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The release of industrial effluents into fresh water is a major contributor of water contamination. Therefore, it is highly desirable to develop a viable solution to this alarming issue to improve the quality of clean water. To enhance the photocatalytic efficiency and hence utilization ratio of CuO, a series of CuO–FeSe2 composites with different varying contents of FeSe2 were prepared through facile synthetic methods. X-ray diffraction (XRD) and energy-dispersive X-rays (EDX) analysis verified that the samples were successfully prepared without any contaminating phases. The average crystallite sizes of CuO and FeSe2 were computed to be 29 and 21 nm respectively. For the CuO–FeSe2 composites, the crystallite sizes varied between 25 and 27 nm. The morphology of CuO was comprised of needle-shaped structures, whereas that of FeSe2 was observed to be flower-shaped structures comprising of irregular crystals. A red shift in the bandgap of CuO–FeSe2 composites was observed with the increase in FeSe2 concentration. The prepared photocatalysts were utilized to evaluate their efficiency under visible light against Rhodamine B (RhB). Among all the prepared composites, CuO–75% FeSe2 revealed a remarkable performance and degraded 96% RhB in 180 min. Rate constants for the degradation of the dye were determined by applying the Langmuir–Hinshelwood model. [ABSTRACT FROM AUTHOR]

Water pollutants of non-biodegradable toxic aromatic dye including Methylene blue (MB) and Rhodamine (RhB) are extremely carcinogenic thiazines used in various industries such as leather industry, paper industry, and the dyeing industry. The presence of dyes in wastewater causes severe threats to human health that are responsible for various harmful chronic or acute diseases and also shows an adverse impact on the environment as it reduces transparency and is harmful to water microorganisms. To overcome severe issues, many traditional techniques have been used to remove toxic pollutants, but these methods are insufficient to remove chemically stable dyes that remain in the treated wastewater. However, the photocatalytic degradation process is an efficient approach to degrade the dye up to the maximum extent with improved efficiency. Therefore, in this work, a new class of two-dimensional (2D) transition metal carbide of Titanium Carbide (Ti3C2Tx) MXene material was used for the organic dyes degradation such as MB and RhB using a photocatalytic process. A layered structure of hexagonal lattice symmetry of Ti3C2Tx MXene was successfully synthesized from the Titanium Aluminum Carbide of Ti3AlC2 bulk phase using an exfoliation process. Further, the XRD spectrum confirms the transformation of bulk MAX phase having (002) plane at 9.2° to Ti3C2Tx MXene of (002) plane at 8.88° confirms the successful removal of Al layer from MAX phase. A smooth, transparent, thin sheet-like morphology of Ti3C2Tx nanosheet size were found to be in the range of 70 to 150 nm evaluated from TEM images. Also, no holes or damages in the thin sheets were found after the treatment with strong hydrofluoric acid confirms the formation Ti3C2Tx layered sheets. The synthesized Ti3C2Tx MXene possesses excellent photocatalytic activity for the degradation of dyes MB, RhB, and mixtures of MB and RhB dyes. MB dye degraded with a degradation percentage efficiency of 99.32% in 30 min, while RhB dye was degraded upto 98.9% in 30 min. Also, experiments were conducted for degradation of mixture of MB and RhB dyes by UV light, and the degradation percentage efficiency were found to be 98.9% and 99.75% for mixture of MB and RhB dye in 45 min, respectively. Moreover, reaction rate constant (k) was determined for each dye of MB, RhB, and mixtures of MB and RhB and was found to be 0.0215 min−1 and 0.0058 min−1, and for mixtures, it was 0.0020 min−1 and 0.009 min−1, respectively. [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]

Recently, visible-light-driven photocatalysis attracts much concerns in the remediation of environmental organic pollutants. In this study, the cerium doped biochar was fabricated through the hydrothermal method, and served as an efficient photocatalyst towards rhodamine B degradation under visible light irradiation. Almost 100% of rhodamine B was removed by 2.0 g·L−1 cerium doped biochar after 60 min of visible light irradiation at pH 3, but only about 25.50% and 29.60% of rhodamine B was removed by cerium dioxide and biochar under identical conditions. The degradation process coincided well with the pseudo-first-order kinetic model, and the photodegradation rate constant of cerium doped biochar was 0.0485·min−1, which was respectively 97 and 44 times that of biochar (0.0005·min−1) and cerium dioxide (0.0011·min−1). According to the trapping experiments and electron spin resonance spectroscopy analysis, h+, O2−∙ and ∙OH all participated in the degradation of rhodamine B in the cerium doped biochar photocatalytic systems, and the function of h+ and ∙OH was dominated. Consequently, the biochar could not only be an excellent carrier for supporting cerium dioxide, but also greatly improved its photocatalytic activity. The band gap of cerium doped biochar was narrower than cerium dioxide, which could improve the separation and migration of photogenerated electron–hole pairs under visible-light excitation, thus ultimately enhanced the degradation of rhodamine B. This work provided a deeper understanding of the preparation of biochar-based photocatalyst and its application in the remediation of environmental organic pollution. [ABSTRACT FROM AUTHOR]

Photocatalysis promotes eco-friendly reactions under mild conditions, and among photocatalytic agents are dyes, which have good redox potential in their excited states. The aim of the current contribution was to design a novel series of coumarins based on DFT analysis of their photochemical properties. The coumarin amide group serves as a linking group to cinnamic acid, allowing for electron delocalization throughout the system and the stabilization of the anionic and cationic species. An electronic structure analysis was performed by calculating vertical excitations and emissions, obtaining conceptual DFT chemical descriptors and nonlinear optical parameters (e.g., first static hyperpolarizability β). The novel coumarin derivatives display a reduction in the HOMO–LUMO energy gap from 6.11 to 4.2 eV, large oscillator strength (1.93), efficient nonlinear optical behavior, and excellent redox potential. Hence, they are promising compounds for photocatalytic activity. The present work shows a series of computational parameters that can be considered for the design of a molecule with potential photocatalytic activity, evaluating in this instance a series of new coumarins, promising from the computational point of view [ABSTRACT FROM AUTHOR]

A facile method for the preparation of porous micro/nano fibers was demonstrated. The TiO2/PVDF/CA-composite micro/nano fibers were prepared by centrifugal spinning and then CA was removed by a selective dissolution: reaction with the solution of Acetic Acid. The obtained TiO2/PVDF/CA micro/nano fibers showed highly porous surfaces after the extraction of CA. The structure and properties of PVDF/CA micro/nano fibers were characterized by fourier transform infrared (FTIR), and thermogravimetry (TG), and scanning electron microscope (SEM). The results indicated that CA could be introduced into the PVDF solution and PVDF/CA-composite fibers could be fabricated via centrifugal spinning successfully. CA is dissolved and pores are formed on the fibers. The morphology image of the fibers was detected by scanning electron microscope (SEM) and showed that many pores aligned the nanofibers. The photocatalytic degradation properties of the treated composite fibers were studied. The results showed that the composite fibers prepared by centrifugal spinning had good degradation effects for different concentrations and dyes, and the composite fibers had good reusability. [ABSTRACT FROM AUTHOR]

Photocatalysis is an innovative method for environmentally friendly wastewater treatment. A development of modern photocatalyst, which is suitable for industrial water purification from hazardous organic compounds, is a global challenging problem. Novelty of this work is in the development of synthetic approach based on hydrothermal treatment in a combination with computational experiment. Oriented attachment mechanism was engaged via hydrothermal treatment to produce SnO2 nanoparticles out of preliminary obtained initial blocks – smaller SnO2 nanoparticles, obtained via precipitation method. The initial blocks and obtained nanoparticles were studied with a large set of methods, such as XRD, FTIR, SSA, HRTEM, XPS, and Raman spectroscopy. The oriented attachment mechanism was studied using a computational method, based on the earlier developed approach, revealing the role of ions, existing in the reaction media, and the path of nanoparticle formation. Initial blocks and obtained nanoparticles were tested as photocatalysts on test solutions of organic dyes (methylene blue, rhodamine 6G and congo red). The more complex the dye structure, the more difficult is photocatalytic decomposition of its molecule. However, optimization of the extraction procedure allowed to achieve up to 90% extraction efficiency. [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]

