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Photo-Fenton catalysis plays an important role in the degradation of organic pollutants in environmental sewage. In this paper, magnetic 0D/1D ZnFe2O4/ZnCO3 rod-like nanocomposites were fabricated by a simple one-pot solvothermal method, and then the produced magnetic 0D/1D ZnFe2O4/ZnO rod-like nanocomposites were formed via calcination at high temperature. The obtained 0D/1D ZnFe2O4/ZnCO3 has been fully investigated by x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and vibrating sample magnetometry. Furthermore, the photocatalytic Fenton reaction of these two catalysts has been preliminarily evaluated for the degradation performance of organic dyes and antibiotics in wastewater. The results showed that, under visible-light irradiation, the ZnFe2O4/ZnCO3 composite material and its product, ZnFe2O4/ZnO, after high-temperature firing can achieve more than 90% photo-Fenton catalytic degradation of Rhodamine B (RhB) and tetracycline (TC) within 30 min, superior to that of ZnFe2O4, ZnCO3 , and ZnO monomers due to their larger specific surface area and more active sites. The magnetization saturation values of ZnFe2O4/ZnCO3-2 and ZnFe2O4/ZnO-2 were, respectively, around 34.20 emu/g and 15.00 emu/g, indicating that both have good magnetic recovery properties. After five cycles of experiments, the photo-Fenton catalytic properties of ZnFe2O4/ZnCO3-2 and ZnFe2O4/ZnO-2 on TC decreased slightly within 30 min, but the Fenton catalytic properties of RhB still maintained more than 98%, indicating that both have good magnetic recovery properties and strong structural stability. A possible photo-Fenton catalytic mechanism has been proposed based on free radical identification, electrochemical impedance spectra, photocurrent curves, and a Mott–Schottky diagram. This study provided two catalysts with excellent performance for the photo-Fenton catalytic degradation of pollutants in water. [ABSTRACT FROM AUTHOR]

Industries persistently contribute to environmental pollution by releasing a multitude of harmful substances, including organic dyes, which represent a significant hazard to human health. As a result, the demand for effective adsorbents in wastewater treatment technology is steadily increasing so as to mitigate or eradicate these environmental risks. In response to this challenge, we have developed an advanced composite known as MOF-5/Cellulose aerogel, utilizing the Pampas plant as a natural material in the production of cellulose aerogel. Our investigation focused on analyzing the adsorption and flexibility characteristics of this novel composite for organic dye removal. Additionally, we conducted tests to assess the aerogel's reusability and determined that its absorption rate remained consistent, with the adsorption capacity of the MOF-5/cellulose aerogel composite only experiencing a marginal 5% reduction. Characterization of the material was conducted through XRD analysis, revealing the cubic structure of MOF aerogel particles under scanning electron microscopy. Our study unequivocally demonstrates the superior adsorption capabilities of the MOF-5/cellulose aerogel composite, particularly evident in its efficient removal of acid blue dye, as evaluated meticulously using UV–Vis spectrophotometric techniques. Notably, our findings revealed an impressive 96% absorption rate for the anionic dye under acidic pH conditions. Furthermore, the synthesized MOF-5/cellulose aerogel composite exhibited Langmuir isotherm behavior and followed pseudo-second-order kinetics during the absorption process. With its remarkable absorption efficiency, MOF-5/cellulose aerogel composites are poised to emerge as leading adsorbents for water purification and various other applications. [ABSTRACT FROM AUTHOR]

Context: The world's energy and environmental requirements are changing due to rapid population growth and industrial growth, and solar cells can be used to meet these demands. Dye-sensitized solar cells (DSSCs) are solar cells in which energy conversion occurs via a process similar to photosynthesis in plants. DSSC development is still in its infancy. DSSCs can operate under cloudy conditions and indirect sunlight and have attracted considerable attention due to their low cost and high efficiency. We designed two metal-free TPA-based dyes (Dye2 and Dye3) based on the reference dye Mg207 (Dye1) by increasing the donor strength of the molecule, as such dyes have shown enhanced efficiency in DSSCs. Moreover, the triphenylamine (TPA) moiety has been demonstrated to be a good donor that prevents charge recombination. Intramolecular charge transfer (ICT) from the donor to acceptor moiety was found in the sensitizers, and electrons were promoted to the conduction band (CB) of the TiO2 semiconductor. The negative binding energy of the dye@TiO2 clusters indicated that dye adsorption on the semiconductor surface was stable. The double donor increased the electron injection and electronic coupling constants in Dye2 and Dye3, indicating that these newly designed dyes have superior charge injection capacity. Accordingly, the efficiencies of DSSCs with Dye2 and Dye3 were 9.77% and 9.62%, respectively, and substitution with the TPA unit at the -R1 and -R2 positions in Dye1 resulted in better power conversion compared to the parent compound (9.09%). Increased donor strength improved photovoltaic performance by increasing current density and light-harvesting efficiency. This is a good molecular design approach for preparing targeted donor- π -acceptor (D- π -A) organic dyes with high DSSC efficiency. Methods: To predict the charge transport and optoelectronic characteristics of the TPA dyes, quantum chemical calculations were carried out using Gaussian16. The ground-state (S0) optimized geometries of the sensitizers were computed by utilizing DFT at the B3LYP/6-31G** level. The absorption spectra (λ max) were computed by employing TD-DFT with various functionals (B3LYP, PBE1PBE, CAM-B3LYP, and BHandHLYP) in the gas and solvent (DCM) phases. Among the studied functionals, BHandHLYP was found to be best at successfully reproducing the experimental data. Thus, the absorption spectra of the newly designed dyes and dye@TiO2 were calculated at the BHandHLYP/6-31G** level. The dye@TiO2 cluster optimizations were carried out at the B3LYP/6-31G**(LANL2DZ) level. [ABSTRACT FROM AUTHOR]

Toxic organic dyes (colorants) are one of the main causes of water pollution that releases destructive effluents in the environment. To overcome this issue, a fundamental need to produce a novel, efficient catalyst for the degradation and mineralization of dye mixtures has arisen. The objective of this research is to develop an eminent Ni-doped magnetic carbon aerogel (Ni-MCA) catalyst using graft co-polymerization method having xanthan gum as backbone doped with Ni-magnetic nanoparticles (Ni-MNPs), that do not show agglomeration and easy to separate. The examination revealed that Ni-MCA provided exceptional magnetic characteristics (Ms = 52.75 emu/g) and potent catalytic activity for the degradation of mono- as well as binary-dye solutions of Congo red (CR) and methyl green (MG) dyes. The formation was verified by various characterization techniques such as FTIR, VSM, XRD, XPS, SEM, TEM, and EDX mapping. Interestingly, Ni-MCA shows faster result on anionic dye CR up to 97% with degradation rate of 5.647 × 10−1 min−1, and MG dye shows degradation of 95.7% with the degradation rate of 2.169 × 10−1 min−1, while dye mixture is showing 90% degradation with rate of 2.159 × 10−1 min−1. [ABSTRACT FROM AUTHOR]

Water, essential for all life, faces contamination challenges due to industrialization and unchecked urban development, producing pollutants such as organic dyes, detergents, heavy metals, and pesticides. This has emerged as one of the most pressing environmental concerns in recent years, with a particular emphasis on organic dyes due to their demonstrated health-related concerns. In this context, this paper reviews the use of photocatalysis as a wastewater treatment method, highlighting its significant potential for removing organic dyes from aqueous solutions. Additionally, the focus is on the design, development, performance enhancement, and overall research progress in fabricating graphene-based semiconductor nanocomposites as photocatalysts. Representative examples are discussed, emphasizing the potential of these nanocomposites in degrading toxic organic dyes through photocatalysis. The enhanced photoactivity is attributed to the synergistic effects of graphene and semiconductor materials, leading to improved light absorption, charge separation, and reactive oxygen species generation. This comprehensive review provides valuable insights to advance wastewater treatment technologies and address environmental impacts caused by organic dye pollution. [ABSTRACT FROM AUTHOR]

