UV-vis Absorption Spectroscopy Studies Research Articles

Enhancement of Fluorescence Mediated by Silver Nanoparticles: Implications for Cell Imaging.

In this study, we report the surface enhanced fluorescence (SEF) of a biologically important organic dye, fluorescein (FL), by silver nanoparticles (Ag NPs) in an aqueous medium and its implications for human cell imaging. The as-synthesized Ag NPs were characterized by dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), and UV-vis absorption spectroscopic studies. The interaction and aggregation of FL dye with Ag NPs and a cationic surfactant, namely, cetyltrimethylammonium bromide (CTAB), were explored by UV-vis absorption and steady-state and time-resolved fluorescence spectroscopic methods. The distance-dependent fluorescence enhancement of FL due to Ag NPs in the solution was also theoretically correlated by three-dimensional finite-difference time-domain (3D-FDTD) simulation. The plasmonic coupling between neighboring NPs facilitated the augmentation of the local electric field, thereby producing various "hotspots" that influence the overall fluorescence of the emitter. J-type aggregates of FL in the presence of the CTAB micelles and Ag NP mixed solution were confirmed by electronic spectroscopy. The density functional theoretical (DFT) study revealed the electronic energy levels associated with different forms of FL dye in the aqueous solution. Most interestingly, the Ag NP/FL mixed system used in fluorescence imaging of human lung fibroblast cells (WI 38 cell line) showed a significantly stronger green fluorescence signal compared to that of FL after an incubation period of only 3 h. This study confirms that the Ag NP mediated SEF phenomenon of the FL dye is also manifested in the intracellular medium of human cells giving a brighter and more intense fluorescence image. The cell viability test after exposure to the Ag NP/FL mixed system was confirmed by the MTT assay method. The proposed study may have an implication as an alternate approach for human cell imaging with higher resolution and more contrast.

Corallocarpus epigaeus mediated synthesis of ZnO/CuO integrated ZrO2 nanoparticles for enhanced in-vitro antibacterial, antifungal and antidiabetic activities

Zirconia based nanocomposites have attracted much research attention in recent years due to their exceptional biomedicinal activities. Rhizome extracts of Corallocarpus epigaeus based ZrO2/CuO–ZnO nanocomposite were green synthesized in a facile synthesis strategy. The nanocomposites were examined with XRD technique for their structural information and FT-IR technique for surface functional group analysis. Electron microscopic images aided to elucidate the CuO and ZnO nanoparticles decorated ZrO2 nanostructures. UV–vis absorption spectroscopic studies of the nanocomposite revealed the characteristic UV absorption of ZrO2 and enhanced visible region absorption for the incorporated nanoparticles. Antibacterial and antifungal studies indicated enhanced activity of nanocomposites over the pristine zirconia nanoparticles. ZrO2/CuO–ZnO nanocomposite had exhibited about 75% of α-amylase inhibition activity, whereas pristine ZrO2 nanoparticles had exhibited only 57% suggesting the worthwhile application in the antidiabetic activity of the nanocomposite.

Size reduction process by novel TVA technique and its effect on enhancement of physical properties of oxide semiconductor pellets

ABSTRACT This work describes a novel approach that can reduce grain as well as particle size of semiconducting pellet samples in the nanoscale range with low-cost and less instrumentation. Herein an instrumental setup was designed and fabricated in-house, referred to as the ‘Thermo-Vibrational Annealing’ (TVA) setup. Here, the concept of grain confinement within the pellet during the recrystallisation phase of annealing was achieved by simultaneously applying both thermal and vibrational mechanical energy to the sample, followed by vibrational dry quenching. In this work, for the case study, ZnO pellets were prepared by using chemical route pyrophoric method followed by annealing at 800°C for 4 hours using this setup. The reduction of particle and grain size by this TVA, in comparison to without vibrational annealing, was confirmed by X-ray diffraction (XRD), high-resolution transmission electron microscopy and scanning electron microscopy studies. The expected changes in other microstructural and optical properties were examined by Raman and UV-Visible absorption spectroscopy studies. Moreover, this work gives references to improve the physical properties not only of ZnO but also of other oxide semiconductor samples using this technique, to be used in multiple sensors and optoelectronic devices.