A functionalized gum acacia–activated carbon-CaO/NiO nanocomposite was synthesized using an eco-friendly sol–gel method. The formed nanocomposite was designed to apply various light sources to enhance the improved removal of organic dyes such as methylene blue, methyl orange, methyl red, and rhodamine B from aqueous media. The band gap energies of CaO, NiO nanoparticles and gum acacia–activated carbon were 3.54, 4.28, and 5.34 eV, respectively, corresponding to a reflection edge of 350, 290, and 232 nm, respectively. The surface area of the synthesized nanocomposite was measured to be 17.892 m2 g−1. Sunlight and 20 mg L−1 of the nanocomposite quenched the dyes (methylene blue, 99.7%; methyl orange, 98.3%; methyl red, 96.7%; and rhodamine B, 93.5%) after 120, 100, 100, and 75 min of irradiation, respectively. However, after 80, 100, 100, and 75 min, the percentage of dyes under UV light irradiation was 98.6%, 95.8%, 98.4%, and 94.2% for methylene blue, methyl orange, methyl red, and rhodamine B, respectively. The nanocomposite showed excellent stability after five cycles of dye reduction. [ABSTRACT FROM AUTHOR]

Dye-contaminated water from industry is hazardous to human and aquatic lives. Membrane technology is considered a viable approach to resolve the issue. Herein, copper oxide nanoparticles (CuO NPs) embedded in porous chitosan membranes have been prepared using a solution-casting approach with sodium tripolyphosphate as a crosslinker and polyethylene glycol as a porogen. The prepared membranes have been characterized by physicochemical, mechanical and photocatalytic properties. FTIR results indicate some hydrogen bonding across CuO NPs and the chitosan matrix. XRD and TGA analyses reveal that the membranes are thermally stable and somehow crystalline. SEM examination indicates that the membrane surfaces express porous/roughened texture. The contact angle measurement indicates that the pure chitosan and CuO NPs-embedded membranes are hydrophobic, whereas PEG-leached porous chitosan membranes express hydrophilicity. CuO NPs reinforcement has significantly improved the tensile strength, whereas the elongation at break decreased. The CuO NPs incorporated in chitosan membranes exhibit exceptional photocatalytic activities against methyl orange and methylene blue dyes for their effective removal from aqueous media. [ABSTRACT FROM AUTHOR]

We synthesized a γ-irradiated chitosan-ZnO-AgNPs (ICZA) composite by using a simple hydrogels method. We evaluated its adsorption/photocatalytic degradation abilities for the removal of an organic dye and its antibacterial activity. The XRD, SEM, TEM, EDS, and FTIR techniques were used to characterize the obtained samples. Based on the adsorption and degradation of methylene blue (MB) in the dark and under UV light irradiation, the adsorption and the photocatalytic activity of the as-obtained samples were evaluated. The optimum conditions for synthesizing the composite were as follows: contact time of 210 min, a dosage of 2 g/L, MB concentration of 40 mg/L, and a solution pH of 8.0. The ICZA had a high adsorption capacity, which was suitable for removing MB from the aqueous solutions; it showed a maximum adsorption capacity (qm) of 92.59 mg/g. The fit of the adsorption isotherms with the Langmuir model was satisfactory. The photocatalytic degradation ability of the composite was also better than that of other catalysts in the presence of UV light, with an apparent rate constant (kapp) of 3.08 × 10−2. The synthesized ICZA also showed good antibacterial activity against Staphylococcus aureus, with a minimum inhibitory concentration (MIC) and a minimum bactericidal concentration (MBC) of 12.5 g/mL and 50 g/mL under light-incubation and dark-incubation conditions. Finally, we discussed the hypothesized mechanism of the adsorption/photocatalytic activity and antibacterial activity of the ICZA composite in this study. [ABSTRACT FROM AUTHOR]

This is due to the fact that TiO2 has the wide energy gap and short life and its photocatalytic active only under ultraviolet light, and so its application is greatly limited. TiO2 can form a heterojunction if combined with other semiconductors to enhance its photocatalytic ability under visible light. In this study, a TiO2/Bi2SiO5 photocatalyst with n–n heterojunction was successfully synthesized by the sol–gel method and hydrothermal method. Eggshell waste has long been used as fertilizer to grow plants or food additives for livestock, or as an adsorbent in metal ions and organic dyes. Using eggshell as a carrier of photocatalyst can possibly reduce its cracking of the substrate. The photocatalyst was deposited on eggshell powder by solid state dispersion (SSD). It was analyzed for the adsorption and degradation of methylene blue by various compositions of the photocatalysts and eggshell powder under visible light. The results demonstrated that the ratio of TiO2/Bi2SiO5: eggshell powder at 1:1 could have the best removal ability. To better facilitate the recovery of the photocatalyst from the aqueous solution, we used the techniques of electrostatic spraying and electrospinning to prepare nylon 6,6 nanofiber membranes with various composite photocatalyst (TiO2/Bi2SiO5/Eggshell/Nylon 6,6 NFM). The nanofiber membrane degraded 98% of methylene blue after 30 min of dark adsorption and 1 h of visible light irradiation. [ABSTRACT FROM AUTHOR]

Using a combination method of roasting process with soda ash (Na2CO3) and hydrochloric acid leaching, a TiO2-based photocatalyst was successfully synthesized from Indonesia ilmenite ore. The study investigated the effect of Na2CO3 ratios, roasting times, and HCl concentration on the physical and photocatalytic properties of the photocatalyst. The results revealed that HCl concentration played a critical role in altering the characteristics of the prepared photocatalyst. TiO2 composition increased by 61% compared to ilmenite ore when 20% HCl was used, whereas Fe2O3 composition decreased by 88%. The physical properties and photocatalytic activity of the prepared TiO2 were similar to those of low-grade commercial TiO2. When conducted to 3 h of low-power (8 W) UV light irradiation, the photocatalyst decomposed Eriochrome Black-T, an organic dye model pollutant, by up to 83%. This study's findings provide crucial implications for further research on recovering TiO2-based photocatalyst from ilmenite ore using a simple method. [ABSTRACT FROM AUTHOR]

Textile wastewater becomes the primary root of environmental pollution due to the rapid infection rates of freshwater, subsurface water, soil, and air. Due to the high absorption abilities of UV and visible light, polymer nanocomposite photocatalyst films (PNPFs) are recognized as potential candidates for textile wastewater treatment. Here, we developed novel cobalt monoxide (CoO)/polyaniline (PANI) PNPFs with high photocatalytic efficiency and stability. The photocatalytic efficiencies of PANI/CoO films were estimated utilizing the degradation of organic dyes and real-textile wastewater (RTW) under various lighting conditions. PANI/CoO PNPF completely decomposed methylene blue and RTW samples in 30 and 45 min under UV light illumination, respectively. We found that the CoO nanoparticles doubled the PANI's photocatalytic decomposition rate. However, under visible light irradiation, their photocatalytic efficiencies almost halved. Moreover, PANI/CoO PNPF exhibited excellent photocatalytic stability by maintaining the photocatalytic performance for up to five cycles with over 95% removal efficiency. This study yielded an efficient and alternative polymer nanocomposite to decompose wastewater sources contaminated with various textile dyes and may be examined for industrial-scale applications in the future. [ABSTRACT FROM AUTHOR]

