Dependence Of Photocatalytic Activity Research Articles

Temperature Dependent Photocatalytic Activity of Bifeo3 Nanoparticles by Sol Gel Method

Temperature Dependent Photocatalytic Activity of Bifeo3 Nanoparticles by Sol Gel Method

A computational study on strain dependent photocatalytic activity of Janus Ga-Al-X-Se (X = S and Se) monolayers

The use of photocatalytic two-dimensional material for water splitting emerges as a significant technology in the field of green energy. Considering this viewpoint, the optoelectronic characteristics, photocatalytic, hydrogen, and oxygen evolution reactions (HER and OER) of the hexagonal GaAlXSe (X = S and Se) monolayers have been assessed in this research study with the help of density functional theory (DFT). The GaAlXSe (X = S and Se) monolayers are energetically, dynamically, and thermally stable. The GaAlSe2 and SGaAlSe monolayers are indirect semiconductors in nature. The absorption coefficient of both the monolayers is up to 105 cm−1. The suitable band alignments reveal that both the monolayers are appropriate for the photocatalytic application across all pH values at equilibrium. The strain dependent photocatalytic behavior of both the monolayers also have been evaluated. The nearly zero values of Gibbs free energies and the appropriate values of overpotentials signify efficient HER and OER catalytic activities of both the monolayers respectively.

Dependence of photocatalytic activity on the direction of the intrinsic dipole in GaOI-based Janus structures

Dependence of photocatalytic activity on the direction of the intrinsic dipole in GaOI-based Janus structures

Photocatalytic and photovoltaic applications of green synthesized titanium oxide (TiO2) nanoparticles by Calotropis gigantea extract

Titanium di oxide (TiO2) nanoparticles were prepared by green synthesis method using leaves, seeds, and flower solvent extract of Calotropis gigantean medicinal plant. The X-ray diffraction (XRD) analysis of the prepared TiO2 nanoparticles shows tetragonal structure of anatase phase TiO2. The quantum confinement of the TiO2 particles by the inclusion of active biomolecules was confirmed by optical studies. The polycrystalline nature of the prepared nanoparticles was confirmed by XRD and SAED analysis. The particle size reduction and increase of band gap energy are noted with Calotropis gigantean leaf assisted TiO2, while it increases with flower and seed assisted TiO2. The prepared nanoparticles exhibit the size dependent photocatalytic activity and solar cell fabrication. Calotropis gigantean leaf assisted TiO2 NPs had the highest photocatalytic activity, completely degrading methylene blue in 60 min with an 96 % of degradation, due to a low recombination rate of photo-generated electrons and holes. The prepared Calotropis gigantean plant assisted TiO2 nanoparticles boosted the concentration of OH• and O2• radicals in the solution, which is beneficial for enhancing the photodegradation rate of organic compounds. Plant derivative based TiO2 nanoparticles are the best candidates due to simplicity and cost-effectiveness leading to economical and operational advantages in the large-scale synthesis of nanoparticles.

Surface chemical states analysis and operational parameters dependent photocatalytic activity of mixed-phase TiO2:Ag photocatalysts

Surface chemical states analysis and operational parameters dependent photocatalytic activity of mixed-phase TiO2:Ag photocatalysts

Dependence of Photocatalytic Activity on the Morphology of Strontium Titanates

Strontium titanates were prepared with different morphologies by varying the ratio of solvents used during the synthesis. The effects of morphology and solvent (ethylene glycol to water) ratio were investigated both on the structure and photocatalytic activity of the samples. Structural properties were determined by X-ray diffraction, scanning electron microscopy, diffuse reflectance spectroscopy, and nitrogen adsorption measurements. The photocatalytic activity of the samples was evaluated by the photocatalytic oxidation of phenol and by the photocatalytic reduction of carbon dioxide. The ratio of solvents notably influenced the morphology, strontium carbonate content, primary crystallite size, and specific surface area of the samples. Samples prepared at low ethylene glycol to water ratios were spherical, while the ones prepared at high ethylene glycol to water ratios could be characterized predominantly by lamellar morphology. The former samples were found to have the highest efficiency for phenol degradation, while the sample with the most well-defined lamellar morphology proved to be the best for CO2 reduction.