Morphology Control of Supramolecular Assembly for Superior CO2Photoreduction

Coordination-driven metallo-supramolecular assemblies are potentially efficient catalysts in photocatalytic CO2 reduction. However, the relationship between morphology and photocatalytic performance remains barely explored. In this work, three metallo-supramolecular assemblies composed of Zn2+ and a flexible tris(terpyridine) ligand have been prepared for noble metal-free CO2 photoreduction on the basis of metal–ligand coordination, hydrogen bonding, and π–π stacking. The three assemblies possess distinct self-assembled morphologies including spherical particle, fibrous-like gel, and microrod. It has been found that the fibrous-like gel exhibits the best catalytic performance in photoreduction of CO2 to CO with a yield of 6.3 mmol g–1 h–1 and 94.7% selectivity over H2 generation. Photoelectrochemical measurements, photoluminescence quenching experiments, and UV–vis absorption spectroscopy studies have demonstrated that the ligand-based electron transfer of the gel is more efficient compared with the other two assemblies.

Interaction of Victoria Blue Dye in Anionic and Cationic Micellar Media: Spectroscopic Study

This manuscript has reported the micellar interaction of cationic triphenylmethane-based dye andquot;Victoria Blue-B (VBB)andquot;. The study was conducted using ionic surfactants viz. Cetyltrimethylammonium Bromide (CTAB)] Sodium Dodecyl Sulphate (SDS), and Sodium Docusate (SD). The behavior of dye in micellar media at concentration ranges of the surfactants mentioned above was monitored by UV-vis absorption spectroscopic study. The solubilization parameters to reveal the interaction of cationic dye in micellar media were assessed. The mathematical calculations of partition constant (Kc), partition coefficient (Kx), binding coefficient (Kb), Gibb’s free energy for partition (ΔGp) and binding (ΔGb) were derived from UV–Vis absorption data. The presence of anionic surfactants caused more bathochromic shifts in the maximum absorption of the dye, which was indicative of strong interactions as compared to the cationic surfactant.

Mg-Doped KFeSO4F as a High-Performance Cathode Material for Potassium-Ion Batteries

Potassium iron sulfate fluoride (KFeSO4F) is a high-voltage positive electrode material for potassium-ion batteries, but its practical performance remains limited due to its moderate electronic conductivity. In this study, we employed Mg ion doping in the Fe site of KFeSO4F to tune the crystallinity and ionic/electronic conductivity. Furthermore, we made a composite with carbon nanotubes to enhance the electrode’s electronic conductivity. In a K-ion cell filled with concentrated potassium bis(fluorosulfonyl)amide/triglyme electrolyte, the KFe0.95Mg0.05SO4F/CNT composite electrode delivers discharge (potassiation) capacities of 107 and 100 mAh g–1 in the first and 100th cycles at a rate of 0.1C with reasonable rate capability. UV–vis absorption spectroscopy studies of Mg-doped KFeSO4F powder samples showed a narrower band gap compared to KFeSO4F. Furthermore, from the combined results of X-ray diffraction and absorption spectroscopy studies, we found that multiple two-phase reaction mechanisms through the Fe3+/Fe2+ redox occurred during the reversible depotassiation/potassiation cycle.

Spectroscopic determination of the role of vanadyl oxygen in room temperature NH3 sensing by V2O5 nanoparticles

In the present study, a multi-modal approach consisting of in-situ photoluminescence, Raman, and UV-Vis absorption spectroscopic studies is carried out along with chemiresistive sensing to unveil the mechanism of NH3 gas sensing by V2O5 nanoparticles in ambient air. V2O5 nanoparticles with an average size of 49 nm show a superior sensor response of 17 ± 1.5 % towards 1 ppm of NH3 gas with a response and recovery time of 96 s and 45 s, respectively. The photoluminescence and UV-Vis absorption studies in the presence of NH3 reveal electron doping to a new energy level at 1.84 eV, resulting in conduction band filling and increase in the optical band gap. The intensity of the photoluminescence spectrum shows an increase in the presence of NH3 gas as a result of this electron doping. The sensor response from the optical sensing carried out by in-situ photoluminescence study is 43 % for 40 ppm of NH3 gas. The vanadyl oxygen site is the most active in the sensing process, as evident by a selective enhancement in the intensity of V–O (vanadyl) bond vibration. This study gives an experimental evidence for the changes in optical and electronic properties of V2O5 on the adsorption of NH3 gas molecules.