In the present study, we have synthesized magnesium oxide (MgO) nanoparticles by a facile and cost-effective chemical co-precipitation method with annealing at three different temperatures (350°C, 450°C, and 550°C) for the removal of various organic dyes. X-ray diffraction studies revealed that the prepared samples are having sizes below 20 nm and with pure phase. Phase transformation of hexagonal Mg(OH)2 nanoparticles to discretely cubical structured MgO nanoparticles has been observed with increasing the annealing temperatures which is also supported by the TGA/DSC analysis. Mg–O stretching vibration peaks in the range of 400–800 cm−1 obtained by FTIR spectroscopy support the formation of MgO nanoparticles. The observed Raman active bands for the annealed sample at 550°C confirm the formation of the nanocrystalline phase since these bands are typically absent in the bulk MgO as well as in Mg(OH)2. The surface morphology of the as-prepared Mg(OH)2 are aggregated nano-petals which changed into spherical shape for MgO annealed at 550°C as studied by field emission scanning electron microscopy (FESEM). The specific surface area of MgO nanoparticles annealed at 550°C using BET isotherms is found to be 37.487 m2g−1. The optical bandgaps of the prepared samples are found to be in the range of 4.4 to 5.1 eV using the Tauc plot. Adsorption studies with a variation of initial brilliant green dye concentration and contact time are carried out along with the studies of adsorption kinetic and isotherm models. Langmuir isotherm model is the most suitable model on the basis of correlation constant with maximum BG dye adsorption capacity onto MgO@550°C which is found to be 63.9 mg/g. The adsorption kinetics followed the pseudo-second-order model. Also prepared pristine MgO nanoparticles showed significant photocatalytic performance for the degradation of various dyes; brilliant green (BG: 88.91%), methylene blue (MB: 79.05%), crystal violet (CV: 76.49%), methyl orange (MO: 68.62%), and brilliant blue (BB: 40.44%) under visible irradiation. MgO nanoparticles could be a promising adsorbent and photocatalyst that may be employed in the treatment of effluents from industries. [ABSTRACT FROM AUTHOR]

It is a great challenge to develop photocatalysts for the degradation of organic pollutants in the aqueous environment, especially those with excellent catalytic performance under visible light conditions. In this work, using graphene oxide (GO) as an electron shuttle agent and carrier, a hybrid of ZIF-8/NH2-MIL-125(Ti) and GO (ZIF-8/NH2-MIL-125(Ti)/GO) was prepared by a simple two-step solvothermal method. The morphology, structure, and combination of the synthesized catalysts were studied. The results showed that graphene oxide and ZIF-8 formed an in situ load on NH2-MIL-125(Ti). The construction of hybrid materials significantly improved the catalytic activity of NH2-MIL-125(Ti) in the visible light range. The degradation activity of the synthesized catalyst was further tested with reactive red dye. The results showed that the catalyst exhibited excellent catalytic removal efficiency for active red, with a degradation rate of 99.8% within 2 h. The prepared hybrid materials have good application prospects in the field of organic pollutant treatment in water. [ABSTRACT FROM AUTHOR]

In the present investigation a promising conducting polymer, Polyaniline (PANI), and ZrO2-PANI nanocomposite are used for photocatalytic degradation of Carbol Fuchsin (CF) dye. Both materials were prepared via the in-situ polymerization method. Various nano-characterization techniques were used to investigate the fabricated materials. The structural investigation of ZrO2 and ZrO2-PANI nanocomposite was performed using X-ray diffraction (XRD). From this investigation, it was observed that ZrO2 belongs to the crystalline tetragonal phase possessing a crystallite size of 15.80 nm. The SEM analysis shows the flakes arrangement for undoped ZrO2, while improved agglomeration has been observed for modified ZrO2-PANI nanocomposite. The Raman shifts can be observed from Raman spectroscopy for both the fabricated materials. Organic dyes are considered to be persistent organic pollutants (POP's) that are toxic in nature. Here one of the POP dyes, CF was used in the photocatalytic efficiency of ZrO2 and ZrO2-PANI nanocomposite. The prepared polymerized catalysts are porous, possessing a high surface area with a tuned band gap, and are found very persistent, and rapid, for the water purification process via the Advanced Oxidation Process. The fabricated catalyst degrades the CF dye within 30 min. [ABSTRACT FROM AUTHOR]

In this work, two new copper-based coordination polymers (CPs), {[CuI(H2PO4)(dpe)]5(dpe)0.5(H2O)7}n (Cu-dpe(I)) and {[CuII(HPO4)(dpe)(H2O)](H2O)3}n (Cu-dpe(II)) (dpe = 1,2-di(4-pyridyl)ethylene), had been successfully constructed by hydrothermal method and solvent evaporation method, respectively, and their crystal structures were determined by single crystal X-ray diffraction. The differences of structure and properties between these two coordination polymers were discussed. The synthetic temperature caused their structure differences. They both exhibit excellent photocatalytic activity toward the degradation of methylene blue (MB) under visible light. The degradation rates of Cu-dpe(I) and Cu-dpe(II) to MB in 120 min under visible light were 88.1% and 97.2%, respectively. Some active free radicals such as ·OH, ·O2−, e− played an important role in degradation of MB. In addition, luminescent experiment revealed Cu-dpe(I) exhibits a relatively high sensitive and selective detection of Fe3+ ions in water solution via fluorescence quenching which was caused by competitive absorption of excitation wavelength energy between Fe3+ and Cu-dpe(I). [ABSTRACT FROM AUTHOR]

Herein we report multifunctional surface-modified CuO nanomaterials were used to fulfill escalating needs in the electrochemical energy storage system and to achieve efficient photocatalysts for the degradation of AR88 organic dye. Due to the atom economy, ease of synthesis, high capacitance, observable electrochemical responsiveness, and low bandgap in CuO-based nanomaterials, its active surface was modified through cationic surfactant CTAB. Surface-modified nanoparticles were characterized using various characterization techniques such as XRD, DRS, FESEM, and TEM. Intriguingly the synthesized materials demonstrated a capacitance of 133 F/g with a long-term charge–discharge cycle of 2000 cycles. In addition, at pH 11, the material also exhibited a superior dye degradation performance under the UV lamp by showing 94.8% AR88 degradation at a catalyst concentration of 1.0 g/L. Hence, we believe this concept would provide novel insights into the preparation of the simplest and cheaper multifunctional materials for next-generation energy storage and photocatalytic applications. [ABSTRACT FROM AUTHOR]

In this study, a series of ternary composite photocatalysts ZnO/g-C3N4/AgCl(x) (x is the amount of AgCl added, x=0.05, 0.1, 0.15 g) were synthesized, and various characterization methods were used to analyze the morphology, structural, and photochemical properties of the above samples. The photocatalytic activity of the obtained samples was evaluated by degrading rhodamine B (RhB) and acid orange (AOII) under xenon lamp irradiation. The results show that the degradation rate of ZnO/g-C3N4/AgCl (0.1 g) is 99% within 60 min, which is much higher than the 38% degradation rate of g-C3N4. After five cycles, the degradation efficiency of RhB and AOII by ZnO/g-C3N4/AgCl (0.1 g) were still 85% and 94%, respectively. In addition to colored dyes, the photocatalytic degradation of colorless tetracycline hydrochloride (TCH) compounds was also investigated to understand the effect of photosensitization on the degradation process. Based on the electronic structure analysis of the DFT calculations, a staggered heterojunction structure was found between g-C3N4, ZnO, and AgCl. The enhanced photocatalytic activity of the ternary composite is mainly attributed to the efficient separation of charge carriers through the synergistic removal of photogenerated electrons in g-C3N4 by ZnO and AgCl. Radical trapping experiments confirmed that •O2− and h+ were the main active species in the reaction system. As a visible light-responsive catalyst, ZnO/g-C3N4/AgCl can be effectively applied to the degradation of organic dye pollutants and has broad application prospects. [ABSTRACT FROM AUTHOR]

