Visible Photoluminescence Research Articles

Formulation of calcium based 8-HQ fluorescent paint for fluorescent paint applications

We report the formulation of luminous paints with calcium-based quinoline complex, bis(8-hydroxyquinoline) (calcium) – Caq2 as a pigment (where Ca = Calcium, q = 8-hydroxy quinoline). Fourier transform infrared (FTIR) spectra, UV–Visible absorption, Photoluminescence (PL) spectra and photometric evaluation of the pigment were probed to evaluate its structural, optical and photometric properties. The excitation spectra of Caq2 pigment portrays a broad excitation peak at 370 nm, while emission spectra reveal a broad peak, registered at 473 nm which falls in the bluish-green region of the visible spectrum. Further, fluorescent paints were formulated on glass slides with epoxy resin/ urea formaldehyde as binder and toluene as solvent. The results reveal the change in intensity of the painted panels in the following order IZnO Epoxy(50%) > IEpoxy based pure pigment > IUF based pure pigment > IZnO Epoxy(10%) > IZnO UF(10%). These results reveal the potential of the pigment as one of the components of fluorescent paint.

Carbon nano-onion as next-generation functional nanomaterial: Synthesis methods and practical applications

Carbon nano-onion (CNO) (also known as onion-like carbon, OLC), exhibiting multiple enclosed fullerene shell structures, as one of the most promising nanoforms, has attracted worldwide attention during the past decades due to its exceptional chemical and physical properties such as non-toxicity, high chemical stability, large sufficient surface area with low density, and superior high electronic and thermal conductivities, visible photoluminescence, etc. Nowadays, functional CNOs have been applied in energy storage devices, supercapacitors, photovoltaics, light-emitting diodes and bio-imaging technology. Since the first observation of CNOs by transmission electron microscopy as a byproduct in the synthesis of carbon black in 1980, numerous experimental and theoretical studies including expressive practical applications of CNOs have been intensively developed in modern chemistry. With respect to synthetic techniques, the high-temperature annealing of nano diamond, detonation of high explosive molecules, arc discharge of graphite, chemical vapor deposition, laser ablation, thermal pyrolysis, hydrothermal carbonization, and microwave pyrolysis have been reported. It has been addressed that the synthesis approach plays a key role in determining the structure of CNOs and resultant properties. This paper reviewed the developments of CNOs through major synthesis methods utilized for a selected wide spectrum of applications, by covering both the past and current progress. The contents outlined in the current review will offer readers comprehensive insights into the design and development of CNO materials.

Beyond the Visible: A Review of Ultraviolet Surface-Enhanced Raman Scattering Substrate Compositions, Morphologies, and Performance.

The first observation of ultraviolet surface-enhanced Raman scattering (UV-SERS) was 20 years ago, yet the field has seen a slower development pace than its visible and near-infrared counterparts. UV excitation for SERS offers many potential advantages. These advantages include increased scattering intensity, higher spatial resolution, resonance Raman enhancement from organic, biological, and semiconductor analytes, probing UV photoluminescence, and mitigating visible photoluminescence from analytes or substrates. One of the main challenges is the lack of readily accessible, effective, and reproducible UV-SERS substrates, with few commercial sources available. In this review, we evaluate the reported UV-SERS substrates in terms of their elemental composition, substrate morphology, and performance. We assess the best-performing substrates with regard to their enhancement factors and limits of detection in both the ultraviolet and deep ultraviolet regions. Even though aluminum nanostructures were the most reported and best-performing substrates, we also highlighted some unique UV-SERS composition and morphology substrate combinations. We address the challenges and potential opportunities in the field of UV-SERS, especially in relation to the development of commercially available, cost-effective substrates. Lastly, we discuss potential application areas for UV-SERS, including cost-effective detection of environmentally and militarily relevant analytes, in situ and operando experimentation, defect engineering, development of materials for extreme environments, and biosensing.