Industrial wastewater has detrimental impacts on aquatic ecosystems and the environment. Among the significant contributors to water pollution are organic dyes, which are frequently released into untreated outflow water. Hence, effective degradation of these dyes and their derivatives using heterogeneous photocatalysts is imperative before discharge. In this study, we successfully synthesized a novel nanocomposite by g-C3N4 coupled with TiO2 and decorated it with Ni followed by cost-effective methods. Immaculate g-C3N4 coupled with TiO2 (TiO2+) and modified with nickel (Ni+) was synthesized through melamine calcination followed by hydrothermal processing. Characterization through diverse electro-analytical techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET), was conducted on the novel photocatalysts. XRD results revealed their high crystallinity, enhanced through modification. The effectiveness of these photocatalysts in degrading the organic dye methylene blue (MB) under UV–Vis light was thoroughly investigated. It also investigated how the results were affected by important factors involving contact time, dye and photocatalyst dosages, pH, and reusability. Among the photocatalysts, the composite g-C3N4-TiO2s, decorated with Ni, exhibited exceptional performance, displaying substantial degradation efficacy. The findings demonstrate that the novel g-C3N4-based photocatalysts are highly efficient at degrading organic dyes, so the work is expected to be the best contribution in the photodegradation study of organic contaminants. [ABSTRACT FROM AUTHOR]

Context: A series of five organic dyes (Mi, i = 1–5) of the D-A'-π-A structure were designed based on reference dye (Ref), and the influence of different auxiliary acceptors (A') on their efficiency in dye-sensitized solar cells (DSSC). Methods: Was studied theoretically using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. In this context, the electronic structures, optical properties, and the parameters influencing the power conversion efficiency (PCE), such as light harvesting efficiency (LHE), electron injection driving force (∆Ginject.), and open circuit photo-voltage (VOC), have been evaluated and discussed. The modification of the auxiliary acceptor (A') in the D-A'-π-A structure of the designed organic dyes has the advantage of significantly decreasing the band gap, which leads to the broadening of the absorption band that is red-shifted and improves the photovoltaic characteristics compared to Ref. Theoretical results reveal that M1, and M5 can be used as excellent sensitizer candidates for DSSC applications. [ABSTRACT FROM AUTHOR]

Amyloid fibrils derived from different proteins have been proved as a promising material for adsorption of various pollutants from wastewater, which showed advantages of low cost and eco-friendliness. However, most of the amyloid fibrils derived from animal-based proteins with high environmental footprint, while more sustainable amyloid fibrils derived from plant materials are desirable. In this study, a plant-derived amyloid fibril was extracted from the commonly used wheat flour with a simple and scalable protein purification and fibrillization process. Interestingly, the amyloid fibrils showed good adsorption capacity towards typical organic dyes (Eosin Y (EY) and Congo red (CR)) from contaminated water. Adsorption kinetic analysis indicated the adsorption process to EY or CR by wheat flour amyloid well fitted with a pseudo-second-order model. The adsorption also followed a Langmuir isothermal model with adsorption capacities of 333 mg/g and 138 mg/g towards CR and EY, respectively. This work demonstrated the feasibility to utilize the plant-based amyloid fibril for organic dyes removal from contaminated water, which provided an affordable, sustainable and scalable tool for organic dyes removal from wastewater. Highlights: The use of plant-based amyloid fibrils for organic dyes adsorption is demonstrated. The wheat flour-derived amyloid fibrils exhibit excellent adsorption performance. The adsorption kinetics and isotherms mechanisms are explored. The plant-based amyloid fibrils provide sustainable tool for pollutant management. [ABSTRACT FROM AUTHOR]

The new design of 6,6′-di(thiophen-2-yl)-4,4′-bipyrimidine (DTB)-based organic dyes (TCIT1-TCIT6) for dye-sensitized solar cell (DSSC) application was systematically designed by a donor (D), π-linker, and acceptor (A) design to form the D-π-D-π-A structure. The exchange–correlation (XC) as well as long-range corrected (LC) functionals were utilized to represent these dyes in density functional theory (DFT) and time-dependent DFT (TD-DFT) techniques. The TD-CAM-B3LYP approach was perfectly matched the DTB dye. Energy gaps between highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) ranged between 1.73-2.92 eV. Their light-harvesting efficiency (LHE) values ranged between 0.001-0.106 eV with dye TCIT5 with the highest value. The open circuit voltage calculated against the DTB as donor moiety ranged 2.45–3.64 eV with positive values to demonstrate their ON position in their solar devices. All the dyes showed a very short excited-state lifetime ranging between 0.0001-0.0051 ns which showed how easily they can shift from an excited- (fluorescent) to ground-state position. Improved results for DSSCs were provided by the intended dyes in addition to their high horizontal dipole moment (µnormal) and open circuit photovoltage (eVOC). It benefits increased efficiency as a result. The findings of the current theoretical analysis show that all D-π-D-π-A dyes may be suitable sensitizers for DSSC applicability. [ABSTRACT FROM AUTHOR]

Water pollution has become a major environmental threat owing to the expeditious development of industries. These industries rapidly release wastewater containing harmful dyes (organic pollutants), which significantly affect the lives of humans and aquatic organisms to a huge extent. Therefore, the elimination of the pollutants in the contaminated water has become the primary need of the moment that is to be treated before it discharges into the environment. This article mainly focuses on the adsorption mechanism of the organic dye methylene blue from wastewater under sunlight using a zinc-metal organic framework (Zn-MOF). The Zn-MOF, being a three-dimensional porous structure was synthesized by the direct precipitation method using zinc metal ions and terephthalic acid (or) benzene-1,4-dicarboxylic acid as a connecting linker. Then, morphological and optical characterizations, along with the analysis of thermal and surface parameters, were performed for the synthesized Zn-MOF. The synthesized Zn-MOF appeared to be in a cubic form with a pore volume of about 0.006 cc/g. It was also found to have a surface area of 4.705 m2/g, with an absorbance range of 239.39 nm. The elemental composition of zinc in the synthesized Zn-MOF was approximately 25.41%, proving that the synthesized MOF is a Zinc-based MOF. As the results showed many properties related to the adsorption mechanism, Zn-MOF was chosen to proceed with the adsorptive application of removing the methylene blue dye from wastewater under sunlight. This application provides an efficient solution for the treatment of wastewater through the adsorption property of Zn-MOF, thereby proving its potential as an adsorbent. [ABSTRACT FROM AUTHOR]

Dye pollution resulting from the discharge of untreated wastewater has become a major environmental concern. In this study, we propose a green and cost-effective approach for the photocatalytic degradation of dye pollutants using a nanocomposite (NC) of manganese oxide (Mn3O4) modified with polyvinylpyrrolidone (PVP). The Mn3O4 nanoparticles (NPs) were synthesized through a green method using a biogenic extract of Pistacia lentiscus leaves. The resulting Mn3O4 NPs were then modified with PVP, a non-ionic polymer, to enhance their stability and catalytic performance. The synthesized Mn3O4/PVP NC was characterized using various analytical techniques, including Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy. The findings showed that the Mn3O4 NPs and Mn3O4/PPV NC exhibit spherical morphology with an average size of 37 nm and 45 nm, respectively. The Mn3O4 NPs and Mn3O4/PVP NC exhibited optical bandgap energies of 1.8 eV and 1 eV, indicating the effective use of these NPs as photocatalysts. The nanocomposite exhibited exceptional catalytic performance in degrading bromophenol blue (BPB) and ortho-toluidine blue (O-TB), achieving degradation rates of 98% and 95% within 75 minutes. In comparison, Mn3O4 NPs showed lower efficiencies with approximately 14% degradation for BPB and 6% for O-TB. Optimal conditions for dye degradation and subsequent cycles were determined, and first-principles calculations revealed insight into the adsorption energy between the dyes and the Mn3O4/PVP surface. This study highlights the potential of Mn3O4/PVP nanocomposite as an effective and eco-friendly catalyst for dye pollutant degradation, offering a promising solution for wastewater treatment across industries. [ABSTRACT FROM AUTHOR]

In this study, the Fe3O4/rGO/Ag magnetic nanocomposite was synthesized and employed as an adsorbent for the removal of tetracycline (TC), crystal violet (CV), and methylene blue (MB) from water samples. The influential parameters in the removal process were identified and optimized using response surface methodology (RSM). Characterization of the product was performed through field emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), vibrating-sample magnetometer (VSM), and X-ray diffraction (XRD) analysis. XRD and SEM analysis revealed the successful synthesis of the Fe3O4/rGO/Ag nanocomposite. EDX analysis elucidated the accuracy and clarity of the chemical composition of the magnetic nanocomposite structure. Additionally, the separation of the nano-adsorbent from the solution can be achieved using a magnetic field. Maximum removal of analytes was obtained at pH of 6, amount of nanocomposite 0.014 g, ultrasonic time of 8 min and concentration of 21 mg L−1. Under optimal conditions, the removal efficiencies for TC, CV, and MB were 91.33, 95.82, and 98.19%, respectively. Also, it was observed that after each adsorption–desorption cycle, Fe3O4/rGO/Ag magnetic nanocomposite had good stability to remove TC, CV, and MB. Achieving nearly 98% removal efficiency in optimal conditions showed that Fe3O4/rGO/Ag magnetic nanocomposite is an effective adsorbent for removing TC, CV, and MB from wastewater samples. [ABSTRACT FROM AUTHOR]

