Detection of organic dyes using Ag NPAs/SMP SERS substrate produced via sandpaper template-assisted lithography and liquid-liquid interface self-assembly.

Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive and reliable fingerprinting technique. However, its analytical capability is closely related to the quality of a SERS substrate used for the analysis. In particular, conventional colloidal substrates possess disadvantages in terms of controllability, stability, and reproducibility, which limit their application. In order to address these issues, a simple, cost-effective, and efficient SERS substrate based on silver nanoparticle arrays (Ag NPAs) and sandpaper-molded polydimethylsiloxane (SMP) was proposed in this work. Successfully prepared via template lithography and liquid-liquid interface self-assembly (LLISA), the substrate can be applied to the specific detection of organic dyes in the environment. The substrate exhibited good SERS performance, and the limit of detection (LOD) of rhodamine 6G (R6G) was shown to be 10-7 M under the optimal conditions (1000 grit sandpaper) with a relative standard deviation (RSD) of 7.76%. Moreover, the SERS signal intensity was maintained at 60% of the initial intensity after the substrate was stored for 30 days. In addition, the Ag NPAs/SMP SERS substrate was also employed to detect crystal violet (CV) and methylene blue (MB) with the LODs of 10-6 M and 10-7 M, respectively. In summary, the Ag NPAs/SMP SERS substrate prepared in this study has great potential for the detection of organic dyes in ecological environments.

Heavy metal ion sensing strategies using fluorophores for environmental remediation.

The main aim of this review is to provide an extensive summary of the latest advances within the emerging research area focused on detecting heavy metal ion pollution, particularly sensing strategies. The review explores various heavy metal ion detection approaches, encompassing spectrometry, electrochemical methods, and optical techniques. Numerous initiatives have been undertaken in recent times in response to the increasing demand for fast, sensitive, and selective sensors. Notably, fluorescent sensors have acquired prominence owing to the numerous advantages such as outstanding specificity, reversibility, and sensitivity. Further, it also explores the discussion of various nanomaterials employed in sensing heavy metal ions. In this regard, the exclusive emphasis is placed on fluorescent nanomaterials based on organic dyes, quantum dots, and fluorescent aptasensors for metal ion removal from aqueous systems to identify the destiny of dangerous heavy metal ions in clean circumstances.

Highly flexible copper tape decorated with Ag nanoarrays as ultrasensitive SERS platforms for multi-hazardous pollutant sensing.

A highly flexible and cost-effective copper tape decorated with silver nanoparticles (Cu-TAg) has been developed for surface-enhanced Raman spectroscopy (SERS) sensing of multi-hazardous environmental pollutants. Highly ordered and spherical-shaped silver nanoarrays have been fabricated using a low-cost thermal evaporation method. The structural, morphological, and optical properties of Cu-TAg sensors have been studied and correlated to the corresponding SERS performances. The size of nanoparticles has been successively tuned by varying the deposition time from 5 to 25 s. The nanoparticle sizes were enhanced with an increase in the evaporation time. SERS investigations have revealed that the sensing potential is subsequently improved with an increase in deposition time up to 10 s and then deteriorates with further increase in Ag deposition. The highest SERS activity was acquired for an optimum size of ~ 37 nm; further simulation studies confirmed this observation. Moreover, Cu-TAg sensors exhibited high sensitivity, reproducibility, and recycling characteristics to be used as excellent chemo-sensors. The lower detection limit estimation revealed that it can sense even in the pico-molar range for sensing of rhodamine 6G and methylene blue. The estimated enhancement factor of the sensor is found to be 9.4 × 107. Molecular-specific sensing of a wide range of pollutants such as rhodamine 6G, alizarin red, methylene blue, butylated hydroxy anisole, and penicillin-streptomycin is demonstrated with high efficiencies for micromolar spiked samples. Copper tape functionalized with Ag arrays thus demonstrated to be a promising candidate for low-cost and reusable chemo-sensors for environmental remediation applications.

Synthesis and Application of Fluorescent Polymer Micro- and Nanoparticles.