Photo-electrochemical sensor based on MoO3/ZnCdS Z-type heterojunction for detecting 4-Nitrophenol and hexavalent chromium

In this study, firstly, ZnxCd1−xS (x = 0.7, 0.5, 0.3) was synthesized. The results from testing show the photocurrent response of Zn0.3Cd0.7S is better than the other two materials. In order to improve PEC performance, different molar amount of MoO3 was introduced to synthesize composites MoO3/Zn0.3Cd0.7S-Y (Y=0.10、0.20、0.25、0.30、0.40). It is found that the properties of the composites are better than MoO3 and Zn0.3Cd0.7S. Furthermore, the results from UV–visible diffuse reflectance spectroscopy (UV–vis DRS) and photoluminescence (PL) indicate MoO3/Zn0.3Cd0.7S-0.3 has the widest visible light absorption range and the most powerful photogenerated carrier separation capability in all samples. On the basis of analysis, a PEC sensor based on MoO3/Zn0.3Cd0.7S-0.3 was constructed to detect 4-Nitrophenol (4-NP) and hexvalent chromium (Cr (VI)). The linear range of 4-NP sensor is 0.05–100 μM, LOD is 0.028 μM (S/N = 3). For Cr (VI), these values are 0.1–240 μM and 0.019 μM, respectively. Simultaneously, the sensor has positive stability, reproducibility and selectivity, and can be utilized in actual samples. Hence, the PEC sensor based on MoO3/Zn0.3Cd0.7S-0.3 will have a promising application to detect 4-NP and Cr (VI).

Dicyanovinyl-capped thiazologermoles with moderate donor-acceptor interaction as visible photoluminescence turn-on sensors for primary amines

Dicyanovinyl-capped thiazologermoles (DTzG-DCV and GIDTz-DCV) were synthesized, and their optical and electrochemical properties were investigated. Both DTzG-DCV and GIDTz-DCV showed solvatochromism, exhibiting red shifts of the photoluminescence (PL) bands with increasing solvent polarity from toluene to DMF, likely due to intramolecular donor–acceptor interaction. Moreover, they served as selective PL sensors, with spectral changes in the presence of amines and fluoride and iodide ions, but not other halogen ions, in solution. DTzG-DCV and GIDTz-DCV underwent a quick and high-yield reaction with n-butylamine to give imine derivatives, accompanied by PL color changes. Similar color changes were observed even in the solid state with n-butylamine and n-hexylamine. In contrast, reactions with secondary and tertiary alkylamines caused no obvious changes in PL color. The color changes are visible to the naked eye under irradiation with a portable UV lamp at 365 nm, and thus DTzG-DCV and GIDTz-DCV can be used for the quick and selective sensing of primary amines.

5-Fluorouracil-loaded designed praseodymium oxide – poly- β-cyclodextrin nanorods for effectively inhibiting breast cancer cells

Breast cancer remains one of the commonly prevailing and challenging diseases. Lanthanide-based nanomaterials are fascinating depending on their unique properties and represent a preferable choice of drug transport, aimed at finding an agent for targeted therapy. It necessitates that lanthanide-based nanocarriers with suitable surface modification and desired physicochemical characteristics are developed for effective anticancer drug delivery, owing to their fascinating light absorption, magnetic, and morphological features. Herein, we report praseodymium oxide nanorods in combination with poly-cyclodextrin as a novel nanocarrier to deliver the chemotherapeutic drug 5-fluorouracil to breast cancer cells. The praseodymium oxide nanoparticles were prepared using a sonochemical method and characterized using routine analytical methods, including X-ray Diffraction, Transmission Electron Microscopy, and X-ray Photoelectron Spectroscopy. The monodisperse rod-shaped structures possess length and width of 200 ± 30 and 72 ± 10 nm, respectively. The nanoparticles are 64.33% crystalline, revealed by XRD. The polymer content in the nanoparticles is ∼37% by weight. Further, the nanoparticles' magnetic, light absorption and photoluminescence characteristics are studied. Low saturation magnetization and insignificant hysteresis properties are observed. Broad absorption and visible wavelength region photoluminescence arise from the praseodymium in the material. The continuous release of the drug cargo and the in vitro anticancer activity are discussed. The loaded drug (5-fluorouracil) is released sustainably, extending over 250 hours. The anticancer activity in vitro is observed with the portion of the drug released from the nanocarrier. The apoptotic action mode of the drug-carrier vehicle is analyzed. The inhibition of cells occurs mainly on the S-phase of the cell cycle. The nanomaterial can function as a drug carrier and is suitable for anticancer therapy. The results reported herein on praseodymium oxide nanoparticles are promising as a nanocarrier and pose the possibility of future in vivo studies.