Context: In this work, we designed ten new organic phenothiazine dyes bridged by different πi-spacers (PTZ1-PTZ10) of D-π-A type based on the synthesized dye CC202-III for their efficacy in dye-sensitized solar cells (DSSC) applications. To learn how various π-spacers affect their performance in DSSCs, these isolated dyes and dye-cluster systems have had their geometries, electronic structures, absorption spectra, dipole moments, and molecular electrostatic potential examined and talked about. Additionally, a number of quantization parameters that affect power conversion efficiency (PCE), including light collection efficiency (LHE), reorganization energy (λtotal), vertical dipole moment (μnormal), strength electron injection driving force (ΔGinject), regeneration driving force (ΔGreg), excited state lifetime (τ), and open circuit voltage (VOC), were calculated in order to identify the organic dyes that would be best suited for DSSC applications. Calculated results revealed that the designed dyes PTZ3, PTZ4, PTZ5, and PTZ10 exhibit a lower energy gap among all dyes compared to the corresponding CC202-III. Additionally, PTZ3, PTZ4, PTZ5, PTZ7, PTZ8, PTZ9, and PTZ10 exhibit significant red-shifted absorption spectra compared to the other dyes with a larger oscillator strength, which improves the photocurrent density of the devices. The findings thus imply that bridge modification is a workable tactic to raise DSSC effectiveness. Method: We used density functional theory (DFT) and time-dependent DFT (TD-DFT) methods to study the electronic and photovoltaic properties of the dyes designed (PTZ1–PTZ10) to assess their effectiveness in DSSCs. DFT and TD-DFT simulations are theoretically used to deeply analyze key characteristics of all organic dyes that affect open-circuit voltage (VOC) and short-circuit current (JSC) to identify structure–property relationships. [ABSTRACT FROM AUTHOR]

Development of nanocomposites as efficient photocatalysts for the removal of hazardous organic pollutants is always in dire demand due to increase in water pollution. In this article, a facile sol-gel method has been used to synthesize cerium oxide (CeO2) nanoparticles followed by their decoration over multi-walled carbon nanotubes (CNTs) and graphene oxide (GO) to construct binary as well ternary hybrid nanocomposites using ultrasonic treatment. The oxygen vacancy defects have been depicted using X-ray photoelectron spectroscopy (XPS) that may result into improved photocatalytic efficiency. The ternary hybrid nanocomposites (CeO2/CNT/GO) showed excellent photocatalytic efficiency towards degradation of rose bengal (RB) dye up to 96.9% in 50 min. CNTs and GO provide the interfacial charge transfer which inhibits the electron-hole pair recombination. The results obtained here indicate that these composites can be effectively utilized as promising materials for the degradation of harmful organic pollutants for wastewater treatment. [ABSTRACT FROM AUTHOR]

Natural dyes have been widely employed in the fabrication of dye-sensitized solar cells (DSSCs). DSSCs are favored for their cost-effective, and simple fabrication process relies on metal-based and organic dyes. The choice of dyes greatly affects the performance of DSSCs. DSSCs have found a lot of applications in indoor, solar power gadgets with reasonable efficiency up to 13%. Nonetheless, despite advances in DSSC technology, the complex photophysics and excited state dynamics associated with natural dyes employed in DSSCs remain elusive and have not been adequately investigated. This information gap emphasizes the need for more study and analysis into the behavior of these dyes, since understanding their underlying principles might lead to major improvements in DSSC performance and efficiency. In this work, we have investigated the fundamental characteristics and excited-state carrier dynamics of natural dye curcumin using ultrafast transient absorption (TA) spectroscopy technique. The curcumin dye shows delay time-dependent positive and negative signals in the TA spectra, which are related to excited state absorption and stimulated emission. We also found that hydrogen bonding and polarity effect of solvent significantly influence the carrier dynamics of curcumin. Ultrafast lifetime component indicates that hydrogen-bond rearrangements are involved in the kinetics of the relaxation process of the S1 state of curcumin photo-sensitizer. [ABSTRACT FROM AUTHOR]

Context: Dye-sensitized solar cells (DSSCs) have displayed huge potential in inexpensive, efficient, and clean solar energy technology. In this work, seven new dyes with the structure D-A'-A were designed in which the thiophene in the reference dye was replaced by auxiliary acceptors (A'). These dyes consist mainly of a pyranylidene-based electron donor D and the cyanoacrylic acid moiety as acceptor A. A computational investigation was carried out on the effect of various auxiliary acceptors A' on the efficiency of D-A'-A dyes in isolation and after binding to the semiconductor TiO2. Optimized structures, geometrical, optoelectronic, and photovoltaic parameters were calculated to predict promising dyes for potential use as solar cell sensitizers, including band gap (Egap), natural bond orbital (NBO) analysis, nonlinear optical properties (NLO), UV–Vis absorption spectra, maximum absorption wavelength (λmax), reorganization energy (λtotal), light-harvesting efficiency (LHE), electron injection driving force (ΔGinject) and open-circuit photovoltage (VOC). The results of this study revealed that all designed dyes, compared to the reference dye, are characterized by small Egap and λtotal values as well as large λmax, in addition to significant NLO properties and large adsorption energy (Eads). Therefore, all studied dyes can be used as sensitizers in DSSC. Methods: Using Density Functional Theory (DFT) approaches with the B3LYP functional and the 6-31G(d,p) basis set, all ground state geometries of the isolated dyes were fully optimized. Time-Dependent Density Functional Theory (TD-DFT) method using the CAM-B3LYP/6-31G(d,p)/IEF-PCM level was applied to simulate the UV–visible absorption properties. All isolated dye calculations were performed using the Gaussian 09 software package. DFT calculations have been carried out with the DMol3 package included in Materials Studio for simulating the adsorption of the investigated dyestuff on the TiO2 surface of anatase (101), using the generalized gradient corrected approximation (GGA) approach of the Perdew-Burke-Ernzerhof (PBE) functional with the basic set of digital double polarisation (DNP). To study the optical performance of dye@TiO2 the PBE/DNP method present in DMol3 was applied. [ABSTRACT FROM AUTHOR]

New organic dyes (H1-H6) for their promising applications as dye sensitized solar cell (DSSCs) were theoretically designed from 6,6′-di(thiophen-2-yl)-4,4′-bipyrimidine (TB) moiety in acceptor (A), π-spacer, and donor (D) type architecture to create A-π-D-π-D-π-A framework. After their benchmarking study against various exchange correlation (XC) and long-range corrected (LC) functional, the CAM-B3LYP produced accurate results so as selected for further density functional theory (DFT) and time dependent DFT (TD-DFT) studies. The frontier molecular orbitals (FMOs) were analyzed for their electron transfer properties, and their energies of the highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO) were used to assess various electronic properties. Their energy differences (EH-L) ranged between 1.69 and 2.03 eV indicating their good responsiveness to electron injection (Ginj) being the values greater than 0.2 eV. The maximum absorbance of the dyes was reported around the 388–406 nm while their starting material (TB) had this value to be 371 nm. This redshift was significant with an intensification of electron-withdrawing groups on the dye structures. The dyes were evaluated for their device related parameters like their light harvesting efficiency, open circuit voltage, exciton binding energies, and exciton life times which were found in their promising values. The dyes were analyzed for their linear (α), first (βtotal), and second (γtotal) order nonlinear responses and were found to have significantly higher responses, not only against their starting materials but also those reported in literature for standard molecules (urea and p-nitric acid). Among the dyes under study, dye H4 exhibits the highest molecular polarizability (α) and hyperpolarizability (β and γ) values thanks to two CN substituted units on each ends. These dyes are most likely to have possible optical and photonic uses. Also, according to the results of the current theoretical research, all of these dyes may function as effective photosensitizer for their DSSC application. [ABSTRACT FROM AUTHOR]