Ce2(MoO4)3 was prepared using dielectric barrier discharge (DBD) plasma method, co-precipitation method and hydrothermal method, respectively, with water/ethanol (W/O) as solvent, oleylamine (OAm) and oleic acid (OAc) as additives. Preparation method showed significant influence on the morphological and structural properties, as well as photocatalytic performance. Ce2(MoO4)3 synthesized with DBD plasma (MO-P) was mainly flowerlike nanosheets, which were beneficial to promoting electron transfer and providing more space for catalytic activity. Also, MO-P samples exhibited more oxygen vacancies, which were conducive to the photocatalytic performance. What's more, MO-P showed lower PL intensity and narrow energy gap, which implied a slow photoelectron–hole pair recombination rate and an increased electron transfer rate. The degradation rate of methyl orange (50 mg/L) could achieve 98% within 12 min with 0.5 g/L MO-P. Hydroxyl radicals (·OH) and superoxide radicals (·O2−) played a major effect. Plasma synthesis method exhibited potential application prospect in photocatalysts preparation. [ABSTRACT FROM AUTHOR]

Photocatalytic degradation of organic dyes in less-toxic products under visible light irradiation is considered a green method which is widely used in this field. In this manuscript, a novel coordination polymer (PUCP1) based hybrid-nanocomposite (PUCP1@rGO) was synthesized. The PUCP1 and nanocomposite were successfully characterized by using various analytical techniques such as SCXRD, FT–IR, PXRD, TGA, FE–SEM, BET and XPS. The PUCP1 exhibits a 2D framework with an uninodal 4-connected net and sql topology. The PUCP1@rGO was applied as a sensitive and selective photocatalyst for significant degradation of Safranin-O (SO) dye. The rGO played an important role in the expansion of photocatalytic activity of the PUCP1 by inhibiting the recombination probability of electron–hole pairs. The results revealed that PUCP1@rGO nanocomposite can degrade 76% of SO dye in only 90 min under visible light at a neutral pH. The PUCP1@rGO was found very sensitive to photocatalytic degradation of SO dye because a very small amount of catalyst (i.e. 10 mg) degrades the 5 μM concentration of SO dye in the presence of light. The PUCP1@rGO is a reusable photocatalyst for up to 5 cycles. Rarely, any sensitive photocatalyst for SO dye is reported in literature than PUCP1@rGO which degrades SO dye in a very small period with significant quantity. Thus, PUCP1@rGO can be used as a promising photocatalyst for the degradation of SO dye. In this work, we have synthesized a novel coordination polymer (PUCP1) and nanocomposite (PUCP1@rGO) by impreganation of rGO in PUCP1 framework.The PUCP1 exhibited selective photocatalytic response towards safranin-O dye under visible light irradiation and impregnation of rGO enhance the photocatalytic properties of PUCP1@rGO nanocomposite as compared to parent PUCP1.The PUCP1@rGO nanocomposite degrade the safranin-O dye up to 76% in 90 min only under visible light. [ABSTRACT FROM AUTHOR]

The importance of pollutant remediation using solar energy is increasingly acknowledged as a viable method to solve the current environmental problems. To date, three-dimensional (3D) graphene architectures have demonstrated excellent photocatalytic performance due to their salient characteristics. The hydrothermal treatment is the commonly reported synthetic protocol in preparing various novel hybrid 3D graphene architectures. This chapter focuses on the recent progress in developing and applying hybrid 3D graphene for the photocatalytic remediation of organic pollutants such as dye molecules, emerging contaminants, and heavy metals. Various novel design based on semiconductor/3D graphene has led to the creation of highly efficient heterojunction photocatalyst. The transformation to a 3D architecture does not only improve the accessible surface area but also enhanced light harvesting capability and charge transport. In addition, we have also made an effort to discuss some photocatalytic antibacterial disinfection innovations. Finally, prospects in the construction of hybrid 3D graphene possessing enhanced photocatalytic materials are presented. [ABSTRACT FROM AUTHOR]

Water bodies are being poisoned by a variety of organic and inorganic pollutants in the modern era of industrial civilization. To solve this vital issue, various scientists and researchers have come up with an eco-friendly method of photocatalysis which is a promising strategy for the removal of organic pollutants especially organic dyes from wastewater. In the present work, we report the enhanced photocatalytic activity of graphene oxide (GO) nanosheets synthesized via a simple, cost-effective, and eco-friendly method. The photocatalytic ability to degrade Malachite green (MG) and Congo red (CR) was investigated as such dyes are primary chemical pollutants in the textile industry. To optimize the conditions for the best performance, experimental variables such as contact time, dye solution concentration, catalyst dose, and pH were adjusted. The present investigation reveals that GO synthesized by the novel route is an extremely efficient photocatalyst for the degradation of MG and CR and observed 100% degradation of MG in 60 min and 85% degradation of CR in 90 min under UV irradiation. The present investigation explores the potential of graphene oxide-based composite materials for future energy and environmental remediation. [ABSTRACT FROM AUTHOR]

Zinc zirconia nanocomposite was synthesized by chemical co-precipitation route using zinc chloride (ZnCl2), zirconium oxychloride octahydrate (ZrOCl2·8H2O), sodium hydroxide (NaOH) and ethylene diaminetetra acetic acid (EDTA). XRD, UV, SEM and EDX measurements were employed to characterize the as-prepared nanoparticles of zinc oxide (ZnO NPs), zirconia (ZrO2 NPs) and the zinc zirconia nanocomposite (ZZNC). Photocatalytic degradation of methylene blue (MB) dye in polluted water was investigated under visible light using ZZNC as the photocatalyst. UV/Vis spectrum confirmed an enhancement in the photocatalytic activity of ZZNC in MB dye-contaminated water. It was observed that more than 80% of the dye was degraded from polluted water while using ZZNC as a photocatalyst in 2.5 h. [ABSTRACT FROM AUTHOR]

Sida rhombifolia leaf extract was used to synthesize heterostructured nanocomposites Ag@CuO/ZnO and Ag@CuO/SnO2 by sol–gel combustion method followed by calcination. Through this ecofriendly approach, we could minimize the utilization of toxic chemicals as the bioactive components present in the plant extract act as capping and complexing agents. XRD studies indicated the formation of various crystalline phases of the congeners of the heterostructured nanocomposites. FESEM studies revealed irregular aggregates for AZC of particle size between 100 and 500 nm whereas uniformly arranged distorted spheres for ASC. The UV-DRS spectra helped to assess the reduced band gap energy from tau plot. The PL emission peaks of ZnO and SnO2 point towards the crystal defects in their lattices. The as-prepared ternary nanocomposites have resistivity to the growth of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeroginosa, Streptococcus mutans and Staphylococcus aureus with greater inhibition zones which showed their superior antibacterial activity. They are proved to be excellent photocatalysts for the degradation of hazardous organic dyes into harmless products and reduction of aromatic compounds into useful chemicals. Thus, the facile, low-cost and environmentally sustainable green synthesis provides Ag@CuO/ZnO and Ag@CuO/SnO2 nanocomposites with multifunctional efficacy. [ABSTRACT FROM AUTHOR]