Study of Concentration and Temperature Dependent Structural, Optical, Photocatalytic and Antimicrobial Activity of MoO3 Thin Films by Ultra Spray Pyrolysis

Molybdenum trioxide was used as a precursor for the deposition of thin films of varied concentrations onto the glass substrate by ultra-spray pyrolysis technique. Solutions of different concentrations viz. 0.05 M, 0.025 M, 0.0125 M were prepared and the substrate temperature varied to study the structural properties like XRD, UV-visible spectroscopy and FESEM of the MoO3 thin films. Being transition metal oxide molybdenum oxide (MoO3), exhibits fascinating chemical, structural, electrical and optical properties. The samples were prepared at different temperatures of 150, 250 and 350 ºC with the spray concentrations varying between 0.05 M, 0.025 M and 0.0125 M while the other spray operating parameters were fixed at their optimum values. X-ray diffraction technique was used to determine the crystalline size and nature of the films. For the substrate temperature 150 ºC, the films obtained are amorphous in nature while the films deposited at 250 and 350 ºC were found to be crystalline in nature giving α-MoO3 phase, which is evident from the X-ray diffraction pattern. The size of the crystal varied from 43 to 65 nm for the prepared samples. The band-gap energy by plotting Tauc plots was found to be in the range 2.51-3.01 eV. FESEM revealed two different types of morphological structures viz., spherical and nanorods. The photocatalytic activity of thin films obtained was estimated from their ability to degrade methylene blue (MB) under UV irradiation with excellent results. Antibacterial activity of thin films was checked against Pseudomonas aeruginosa for 1, 6, 10 and 96 h.

Synthesis and application of CdS nanorods for LED-based photocatalytic degradation of tetracycline antibiotic

With the rapid development of pharmaceutical industrialization, increased consumption of drugs and discharged sewage contains antibiotics that lead to water contamination. For this purpose, removal of antibiotics from aquatic environment is emphasizing the need to produce clean water using easy separable catalysts through photocatalytic water remediation and thus the semiconductor photocatalysts have presently gained fascinating unprecedented research attention. Herein, we present the synthesis of semiconductor CdS nanorods by a facile hydrothermal procedure using ethylene diamine as a coordinating agent. Then, we subsequently studied the photocatalytic activity of CdS nanorods under blue and white LED light irradiation for the degradation of tetracycline antibiotic as a model compound. The light dependent photocatalytic activity of CdS nanorods demonstrated that CdS nanorods possess higher catalytic efficiency in presence of blue light compared to white light toward the photocatalytic degradation of tetracycline antibiotic. We have also studied the photocatalytic activity in presence of various light intensity. These CdS nanorods exhibited the highest tetracycline degradation efficacy of 95.6% within 60 min in presence of blue light (intensity: 200W/m2) without any supplementary oxygen sources during the degradation reaction. The photocatalytic mechanism of the tetracycline degradation has been elucidated by scavenging experiment. The experimental results indicate the formation of reactive oxygen species during photocatalytic degradation of tetracycline antibiotic. This work represents an alternative route to develop heterogeneous photocatalyst for antibiotics degradation due to the outstanding efficiency and stability of the CdS nanorods as well as easy separation through simple filtration method. It is anticipated that this work will shed light in the practical applications of CdS nanorods for environmental remediation through wastewater treatment.

Oxygen Vacancy and Adsorbed Superoxides Dependent Photocatalytic Activity of TiO2 Quantum Dot Thin Films for Degradation of Methylene Blue with Variation of Precursor Concentration

Growth of TiO2 quantum dot thin films on ITO glass substrate by hydrothermal method at 180 °C with variations of titanium precursor concentration (0.3, 0.5, 0.7, and 1 ml) is reported. UV–vis absorption spectrum shows a strong absorbance peak in the UV region. The bandgap of samples ranged from 3.2 to 3.6 eV. FESEM analysis shows a layered sieve-like porous morphological structure. The particle size is less than 10 nm. The FTIR analysis reveals the presence of isolated adsorbed Ti–OH and –OH groups which take part in photocatalysis reactions to oxidize dye molecules. The superoxides and hydroxyl radicals were yielded by the protonation process. The oxygen vacancies, confirmed from XPS analysis, play an important role in the formation of impurity level states below the conduction band with the accumulation of a large number of electrons. These electrons further take part in the hydrogen production process. This investigation demonstrates that thin film with 0.5 ml precursor volume shows enhanced MB dye degradation activity under UV light. The PL emission is quenched in the UV region for a sample having 0.5 ml precursor volume, enhancing the probability of charge carrier separation. Thus significant results in photocatalytic MB dye degradation activity are obtained.