Industrial effluents are a leading major threat for water contamination, subsequently which results in severe health associated risks. Hence, purifying wastewater before releasing into the water resources is essential to avoid contamination. In this study, ZnO/Cu-DPA nano-composites were prepared by altering the percentage of Cu-DPA (20%, 30%, 40%, and 50% which are denoted to be ZnO/20%Cu-DPA, ZnO/30%Cu-DPA, ZnO/40%Cu-DPA and ZnO/50%Cu-DPA) using a simple mechanical grinding process. Several spectroscopic studies were employed such as electron paramagnetic analysis (EPR), powdered X-ray diffractometer (PXRD), UV–Vis absorbance spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscope to characterize these nano-composites. The photo-catalytic activities of the prepared nano-composites were studied by degrading MB under visible light irradiation. ZnO, ZnO/20%Cu-DPA, ZnO/30%Cu-DPA, ZnO/40%Cu-DPA and ZnO/50%Cu-DPA degradation efficiencies were determined to be 71.8, 78.5, 77.1, and 66.1%, respectively. Among the composite catalysts, the ZnO/20%Cu-DPA coupled system are demonstrated the best efficiency (87%) for photo-degradation of MB within 80 min when exposed to visible light. The ZnO/Cu-DPA nano-composites had a greater MB photodegradation efficiency than pristine ZnO owing to p-n heterojunction in the linked system. Under visible light irradiation, the ZnO/20%Cu-DPA catalysed the conversion of dissolved O2 to hydroxyl radicals (OH·), triggering the reduction of MB. This suggests that ·OH is the primary specific active radical involved in the photo-catalytic decomposition of MB. Furthermore, EPR analysis indicates the existence of ·OH in the photo-catalytic system. The proposed nano-composites (ZnO/20%Cu-DPA) reusability was investigated across three cycles as the most efficient photo-catalyst. The results show that, the ZnO/Cu-DPA nano-catalyst is a potential candidate for the remediation of dirty water. [ABSTRACT FROM AUTHOR]

A series of efficient donor-π-acceptor tiny organic dyes NA1, NA6, and NA7 were developed as co-sensitizers to improve the photovoltaic performance of the black dye-based dye-sensitized solar cells (DSCs). Dye aggregation on the TiO2 surface was reduced, and improved sensitizer coverage was achieved through the introduction of a long alkoxy group in the donor part, the tuning of the anchoring parts, and the π-spacer of the co-sensitizer NA6. The spectral photoresponse was thereby dramatically improved across the spectrum from the ultraviolet to the visible range, and the recombination process was suppressed for the (black dye+NA6) co-sensitized cell compared with a single black dye. The co-sensitized black dye+NA6-based DSCs show a considerable increase in Voc (open-circuit voltage), Jsc (short-circuit current density), and FF (fill factor) to 721 mV, 21.64 mAcm−2 and 0.733, respectively. A higher efficiency of 11.43% was, consequently, achieved for the (black dye+NA6) co-sensitized cell compared to 10.56% for the DSCs based on a single black dye. [ABSTRACT FROM AUTHOR]

In this work, seven organic dyes were designed (M2–M7) to have the D-π1-Ai-π2-A structure from the reference dye M1, which has the D-π1-π2-A structure. By inserting different auxiliary acceptors Ai (i = 1–7) between the π1 and π2 onto the reference dye M1, we obtained the designed dyes to study their photovoltaic properties for use in DSSC devices. The geometrical structures, absorption spectrum properties, nonlinear optical properties (NLOs), energy levels, frontier molecular orbitals, and some photovoltaic parameters were theoretically investigated using density function theory (DFT) and time-dependent DFT (TD-DFT) methods, with the aim of improving the DSSC performance of the designed dyes. The theoretical results reveal that the designed dyes would be used as potential sensitizers in DSSCs due to their very small energy gaps, broad absorption spectra, higher NLO properties, lower reorganization energy (λtot), lower regeneration driving force (ΔGreg), longer excited lifetime (τ), higher vertical dipole moment (µnormal), reasonable electron injection driving force (∆Ginj), and equally reasonable light-harvesting efficiency (LHE) compared to the reference dye M1. Furthermore, the designed dyes (M2–M8) have better charge transferability, the highest stabilization energy, and the highest ability of electron-donating and electron-accepting, resulting in a high short-circuit current and better power conversion energy (PCE) compared to reference dye M1. These results show that the introduction of different auxiliary acceptors Ai can most effectively improve the photovoltaic performance of our system. [ABSTRACT FROM AUTHOR]

The importance of water for all living organisms is unquestionable and protecting its sources is crucial. In order to reduce water contaminants, like toxic metals and organic dyes, researchers are exploring different techniques, such as adsorption, photocatalytic degradation, and electrolysis. Novel materials are also being sought. In particular, biopolymers like guar gum and xanthan gum, that are eco-friendly, non-toxic, reusable, abundant and cost-effective, have enormous potential. Gum-based nanocomposites can be prepared and used for removing heavy metals and colored dyes by adsorption and degradation, respectively. This review explains the significance of gum-based nanomaterials in waste water treatment, including preparative steps, characterization techniques, kinetics models, and the degradation and adsorption mechanisms involved. [ABSTRACT FROM AUTHOR]

Dispersion of colloidal particles in water or oil is extensively desired for industrial and environmental applications. However, it often strongly depends on indispensable assistance of chemical surfactants or introduction of nanoprotrusions onto the particle surface. Here we demonstrate the omnidispersity of hydrophilic-hydrophobic heterostructure particles (HL-HBPs), synthesized by a surface heterogeneous nanostructuring strategy. Photo-induced force microscopy (PiFM) and adhesion force images both indicate the heterogeneous distribution of hydrophilic domains and hydrophobic domains on the particle surface. These alternating domains allow HL-HBPs to be dispersed in various solvents with different polarity and boiling point. The HL-HBPs can efficiently adsorb organic dyes from water and release them into organic solvents within several seconds. The surface heterogeneous nanostructuring strategy provides an unconventional approach to achieve omnidispersion of colloidal particles beyond surface modification, and the omnidispersible HL-HBPs demonstrate superior capability for dye recycle merely by solvent exchange. These omnidispersible HL-HBPs show great potentials in industrial process and environmental protection. Dispersion of colloidal particles in water or oil is desired for industrial and environmental applications but it often strongly depends on indispensable assistance of chemical surfactants or introduction of nanoprotrusions onto the particle surface. Here, the authors demonstrate the omnidispersity of hydrophilic-hydrophobic heterostructure particles, synthesized by a surface heterogeneous nanostructuring strategy. [ABSTRACT FROM AUTHOR]

The disposal of textile pollutants tainted by soluble organic dyes into the water without proper treatment may adversely impact the aquatic environment, humans, plants, and animals due to their toxic nature. As a result, the goal of this work is to look into the adsorptive removal of Eriochrome Black T (EBT) dye (as a model of soluble anionic organic dyes) from aqueous solution using a green synthesis nanoporous activated carbon @ Aluminum based metal–organic frameworks (AC@Al-MOFs) from a lemon peel waste as an inexpensive biosorbent. The physicochemical properties of Al-MOF and AC@Al-MOF composite were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), and the impact of varied parameters on adsorption efficiency of Eriochrome Black T (EBT) including pH, dye concentrations, contact time and adsorbent dose, was examined. The experimental isotherms data were analyzed using Langmuir and Freundlich isotherm equations. The best fit was obtained by the Langmuir model with high correlation coefficients (R2 = 0.9976) with a maximum monolayer adsorption capacity of 303.0 mg/g. The results suggest that AC@Al-MOF composite is a potential choice for removing EBT dye molecules from aqueous media. [ABSTRACT FROM AUTHOR]

The enhanced photocatalytic process of GMNT NCs was achieved by wet impregnation. The resulting sample was examined using numerous analytical techniques to determine its composition, morphology, structure, and optical properties. GMNT photocatalyst showed impressive photocatalytic degradation efficiency (91.75%) over RhB dye in 100 min, when exposed by visible illumination. The photoreaction rate constant of GMNT ternary PCs (0.0233 min−1) was 6.2 times faster than bare GCN (0.0037 min−1), GMS (0.0055 min−1), and GCNT (0.0124 min−1) against RhB dye. Besides, they have considerable stability against RhB dye degradation after five cycles. A trapping experiment with a variety of scavengers also reveals that photogenerated charge carriers hole pair and ⋅O2− radicals play a prominent role in the photodegradation process. GMNT nanocomposite has been shown to enhance photocatalytic performance by suppressing e−–h+ pair separation and recombination efficiency. Hence, GMNT PCs have shown high potential for various environmental applications, including wastewater treatment. [ABSTRACT FROM AUTHOR]