Fluorescent polymer particles have witnessed an increasing interest in recent years, owing to their fascinating physicochemical properties as well as wide-ranging applications. In this review, the state-of-the-art research progress of fluorescent polymer particles in the past five years is summarized. First, the synthesis protocols for fluorescent polymer particles, including emulsion polymerization, precipitation polymerization, dispersion polymerization, suspension polymerization, nanoprecipitation, self-assembly, and post-polymerization modification, are presented in detail. Then, the applications of the resulting beguiling particles in anticounterfeiting, chemical sensing, and biomedicine, are illustrated. Finally, the challenges and opportunities that exist in the field are pointed out. This review aims to offer important guidance and stimulate more research attention to this rapidly developing field.

Chiral Diketopyrrolo[3,4-c]pyrrole-1,2,3-1H-triazole Dyes with Highly Tuneable Properties in Solution and Thin Films.

We have studied the impact of achiral substituents on the chiral supramolecular architectures of diketopyrrolo[3,4-c]pyrrole-1,2,3-1H-triazole (DPP) dyes. We decorated the same chiral DPP motif with substituent groups on the nitrogen atoms of the lactam moiety: the hydrophobic n-octyl alkyl chain, the hydrophilic tri(ethylene glycol) (TEG) chain and the thermo-cleavable tert-butoxycarbonyl (t-Boc) carbamate group. In spite of having identical conjugated chromophore and chiral appendages, in aggregated form the three dyes displayed profoundly different optical, chiroptical, electrochemical and thermal features. ECD measurements revealed differences in the aggregation modes, which would be inaccessible by most other techniques. We found strong chiroptical features, which would have major implications in the context of chiral organic opto-electronics and in the development of other highly innovative technological applications.

A Multi-Pyridine-Anchored and -Linked Bilayer Photocathode for Water Reduction.

The development of efficient photocathodes is of critical importance for the constructions of promising tandem photo-electrochemical cells. Most known dye-sensitized photocathodes are prepared with the conventional carboxylic or phosphonic acid anchors and require the presence of other terminal linking groups to connect catalysts; they suffer from high synthetic difficulty and low adsorption stability in aqueous media. Here, a compact bilayer photocathode has been prepared by using a pyrene-based photosensitizer with multiple terminal pyridine moieties as both the anchoring and linking groups to connect a Co hydrogen-evolution catalyst to the NiO substrate. The catalyst and dye molecule are assembled in a layer-by-layer manner on NiO through the metal-pyridine coordination. This photocathode exhibits good dye adsorption stability in aqueous media. A stable cathodic photocurrent of 70 µA cm-2 was achieved, with H2 being generated at the photocathode under the visible-light irradiation. The Faraday efficiency of H2 evolution was estimated to be 9.1 %. Transient absorption spectral studies suggest that the interfacial hole transfer occurs within a few picoseconds. The integration of the organic photosensitizer with pyridine anchoring and linking groups is expected to provide a simple method for the fabrication of stable and efficient photocathodes.

Yolk-shell Co3 O4 @Fe3 O4 /C Nanocomposites as a Heterogeneous Fenton-like Catalyst for Organic Dye Removal.

The yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites with Co3 O4 as the core, Fe3 O4 /C as the shell, and a cavity structure were synthesized by the hard template method. The physical and chemical properties of the composites were characterized by SEM, TEM, XRD, TGA, XPS, BET, and VSM. The specific surface area of yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites is 175.9 m2  g-1 , showing superparamagnetic properties. The yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites were used as heterogeneous Fenton catalysts to activate peroxymonosulfate (PMS) to degrade MB, which showed high catalytic degradation performance. The degradation rate of MB reached 100 % within 30 min under the circumstances of the yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites dosage of 0.1 g L-1 , the PMS dosage of 1.0 g L-1 , the initial MB concentration of 100 mg L-1 , an initial pH of 5.5, and a temperature of 30±2 °C. The enhanced catalytic performance of the yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites can be attributed to the synergistic effect of the two catalytically active materials and the middle cavity. The effects of different operating parameters and co-existing anion species on MB degradation were also investigated. Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed that the formation of SO4 ⋅- in the yolk-shell Co3 O4 @Fe3 O4 /C/PMS system contributes to MB degradation. In addition, yolk-shell Co3 O4 @Fe3 O4 /C nanocomposites can be easily separated from the pollutant solution under the action of an external magnetic field, and the degradation rate of MB can still reach 98 % after five cycles, indicating that it has good stability and reusability and has broad application prospects in the field of water purification.