Morphology dependent photocatalytic activity of ZnO nanostructures-A short review

Zinc oxide (ZnO) is a material that is flexible with distinctive characteristics, such as high sensitivity, wide-ranging, non-toxicity, strong compatibility and strong isoelectricity point that support the consideration with a few exceptions. The advantages for energy and biological science applications depend on nanostructured morphology ZnO based material are regularly studied. These review works concentrate on the recent development in ZnO morphological depends nanomaterial, nanocomposites, and doped materials for the photocatalyst activities.

Size Dependent Photocatalytic Activity of ZnO Nanosheets for Degradation of Methyl Red

In this work, ZnO nanosheets with a tunable thickness were produced by microwave-assisted hydrothermal based method. The product was well characterized by various tools such as XRD, SEM, EDX spectroscopy, TEM, and Raman spectroscopy. ZnO nanosheets were highly crystalline and possessed single phase with the wurtzite structure. The ZnO nanosheets have thickness ranging from 20 to 50 nm, as shown by the micrographs of SEM. The SAED pattern infered that the ZnO nanosheets have single crystal nature with preferential growth direction along [0001]. ZnO nanosheets with E2high mode of wurtzite structure was observed by Raman scattering spectra. The photodegradation of methyl red using ZnO nanosheets was measured under UV light irradiation. In comparison with the commercial ZnO, ZnO nanosheets showed higher efficiency in photodegradation of organic dyes. The thinner the nanosheets, the higher their performance, which can be explained based on surface area. The excellent performance of ZnO nanosheets in photodegradable organic dyes might be important in environmental treatment and photocatalysis applications.

Impact of photosensitizer orientation on the distance dependent photocatalytic activity in zinc phthalocyanine-nanoporous gold hybrid systems.

Nanoporous gold powder was functionalized in a two-step approach by an azide terminated alkanethiol self-assembled monolayer (SAM) and a zinc(ii) phthalocyanine (ZnPc) derivative by copper catalyzed azide-alkyne cycloaddition (CuAAC). A series of different hybrid systems with systematic variation of the alkyl chain length on both positions, the alkanethiol SAM and the peripheral substituents of the ZnPc derivative, was prepared and studied in the photooxidation of diphenylisobenzofuran (DPBF). An enhancement by nearly one order of magnitude was observed for the photosensitized singlet oxygen (1O2) generation of the hybrid systems compared to the same amount of ZnPc in solution caused by the interaction of the npAu surface plasmon resonance and the excited state of the immobilized sensitizer. This interaction was shown to be distance dependent, with decreasing activity for short SAMs with alkyl chain lengths < 6 methylene groups caused by quenching of the excited state via electron transfer as well as decreasing activity for SAMs with n > 8 methylene groups due to decreasing energy transfer for long distances. An unexpected distance dependent behaviour was observed for the variation of the peripheral alkyl chain on the photosensitizer revealing a planar orientation of the immobilized photosensitizer on the nanoporous gold surface by a penta-coordinated central zinc ion through interaction with free azide groups from the self-assembled monolayer.

Shell thickness dependent photocatalytic activity of TiO2/ZnS core-shell nanorod arrays

Rutile TiO2 nanorod arrays (NRAs) were first fabricated via solvothermal route using Ti foil as both substrate and titanium source, then TiO2/ZnS core-shell heterostructure NRAs were synthesized by successive ionic layer adsorption and reaction (SILAR) method using the TiO2 NRAs as a sacrificial template. The diameters of TiO2 nanorods ranged from 20 to 200 nm, and the thickness of ZnS shell varied from 3 to 20 nm. The photocatalytic activities of the samples were compared by the degradation of rhodamine B (RhB) water solution under simulated sunlight irradiation. All TiO2/ZnS NRAs exhibited higher photocatalytic activities than bare TiO2 NRAs, and the optimal ZnS shell thickness of TiO2/ZnS NRAs was 10 nm. Furthermore, TiO2/ZnS NRAs possessed excellent reusability.