Reactions of cisplatin and oxaliplatin with penicillin G: implications for drug inactivation and biological activity

Determination of the toxicity of compounds toward cancer cells is a frequent procedure in drug discovery. For metal complexes, which are often reactive prodrugs, care has to be taken to consider reactions with components of the cell culture medium that might change the speciation of the metal complex before it is taken up by the cells. Here, we consider possible reactions between the clinical platinum drugs cisplatin and oxaliplatin with penicillin G, an antibiotic added routinely to cell culture media to prevent bacterial contamination. Platinum has a high affinity for ligands with sulfur donors. Penicillin G is an unstable thioether that degrades in a range of pathways. Nuclear magnetic resonance (NMR) and UV–Vis absorption spectroscopic studies show that reactions with cisplatin can occur within minutes to hours at 310 K, but more slowly with oxaliplatin. The identities of the Pt- adducts were investigated by mass spectrometry. The marked effect on cytotoxicity of co-incubation of cisplatin with penicillin G was demonstrated for the HeLa human cervical cancer cell line. These studies highlight the possibility that reactions with penicillin G might influence the cytotoxic activity of metal complexes determined in culture media.Graphical abstract

Catalytic degradation of Methylene blue dye and Antibacterial study of silver nanoparticles obtained using Murraya Koenigii leaf Extract

Introduction: The development of eco-friendly, cost-effective green protocol for the synthesis of nanomaterials is a significant feature of nanobiotechnology connecting synthesis of nanomaterials using microorganisms, including bacteria, viruses, fungi as well as plant and animal based products (1). There is much room of more development in the synthesis of nanoparticles using different biological resources as the source of reducing and stabilizing agents and their potential applications. Silver nanoparticles (AgNPs) are of great interests owing to their optical, electrical, catalytic, and antibacterial properties (1). For waste-water treatment, nanoparticles can exhibit effectiveness in catalytic dye degradation due to the characteristic catalytic properties of nanoparticles (2). In this paper, we have demonstrated an eco-friendly green approach for the room temperature synthesis of biocompatible AgNPs by the reduction of aqueous silver ions using Murraya koenigii (Mk) leaf extract. Methods: The aqueous plant extract was prepared by taking 10 g of pulverized Mk leaves in a 500 mL Erlenmeyer flasks with 60 mL of Milli-Q water and refluxed it for 15 min with constant stirring using magnetic stirrer (2). 9 mL (0.625%) NH3 solution was added to 2 L of 10-3 M aqueous AgNO3 solution followed by the addition of 90 mL of aqueous Mk leaf extract at controlled pH = 7 and homogenized by using a magnetic stirrer. Then the reaction mixture was kept for 5 h at room temperature followed by centrifugation at 6000 rpm for 30 min. The envisaged color change from transparent yellow to dark brownish indicates the formation of AgNPs (2). Results & Discussions: Synthesized AgNPs were well characterized by UV-Visible absorption spectroscopy, FTIR spectroscopy, XRD, DLS, HRTEM and EDX studies. AgNPs would exhibit SPR band at 402 nm. FTIR studies confirmed the presence of different biomolecules responsible for the stabilization as well as formation of AgNPs. Surface morphologies and size distribution of synthesized AgNPs were determined by HRTEM and DLS techniques, respectively. The average particle size was found 20 nm. XRD analysis confirmed the formation of face-centered cubic (FCC) crystalline lattice of AgNPs. EDX studies confirmed the presence of elemental silver (Ag). AgNPs can act as photocatalyst for the degradation of methylene blue (MB) used as a model cationic dye. AgNPs were nontoxic in nature as concluded from cytotoxicity studies and also exhibited substantial antibacterial activities towards gram-positive and gram-negative bacteria. Conclusions: In the present study, stable AgNPs were successfully prepared by a green route using aqueous Murraya koenigii leaf extract in simple, cost-effective, eco-friendly way using less hazardous reagents and solvents, and thereby non-toxic towards both human health and the environment. AgNPs were almost spherical in shape, crystalline in nature, with an average diameter of 20 nm. AgNPs showed catalytic activity for the degradation of a cationic dye MB. AgNPs were nontoxic in nature and can exhibit considerable antibacterial activity towards both gram-positive and gram-negative bacteria. Keywords: Biosynthesis, AgNPs, photocatalysis, methylene blue, antibacterial activity Acknowledgment: UKS would like to acknowledge financial support from the projects funded by the DHESTBT (Department of Higher Education, Science, Technology and Biotechnology), Government of West Bengal (Memo no. 161(sanc)/ST/P/S&T/9G-50/2017.