The generation of electricity using solar energy is an effective system to overcome the current global energy crisis. In this regard, developing new semiconductor materials can be of great interest in overcoming the challenge of charge carrier recombination and, hence, improving the power conversion efficiency (PCE) in photovoltaic devices, particularly dye-sensitized solar cells (DSSCs). Here, reduced graphene oxide-Sr0.7Sm0.3Fe0.6Co0.4O3 (RGO-SSFC) nanocomposites were synthesized using the hydrothermal method and characterized with the aid of microscopic and spectroscopic techniques, as well as a vibrating sample magnetometer, and further tested for application as photoanodes in DSSCs. Scanning electron microscopy revealed the presence of RGO nanosheets that were fully decorated by irregular- and spherical-shaped SSFC nanoparticles. Fourier-transform infrared spectroscopy confirmed the strong synergistic interaction of the RGO-SSFC nanocomposites. The large surface area of RGO-SSFC nanocomposite photoanodes facilitated effective dye loading, high photon absorption, and efficient electron transfer, resulting in better device performance. Compared to RGO-SSFC-0.1 and RGO-SSFC-1.0, the RGO-SSFC-0.5 nanocomposite showed an enhanced open-circuit voltage (Voc) of 0.84 V, short-circuit current density (Jsc) of 14.02 mA cm−2 , and a PCE of 7.25%. Eosin B and MK-2 organic dyes used as photosensitizers coated on the RGO-SSFC semiconductors resulted in low-cost DSSC photoanodes. [ABSTRACT FROM AUTHOR]

Context: Since 1991 when Grätzel et al. improved the conversion efficiency of dye-sensitized solar cells to 7.1% by applying nano technology as the first time, the researches on dye-sensitized solar cells have received widely attentions. The organic dye without precious metals has a lower cost, which is easily to get synthesized and its structure is easily decorated, owing a higher photoelectric conversion efficiency at the same time. Therefore, in recent years, the organic dye has attracted people's attentions more and more. In order to better understand the relationship between structure and properties of dye molecules, with ZL003 as a prototype, molecular modifications are then made and a scheme, with rigid fused π-bridge comprising electron-rich and deficient segments. The calculated results indicate that the π-bridge containing dithienopyrrolobenzothiadiazole and dipyrrolo-dithienobenzothiadiazole as π-bridge has been demonstrated to be successful to significantly redshift the absorption maximum wavelength, extend the lifetime of the first excited state, and decrease the energy gap between the highest occupied molecule orbital (HOMO) and the lowest unoccupied molecule orbital (LUMO). It is hoped that the calculation result of this paper would provide theoretical basis for the experimental synthesis of more efficient dye molecules. Method: All calculations were performed in Gaussian 09 program package. The ground state geometries (S0) and the first excited state (S1) were optimized using density function theory (DFT) with the hybrid function B3LYP functional, coupled with the 6-31G(d, p) basis set for optimization of molecule ground state conformations. TD-DFT calculations of excited state energies and absorption spectra were performed using MPWPW91 functional combined with the 6–31 + G (d) basis set. [ABSTRACT FROM AUTHOR]

Globally, treating and disposing of industrial pollutants is a techno-economic challenge. Industries' large production of harmful heavy metal ions (HMIs) and dyes and inappropriate disposal worsen water contamination. Much attention is required on the development of efficient and cost-effective technologies and approaches for removing toxic HMIs and dyes from wastewater as they pose a severe threat to public health and aquatic ecosystems. Due to the proven superiority of adsorption over other alternative methods, various nanosorbents have been developed for the efficient removal of HMIs and dyes from wastewater and aqueous solutions. Being a good adsorbent, conducting polymer-based magnetic nanocomposites (CP-MNCPs) has drawn more attention for HMIs and dye removal. Conductive polymers' pH-responsiveness makes CP-MNCP ideal for wastewater treatment. The composite material absorbed dyes and/or HMIs from contaminated water could be removed by changing the pH. Here, we review the production strategies and applications of CP-MNCPs for HMIs and dye removal. The review also sheds light on the adsorption mechanism, adsorption efficiency, kinetic and adsorption models, and regeneration capacity of the various CP-MNCPs. To date, various modifications to conducting polymers (CPs) have been explored to improve the adsorption properties. It is evident from the literature survey that the combination of SiO2, graphene oxide (GO), and multi-walled carbon nanotubes (MWCNTs) with CPs-MNCPs enhances the adsorption capacity of nanocomposites to a large extent, so future research should lean toward the development of cost-effective hybrid CPs-nanocomposites. [ABSTRACT FROM AUTHOR]

This study presents the results of synthesis and characterization of nanoparticles of cobalt ferrite (CoFe2O4) and nickel ferrite (NiFe2O4) using co-precipitation method followed by application for removal of hazardous organic textile dyes of thiazole yellow G (TYG) and alizarin yellow R (AYR). XRD analysis confirmed formation of cubic spinel structure with average crystallite sizes at 16.07 nm and 13.84 nm for CoFe2O4 and NiFe2O4, respectively. Field emission scanning electron microscopy (FESEM) analysis showed agglomeration of spherical shape morphology with uniformly distributed Co, Ni, Fe, and O elements. The surface area calculated from Brunauer–Emmett–Teller (BET) analysis was 64 m2/g and 62 m2/g for CoFe2O4 and NiFe2O4, respectively. Vibrating sample magnetometer (VSM) showed super-paramagnetic behavior for all samples with magnetic saturation (Ms) at 7.269 and 6.61 emu/g for CoFe2O4 and NiFe2O4, respectively. The adsorption influencing parameters such as pH of solution, quantity of adsorbent, and contact time on dye removal efficiency were thoroughly investigated. Overall, acidic condition of samples with pH at 4 favored the maximum removal efficiency by CoFe2O4 as 98, 97, and 93%, and by NiFe2O4 as 96, 93, and 92%, respectively, for TYG, AYR, and mixture sample. The Langmuir adsorption isotherm model describes the equilibrium of all samples with the best fit of coefficient of determination (R2). The adsorption results fitted well with a pseudo-second-order kinetic model for all samples. The regeneration-reuse ability of adsorbents and cost estimation analysis of the dye removal process suggested that the economic suitability of nano-adsorbents for remediation of textile effluents was favored. The estimated thermodynamic parameters inferred that the removal of organic dyes onto the surface of CoFe2O4 and NiFe2O4 is a spontaneous, favorable, and exothermic physical adsorption process. [ABSTRACT FROM AUTHOR]

Here, we synthesized metal-free organic dye (CCPICPB) with two carbazole donor groups and two anchoring groups that exhibit a panchromatic absorption in the near-infrared range of up to 750 nm. To study the photophysical properties of synthesized CCPICPB dye, the UV–Vis and cyclic voltammetric experiments were studied and the obtained results were validated with theoretical simulation studies. After that, the solvothermal approach is used to synthesize pristine anatase and calcium (Ca)-doped TiO2 microspheres with a smooth morphology. These microstructures are examined in depth using XRD, electron microscopy and electrochemical analysis methods. On TiO2 and Ca-doped TiO2 photoanode materials, we first evaluated the performance of CCPICPB dye. Upon our optimized experimental condition, the 3% Ca-TiO2 photoanode-based device exhibits an efficiency of 4.04%, which is greater than that of the pristine TiO2 photoanode-based device (2.93%). Because of the quicker electron transport in the Ca-TiO2 film, the short-circuit current density and efficiency of DSSCs were improved. Moreover, when the CCPICPB dye was used as a co-sensitizer with the common Ru(II) dye (Z907), interestingly it showed the highest efficiency (6.11%) when compared with Z907 alone (5.12%). This improved efficiency of the co-sensitized device resulted from greater VOC conjugated with improved JSC. The JSC was improved because CCPICB dye could compensate for the photocurrent loss caused by redox electrolyte while the VOC was improved because electron recombination was inhibited under the co-sensitization conditions. [ABSTRACT FROM AUTHOR]

