocatalytic hydrogen generation and dye degradation

This study focuses on the hydrothermal synthesis and characterization of Concentration dependent Co3O4@VO2 nanocomposites with varying molar ratios of Co3O4 to VO2 (2:1, 1:1, and 1:2) for efficient hydrogen generation and dye degradation. The structural and morphological characteristics of the prepared nanocomposites were analysed using x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Crystallographic analysis using XRD confirmed the formation of crystalline Co3O4 with a monoclinic structure, while the presence of VO2 was identified by characteristic peaks in the XPS. Microscopic analysis using SEM and TEM revealed well-dispersed nanocomposites with nanoscale dimensions. Photocatalytic activities were evaluated for hydrogen evolution and dye degradation, with the nanocomposite featuring a 2:1 ratio of Co3O4 to VO2 (CV-21) demonstrating significantly enhanced performance. CV-21 exhibited a lower onset potential and higher current density for hydrogen evolution (2270μmol/h/g), indicating improved photocatalytic activity. Additionally, it displayed rapid and superior dye degradation (93% within 10 min) under sunlight compared to Victoria blue B (VBB) dye. The Co3O4@VO2 nanocomposites, particularly CV-21, demonstrate enhanced photocatalytic performance for hydrogen generation and dye degradation compared to pristine VO2 and Co3O4. This improvement possibly due to synergistic effects between Co3O4 and VO2, optimized structural characteristics, and improved interfacial properties in the nanocomposite structure. These findings highlight the promising potential of Co3O4@VO2 nanocomposites, particularly CV-21, for environmental remediation applications.

An effective approach to improve photocatalytic dye degradation and electrochemical properties of MoO3 nanoparticles

An effective approach to improve photocatalytic dye degradation and electrochemical properties of MoO3 nanoparticles

Synthesis and characterization of alpha and beta cobalt hydroxide nanostructures for photocatalytic dye degradation and supercapacitor applications

Alpha and beta cobalt hydroxide nanostructures were synthesized by hydrothermal method and characterized using X-ray diffraction and electron microscopy. The turbostatic alpha-Co(OH)2 has large interlayer spacing compared to the beta-Co(OH)2 and is less explored in the literature. Both nanostructures were efficient in degrading methylene blue dye in the presence of visible light. Under identical conditions, the rate constant of photocatalytic dye degradation in the presence of alpha and beta cobalt hydroxide was calculated as 60.22 × 10−3 min−1 and 19.05 × 10−3 min−1, respectively, which is highest when compared to the previous reports. The superior activity of alpha-Co(OH)2 when compared to beta-Co(OH)2 is also demonstrated in this work. Additionally, a Csp value of 137 F/g and 2.4 F/g, respectively, at a current density of 1 A/g, was obtained from the GCD analysis of devices made using alpha-Co(OH)2 and beta-Co(OH)2. A higher cyclic stability and power density were observed for alpha-Co(OH)2 when compared to beta-Co(OH)2. The findings suggest that alpha and beta cobalt hydroxide nanostructures hold promise as effective catalysts for dye degradation and potential materials for high-performance supercapacitors. Further investigations into the unique properties of the relatively superior alpha-Co(OH)2 could lead to advancements in environmental remediation and energy storage technologies.

Visible light-induced photocatalytic degradation of methylene blue dye using pure phase bismuth ferrite nanoparticles

The degradation of organic dyes in wastewater has become a significant environmental issue, requiring the development of degradation technologies that are both effective and environmentally friendly. The present study employed the sol-gel approach to synthesize nanoparticles of phase pure bismuth ferrite (BiFeO3). The nanoparticles were assessed for their ability to efficiently degrade methylene blue (MB) dye, especially under visible light irradiation. The X-ray diffractogram (XRD) confirmed the formation of BiFeO3 nanoparticles, with an average crystallite size of 48 nm. The material's band gap, with a value of 1.84 eV, demonstrates its capacity to effectively absorb light, including wavelengths within the visible spectrum. Scanning electron microscopy (SEM) was used to identify porous aggregated particles. Both Raman and Fourier transform infrared spectroscopy (FTIR) confirm the successful synthesis of pure BiFeO3 in the desired phase. The BiFeO3 photocatalyst exhibited a significant surface area and isotherms of type IV, a characteristic typically observed in mesoporous materials, as determined by the Brunauer-Emmett-Teller (BET) analysis. The efficacy of BiFeO3 nanoparticles in facilitating the decomposition of MB in a water-based solution was evaluated by visible light photocatalysis. An efficiency degradation of 98.49 % was recorded for MB within 2 h.

Temperature-controlled morphology and enhanced functionalities of hydrothermally synthesized SrFe2O4 nanostructures for multifaceted applications

In this study, we investigate the effect of synthesis temperature on the morphology and properties of spinel strontium ferrite (SrFe2O4) nanostructures, synthesized using a surfactant-free hydrothermal method. We demonstrate that by varying the temperature from 85 °C to 160 °C, we can control the morphology of SrFe2O4, transitioning from nanoribbons to dendritic structures, and finally to hexagonal nanoplatelets. These morphological changes correspond to significant enhancements in both magnetic and photocatalytic performance. The saturation magnetization (Ms) notably increases by up to 70 % at higher synthesis temperatures. Additionally, these nanostructures show improved efficiency in photocatalytic degradation of methylene blue dye, indicating their potential for environmental remediation. The dielectric properties of the various morphologies were also characterized, suggesting applications in electronics and energy storage. This study establishes a clear link between synthesis conditions, resulting structures, and functional performance in SrFe2O4 nanostructures, contributing to the development of advanced materials.