Structural and optical behavior of SnS2/NiFe2O4 NCs prepared via novel two-step synthesis approach for MB and RhB dye degradation under sun light irradiation

The present investigation focuses on facile two-step synthesis approach fabrication of tin sulfide (SnS2)/ nickel ferrite (NiFe2O4) nanocomposites (NCs) for the first time. The crystallinity and phase purity of the prepared material was investigated in powder X-ray diffraction (PXRD) studies. The presence of functional groups (stretching and bending vibration) was primarily determined by the Fourier Transform Infrared Spectroscopy (FT-IR) analysis. As well as, optical behavior of the synthesized samples was determined in UV–Vis absorption spectroscopic studies, and the presence of surface defects was established by PL spectroscopic studies. From the FESEM analysis, sponge-like structure was attained and Ni, Fe, Sn, S and O elemental component was determined by the EDAX spectrum analysis. The as-prepared SnS2/NiFe2O4 NCs exhibit superior photocatalytic performance and high stability toward the reduction of methylene blue (MB) and rhodamine B (RhB) dyes under irradiation of direct sunlight. The synthesized nanocomposites showed an efficient photocatalytic activity with a high reaction kinetic rate.

Tetra(4-methoxyanilinium) hexachlorostannnate (IV), dichloride: Synthesis, crystal structure, hirshfeld surface analysis, DFT calculations, thermal properties and third-harmonic generation measurement of nonlinear optical susceptibility

New hybrid organic–inorganic material has been obtained at room temperature by the reaction of tin chloride with 4-methoxyaniline in acidified water: tetra(4-methoxyanilinium) hexachlorostannnate (IV), dichloride ([SnCl6]2−, 4(C7H10NO)+, 2Cl−), (I). Synthesized compound has been fully characterized by single-crystal X-ray diffraction, FTIR and UV–visible absorption spectroscopy studies, TGA/DTA and SEM/EDS analyses. Crystal structure of (I) was determined by single-crystal X-ray diffraction analysis. The structure is governed by charge assisted N+–H···Cl cation–anion hydrogen bonds that permit alternation between organic/inorganic layers. The intermolecular interactions were investigated using Hirshfeld surface analysis. The thermal behavior of (I) was also discussed using TGA/DTA which showed the thermal stability of the compound upto 190°C. The DFT calculations have been performed by using the B3LYP method at the LANL2DZ level. For the new hybrid compound, we have also measured the value of the electronic part of third-order nonlinear optical susceptibility χ3 using third harmonic generation (THG) method at 1064 nm.

A Series of Ultra-Efficient Blue Borane Fluorophores.

We present the first examples of alkylated derivatives of the macropolyhedral boron hydride, anti-B18H22, which is the gain medium in the first borane laser. This new series of ten highly stable and colorless organic-inorganic hybrid clusters are capable of the conversion of UVA irradiation to blue light with fluorescence quantum yields of unity. This study gives a comprehensive description of their synthesis, isolation, and structural characterization together with a delineation of their photophysical properties using a combined theoretical and experimental approach. Treatment of anti-B18H22 1 with RI (where R = Me or Et) in the presence of AlCl3 gives a series of alkylated derivatives, Rx-anti-B18H22-x (where x = 2 to 6), compounds 2-6, in which the 18-vertex octadecaborane cluster architectures are preserved and yet undergo a linear "polyhedral swelling", depending on the number of cluster alkyl substituents. The use of dichloromethane solvent in the synthetic procedure leads to dichlorination of the borane cluster and increased alkylation to give Me11-anti-B18H9Cl2 11, Me12-anti-B18H8Cl2 12, and Me13-anti-B18H7Cl2 13. All new alkyl derivatives are highly stable, extremely efficient (ΦF = 0.76-1.0) blue fluorophores (λems = 423-427 nm) and are soluble in a wide range of organic solvents and also a polystyrene matrix. The Et4-anti-B18H18 derivative 4b crystallizes from pentane solution in two phases with consequent multiabsorption and multiemission photophysical properties. An ultrafast transient UV-vis absorption spectroscopic study of compounds 4a and 4b reveals that an efficient excited-state absorption at the emission wavelength inhibits the laser performance of these otherwise remarkable luminescent molecules. All these new compounds add to the growing portfolio of octadecaborane-based luminescent species, and in an effort to broaden the perspective on their highly emissive photophysical properties, we highlight emerging patterns that successive substitutions have on the molecular size of the 18-vertex borane cluster structure and the distribution of the electron density within.