Preparation of Iron Oxalate from Iron Ore and Its Application in Photocatalytic Rhodamine B Degradation

In this study, iron oxalate dihydrate (FOD-ore) was produced from iron ore by the process using oxalic acid to extract iron, followed by photo-reduction. Several techniques, such as X-ray powder diffraction (XRD), Raman, scanning electron microscopy with energy dispersive X-Ray analysis (SEM-EDX), ultraviolet–visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL), and X-ray photoelectron spectroscopy (XPS), were used to determine the physicochemical properties of the FOD-ore sample. To compare the photocatalytic activity of FOD-ore, commercial hematite (Fe2O3) was used as a precursor to creating iron oxalate (FOD). The FOD-ore was applied to the photocatalytic degradation of rhodamine B (RhB), a model organic pollutant in wastewater. Using the produced FOD-ore, we were able to degrade more than 85% of RhB within 90 min at a rate approximately 1.4 times higher than that with FOD. FOD-ore demonstrated greater light absorption than FOD, resulting in improved RhB degradation performance. Moreover, the enhanced separation and transport of photogenerated electron-hole pairs can be attributed to the increased photocatalytic RhB degradation rate of FOD-ore, confirmed by photoluminescence results. Therefore, FOD-ore can be utilized as a potential photocatalyst in the degradation process for other organic pollutants under light irradiation.

Impact of pendant group on the clustering-triggered emission property and gelation behavior of poly(thioether) derivatives

Nonconventional luminogens, represented by clustering-triggered emission (CTE) materials, have attracted increasing attention owing to their unique intrinsic emission and promising applications. However, the influencing factors of clustering-triggered emission and gelation behavior remain poorly understood. Herein, a series of poly(thioether)s with different pendant groups were synthesized and their unique properties were studied. Owing to the similar molecular structure, all five poly(thioether)s exhibited visible photoluminescence, but the intensity varied when the pendant group or solvent changed, which could be attributed to different clustering degree between polymer chains. Moreover, poly(thioether)s with different pendant groups showed the diverse gelation behavior during polymerization process. The impact of pendant group on the clustering-triggered emission property and gelation behavior of poly(thioether) derivatives were investigated in detail, which might be of great fundamental value for the rational design of functional nonconventional luminogens for biological and medical applications.

Bio synthesis and characterization of tin oxide for photocatalytic, anti-microbial and anti-oxidant applications

The advancement of new synthetic ways for the preparation of monodispersed nanocrystals by the use of cheap, non-toxic and environmentally benign materials become a challenge to the research community in science. The present study deals with the biosynthesis of SnO2 nanoparticles making use of the extract of Garcinia Cambogia as reducing and stabilizing agent. This method is simple, efficient, economic, harmless and eco-friendly. The morphological, surface, and structural studies have been conducted by employing X-ray diffraction analysis (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), Brunauer-Emmet-Teller (BET), Fourier -Transform Infrared spectroscopy (FT-IR) and Raman Spectroscopy. The thermal and optical studies have been performed using TG-DTA analysis, UV–Visible diffuse reflectance spectroscopy and Photoluminescence spectroscopy. The photocatalytic activity of NPs is investigated against methylene blue. Agar well diffusion method is used to study the antibacterial action of the SnO2 nanoparticles with Gram-positive S.aureus along with Gram-negative E. coli. The anti-oxidant activity of SnO2 nanoparticles is confirmed using the DPPH assay.