Synthetic Titanosilicate Additives for Special Cement Composites

Abstract—The effect of titanosilicate powder by-products of different composition and dispersion on the cement stone hardening kinetics and the main technical properties are studied. It is shown that titanosilicate additives act as a modifier promoting cement hydration and, accordingly, hardening. Moreover, the higher the specific powder surface, the greater the initial strength of the cement stone. The titanosilicate product with the highest BET surface area (50.2 m2/g) is overactive, which contributes to an increase in the cement stone strength factor at 1 day by 39–59% compared with the reference composition. It is established that the optimal amount of the composition additive in which the cement stone is maximally strong is 1 wt %. It is shown that the presence of a photocatalytic titanosilicate additive in the cement stone provides its capacity for self-cleaning. The most intense degradation of dyes, up to complete decomposition, is observed in samples modified with powder with the highest BET surface area. No dependence of photocatalytic activity on the amount of additive in the cement stone is detected. The obtained results can be used in the technology of modern construction materials with special properties.

Detoxification of dye contaminated water by Mn $$^{2+}$$ 2 + -doped ZnS nanostructures

Chemical co-precipitation route was successfully employed to synthesize polyethylene glycol-coated pure and doped $$\hbox {Zn}_{1-x}\hbox {Mn}_{x}\hbox {S}\,(0\le x \le 0.1)$$ nanoparticles. The crystallographic and morphological analyses have been done by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The formation of cubic crystal structure and quasi-spherical morphology has been revealed by XRD and TEM, respectively. The optical analyses have been done by UV–Vis absorption spectroscopy and energy resolved photoluminescence spectroscopy. Energy dispersive X-ray spectroscopy study has been carried to analyse the elemental composition. The doping concentration dependent photo-catalytic activity was checked to analyse the photo-catalytic potential of $$\hbox {Zn}_{1-x}\hbox {Mn}_{x}\hbox {S}$$ nanoparticles under UV irradiation.

Shell thickness dependent photocatalytic activity of EDTA-assisted Ag/ZnO core-shell nanoparticles under sunlight irradiation

Functionalized Ag/ZnO core–shell (CS) nanoparticles (NPs) with ethylenediaminetetraacetic acid (EDTA) having same core size but with different shell thickness are successfully prepared through a simple and low cost wet chemical process. Different physiochemical characterizations including transmission electron microscopy, x-ray diffraction, Brunauer-Emment-Teller surface area analysis, zeta potential analysis, thermal gravimetric-differential analysis, UV-visible absorption spectroscopy, Photoluminescence Spectroscopy and Fourier-transform infrared Spectroscopy have been involved to characterize the samples. The thickness of ZnO shell of Ag/ZnO CS NPs is found to be increasing with increasing molar ratio of EDTA/Zn2+. The LSPR wavelength of Ag core is shifting to longer visible wavelength with increasing the shell thickness of Ag/ZnO CS NPs because of the increase in the dielectric constant of the sourrounding environment. The increasing shell thickness of Ag/ZnO CS NPs makes a strong effect on the decrease in the fluorescence intensity of UV emission of ZnO. This quenching of PL intensity has been further verified by transient fluorescence (FL) spectra. The Nyquist plots also provide evidence of higher electron-transfer rate of the Ag/ZnO CS NPs of having higher shell thickness. The photocurrent measurement confirms electron-charging of Ag core in Ag/ZnO CS NPs. Variation of concentration of EDTA as anionic surfactant causes variation of surface charge of Ag/ZnO CS NPs. With increasing the shell thickness, photodegradation efficiency of Ag/ZnO CS NPs towards methylene blue (MB) degradation enhances under sunlight irradiation. This enhancement in photocatalytic efficiency with increasing the shell thickness is achieved due to the higher surface area, higher charge transfer efficiency, extended light absorption towards visible region and more negative zeta potential of Ag/ZnO CS NPs.