In spite of the efficient redox properties of CeO2 originating from the easy inter-conversion of the Ce4+/Ce3+ couple, its large band gap (~ 3 eV) limits its photocatalytic application. Herein, we report a novel one-pot method to synthesize phase-pure Mn-doped CeO2 nanoparticles (average size ~ 7 nm) well dispersed in a network of carbon nanotubes (CNT) and also attached onto the CNT surface, as confirmed by transmission electron micrographs. The Mn and CNT content in ceria were optimised based on ability for synergistic sorptive-photocatalytic removal of a model cationic dye under UV–visible light. Diffuse reflectance spectra revealed narrowed optical band gap (only ~ 1.8 eV) in the optimised visible light active Mn-CeO2/CNT nanohybrid resulting from increased defect states due to multivalent Mn dopants (confirmed by X-ray photoelectron spectroscopy). N2 adsorption–desorption data confirmed large increase in the specific surface area compared to ceria nanoparticles leading to improved dye adsorption. The arrest of recombination of photogenerated carriers (suggested by photoluminescence quenching) due to conductive CNT support further contribute to enhancing photocatalytic activity. Thus, the findings presented in this article are relevant to materials research for environmental remediation from a surface and band gap engineering point of view. [ABSTRACT FROM AUTHOR]

A novel soft-chemical synthesis method was used to synthesis nanostructured α-Bi2O3. The method uses chitosan (Cs) and sodium alginate (Alg) as directing agents, representing an environmentally friendly approach that has not been explored previously for this oxide. The impact of these biopolymers on the formation of α-Bi2O3 is thoroughly examined using the precipitation method. The resulting α-Bi2O3 catalysts are characterized using FTIR, XRD, UV/Vis, EDX, SEM, and BET techniques, and they are subsequently utilized for the photocatalytic degradation of Acid Orange 7 (AO7). It is found that both α-Bi2O3-Cs and α-Bi2O3-Alg photocatalysts demonstrate remarkable stability and high photocatalytic activity in degrading AO7 under both ultraviolet-B and visible light. Notably, 90% dye removal at a pH of 6.31 is achieved by α-Bi2O3-Cs without the need for further pH adjustment, contrasting with the 55% achieved by α-Bi2O3-Alg. The pollutant's decomposition was confirmed through LC–MS analysis. Furthermore, the influence of the templating agent on the morphology of the photocatalyst and its efficiency in photodegradation is observed. Optimization studies utilizing Central Composite Design (CCD) and degradation kinetics were reported. Additionally, the adsorption mechanism of AO7 on α-Bi2O3 catalyst is investigated using Density Functional Theory (DFT), and Fukui functions are employed to predict photocatalytic degradation. The consistency between DFT findings and experimental results enhances the comprehension of the mechanisms involved in AO7 dye degradation using α-Bi2O3 catalysts.Graphical Abstract: A novel soft-chemical synthesis method was used to synthesis nanostructured α-Bi2O3. The method uses chitosan (Cs) and sodium alginate (Alg) as directing agents, representing an environmentally friendly approach that has not been explored previously for this oxide. The impact of these biopolymers on the formation of α-Bi2O3 is thoroughly examined using the precipitation method. The resulting α-Bi2O3 catalysts are characterized using FTIR, XRD, UV/Vis, EDX, SEM, and BET techniques, and they are subsequently utilized for the photocatalytic degradation of Acid Orange 7 (AO7). It is found that both α-Bi2O3-Cs and α-Bi2O3-Alg photocatalysts demonstrate remarkable stability and high photocatalytic activity in degrading AO7 under both ultraviolet-B and visible light. Notably, 90% dye removal at a pH of 6.31 is achieved by α-Bi2O3-Cs without the need for further pH adjustment, contrasting with the 55% achieved by α-Bi2O3-Alg. The pollutant's decomposition was confirmed through LC–MS analysis. Furthermore, the influence of the templating agent on the morphology of the photocatalyst and its efficiency in photodegradation is observed. Optimization studies utilizing Central Composite Design (CCD) and degradation kinetics were reported. Additionally, the adsorption mechanism of AO7 on α-Bi2O3 catalyst is investigated using Density Functional Theory (DFT), and Fukui functions are employed to predict photocatalytic degradation. The consistency between DFT findings and experimental results enhances the comprehension of the mechanisms involved in AO7 dye degradation using α-Bi2O3 catalysts. [ABSTRACT FROM AUTHOR]

This study deals with the toxicity of the treated solutions of two types of dyes, namely, the anthraquinonic Reactive Bleu 19 dye (RB19) and the bi-azoic Direct Red 227 dye (DR227), which are treated in single and binary mixture systems. The target molecules were removed by the photocatalysis process using ZnO as a catalyst, which was calcined at two temperatures 250 and 420 °C (ZnO250 and ZnO420) prepared in the lab by the one-step calcination method. XRD, TEM, EDX, XPS, FT-IR, BET, RAMAN, and EPR analyses were carried out to characterize the catalyst material. While the phytotoxicity was being conducted using watercress seeds, the cytotoxicity took place using a cell line (raw) and an intestinal cell (caco-2). The XRD analysis showed the partial calcination of ZnO250 and the presence of anhydrous zinc acetate along with the ZnO nanoparticles (NPs). This result was not observed for ZnO420. Despite the complete discoloration (100%) of all the final solutions, ZnO250 exhibited a high cytotoxicity and phytotoxicity against the RB19 dye after the photocatalytic treatment; however, it was not the case of ZnO420 which was selected as an eco-friendly photocatalyst for the degradation of organic dyes based on the results of removal efficiency, cytotoxicity, and phytotoxicity. [ABSTRACT FROM AUTHOR]

Herein, cost-effective TiO2/Cu2O nanoparticles were synthesized via a simple reaction route and applied-for efficient photodegradation of methylene blue (MB) as a model organic dye. Due to the high surface area of TiO2/Cu2O nanoparticles, adsorption and photodegradation properties were evaluated toward MB degradation, showing a high adsorption yield of about 95.7% along with a 100.0% photodegradation efficiency. The effective factors on both adsorption and photodegradation process including pH, initial concertation of organic dye, amount of TiO2/Cu2O nanoparticles, and temperature were optimized via the one-factor-at-a-time optimization method. The photocatalytic performances of TiO2/Cu2O nanoparticles were compared with the activity of both Degussa p25 TiO2 and Cu2O nanoparticles, showing very higher adsorption and photodegradation yields toward dye degradation. It should be noted that the mechanism of the photodegradation of MB on the surface of TiO2/Cu2O nanoparticles was investigated, revealing an adsorption/photodegradation reaction pathway for this phenomenon. [ABSTRACT FROM AUTHOR]

In this work, we have synthesized MoS2 nanosheets (NSs) through hydrothermal as well as liquid-phase sonication methods and studied their ability to degrade organic dyes, methyl red (MR) and methylene blue (MB) under visible light irradiation. The as-synthesized photocatalysts have been characterized by powder X-ray diffraction, Raman Spectroscopy and transmission electron microscopy to confirm their structure and surface morphology. XRD patterns show that crystalline nature of MoS2 NSs prepared by hydrothermal method appears at 160°C for 15 h. In contrast, sharp and intense diffraction peaks appear for liquid exfoliation method even at room temperature, exhibiting better crystallinity of the as-prepared NSs. The difference (∆) of ~25 cm−1 between E12g and A1g modes of Raman spectra indicates formation of 5–6 layers of MoS2 from both the synthesis routes. UV–Vis spectroscopy has been utilized to study the degradation of dyes by MoS2 NSs as catalyst. Hydrothermally assisted synthesis of MoS2 NSs exhibit lesser degradation efficiency with 58.92% for MR and 49.28% for MB, while exfoliation-assisted MoS2 NSs act as better photocatalyst with 63.40 and 62.40% degradation of MR and MB, respectively. Faster degradation rate for MR compared to MB has been attributed to the presence of lesser chromophoric sites in MR. [ABSTRACT FROM AUTHOR]