Cost-effective scalable synthesis of few layers MoS2 based thin film for sunlight enforced photocatalytic activity

Abstract Two-dimensional (2D) semiconductor nanostructures have gained tremendous interest in the field of environmental remediation and water purification. Nanostructures coated surfaces provide new insight for the development of cost-effective advanced photocatalyst. In this study, 2D-MoS2 nanosheets based coating has been developed through the combined effort of the exfoliation and a spin coating method. Microscopy analysis inferred the formation of nanosheets from the bulk structured MoS2 with the reduction in their average dimensions. Exfoliated MoS2 nanosheets formed in 18 h reaction time has average length ~1019 nm and width~544 nm. Cross-sectional SEM studies confirm the formation of MoS2-PVA thin films with different orientation of MoS2 nanosheets. UV–Vis absorption spectroscopy studies exhibit two peaks at 619 nm and 680 nm with improved optical absorption. The XRD and Raman spectroscopy analysis reveals the 2H-phase of MoS2 nanosheets. 2D-MoS2-PVA composite thin film was tested as an advanced photocatalyst coating for the breakdown of methylene blue (MB) and malachite green (MG) pollutant molecules under sunlight. 2D-MoS2-PVA composite thin film decomposed the 5 μM solution of MB and MG molecule solutions in 80 min and 40 min, respectively, under sunlight (800 W/cm2). The efficient photodegradation performance of the 2D-MoS2-PVA composite indicates their potential usage in other environmental applications.

Identifying the Stoichiometry of Metal/Ligand Complex by Coupling Spectroscopy and Modelling: a Comprehensive Study on Two Fluorescent Molecules Specific to Lead.

Two new chemosensors for lead (II) were synthesized based on 5-((anthracen-9-ylmethylene) amino)quinolin-10-ol (ANQ). ANQ was modified in the para position of the imine group via a methoxy link either with methylmethacrylate (ANQ-MMA) or styrene (ANQ-ST). Complexation of those molecules with Pb2+ was studied at room temperature using UV-Visible absorption and fluorescence spectroscopies. Thanks to the UV-visible absorption spectroscopy, it appeared that ANQ-MMA formed 1:1 and 1:2 complexes with lead (II) and ANQ-ST only 1:1 complex. For both molecules, the fluorescence excitation-emission matrices (EEM) signal intensity increased from 0 to 100μmol.L-1 of lead (II) followed by a saturation for higher concentrations. The decomposition of the obtained EEMs gave a set of empiric fluorescent components that have been directly linked to the distribution of lead complexes obtained with the UV-visible absorption spectroscopy study. This correlation allowed to evidence metal/ligand complex stoichiometry and emerge as a new method to identify empiric components. Moreover, the two ligands showed a promising selectivity for Pb2+, turning them interesting probes for this hazardous metal.

The influence of UV light on the azathioprine photodegradation: New evidences by photoluminescence

Abstract In this work, we report a photodegradation process of azathioprine (AZA) highlighted by correlated studies of photoluminescence (PL) and the UV-VIS and IR absorption spectroscopy. The photodegradation process of AZA is observed by the gradual increasing in the intensity of the PL spectrum recorded under the excitation wavelength of 300 nm. This behaviour is accompanied, in the photoluminescence excitation (PLE) spectra, by a gradual intensity decreasing of the PLE band situated in the 250–320 nm spectral range simultaneous with the intensity increasing of the PLE band localized in the 325–425 nm spectral range. Regardless if the immunosuppressive compound is in the state of powder, tablet or solution, the PL and UV-VIS absorption spectroscopy studies have demonstrated that a photodegradation process under UV light takes place. According to the PL studies carried out in ambient and vacuum condition, the photodegradation process of AZA was demonstrated to be influenced by the oxygen from air. The presence of a new IR band with maximum at 1745 cm−1 confirms the AZA photodegradation pathway proposed in this work.