Synthesis of ZnO nanowires by thermal chemical vapor deposition technique: Role of oxygen flow rate

Novel catalyst-free synthesis of hierarchical zinc oxide (ZnO) nanowires (NWs) by atmospheric pressure thermal chemical vapor deposition (TCVD) technique and the impact of different oxygen (O2) flow rates (25, 50, 75, and 100 mL/min) on the optical behavior, crystalline structure, emission response, and surface morphology of the prepared samples were studied in detail. The hierarchical ZnO NWs were characterized by ultraviolet–visible (UV–Vis) spectrophotometer, X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, and field emission scanning electron microscope (FESEM) measurements. The physical characteristics of the samples were found to be intensely influenced by the O2 flow rate. UV–Vis spectrophotometer measurements indicated that the optical energy gap (Eg) of the samples varies from 3.24 eV to 3.10 eV with regulating O2 flow rates from 25 to 100 mL/min. XRD analyses confirmed that all the prepared samples were polycrystalline in nature with hexagonal wurtzite-type crystal structure and a strong preferential direction along the (002) plane. Photoluminescence results revealed that oxygen vacancies were the major defects causing the blue emissions. Besides, the higher flow rate of O2 (100 mL/min) was efficient in decreasing the number of oxygen vacancies accountable for wide visible emission band intensity. FESEM images demonstrated a high density of hierarchical ZnO NWs with diameters ranging from 33 ± 2 nm to 88 ± 5 nm. Based on the FESEM observations, the potential growth mechanism of the hierarchical ZnO NWs was a vapor-solid (VS) process. Our simple systematic process for growth and characterization may provide toward the development of the hierarchical ZnO NWs-based gas sensors.

Infrared to Visible Upconversion Photoluminescence from Nd-doped Yttria Ceramic for Optical Applications

Upconversion photoluminescence (UCPL) attracts great attention in the field of optics and solid state lightening applications. Thus, in order to understand the underlying mechanisms of UCPL, this work reports on the spectral and kinetic properties of up and down conversion photoluminescence (PL) from Nd-doped Y2O3 ceramic. The energy transition levels and the possible excitation mechanisms are discussed. Nd-doped Y2O3 nanocrystals have been prepared via co-precipitation method then subjected to sintering process for ceramic production. The X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements have been used to reveal the formation of nanocrystals and the crystal phase of the prepared Nd-doped Y2O3 powders. It is found that the PL down conversion (DCPL), from ceramic sample, demonstrates well-resolved narrow emission lines related to the near-infrared transitions in Nd ions, when excited by different UV–visible wavelengths. On the other side, a visible upconversion PL (UCPL) has been detected under excitation by a 1064-nm pulsed laser. In addition, the UCPL together with the photoluminescence excitation (PLE) results have been used to confirm the proposed energy levels for the upconversion process. Moreover, the excitation power dependence of the UCPL and time-resolved photoluminescence (TRPL) have been measured in order to determine the dominant excitation mechanism responsible for the upconversion. our findings suggest that the excited state absorption mechanism (ESA) is likely the possible mechanism of UCPL process in rare earth (Nd) single-doped Y2O3 ceramic.

Silicon Compound Nanomaterials: Exploring Emission Mechanisms and Photobiological Applications