In this study, a novel CdS/BiOBr heterojunction comprising CdS quantum dots (QDs) decorated on BiOBr nanoflakes (NFs) was successfully synthesized by a facile microwave-assisted aqueous chemical synthesis technology. The crystal structure, chemical composition, and optical and electric properties were characterized by various techniques. The results demonstrated that cubic CdS QDs are planted uniformly on {001}-faced exposed tetragonal BiOBr NFs with about 30 nm thicknesses. The formation mechanism for CdS/BiOBr nanostructure was proposed. The photocatalytic performance of CdS/BiOBr heterojunction was greatly enhanced by the decomposition of organic pollutant under visible light irradiation. In particular, sample CB-3 exhibited the best photocatalytic activity for the degradation of malachite green, the fastest pseudo-first-order kinetic rate constant of which reached 0.125 min−1, 4.4, 22.6, and 3.2 times higher than that of BiOBr, CdS and the physical mixture, respectively. The direct Z-scheme photocatalytic mechanism for CdS/BiOBr heterojunction could be attributed to the perfect band matching and the efficient charge carrier separation and transfer. Furthermore, the highly efficient photocatalytic performance for the degradation of Congo red (CR) and methyl red (MR) suggests a promising application in industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

In this work, ultrathin Bi2WO6 nanosheets (BWO NS) was synthesized by two-step hydrothermal process, which exhibited a lamellar structure with a thickness of about 10 nm and a transverse length of 100–400 nm. The piezoelectric properties and photocatalytic properties of BWO NS were coupled successfully, and the piezo-photocatalytic activity was studied through the decomposition of 10 mg L− 1 Rhodamine B (Rh B). The results showed that the degradation ratio of BWO NS for Rh B was about 98.39% within 70 min, which was higher than that of sole piezocatalysis (48.98%) and photocatalysis (61.84%). There was no significant degradation of the catalytic performance observed after being recycled four times. Moreover, piezo-photocatalysis of BWO NS efficiently produced active radicals that the major reactive oxidative species (ROS) such as superoxide radicals (·O2−) and hydroxyl radicals (·OH) were confirmed by radical capture experiment. The excellent piezo-photocatalysis of BWO NS endows it the potential application for decomposing organic dye via making full advantage of the vibration and solar energy present in natural environments. [ABSTRACT FROM AUTHOR]

In order to improve the treatment efficiency of printing and dyeing wastewater, the carbon nanotubes-silver-modified-titanium dioxide (CNTs-Ag-TiO2, CAT) ternary composite was prepared by a mechanical mixing method. It was found that the morphology of the prepared CAT sample was uniformly coated with strips of CNTs, speckled Ag, and lumpy TiO2. The (002) crystal plane of CNTs, the (101) crystal plane of TiO2, and the (111) crystal plane of Ag were observed, which possessed functional groups such as Ti-OH and Ti-O-C, indicating that the prepared CAT sample had photocatalytic reaction sites. The visible light utilization of titanium dioxide can be improved. The treatment effect of different proportions of CNTs-Ag-TiO2 on Congo red wastewater was tested, and the results showed that the optimum degradation effect of Congo red wastewater was CNTs: Ag = 10:1, and the doped amount of CNTs/Ag was 15%, and the removal rate of Congo red wastewater could reach 100% within 140 min. The excellent removal effect of CAT ternary composite on Congo red wastewater provided a new idea and way for the modification of TiO2 and its composites for the potential of organic dyes degradation. [ABSTRACT FROM AUTHOR]

The reduced graphene oxide dopped equaixial geometry TiO2 (rGO/egTiO2) composite as photocatalyst was synthesized hydrothermally with various mass ratios of tetrabutyl titanate. The photocatalyst is considered to be rGO/equaixial geometry TiO2 in terms of modifying the combined reduced graphene Oxide and TiO2. The rGO plays a vital role in rGO/egTiO2 composite as photocatalysts were analyzed in methylene blue (MB) and rhodamine B (RhB) photocatalytic degradation under UV and simulated solar light irradiation. This synthesized catalyst was characterized by various analytical techniques such as XPS, XRD, SEM, BET, and TEM. The rGO/egTiO2 composite exhibits enhanced photocatalytic performance with degradation rates of 97.5 and 97% on RhB and MB for 60 min under UV radiation respectively, while the degradation rate of 94 and 92 % was observed on the same dyes for 6 h under the simulated sunlight radiation. The enhanced photocatalytic performance of the rGO/egTiO2 composite under ultraviolet irradiation source was owing to a high separation efficiency of the photo-induced electron-hole pairs, while the photocatalytic performance under simulated sunlight radiation was due to the photosensitive and charge separator behavior of rGO. This offers us an excellent potential of significant photocatalytic activity for the removal of organic contaminants from wastewater. [ABSTRACT FROM AUTHOR]

In response to an increasing desire for modern industries to be both green and sustainable, there has been increasing research focus on the reutilization of natural waste materials to effectively remove and degrade toxic wastewater effluents. One interesting food industry waste product is clam shell. Here a new photocatalytic nanomaterial derived from marine clam shells was successfully prepared and characterized. Thereafter the material was applied for the removal of two target dyes from aqueous solution, where the effect of both catalyst dose and initial dye concentration on adsorption and photocatalysis was investigated. The maximum adsorption capacities of methylene blue (100 mg/L) and Congo red (500 mg/L) were 123.45 mg/g and 679.91 mg/g, respectively, where adsorption followed pseudo second order kinetics predominantly via a chemical adsorption process. The photodegradation removal efficiencies of the two dye solutions under visible light irradiation were 99.6% and 83.3% for MB and CR, respectively. The excellent degradation performance in a mixed dye solution, with strong degradation capability and low cost, demonstrated that the clam shell catalyst material was a good candidate for practical field remediation of dye contaminated wastewater. [ABSTRACT FROM AUTHOR]

A composite consisting of reduced graphene oxide aerogel/titanium dioxide/molybdenum disulfide (abbreviated as RGO aerogel/TiO2/MoS2) was developed for the removal of organic dyes from solution cooperatively by adsorption and photocatalytic degradation mechanisms. The composite was successfully synthesized by stepwise layered assembly integration, including sol-gel and physical vapor deposition (PVD) methods. The resulting multi-component composite material featured a high specific surface area (255.441 m2/g) containing a myriad of negatively charged carboxylate functional groups on the surface of the composite, which enabled the composite material to demonstrate a high removal efficiency of cationic dyes, such as rhodamine B, from solution. In addition, the composite featured optimal optical and photocatalytic properties for facilitating efficient photodegradation of the dye molecules, including a large absorbance in the visible light region and a fast transfer of photogenerated electron-hole pairs. Moreover, electron paramagnetic resonance (EPR) analysis and reactive oxygen species scavenging experiments confirmed that superoxide radicals (O2•–), holes (h+), and hydroxyl radicals (•OH) were involved in photocatalytic degradation of the organic dyes. [ABSTRACT FROM AUTHOR]