Unraveling the Photophysical Characteristics, Aromaticity, and Stability of π-Extended Acene-Quinodimethyl Thioamides†.

Poly-aromatic systems that contain quinodimethyl (QDM) units are appealing for several photonic and spintronic applications owing to the unique electronic structure, aromaticity, and spin state(s) of the QDM ring. Herein, we report the synthesis and characterization of novel QDM-based chromophores 1-3, which exhibit unique photo-excited behavior and aromaticity. Extending the aromatic core with a biphenyl/phenanthryl- and a pyrrolo-fragment led to reducing the optoelectronic bandgap and modulating the photophysics QDM 1-3. Yet, QDM 2 and 3 suffer from "aromaticity imbalance" and become relatively unstable compared to the parent compound QDM 1. Further assessment of local aromaticity using computational tools revealed that the pseudo-quinoidal ring B is the main driving force allowing to easily populate the excited triplet state of these chromophores. The present study provides complementary guidelines for designing novel non-classical poly-aromatic systems.

Ce2(MoO4)3 synthesized with oleylamine and oleic acid as additives for photocatalysis: effect of preparation method.

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.

Control of Fluorescence of Organic Dyes in the Solid-State by Supramolecular Interactions.

Fluorescent organic dyes play an essential role in the creation of new "smart" materials. Fragments and functional groups capable of free rotation around single bonds can significantly change the fluorescent organic dye's electronic structure under analyte effects, phase state transitions, or changes in temperature, pressure, and media polarity. Dependencies between steric and electronic structures become highly important in transition from a solution to a solid-state. Such transitions are accompanied by a significant increase in the dye molecular structure's rigidity due to supramolecular associates' formation such as H-bonding, π···π and dipole-dipole interactions. Among those supramolecular effects, H-bonding interactions, first of all, lead to significant molecular packing changes between loose or rigid structures, thus affecting the fluorescent dye's electronic states' energy and configuration, its fluorescent signal's position and intensity. All the functional groups and heteroatoms that are met in the organic dyes seem to be involved in the control of fluorescence via H-bonding: C-H···N, C-H···π, S = O···H-C, P = O···H, C-H···O, NH···N, C - H···C, C - H···Se, N-H···O, C - H···F, C-F···H. Effects of molecular packing of fluorescent organic dyes are successfully used in developing mechano-, piezo-, thermo- fluorochromes materials for their applications in the optical recording of information, sensors, security items, memory elements, organic light-emitting diodes (OLEDs) technologies.

Probing Single-molecule Interfacial Electron Transfer Inside a Single Lipid Vesicle.

Inhomogeneity in single molecule electron transfer at the surface of lipid in a single vesicle has been explored by single molecule spectroscopic technique. In our study we took Di-methyl aniline (DMA), as the electron donor (D) and three different organic dyes as acceptor. These dyes are C153, C480 and C152 and they reside in different regions in the vesicle depending upon their preference of residence. For each probe, we found fluctuations in the single-molecule fluorescence decay, which are attributed to the variation in the reactivity of interfacial electron transfer. We found a non-exponential auto-correlation fluctuation of the intensity of the probe, which is ascribed to the kinetic disorder in the rate of electron transfer. We have also shown the power law distribution of the dark state (off time), which obeys the levy's statistics. We found a shift in lifetime distribution for the probe (C153) from 3.9 ns to 3.5 ns. This observed quenching is due to the dynamic electron transfer. We observed the kinetic disorderness in the electron transfer reaction for each dye. This source of fluctuation in electron transfer rate may be ascribed to the inherent fluctuation, occurring on the time scale of ~ 1.1 ms (for C153) of the vesicle, containing lipids.