After the first visible photoluminescence (PL) from porous silicon (pSi), continuous efforts are made to fabricate Si‐based compound nanomaterials embedded in matrices such as oxide, nitride, and carbide to improve optical performance and industrial acceptability. These nanomaterials’ functional and desired properties (nanoparticles and quantum dots embedded in matrices) can vary significantly when embedded in technologically relevant matrices. However, exploring the exact emission mechanisms is one of the remaining challenges from the past few decades. To cover this gap, this review discusses the morphological and optoelectronic properties of Si‐based compound nanomaterials and their correlation with the quantum confinement effect and different surface states to find precise emission mechanisms. One of the biggest challenges of using silicon nanomaterials in the biological sector is the development of sensitive materials of low/acceptable toxicity for identifying target analytes either inside/outside the biological platforms. In this scenario, silicon‐based compound matrices can offer different characteristics and advantages depending on their size configurations and PL emission mechanisms. On the other hand, a proper understanding of these multifaceted silicon nanomaterials’ optical properties (emission mechanisms) can be exploited for pathogen detection and in situ applications in cells and tissues, embarking on a new era of bioimaging technology.

Impact of Ti doping and annealing temperature on structural and opto-magnetic properties of tungsten oxide (WO3)

ABSTRACT Pure and Ti-doped WO3 nano systems synthesized by the solid state reaction method and annealed at different temperatures, were studied for changes in structural, optical and magnetic properties. X-ray diffraction, Raman, UV–Vis, photoluminescence spectroscopy, vibrating sample magnetometer (VSM) techniques were employed for structural, optical and magnetic characterization to study the modification of the electronic structure and disorder developed in the samples. Inclusion of Ti ions leads to degradation in the crystallinity of the monoclinic single phase system with an increase in the content of the dopant ions, whereas increased annealing temperature enhances crystallinity. A red shift in the optical band gap indicates the production of defect states. As the annealing temperature is raised, the amount of visible photoluminescence (PL) emissions caused by oxygen vacancies decreases. Magnetic experiments demonstrate the ferromagnetic properties of the prepared samples, which exhibit a decrease with Ti doping and an increase in annealing temperature.

Anthracene and β-cyclodextrin-based semi-conducting rotaxanes: Effect of the benzylation on the physico-chemical and electrical properties

In this work, we report the benzylation of an anthracene and β-Cyclodextrin-based rotaxane. Then, a comparative study between the physicochemical and electrical properties of the modified rotaxane (R-Bn) and those of the pristine supramolecule (R) was conducted. We noted an important improvement of the solubility of the rotaxane following the o-benzylation of the β-Cyclodextrin hydroxyl groups. The analysis of the surface topography of the rotaxane films using atomic force microscopy (AFM) showed a smoother surface morphology for the supramolecular assembly R-Bn. Also, we have demonstrated that the introduction of benzyl moieties induces a remarkable broadening and a bathochromic shift of the UV–visible absorption and photoluminescence spectra, an improvement in the fluorescence yield as well as a reduction of the optical and electrochemical band gaps. In addition, a white photoluminescence was emitted from R-Bn thin layer while a blue emission was observed in the case of the primitive rotaxane film (R). Regarding the electrical measurements, the benzylation of the rotaxane induced a dramatic decrease of the threshold voltage (from 3.70 V to 1.55 V) and the dynamic resistances (from 113.84 kΩ to 11.51 kΩ), an important increase by one order of magnitude of the charge carrier mobility and a drastic increase of the conductivity by 5 orders of magnitude.

Corrosion inhibition properties of expired Broclear medicine and its carbon dot as eco-friendly inhibitors for mild steel in 15% HCl

Eco-friendly, hydrophilic and economical carbon dot (CD) of expired dated Broclear tablets (EBD-CD) was synthesized by hydrothermal method and its identification as a carbon dot was confirmed by high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR), ultraviolet–visible spectroscopy (UV–vis) and photoluminescence (PL) spectroscopy. Corrosion inhibition efficiency of expired dated Broclear (EBD) and its carbon dot (EBD-CD) was analysed by gravimetric and electrochemical methods for mild steel (MS) in 15% HCl solution. The corrosion inhibition efficiency of synthesised EBD-CD was found higher at each concentration compared to EBD. The corrosion inhibition efficiency obtained from gravimetric method for EBD-CD and EBD was 95.2% and 89.1%, respectively, at 303 K and 100 ppm concentration. The inhibition efficiency of both inhibitors increases on increasing concentration and decreases on increasing temperature. The mixed type adsorption of inhibitor molecules on MS surface is the main factor to reduce corrosion of MS. Both inhibitors obey Langmuir adsorption isotherm. The surface study of uninhibited and inhibited MS surface was performed by using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) analysis. Whereas, the composition of adsorbed inhibitor film on MS surface was analysed by X-ray photoelectron spectroscopy (XPS) study.