Surfactant assisted self-assembly of Ag+ containing nanocrystals and their facet dependent photocatalytic activity

This work demonstrates a general route for synthesis of nanocatalysts containing silver ions using surfactants.

Self-assembly synthesis of BiVO4/Polydopamine/g-C3N4 with enhanced visible light photocatalytic performance

BiVO4/PDA(Polydopamine)/g-C3N4 was synthesized by facile ultrasonic dispersion and self-assembly at the room temperature, and monoclinic BiVO4 was embedded on PDA/g-C3N4 sheet, which PDA was first formed in situ on the surface of g-C3N4 via self-polymerization of dopamine. The dependence of photocatalytic activity on the structural, electronic and optical properties of the BiVO4/PDA/g-C3N4 nanostructure has been explored using XRD, XPS, TEM, SEM, DRS, PL, BET and photocurrent. The BiVO4/PDA/g-C3N4 photocatalysts show higher activity of glyphosate degradation than BiVO4, g-C3N4 and BiVO4/g-C3N4 under visible light irradiation. The enhanced activity of BiVO4/PDA/g-C3N4 can be significantly attributed to the improved visible light absorption, enhanced specific surface area and increased charge separation. PDA has a strong and irreversible binding ability onto BiVO4 and g-C3N4 to form BiVO4/PDA/g-C3N4. This simple method at the room temperature is promising for the synthesis of high performance composite photocatalysts for different applications, such as pollutant degradation, photocatalytic splitting water, etc.

Light-Assisted Synthesis of Hierarchical Flower-Like MnO2 Nanocomposites with Solar Light Induced Enhanced Photocatalytic Activity

We have demonstrated a novel solution chemistry route for the synthesis of nanoscale hierarchical flower-like MnO2 through a light-assisted decomposition of a manganese precursor over the surface of a clay nanotube. By tuning the reaction conditions, we have successfully synthesized δ-MnO2 flowery nanostructures comprising assemblies of intersected nanosheets and subsequently studied their photocatalytic activity for the degradation of organic dyes under natural sunlight irradiations. The crystallographic phase dependent photocatalytic activity of MnO2 nanocomposites has also been carried out toward the photodegradation of dyes, indicating δ-MnO2 nanostructures possess higher catalytic efficiency compared to α-MnO2. The underlying mechanism demonstrates the formation of reactive oxygen species, which in turn facilitate the degradation of dyes and also substantiates that there is no need of any supplementary oxygen sources during photodegradation. The outstanding performance of the hierarchical δ-MnO2 nano...

CuO/ZnO nanorods: An affordable efficient p-n heterojunction and morphology dependent photocatalytic activity against organic contaminants

In the present study, we report morphology dependent photocatalytic activity of CuO/ZnO nanorods by simple chemical synthesis for the first time. The nanorod morphology was clearly evidenced by field emission scanning electron microscope (FESEM) and hig resolution transmission electron microscope (HRTEM) analysis and confirmed the particle size of 20 nm. The composition and oxidation states of the CuO/ZnO nanorods were confirmed by XPS analysis. The potential efficacy of CuO/ZnO nanorods was evaluated towards the photocatalytic degradation of congo red (CR) and rhodamine B (RhB) dye solution. Very interestingly, the CuO/ZnO nanorods showed significantly superior photocatalytic activity compared to CuO, ZnO, a mixture of nano CuO and nano ZnO. The complete degradation of dye solution was successfully achieved within a short span of time. The effects of the different operational parameters viz amount of photocatalyst loading, initial concentration and pH were evaluated and the optimum condition for the superior activity was discovered. The prevention of the electron-hole pair recombination was strongly evidenced by photoluminescence (PL) analysis. Importantly, active involvement of hydroxyl radical in the photocatalytic degradation mechanism was strongly supported by the trapping experiments using different scavengers and fluorescence analysis. The CuO/ZnO nanorods photocatalyst also showed excellent degradation activity against the mixed dye solutions (CR and RhB). The stability and reusability results were clearly indicated that the sustainability of the CuO/ZnO nanorods in the photocatalytic reaction.