α–β Bi2O3 modified with Cu2+ ions in various compositions have been synthesized by hydrothermal process. The crystallinity, surface structure, elemental compositions and optical characteristics were uncovered by relevant techniques including XRD, SEM, EDX, XPS, PL, and UVDRS. Total organic carbon (TOC) analysis was performed to determine the dye degradation efficiency of photocatalyst. Highly crystalline Bi2O3 nanoparticles consisting of α–β phase heterojunctions were observed possessing crystallite sizes in the range of 30–40 nm. The photocatalytic activity of Cu2+-modified Bi2O3 composites was studied using RhB dye under the illumination of visible light. The results reveal that addition of Cu2+ ions into Bi2O3 lattice significantly improved the degradation rate over the pure sample. The highest activity was obtained for sample containing 2 mol % Cu in Bi2O3 lattice where complete degradation of the pollutant was attained in 120 min. The increased activity is largely ascribed to the effective separation of charge carriers due to Cu2+ doping and formation of α–β phase heterojunctions in Bi2O3.The effect of pH conditions and role of active species on degradation kinetics were also examined. [ABSTRACT FROM AUTHOR]

TiO2 mesoporous microspheres were prepared by water heating reflux of TiO2 precursors obtained via hydrolysis of tetrabutyl titanate. TiO2 microspheres were printed on FTO glass substrate and sensitized with CdS nanoparticles for forming CdS/TiO2 thin film via a successive ionic layer adsorption and reaction process. TiO2 microspheres and CdS/TiO2 thin film were characterized using field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis, N2 adsorption desorption measurements, X-ray photoelectron spectroscopy, and UV–Vis absorption spectra. The results indicated that water heating reflux contribute to the crystallization of TiO2 from the amorphous to anatase phase. TiO2 mesoporous microspheres with higher surface area of 268.53 m2/g were formed during the water heating reflux process. A photoresponsive test suggested that the introduction of CdS improves light utilization of TiO2 mesoporous microspheres and reduces recombination of photogenerated electron–hole pairs. Photocurrent density of TiO2 microspheres sensitized with CdS nanoparticles reached 0.2 mA/cm2 while pure TiO2 only obtained 0.036 mA/cm2. The photodegradation performance of the CdS/TiO2 thin film was further investigated. Photodegradation efficiency of CdS/TiO2 thin film reach about 95% within 120 min due to the synergistic effect of CdS and TiO2 heterostructure. The possible catalytic mechanism was also proposed. [ABSTRACT FROM AUTHOR]

The fabrication of highly efficient photocatalyst with excellent catalytic activity and robust stability is urgently desired. Herein, ternary TiO2/polyaniline /graphene composite was successfully prepared through a facile route. The morphologies, crystal phases, optical and electrochemical properties of the prepared photocatalysts were systematically investigated by XRD, SEM, TEM, FT-IR, PL, photocurrent response techniques. The resultant TiO2/polyaniline/graphene sample exhibited superior photodegradation performance towards organic dyes elimination (such as Rhodamine B, Methylene Blue, and Methyl Orange) under visible light irradiation, which was higher than that of pristine TiO2. Moreover, a cycling experiment revealed that as-prepared composite catalyst showed enhanced durability. Based on the above results and discussion, a plausible photocatalytic mechanism of ternary TiO2/polyaniline/graphene hybrid was proposed. Therefore, this work supplies a facile route to design highly efficient and stable photocatalysis for water purification. [ABSTRACT FROM AUTHOR]

The domestic and industrial sewage contains an extensive range of various organic compounds. Due to the toxicity of these materials, their degradation is considered one of the great environmental challenges. To address this problem, SnO2 nanoparticles (NPs) were synthesized via a green route, and they were used as an efficient catalyst for the degradation of an organic dye. In the stage of synthesis of nanoparticles, Thymus vulgaris L. extract acted as an efficient capping agent and renewable reducing agent, and SnO2 NPs were synthesized without addition of any hazardous surfactants. The successful synthesis of SnO2 NPs was confirmed by XRD, FT-IR, SEM, EDX, and TEM. The photocatalytic performance of SnO2 NPs was examined for the degradation of eriochrome black-T (ECBT) as a toxic organic dye in aqueous medium under ultraviolet irradiation. Furthermore, the response surface methodology (RSM) with central composite design (CCD) model was carried out to study of the effects of three different operational parameters on degradation of ECBT. In this design, initial pH of solution (3–11), reaction time (0.5–4 h), and the catalyst loading (0.05–0.12 g) were selected as three factors, whereas the degradation efficiency was chosen as the response. The results of the experimental design indicated that initial pH and catalyst loading were highly significant factors, whereas the reaction time was less important than other factors. Also, recyclability of catalyst was investigated, and the obtained results showed that SnO2 NPs could be easily recovered and reused for at least 4 cycles without any significant decrease in their activity. [ABSTRACT FROM AUTHOR]

Recently, graphitic carbon nitride (GCN) has been found to be of great interest in various sustainable applications. In this study, a simple preparation method using urea was utilized to synthesize GCN. In order to understand various morphological, structural, and optical aspects of the as-prepared sample, GCN was characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Brunauere-Emmette-Teller (BET), scanning electron microscopy (SEM), and diffused reflectance spectra (DRS) analysis. The visible-light-driven photocatalytic activity of prepared GCN was analyzed for various cationic dyes (Crystal violet, rose bengal, rhodamine B, auramine O, methylene blue) and anionic dyes (phenol red, xylenol orange, cresol red, methyl orange). The calculated efficiencies of degradation and values of apparent rate constant for all dye samples suggested that cationic dyes are more actively degraded using GCN than anionic dyes. In addition, GCN was further analyzed for its splendid antibacterial activity against pathogenic bacteria (Klebsiella pneumonia and Escherichia coli). The synthesized photocatalyst holds a bright scope for the efficient remediation of organic pollutants and bacterial disinfection in wastewater. [ABSTRACT FROM AUTHOR]

A novel bismuth vanadate–silicon dioxide–graphene oxide (BiVO4/SiO2/GO) nanocomposite was synthesized successfully by using hydrothermal method. The as-prepared nanocomposite was characterized by various techniques, including X-ray diffraction (XRD), field emission scanning electron microscope (SEM), and Brunauer–Emmett–Teller (BET). The photocatalytic activity of nanoparticles was evaluated by measuring the removal efficiency of methylene blue (MB) in aqueous solution under visible light irradiation. The results indicated that BiVO4, BiVO4/SiO2, and BiVO4/SiO2/GO exhibited the same diffraction peaks of monoclinic scheelite structure due to the higher content of BiVO4 in the nanocomposite system. The BiVO4 and BiVO4/SiO2 were uniformly agglomerated from irregular particles with the different level of aggregation and the size of several micrometers. In the meantime, BiVO4 and SiO2 particles were adhered firmly on the GO sheets in BiVO4/SiO2/GO nanocomposite. The BiVO4/SiO2/GO nanocomposite showed a much higher efficiency than the pure BiVO4 and the BiVO4/SiO2 hybrid material for MB removal efficiency due to the considerably increased specific surface area and pore size by the adhesion of BiVO4 and SiO2 on GO sheets. [ABSTRACT FROM AUTHOR]