Interfacially Polymerized ß-Cyclodextrin Film for Rapid Removal of Organic Dyes.

Porous cyclodextrin-based polymers are widely used for the rapid removal of organic pollutants in water. Traditional cyclodextrin-based polymers are prepared in the organic phase, which is time consuming and costly. Herein, a novel cyanuricchloride (TCT) cross-linked porous ß-cyclodextrin-based thin-film composite membrane is designed in the aqueous phase by interfacial polymerization. A self-standing TCT-CDP film is formed instantly at the surface of water phase at room temperature. Several different water-soluble organic dyes such as Methylene Blue, Neutral Red, Auramine, Brilliant Green, and Crystal Violet are selected for rejection study with TCT-CDP membrane. The effective rejection of TCT-CDP membrane for typical dyes is up to 99%, indicating TCT-CDP membrane exhibit excellent selectivity for separation of organic dyes from water.

Nano-sized and microporous palladium catalyst supported on modified chitosan/cigarette butt composite for treatment of environmental contaminants.

This study reports a versatile process for the fabrication of a microporous heterogeneous palladium nanocatalyst on a novel spherical, biodegradable, and chemically/physically resistant catalyst support consisting of chitosan (CS) and cigarette waste-derived activated carbon (CAC). The physicochemical properties of the microporous Pd-CS-CAC nanocatalyst developed were successfully determined by FTIR, XRD, FE-SEM, TEM, BET, and EDS techniques. TEM studies showed that the average particle size of the synthesized Pd NPs was about 30 nm. The catalytic prowess of microporous Pd-CS-CAC was evaluated in the reduction/decolorization of various nitroarenes (2-nitroaniline (2-NA), 4-nitroaniline (4-NA), 4-nitrophenol (4-NP), and 4-nitro-o-phenylenediamine (4-NPD)) and organic dyes (methyl red (MR), methyl orange (MO), methylene blue (MB), congo red (CR), and rhodamine B (RhB)) in an aqueous medium in the presence of NaBH4 as the reducing agent at room temperature. The catalytic activities were studied by UV-Vis absorption spectroscopy of the supernatant at regular time intervals. The short reaction times, mild reaction conditions, high efficiency (100% conversion), easy separation, and excellent chemical stability of the catalyst due to its heterogeneity and reusability are the advantages of this method. The results of the tests showed that reduction/decolorization reactions were successfully carried out within 10-140 s due to the good catalytic ability of Pd-CS-CAC. Moreover, Pd-CS-CAC was reused for 5 consecutive times with no loss of the initial shape, size, and morphology, confirming that it was a sustainable and robust nanocatalyst.

Photodegradation of hazardous organic pollutants using titanium oxides -based photocatalytic: A review.

Titanium oxide-based photocatalysts (TOBPs) have been widely utilized as potential materials for numerous applications, such as wastewater treatment, water-splitting reactions, carbon dioxide (CO2) reduction and photosynthesis. However, the large bandgap of intrinsic TiO2 limits their absorption toward visible light, which is the central part of the solar spectrum, resulting in low photocatalytic activities under sunlight. To overcome this obstacle, several strategies, such as doping with either metal or non-metal elements or combining with other compounds, are efficient ways to reduce the bandgap of TiO2, leading to effectively extending their absorption toward the visible region and increasing their catalytic performance. In this review, we discussed the application of TOBPs for the photodegradation of hazardous organic pollutants in wastewater to produce quality reused water. The synthesis of TiO2 and the enhancement of photocatalytic activities of TOBPs by different techniques with detailed information were provided. Application of TOBPs for decomposing hazardous organic pollutants such as dyes, phenolic compounds and pharmaceuticals under optimum conditions have been listed. Also, the photodegradation mechanisms of hazardous organic compounds have been investigated. This work also brings ideas for future perspectives and research plan to inhibit the disadvantages and expand the application of TOBPs to remove toxic organic pollutants.

Application of zeolite based nanocomposites for wastewater remediation: Evaluating newer and environmentally benign approaches.