Heat-Resistant Polymers with Intense, Visible Photoluminescence Functionality and Fluorescence Probing Application

Heat-resistant polymers with an intense, visible photoluminescence (PL) functionality are presented. A polybenzoxazole (PBO) containing hexafluoroisopropylidene (HFIP) side groups exhibited an intense purple PL with a quantum yield, ΦPL, of 0.22 (22%), owing to the effectively disturbed concentration quenching (CQ) in the fluorophore units by the bulky HFIP side groups. The chain ends of a wholly cycloaliphatic polyimide (PI), derived from 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) and 4,4′-methylenebis(cyclohexylamine) (MBCHA), were modified with conjugated monoamines. The PI derived from 2,3,6,7-naphthalenetetracarboxylic dianhydride (2,3,6,7-NTDA) and MBCHA exhibited a very high glass transition temperature (Tg = 376 °C) and purple fluorescence from the S1(π,π*) state. However, its ΦPL value was lower than expected. A pronounced effect of fluorophore dilution using CBDA on the PL enhancement was observed. This is closely related to the planar structure of the 2,3,6,7-NTDA-based diimide units. By contrast, the counterpart using an 2,3,6,7-NTDA isomer, 1,4,5,8-NTDA, was virtually non-fluorescent, despite its sufficient dilution using CBDA. The PI film obtained using 3,3″,4,4″-p-terphenyltetracarboxylic dianhydride (TPDA) with a non-coplanar structure and MBCHA exhibited an intense blue fluorescence spectrum (ΦPL = 0.26) peaking at 434 nm. The dilution approach using CBDA enhanced its fluorescence up to a high ΦPL value of 0.41. Even when TPDA was combined with an aromatic diamine, 2,2′-bis(trifluoromethyl)benzidine (TFMB), the intense blue fluorescence was observed without charge-transfer fluorescence. A semi-cycloaliphatic PI derived from TFMB and a novel cycloaliphatic tetracarboxylic dianhydride, which was obtained from a hydrogenated trimellitic anhydride derivative and 4,4′-biphenol, was used as another host polymer for 9,10-bis(4-aminophenyl)anthracene (BAPA). The BAPA-incorporating PI film resulted in a significant PL enhancement with a considerably high ΦPL of 0.48. This PI film also had a relatively high Tg (265 °C). A reactive dye, N,N′-bis[4-(4-amino-3-methylbenzyl)-2-methylphenyl]-3,4,9,10-perylenetetracarboxydiimide, was harnessed as a fluorescence probe to explore transamidation between polyimide precursors in solution.

Elaboration of Silicon Nanostructures with Vapor-Phase Silver Assisted Chemical Etching: Correlation between Structural and Optical Properties.

Based on the widely used wet metal-assisted electroless etching, we develop in this work a novel vapor-phase silver-assisted chemical etching (VP-Ag-ACE) suitable for the elaboration of highly doped p-silicon (Si) nanostructures with strong, visible, and multi-peak photoluminescence (PL) emissions. The lateral and vertical etching rates (LER and VER) were discussed based on the etching mechanism of the VP-Ag-ACE. The antireflective suitability of the vapor-etched layer has been evaluated by a reflectivity measurement and exhibits reflectivity values lower than 3%. The PL emission at both room and low temperatures emissions were deeply discussed and correlated with the structural properties of the Si morphologies and their surface states based on the FTIR results.