A new coordination polymer with the chemical formula of [Co2(TIPA)(HCOO) (NDC)1.5]·4DMF·CH3OH·2H2O (1) has been successfully prepared by using naphthalene-2,6-dicarboxylic acid (H2NDC) and tris(4-(1H-imidazol-1-yl)phenyl)amine (TIPA) as coordination ligands and a mixed solvent of water, MeOH and DMF as the solvent system. Complex 1 shows light adsorption in the visible region because of the charge transition from ligand to the metal, which could be used for visible light degradation of rhodamine B and methylene blue with highly photocatalytic efficiency. Furthermore, the mechanism of photocatalysis was hypothesized and verified in detail by the reaction of photocatalysis in the existence of mannitol, a hydroxyl radical scavenger, and 1,4-benzoic acid, a collector. Furthermore, the treatment activity of the compound against pelvic inflammatory disease (PID) was evaluated in this research. The MBC of the compound against Uu was measured in vitro. In addition to this, the ELISA detection of IL-1β and IL-6 also measured to evaluate the anti-inflammatory effect of the compound on PID. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalytic (PC) degradation of organic dyes in aqueous solution with semiconductor oxides has been very effective in relation to conventional methods for the wastewater treatment. In this paper, MgWO4 powder was synthesized by the complex polymerization method and heat-treated at 900 °C for 2 h. Their structure, morphology and optical behavior were characterized by different techniques. First-principles quantum mechanical calculations based on the DFT in the B3LYP level was employed to obtain their electronic band structure (EBS) and density of state (DOS). Moreover, we have investigated the PC properties for the discoloration of three organic dyes. XRD patterns indicate that MgWO4 powders present a monoclinic structure. FE-SEM and TEM images showed that these powders are composed of several nanoparticles. UV–Vis spectrum displays an optical band gap of 4.33 eV, while EBS calculation showed a direct band gap value of 4.49 eV. DOS data revealed that the main orbitals involved in the electronic structure are O-2p orbitals in the valence band and W-5d orbitals in the conduction band. Finally, it was obtained the best PC activity of MgWO4 powders with discoloration of 84% for bromocresol green dye, while the discoloration for methyl orange and rhodamine B dyes were 56% and 29%, respectively. The electronic structure, morphology and photocatalytic properties of MgWO4 powders synthesized by complex polymerization method calcinated at 900 °C for 2 h have been explained for the first time. [ABSTRACT FROM AUTHOR]

Water pollution has become a universal health problem due to frequently discharged toxic chemical effluents and contamination from pathogenic bacteria. Amidst all this, nanocomposites have gained wide interests owing to their promising application as photocatalysts and antibacterial agents. In the present study, hybrid Ag/SWCNT/PPy (Silver nanoparticles/Single-walled carbon nanotubes/Polypyrrole) based ternary nanocomposites were synthesized by applying facile and cost-effective one-pot synthesis approach. The morphological studies (SEM and TEM) revealed that the synthesized ternary nanocomposite possesses a core–shell type of structure where spherical Ag NPs anchored SWCNTs act as core and PPy formed a shell over it. The composites were also characterized by FTIR, XRD and UV. Ag/SWCNT/PPy was used as an efficient photocatalyst for degrading toxic organic dyes like RB (rose bengal) and MB (methylene blue). It showed high degradation rates of 91% and 89.3% against RB and MB dyes respectively within 100 min. of UV irradiation time. Owing to the synergistic effect of Ag NPs, SWCNTs and PPy, the synthesized ternary nanocomposite also inhibited the growth and multiplication of tested bacteria such as S. aureus, B. cereus, E. coli and P. aeruginosa completely within 24 h. Overall, Ag/SWCNT/PPy possesses a superior potential than Ag NPs and Ag/SWCNTs for their use in the development of photocatalysts and anti-bacterial agents, thereby paving a way for the treatment of wastewater and bio-remediation in near future. [ABSTRACT FROM AUTHOR]

The objective of this research is to study the effects of zirconium and silver co-dopants on the photocatalytic reactivity of TiO2. Zirconium and silver co-doped titanium dioxide (Zr-Ag co-doped TiO2) was synthesized by sol-gel method. The molar ratio of silver was fixed at 5% mol, while the molar ratio of zirconium was varied at 5, 10, and 15% mol. The synthesized photocatalysts were calcined at 500 °C for 5 h. The characteristics of the photocatalysts were examined by X-ray diffraction spectroscopy (XRD), ultraviolet-visible spectroscopy (UV-Vis), and field emission scanning electron microscope (FESEM). The XRD results indicated that the anatase phase of TiO2 and metal doping did not affect the crystal phase of TiO2, and the FESEM confirmed the presence of silver and zirconium in co-doped TiO2. After doping, the band gap energy of the doped TiO2 was significantly reduced due to the red shift effect. The photocatalytic reactivity and kinetics of the photocatalysts were investigated by photocatalytic decolorization of methylene blue (MB) under UV and fluorescent light. Photocatalytic decolorization of MB dramatically improved when TiO2 was co-doped with silver and zirconium. The antibacterial efficiency of Zr-Ag co-doped TiO2 against Escherichia coli (E. coli) was also investigated under fluorescent light and in the dark. The synergistic effects of zirconium and silver dopants on the photocatalytic and antibacterial activity of TiO2 were observed. The 5% mol of silver and 10% mol of zirconium co-doped TiO2 exhibited the highest decolorization efficiency at 98.07% under fluorescent light and could completely inhibit E. coli under fluorescent light within 20 min. [ABSTRACT FROM AUTHOR]

The photocatalytic activity of Mn2+ doped ZnS quantum dots stabilized by glutathione capping agent in aqueous media was studied in situ by photoluminescence spectroscopy. The methylene blue was chosen as model organic dye for photodecomposition under excitation in near UV-range. It is shown that the rate of photodegradation of the methylene blue depends strictly on the concentration of the manganese activator ions and the presence of its own intrinsic defects in the host ZnS crystal lattice. It is found that the most effective photocatalyst are ZnS quantum dots doped with 0.25 at % of Mn2+ providing the total dye decolorization within 5 minutes. [ABSTRACT FROM AUTHOR]

Existing industrial titania production lines and their intermediate products are economically attractive precursors for synthesis of highly concentrated TiO2 coating sols and soluble nanopowders. Refluxing of aliphatic alcoholic TiOCl2 solutions (with up to 500 g TiO2/L) allows straightforward formation of nonaggregated anatase nanocrystals with size between 5 and 8 nm. Surface modification of these nanoparticles with organosilanes shifts the pH value of point of zero charge from initially 5.3 down to around 2.8. At appropriate Ti/Si ratios, complete suppression of the anatase ultraviolet (UV) photoactivity is possible. Furthermore, we address the optical and photocatalytic data of transparent nanocrystalline layers produced from superconcentrated ZnxTiyOz heterosols. Depending on the Zn/Ti ratio and processing temperature, colorless cubic c-ZnTiO3 and c-Zn2TiO4 spinel nanophases or coupled r-ZnTiO3-ilmenite/r-TiO2-rutile heterojunctions (Zn/Ti = 2/3) can be produced. The cubic spinel films are indirect semiconductors showing band gap transition of around 3.7 eV. In contrast, r-ZnTiO3-ilmenite films have slightly lower band gap of around 3.6 eV. Organic dye photodegradation studies reveal the highest catalytic activity for the coupled r-ZnTiO3-ilmenite/r-TiO2-rutile systems compared with colored (nitridated) or colorless cubic spinel film samples. [ABSTRACT FROM AUTHOR]

In this work, the fabrication of MoS2-Polyaniline (PANI) nanocomposites, by in situ polymerization, has been described and its application as a photocatalyst for the degradation of organic pollutants such as methylene blue (MB) and 4-chlorophenol (4-CP), has been reported. The disadvantages of MoS2 such as poor electronic conductivity and agglomeration between the nanosheets, was overcome by intercalating 2D MoS2 layers with 1D conducting polymer, Polyaniline (PANI). The composite material was characterised by SEM, TEM, BET, XRD, FTIR, UV–Vis spectroscopy and XPS, indicating proper intercalation between MoS2 nanosheets and PANI. Consequently, the synthesized composites were used for the degradation of MB and 4-CP, followed by kinetic investigations to determine the rate kinetics. The photoactivity of the nanocomposite is explained by the transfer of photogenerated electrons from PANI to the CB of MoS2, thus preventing the direct recombination of electrons and holes. Hence, a positive synergistic effect between MoS2 and PANI resulted in efficient photocatalytic degradation of organic dyes like MB. [ABSTRACT FROM AUTHOR]