Significant progress has been made in developing organic compounds by modifying carbazole (Cz) based donor–spacer–acceptor (D–π–A) type dye molecules. The Cz-1–Cz-3 dyes were theoretically designed and experimentally synthesized successfully. Herein, we report the synthesis, photophysical properties and electrochemical characterization (quasi-reversible oxidation processes) of three Cz-based compounds. The calculated results agree well with the available experimental data of absorption spectra, HOMO–LUMO energy levels and band gaps using the time-dependent density functional theory. Furthermore, the results from natural bond orbital calculations were analyzed with the computational electronic structure and charge transfer (conjugative interaction) in molecular systems. The result shows fluorescence time-correlated single-photon counting between 4.32 ns, 4.25 ns, and 13.2 ns, and green to blue (λPL = 431–881 nm) emission for complexes Cz-1–Cz-3 in DMF solution. The Cz-3 compound showed excellent photovoltaic properties, with power conversion efficiency of 5.68%. These results clearly reveal that modification of the electron-withdrawing capability in D–π–A conjugated metal-free organic dyes is an effective way to improve the optical and electrical properties of organic photovoltaic (PV) devices. [ABSTRACT FROM AUTHOR]

Background: In the present work, DFT and time-dependent DFT calculations were performed to investigate the role of anchoring groups on the photophysical properties and reveal structure-property correlations of triphenylamine (TPA) derivatives. The selected anchoring groups are tetrazole, acrylamide, hydantoin, and rhodanine. Results: Our results show that the different anchoring groups employed alter the planarity, intramolecular charge transfer properties, and HOMO-LUMO gap and hence influence the optoelectronic properties of the dyes. Although all molecules fulfill the basic requirements with suitable energy levels, band gap, absorption, and charge transfer properties, the dye with rhodanine acceptor (TPA4) was the most promising candidate due to its lowest HOMO-LUMO gap, red-shifted highest λmax absorption value, better ICT pattern, low total reorganization energy, and good electron injection properties. Overall, it is anticipated that the results of this investigation will point to new avenues for the experimental fabrication of remarkably effective metal-free organic dyes for solar cell applications. [ABSTRACT FROM AUTHOR]

Context: The improvement of new organic flavone-based donor-spacer-acceptor (D-π-A) type dye molecules of the 3-(4-hydroxypiperidin-2-yloxy)-7-hydroxy-2-(3,4-dihydroxyphenyl)-4H-chromen-4-one (D1), 7-hydroxy-2-(3,4-dihydroxyphenyl)-3-(piperidin-4-yloxy)-4H-chromen-4-one (D2), and 3-((2-aminopyridin-4-yloxy)methoxy)-7-hydroxy-2-(3,4-dihydroxyphenyl)-4H-chromen-4-one (D3) were successfully designed and synthesized for dye-sensitized solar cells (DSSCs). Methods: Here, we discuss the synthesis of flavone compounds as well as their photophysical and electrochemical characterization. Using the Gaussian 09w software, the electronic structures and apsorption spectra have been calculated at the B3LYP, B3PW91, CAM-B3LYP, MPW1PW91, PBEPBE, and ωB97XD theory with the 6-311G(d,p) basis sets. Results: The computed values of the D2 molecule ground state optimized HOMOs-LUMOs energy is well positioned for advantageous charge transfer (CT) into the semiconducting material (TiO2) as well as the electron injection process. With a high power conversion efficiency (PCE) of 3.46% (VOC = 0.718 V, JSC = 7.07 mA cm−2, and FF = 0.68), the D2 compound also demonstrated good photovoltaic (PV) properties. Conclusion: These findings unequivocally demonstrate that altering the D-π-A metal-free organic material electron-withdrawing capacity is a useful strategy for enhancing the optical and electrical characteristics of the organic PV system. [ABSTRACT FROM AUTHOR]

Novel organic dyes were designed (MAX114-1–MAX114-7) by adding different π-spacer groups to the reference dye (MAX114) for high efficiency of dye-sensitized solar cells (DSSCs). Their geometries, electronic structures and optical properties and photovoltaic performance were theoretically investigated by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Photovoltaic parameters influencing power conversion efficiency (PCE) were calculated and discussed for DSSC applications, such as light-harvesting efficiency (LHE), electron injection driving force (∆Ginj), dye regeneration driving force (∆Greg), nonlinear optical properties (NLO) and reorganization energy. The optimized geometries of designed dyes have more coplanarity than the MAX114, which is beneficial for efficient intramolecular charge transfer and the suppression of dye aggregation. The energy gaps of the designed dyes have significantly decreased compared to MAX114, leading to red-shifted absorption spectra and improved light-harvesting ability. It was found that the studied dyes have good electron injection and dye regeneration performance due to a more negative value of ∆Ginj and a lower value of ∆Greg. The results show that the designed dyes have a higher μnormal, higher LHE, higher NLO properties, lower ∆Greg, reasonable ∆Ginj, and a better balance of λh and λe, resulting in a higher VOC and JSC than MAX114. This indicates that the designed dyes (MAX114-1–MAX114-7) could be used as sensitizers to improve the effectiveness of DSSC devices. [ABSTRACT FROM AUTHOR]

Starting with Coumarin-6 dye, two novel D-π-A organic dyes C6X and C6N have been designed by attaching carboxylic acid and cyanoacrylic acid groups as anchoring groups to Coumarn-6 dye, respectively, to understand their potential use in dye-sensitized solar cells (DSSCs). The electronic structure and photophysical and photovoltaic properties of the novel designed dyes were studied using density functional theory DFT and time-dependent density functional theory TD-DFT with the Becke3-Parameter-Lee–Yang–Parr (B3LYP) functional and the 6-31G (d, p) basis set. Optimized structure and electronic properties (highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital (ELUMO), and energy difference (Eg) between HOMO and LUMO) were calculated showing that C6N has the smallest band gap with the larger absorption region. Density of states (DOS), molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, non-linear optical (NLO) properties, UV–vis spectra, as well as some crucial parameters affecting the photovoltaic performance of DSSCs, such as light-harvesting efficiency (LHE), electron injection driving force (ΔGinject), dye regeneration driving force(ΔGreg), and the excited state life time(τe), were calculated to study the effect of the anchoring group on the DSSC performance. Additionally, the adsorption of C6X and C6N dyes on the TiO2 anatase (101) surface and the mechanism of electron injection were also investigated using a dye–(TiO2)9 cluster model using TD-B3LYP calculation. The calculated adsorption energies of the dyes suggest a strong adsorption of dyes to a TiO2 surface. The results show that C6N may be theoretically a good candidate as sensitizer of DSSC application. [ABSTRACT FROM AUTHOR]

Nowadays, aquatic pollution is one of the most important global challenges, due to discharges a wide variety of various hazardous materials from different activities which have significant environmental, economic and healthy impacts. Industries and activities related to organic dyes onsume large amounts of water and contribute significantly to the growing problem of water pollution. The current study describes the conversion of plant wastes into activated carbon sphere incorporated sulfonated polystyrene (AC/SPS) for adsorptive removal of Rhodamine B (RhB) and Congo Red (CR) dyes in a batch process. The prepared materials were characterized by different techniques such as XRD, FTIR, FESEM, TEM, BET-BJH, and TGA. The AC/SPS in weight ratio of 10% was used as a novel adsorbent for RhB and CR remediation. Batch adsorption experiment have been studied by investigating the effect of contact time, adsorbent dose, initial pH, and temperature. The maximum removal efficiency of RhB and CR onto AC/SPS under optimized conditions was estimated to be 34% and 98%, respectively. In addition, it has been found that Freundlich model provided the most appropriate fit for the adsorption of both RhB and CR dyes. Based on the thermodynamic study, it was proven that the adsorption process for both dyes is endothermic and spontaneous. The change in entropy was estimated to be 190.59 and 65.40 J/mol K for CR and RhB dyes, respectively. The kinetic study revealed that the adsorption of CR and RhB dyes followed the pseudo-second order and pseudo-first order kinetic models, respectively. [ABSTRACT FROM AUTHOR]