Enhancement of UV luminescence in Zn/ZnO nanocomposites synthesized by controlled thermal oxidation of Zn nano-octahedrals

Defect-free photoluminescence (PL) emission is always desirable for the practical applications of functional materials. The presence of metal nanostructures near the semiconductor can result in a reduction of defect emission, if present. Here, the enhancement of ultraviolet (UV) PL emission of Zn/ZnO nanocomposites (NCs) has been demonstrated with a corresponding reduction of defect-mediated PL emission. Zn/ZnO NCs have been synthesized by annealing of Zn nano-octahedral in the air (at 500 °C for 5 h). Annealing at 800 °C has been found to result in the complete oxidation of Zn and the formation of ZnO nanoparticles (NPs). UV and visible PL emissions have been observed from Zn nano-octahedral, Zn/ZnO NCs, and ZnO NPs. The observed PL emissions from Zn have been argued as due to transitions of electrons from sp band to the upper states of 3 d band. For ZnO and Zn/ZnO, UV emission is due to near-band-edge emission of ZnO and visible PL emissions are due to the presence of defect states in ZnO. About 2.15-fold enhancement of UV PL emission of Zn/ZnO NCs has been argued as due presence of metallic Zn in the Zn/ZnO NCs. Thus, the present study can open up a new avenue for Zn/ZnO NCs for possible applications in UV regions.

Application of CdTe quantum dots sensitized titanate nanotubes in photocatalytic degradation of organic pollutants under visible light irradiation

The use of solar-driven photocatalysis for the degradation of recalcitrant organic waste from water is a promising and environmentally friendly technology to meet the challenge of mitigating increasing global pollution. This paper presents a new composite of layered H2Ti3O7 hydrothermal nanotubes (TNT) with cadmium telluride quantum dots prepared by the simple mixing suspensions of both components in TNT/CdTe-QDs ratios in the range of 1:0.005–1:0.03. The products were characterized by X-ray diffraction, spectroscopic techniques such as Fourier transform infrared, Raman scattering, UV–visible diffuse reflectance, photoluminescence, and X-ray photoelectron spectroscopy, as well as by scanning and transmission electron microscopy. The photocatalytic performance of the products was tested by photocatalytic degradation of two molecular models of contaminants, methyl orange (MO) and 4-chlorophenol (4-CP). Nearly 100 % removal of organic contaminants was achieved and the degradation rate of MO and 4-CP under simulated sunlight in the presence of QDs was approximately five and four times faster than using TNT alone, respectively. The degradation rate response in the presence of specific radical scavengers corresponds to a direct Z-scheme photocatalysis. Recycling experiments demonstrated a structurally stable catalyst that maintains its efficiency after five irradiation cycles. Photoelectrochemical and photocurrent measurements validated the synergistic effect observed, reflecting that heterojunction promotes the transfer of photogenerated electrons and holes, decreasing recombination changes and improving photocatalytic activity.

Synthesis of PEDOT: PSS thin film doped with silver nanoparticles via green approach and study their refractive indices and dispersive parameters using Wemple–DiDomenico (WDD) single oscillator model

Silver nanoparticles (AgNPs) synthesised via green synthesis using clove extract were incorporated into PEDOT:PSS polymers using the chemical solution deposition technique (CSD), and the effect of surface plasmon resonance in the nanocomposites was investigated. To assess the effect of Silver nanoparticles (AgNPs) (and surface plasmon resonance) on the polymer, TEM, UV–Visible spectroscopy, FTIR, Ellipsometry, and Photoluminescence are used. The surface plasmon peak of the curves in UV–Vis spectroscopy study of these films has shifted towards the infrared region, which may be useful in increasing the efficiency of optical devices. The optical band gap calculated using UV–Vis results reduced from 1.77eV for pure PEDOT: PSS to 1.53eV for the nanocomposite. Ellipsometry data is used to calculate Ψ, Δ values and thickness of films. The Wemple-DiDomenico (WDD) single oscillator model was used to analyse and estimate the dispersion parameters of these films. Refractive indices the films were calculated in the range 1.256–1.643 using the Ellipsometry data.