The presence of heavy metal ions and emerging pollutants in water poses a great risk to various biological ecosystems as a result of their high toxicity. Consequently, devising efficient and environmentally friendly methods to decontaminate these waters is of high interest to many researchers around the world. Among the varied water treatment and desalination means, adsorption and photocatalysis have been widely employed. However, the discussion and analysis of the use of zeolite-based composites as adsorbents are somehow minimal. The porous aluminosilicates (zeolites) are excellent candidates in wastewater treatment owing to various mechanisms of pollutants removal that they possess. The purpose of this review is thus to provide a synopsis of the current developments in the fabrication and application of nanocomposites based on zeolite as adsorbents and photocatalysts for the extraction of heavy metals, dyes and emerging pollutants from wastewaters. The review goes on to look into the effect of weight ratio on photocatalyst, photodegradation pathways, and various factors that influence photocatalysis and adsorption.

Performance comparison of photodynamic antimicrobial chemotherapy with visible-light-activated organic dyes: Rose bengal, crystal violet, methylene blue, and toluidine blue O.

This study evaluated the photobiocidal performance of four widely distributed visible-light-activated (VLA) dyes against two bacteria (Staphylococcus epidermidis and Escherichia coli) and two bacteriophages (phages MS2 and phi 6): rose bengal (RB), crystal violet, methylene blue, and toluidine blue O (TBO). The photobiocidal performance of each dye depended on the relationship between the type of dye and microorganism. Gram-negative E. coli and the non-enveloped structure of phage MS2 showed more resistance to the photobiocidal reaction than Gram-positive S. epidermidis and the enveloped structure of phage phi 6. RB had the highest potential to yield reactive oxygen species. However, the photobiocidal performance of RB was dependent on the magnitude of the surface charge of the microorganisms; for example, anionic RB induced a negative surface charge and thus electrical repulsion. On the other hand, the photobiocidal performance of TBO was observed to be less affected by the microorganism type. The comparative results presented in our study have significant implications for selecting photodynamic antimicrobial chemotherapy (PACT) dyes suitable for specific situations and purposes. Furthermore, they contribute to the advancement of PACT-related technologies by enhancing their applicability and scalability.

Mechanistic insights into efficient peroxymonosulfate activation by NiCo layered double hydroxides.

The efficient removal of organic refractory pollutants such as dyes and antibiotics in wastewater is crucial for protecting the environment and human health. In this work, a NiCo-layered double hydroxide (NiCo-LDH) with a uniform microspherical, hierarchical structure and a high surface area was successfully synthesized as an effective peroxymonosulfate (PMS) activator for the degradation of various organic dyes and antibiotics. The influence of various parameters on the catalytic activity of the NiCo-LDH was determined. Radical scavenger studies unveiled the major reactive oxygen species (ROSs) generated in the NiCo-LDH/PSM system to be 1O2, SO4•-, and O2•-. Ex-situ X-ray photoelectron spectroscopy (XPS) analysis uncovered the role of Co sites and oxygen vacancy as active sites and revealed the reversible redox properties of NiCo-LDH based on Co2+/Co3+ cycles. The activation mechanism and Rhodamine B (RhB) degradation pathways were experimentally studied and proposed. The NiCo-LDH is highly versatile, reusable and stable as shown by post-catalysis characterizations. This work shows the excellent catalysis performances and provides insights into the activation mechanism of PMS by NiCo-LDH for organic pollutant remediation.

Luminescent light diffuser for diffuse lighting applications.