Organic dyes, porphyrins and inorganic complexes containing imidazole (IM) motifs have been demonstrated as a new class of sensitizers in dye-sensitized solar cells (DSSCs). Particularly, the amphoteric nature of IM-based motifs allows them to be used as donors (D), auxiliary donors (DA), linker/branch (π), or acceptors (A) in D–π–A-based organic dyes and porphyrins and also employed as cyclometalated heteroleptic and ancillary ligands in the Ru(II) and Ir(III) complexes for DSSCs. It is noteworthy that the introduction of IM chromophores in the dyes of D–π–A configuration can improve the light-harvesting properties and prohibit the charge recombination reactions due to the extension of the π-conjugated structures and hydrophobic nature. Similarly, in the case of inorganic complexes, the presence of IM motifs as ligands can improve the light-harvesting ability, give facilely tuned HOMO and LUMO energy levels, increase the charge recombination resistance and photostability. This results in enhanced photocurrent (JSC) and photovoltage (VOC) and consequently solar-to-power conversion efficiency (η) of DSSC devices based on Ru(II) and Ir(III) complexes. Considering the interesting DSSC applications of IM-derived molecules, in this review, we therefore comprehensively discuss their photophysical, electrochemical and photovoltaic properties reported so far and establish their structure–activity relationship to further advance the η of DSSCs. To the best of our knowledge, there is no such a review interpreting the importance of molecules possessing IM-motifs for DSSC applications to date. [ABSTRACT FROM AUTHOR]

The unregulated industrializations has poses serious threat to entire ecosystem by releasing untreated effluents containing hazardous dyes to fresh water. In the forefront polycationic ferrite (ternary ferrite)-chitosan microspheres were used to address the issue of synthetic dyes, contaminating water bodies. In the current study, visible light assisted ternary ferrite Fe2Ni0.5Cu0.5O4 (CNF-NPs) photocatalyst along with their binary ferrite photocatalysts Fe2CuO4 (CF-NPs) and Fe2NiO4 (NF-NPs) were prepared by a facile approach to compare the efficiency of ternary and binary ferrites photocatalysts for degradation of dye. Additionally, chitosan was used to support ferrites, and different chitosan-supported ternary ferrite microspheres (CNF-CM) and binary ferrite microspheres (CF-CM and NF-CM), were tailored respectively. FTIR analysis of CNF-CM composites shows presence of all the characteristics peaks of chitosan and CNF NPs confirming its synthesis. The calculated average crystallite size (18 nm) were obtained from Scherrer's equation applied to XRD data. The composition of CNF-NPs was confirmed by EDX analysis. The CNF-CM has 860 μm microsphere size with a smooth surface as shown in SEM images. The calculated optical band gap of the synthesized photocattalyst lies in visible region (2.01) obtained from Tauc’s plot. The photocatalyst CNF-CM showed 93% degradation efficiency for hazardous methylene blue (MB) and 90% efficiency for rhodamine b (RB) dyes within 140 min of sunlight irradiation at optimum conditions. Inorder to validate the photocatalytic efficiency of the CNF-CM, the experimental conditions were also optimized by statistical optimization methods (RSM, ANN). The ANOVA adequate precision (AP) value of 17.83 (> 4) for MB and 16.91 for RB suggests that the projected output variable range is relatively larger compared to the average standard error, further affirming the competence of the quadratic model. [ABSTRACT FROM AUTHOR]

The series of dyes derived from the fluorescein "2–(3–hydroxy–6–oxo–6Hxanthene–9–yl) benzoic acid" with introduction of different acceptor functional groups at the para position were designed as material sensitizers for solar cells. DFT and TD–DFT with B3LYP hybrid function at 6–31G (d,p) basis set were simulated to investigate the significant properties of all isolated dyes together with utilizing a Lanl2DZ basis set of titanium atom of dyes adsorbed on a TiO2 as complex systems in the gas phase at the ground and excited state. The resulted values of electronic parameters such as HOMO, LUMO levels, energy gap and dipole moment of the dyes can be employed to improve the efficient dyes of solar cell. The range of the energy of HOMO was from − 4.903 to − 6.258 eV, LUMO from − 3.010 to − 2.727 eV, the energy gab from 3.539 to 1.926 eV, and the dipole moment from 9.306 to 11.627 Debye of all dyes. The calculated data demonstrated better electronic properties, driving force, chemically reactivity, open–circuit photo-voltage, redox, light harvesting efficiency, oscillator strength, light absorption spectra, electron injection, oxidation potential energy and electron regeneration. Moreover, the favored dye charge transfer and adsorption process on model, including dye–oxide couple (Ti(OH)3H2O) was examined. The calculations which were based on the DFT method showed excellent photoelectric conversion efficiency and strong binding of the dyes on the surface of TiO2. Additionally, there is a probability that the electron injection process happening from each examined molecule to the conduction band of TiO2 and the succeeding regeneration. As a result, the theoretical results can be useful for to synthesize novel, highly photo– effective materials and can play the significant role of sensitizers in DSSC applications. [ABSTRACT FROM AUTHOR]

In this research, four novel push-pull organic dyes with D–π–A structural configuration with a variety of π-spacer segments were investigated from the structural, electronic, optical and photovoltaic characteristics viewpoints, using density functional theory approaches. In fact, we modulated the π-spacer segment by inserting C–C double and triple bonds and phenyl and anthracene units to examine the further improvements in the light-harvesting capability of these dyes in dye-sensitized solar cells (DSSCs). It was corroborated that using C–C triple bond in conjunction with phenyl group as π-linker will reduce the light-harvesting efficiency values in comparison with C–C double bond group, leading to the lower power conversion efficiency of DSSCs. In this context, we made a revision and presented a newly designed dye structure by inserting anthracene together with C–C triple bond and investigated their notable planar π-conjugation effect as an excellent candidate for DSSCs applications. [ABSTRACT FROM AUTHOR]

Novel organic dyes system containing responsible group for using in dye-sensitized solar cells and effective anchoring group for improving interaction between dye (photosensitizers) and nanolayer were designed and prepared. All intermediates and organic dyes were purified and analyzed using analytical techniques. The results confirmed the structure of intermediates and organic dyes. Dye-coated TiO2 and ZnO semiconductors were used for the preparation of the photoanode. The synthesized dyes were trapped in J-aggregation, reflected J-aggregation, and red shift in UV–Vis spectra of dyes in solution relative to the coated on nanomaterials. Cyclic voltammetry and DFT methods were used to evaluate the energy levels of the synthesized compounds. Dye-sensitized solar cells were also prepared and evaluated under standard conditions, using the synthesized compounds. The efficiency of Dye 8 as photosensitizer on TiO2 and ZnO was 6.65% and 6.37%, respectively. [ABSTRACT FROM AUTHOR]

A new series of metal-free organic dyes (SM1-5) with dual anchors are synthesized for application in dye-sensitized solar cells (DSSC). Here, a simple triphenylamine (TPA) moiety serves as the electron donor, while di-cyanoacrylamide and di-thiazolidine-5-one units serve as the electron acceptors and anchoring groups. To understand the effect of dye structure on the photovoltaic characteristics of DSSCs, the photophysical and electrochemical properties, as well as molecular geometries calculated from density functional theory (DFT), are used for dyes SM1-5. The extinction coefficients of the organic dyes SM1-5 are high (5.36–9.54 104 M−1 cm−1), indicating a high aptitude for light harvesting. The photovoltaic studies indicated that using dye SM4 as a sensitizer showed a power conversion efficiency (PCE) of 6.09% (JSC = 14.13 mA cm−2, VOC = 0.624 V, FF = 68.89%). Interestingly, SM4 showed the highest values of VOC among all dyes, including N-719, due to its maximum dye coverage on the TiO2 surface, enhancing charge recombination resistance in the sensitized cell. The good agreement between the theoretically and experimentally obtained data indicates that the energy functional and basis set employed in this study can be successfully utilized to predict new photosensitizers' absorption spectra with great precision before synthesis. Also, these results show that bi-anchoring molecules have a lot of potentials to improve the overall performance of dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]

In this study, the newly designed organic dyes (CBS1-CBS3) were designed by the donor (D), π-linkers (π) and acceptor (A) to forming the D-π-A structure. Besides, the screened efficient spacer dye sensitizers were simulated by the density functional theory (DFT) and time-dependent DFT (TD-DFT) methods for dye-sensitized solar cell (DSSC) application. First, the optical absorption peak of CB1 dye was analyzed by the different exchange–correlation (XC) and long-range corrected (LC) functionals with 6-31G(d) basis set. As a result of functional, TD-CAM-B3LYP method nearly well matched with the literature data of CB1. The computational outcomes were shown that the highest occupied molecular orbitals (HOMOs) and lowest unoccupied MOs (LUMOs) of the CBS1-CBS3 dyes confirmed useful response on the electron injection ( Δ G inject ) and dye regeneration ( Δ G reg ). Therefore, the short-circuit current density ( J SC ) key factors of the light harvesting efficiency (LHE), Δ G inject and Δ G reg in CBS1-CBS3 dye derivatives were superior performance of the DSSCs. In addition to the highest vertical dipole moment (µnormal) and open circuit photovoltage ( e V OC ) of the planned dyes were better performance for DSSCs. Hence, it benefits to higher efficiency. The present theoretical investigation results demonstrate that all the D-π-A dyes may be capable sensitizers for DSSC application. [ABSTRACT FROM AUTHOR]

Meeting the requirements and developments of modern society will be unachievable without a sustainable source of energy. However, dye sensitized solar cell (DSSC) has been found worthy to produce reliable energy source. Recently, researchers have inputted great effort toward the modulation of organic dyes to achieve highly efficient dye sensitizers for solar cell purposes. Herein, D-π-A architectural design was employed to generate ten phenoxazine-based dye engineered with five different thiophene π-linkers and two acceptor units. Density functional theory (DFT) and time-dependent DFT were used to optimize the molecules in order to cognize their intramolecular charge transport, optoelectronic properties, light-harvesting efficiency (LHE) and open-circuit voltage (Voc). DFT conceptual was engaged to elucidate the chemical reactivity parameters of the photosensitizers. Among the π-linkers employed, 2,6-diethenylbisthieno[3,2-b:2′,3′-d]thiophene (D3) remarkably improved the intramolecular charge transfer, thus generated an exceptional HOMO/LUMO energy gap (Eg), strong bathochromic shift, suitable LHE and notable Voc. The qualities of the dyes were further enhanced by replacing 2-cyano-2-pyran-4-ylidene-acetic acid with cyanoacrylic acid acceptor moiety. Comparison of these systems with other reported molecules reveals that majority of the simulated poses improved properties that are recommendable for solar cells applications. [ABSTRACT FROM AUTHOR]

Ruthenium-based metal complex dyes have been employed extensively in dye-sensitized solar cells (DSSCs) as photosensitizers, but the cost and toxicity of metal complexes have promoted the development of metal-free organic dyes. The present investigation deals with the synthesis of hemicyanine and Dicyanoisophorone (DCI) based dyes adopting the D-π-A strategy, and their application on sensitization of nano-crystalline ZnO electrodes by appending the carboxyl (COOH) anchoring group as a pendant on the primary skeleton of dyes. Dyes have been characterized by UV, FTIR, and NMR spectroscopic studies. Absorption maxima (λmax) were found in the region 416-551 nm while emission wavelength (λem) was observed in the range 575-685 nm. Cyclic voltammetry and DFT calculations were used to estimate redox potential and band gap energies of dyes. [ABSTRACT FROM AUTHOR]

Some novel metal-free 1,2,4-triazole compounds A1-A8, based on the 3,5-bis(2-hydroxyphenyl)-1,2,4-triazole derivatives were examined for photovoltaic properties using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations to test their suitability as metal-free organic dyes for use in dye-sensitized solar cells (DSSCs). Through deductive logic, the fluorescence emission (Φf) and charge collection (ηc) efficiencies of these compounds as dyes were obtained and used to determine each dye's incident conversion efficiency (IPCE). From the analyses, A2 displayed the highest IPCE value, followed by A6 and A1. This technique is restricted to evaluating compounds for potential metal-free organic dyes only. [ABSTRACT FROM AUTHOR]

In this work, the newly designed phenothiazine-based organic dye (PT-BTBA, PT-EBTBA, and PT-EBTEBA) derivatives were screened and investigated for dye-sensitized solar cell (DSSC) application. The literature dye of SB covers the electron-donor (D) in phenothiazine and cyanoacrylic acid in electron-acceptor (A) based on D-A structure. In order to improve the π-conjugation and acceptor group effects on the SB dye were theoretically investigated. The effect of D-π-A designed dyes on the optical absorption spectra and photovoltaic (PV) parameters was implemented by the density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations. Also, the hybrid functionals were initially evaluated to establish an accurate methodology for calculating the first-singlet absorption peak of SB dye. Consequently, TD-CAM-B3LYP functional and 6-311++G(d,p) theory were well matched with the literature data. According to this result, phenothiazine-4-((7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)ethynyl)benzoic acid (PT-EBTEBA) dye has the strong group for more red-shifted and successful electron injected into the conduction band edge of TiO2 surface. It is expected to provide some theoretical guidance on designing photosensitive with new metal-free organic dyes for use in DSSCs yielding highly efficient performance. [ABSTRACT FROM AUTHOR]

The rate of environmental pollution augmenting at an alarming rate due to the continuous disposal of toxic dyes directly into the environment and water streams. The direct contact of dyes with water resources directly affects the living beings. The identification of superior methods for the treatment of water pollution caused due to effluent dyes needs higher consideration among researchers for the well-being of living flora and fauna. The available methods for controlling the decontamination of water through toxic dyes have various drawbacks. So, it is highly significant to develop such materials which can easily adsorb the dyes without causing any toxic effect on the environment and living beings. While keeping all the facts in mind, the current work highlights the comparative enhancement in adsorption capacity and selectivity of Brij-58-coated selenium nanoparticles (Brij-58@Se NPs) towards the removal of bromophenol blue (BB) dye from series of chosen dyes in aqueous media. The fabricated Se NPs were methodically characterized and the adsorption behaviour displayed fast adsorption efficiency (98% within 6 min) for BB dye out of series of chosen dyes. The optimization studies were carried out to verify the influence of working variables such as pH (2.0–12.0), response time (1–10 min), dosage amount (0.1–80 mg/l) and concentration of BB dye (1–70 ppm). The adsorption process found to be best fitted for Freundlich adsorption isotherm and pseudo first-order kinetic model. The interference studies of different cationic, anionic species including dyes or metal ions suggested the higher efficiency of Brij-58@Se NPs for adsorptive removal of BB dye from aqueous media. The efficacy of the adsorbent was further tested in six different water resources and displayed 95% adsorption efficiency for BB dye in different wastewater samples. Therefore, Brij-58@Se NP is expected as a potential adsorbent for the adsorption of organic dyes from wastewater samples. [ABSTRACT FROM AUTHOR]

The investigation of dye-sensitized solar cells (DSSCs) based on different donor groups linked with cyanoacrylic acid electron acceptor by Selenophene as π-bridged (D-π-A) was performed based on density functional theory (DFT) time-dependent DFT (TDDFT). Different functional were tested W97XD, PBEPBE, CAM-B3LYP, and B3PW91, and compared with experimental results of the reference D1. The theoretical results with CAM-B3LYP functional at 6-311G (d,p) basis sets were capable of predicting the absorption maximum that has been reported experimentally. Calculations were made to establish the conformational orientation of the cyanoacrylic acid group and evaluate the effect of changing donor units' on the electronic properties of the ground state. Structural and electronic properties, along with the photovoltaic properties, were investigated. The LUMO and HOMO energy levels of these dyes can positively affect the process of electron injection and dye regeneration. Light-harvesting efficiency (LHE), injection driving force (ΔGinject), and total reorganization energy (total) were also discussed. To further support the previous proprieties, electronic excited state energies were obtained by TDDFT// CAM-B3LYP/6-311G(d,p) calculations. The calculated results of these dyes reveal that D8 dye possessing triphenylamine donor unit has the best electronic, optical properties, and photovoltaic parameters. [ABSTRACT FROM AUTHOR]

In the present work, the structural and electronic properties of the D-D′-π-A organic dye with two donors have been calculated theoretically by DFT/time-dependent DFT method. In order to prove their efficiency as sensitizers, a comparative study was performed with a series of D-π-A architecture with one donor. The results of light-harvesting efficiency (LHE), open circuit voltage (Voc), free energy injection (∆Ginj), free energy dye regeneration∆Greg,excited-state lifetimes for the two series reveal that the D-D′-π-A dyes are promising for the design of new sensitive dyes in solar cells. [ABSTRACT FROM AUTHOR]

The phenyl-conjugated oligoene dye 2-cyano3-(4-diphenylaminophenyl)prop-2-enoic acid (SKS) was synthesized by chemical method, and its structure was confirmed by 1H NMR and 13C NMR analysis. Solar cell was made using TiO2 (P-25) as photoanode, synthesized oligoene SKS dye as sensitizer, I-/I3- as electrolyte, and platinum as counter electrode. The overall power conversion efficiency of SKS dye based solar cell was 1.76 %. The functional groups were identified from the FTIR spectrum. The optical, electrochemical, and thermal properties were analyzed. The photostability of SKS dye was analyzed before and after various light irradiation by UV-Vis NIR absorption spectrum. [ABSTRACT FROM AUTHOR]