The lighting industry currently accounts for a significant proportion of all energy demand. Luminescent white lighting is often impure, inefficient, expensive, and detrimentally emits as a point source, meaning the light is emitted from a focused point. A luminescent light diffuser offers the potential to create a spatially broad lighting fixture. We developed a luminescent light diffuser consisting of three commercially available luminescent dye species (rhodamine 6G, fluorescein, 7-diethylamino-4-methylcoumarin) dispersed within a polymer matrix (polyvinyl alcohol), or commercial paint, and coated on a planar waveguide. A Light-emitting diode (LED) (385 nm) is directed into the waveguide which excites the luminescent species, coating the panel, creating a device that emits spatially broad pure white light. As the emission depends on escape cone emission from the waveguide, the device's emission was found to depend highly on the coating film quality and components. We present two systems: a small 40 mm × 40 mm prototype, made using standard water-soluble polymer (polyvinyl alcohol), to study the underlying operational principles, and a 100 mm × 100 mm device with optimized efficiency fabricated with a clear commercial paint. By doping the polymer matrix with scattering silica microparticles we achieved a maximum photon outcoupling efficiency of 78%, whilst maintaining colour purity with an increased device size of more than 300 times (compared with the input LED). This work shows that it is possible to construct an inexpensive and spatially broad lighting source, whilst maintaining colour purity at a low cost.

A review on biological synthesis of ZnO nanostructures and its application in photocatalysis mediated dye degradation: An overview.

Zinc oxide (ZnO) has several industrial applications due to its versatile properties, which lead to its continuously increasing demand in different industrial sectors. Additionally, ZnO nanostructures possess unique photocatalytic activity, and because of this, they are being applied to degrade organic dyes through photocatalysis for wastewater treatment. Nevertheless, chemical synthesis methods to develop ZnO nanostructures have raised concerns related to environmental issues, furthermore, these methods are found to be costly and tedious. As a result, the synthesis of ZnO nanostructures using green methods is gaining popularity due to its low cost and eco-friendly mode, while avoiding the use of toxic chemicals. Green synthesis of ZnO nanostructures using different biological approaches involving plants, algae, and different microorganism-derived bioactive compounds has been well reported for diverse applications. Among different applications, ZnO nanostructures that enable photocatalysis to degrade dye have been found to be imperative for wastewater treatments. Therefore, the current review explores recent studies on green synthesis approaches to prepare ZnO nanostructures via adopting different biological methods that rely on plants, algae, and bacterial microorganisms. The properties of ZnO nanostructures, along with their green synthesis routes and feasible mechanisms, have also been discussed in this review. This review focuses on the use and efficiency of green route synthesized ZnO nanostructures as nanophotocatalysts for the degradation of organic dyes in wastewater treatment. Additionally, existing challenges in green synthesis methods and the efficiency of ZnO nanostructures to degrade organic dyes following photocatalysis has been discussed.

Facile and green synthesis of ZnO nanoparticles for effective photocatalytic degradation of organic dyes and real textile wastewater.

Remediation of organic dyes from wastewater in textile industries is a big challenge to decreasing water pollution. This study was aimed at the preparation of ZnO nanoparticles (NPs) and their application as a photocatalyst for the degradation of methylene blue (MB), sunfix red (SR) and real textile wastewater (RTW) under both UV and visible irradiations. The ZnO NPs were synthesized with a green Thymus vulgaris leaf extract-supported approach following the calcination process. 50 mg L-1 MB and 50 mg L-1 SR dyes were completely photodegrade under UV irradiation after only 20 and 45 minutes, respectively, in the presence of 1.0 mg/mL ZnO NPs. When they are exposed to visible light, the degradation efficiency reached 91 and 75% within 60 and 120 min, respectively. Photocatalytic measurements of RTW depict that 95% (within 60 min under UV illumination) and 79% (within 90 min under visible illumination) were degraded, respectively. The enhanced photodegradation can be attributed to the narrowing of the bandgap of the ZnO NPs, high crystallinity and nearly hexagonal morphology with an average size of 20-30 nm. The present results show that ZnO NPs could potentially be applied for high-efficiency degradation of organic dyes and RTW under both UV and visible light irradiation.

We report for the first time, Thymus vulgaris leaf extract­assisted synthesis of ZnO nanoparticles (NPs) has been applied as a photocatalytic dye and RTW degradation. Second, our synthesis approach is more facile and simple than the previous method where complex hydrothermal or solvothermal methods have been applied, which leads to a complex preparation procedure. We systematically prepared ZnO materials in taking account into the variable Thymus vulgaris/ZnO precursor ratio, different calcination temperature and time and in detail, their photocatalytic activity has been fully investigated.