Evolution of SPR in 120 MeV silver ion irradiated Cu (18%) C60 nanocomposites thin films

Copper metal embedded fullerene C60 thin films are deposited on various substrates via resistive heating co evaporation technique. Rutherford back scattering simulated spectrum confirms the thickness and composition of thin film to be ~ 32 nm and ~ 18 at%, respectively. The deposited thin films are irradiated by 120 MeV Ag ion beam for different fluences within the range, from 1 × 1012 to 3 × 1013 ions/cm2. UV–vis absorption spectroscopy study reveals the appearance of surface plasmon resonance (SPR) band in pristine thin film at ~ 622 nm; this phenomenon is ascribed to the presence of copper nanoparticles in C60 matrix. The SPR band intensity increases with rising fluences, which is suggestive of the growth of Cu nanoparticles. Growth of Cu nanoparticles is further confirmed by transmission electron microscopic (TEM) and X-ray diffraction (XRD) study. Whereas the conversion of C60 into amorphous carbon (a-C) is confirmed by Raman spectroscopy, XRD results of pristine Cu–C60 thin film record the presence of Cu2O within the nanocomposite thin film. However, both X-ray photoelectron spectroscopy (XPS) and XRD studies on irradiated thin film samples authenticate the growth of Cu metal nanoparticles with concurrent removal of oxygen.

Luminescent versus non-luminescent uranyl–picolinate complexes

Luminescence of uranyl ion (UO22+) complexed with picolinate (PA) has been studied in aqueous and acetonitrile medium. In aqueous medium, for UO22+ to PA ratio of up to 1:20, a 1:1 non-luminescent specie with stability constant of log β = 3.88 was formed. On the contrary, formed specie in acetonitrile medium was luminescent and the enhanced luminescence was due to sensitization by PA and reduction in non-radiative decay channels. UV–Vis absorption spectroscopy studies revealed that the luminescent specie was 1:2 type complex. Density functional theory and DLPNO-CCSD(T) methodologies were applied to arrive at the lowest-energy structures of the 1:1 and 1:2 uranyl–picolinate complexes.

In situ high-pressure spectroscopic studies using moissanite (4H-SiC) anvils

We examined the Raman scattering and IR absorption spectroscopy of 4H-SiC and its performance as an anvil material for high-pressure UV-visible absorption spectroscopic measurements. The first- and second-order Raman peaks of 4H-SiC and diamond do not coincide. 4H-SiC does not have obvious signals from 2330-5000 cm-1, suggesting that 4H-SiC anvils are beneficial for high-pressure studies of samples whose Raman signals locate in the region of diamond. Above 1800 cm-1, the transmitted signal of 4H-SiC in the IR absorption spectra, measured through 4.6 mm thickness is much higher than that of type IIa diamond. An in situ high-pressure UV-visible absorption spectroscopy study on CdI2 was carried out up to 28.0 GPa using 4H-SiC anvil cells (4H-SAC) with a 400 μm culet and the acquired band gap narrowed with increasing pressure. These results show that 4H-SiC has an excellent performance in high-pressure spectroscopic studies.

Optical, spectral and photovoltaic characterization of natural dyes extracted from leaves of Peltophorum pterocarpum and Acalypha amentacea used as sensitizers for ZnO based dye sensitized solar cells

The ZnO nanorods were synthesized using hydrothermal method. The morphologies, crystalline nature and optical properties of the synthesized ZnO nanorods were characterized by X-ray diffractometer, High-resolution scanning electron microscopy [HRSEM], and UV–Vis absorption spectroscopic studies. A thin layer of ZnO nanorods were spread on transparent conducting FTO coated glass plate using Doctor Blade method. Natural dyes extracted from Peltophorum pterocarpum and Acalypha amentacea leaves with solvents such as water and ethanol were used as sensitizers to fabricate dye sensitized solar cells (DSSCs). The extracted dyes were characterized by Fourier transform infrared (FTIR) and UV–Visible absorption spectroscopy. The FTIR confirms the presence of anthocyanin, carotene and chlorophyll molecules in the dye extracts. The influence on the different parameters such as open circuit voltage (VOC) short circuit current (JSC), fill factor (FF), and power conversion efficiency (η) of the dye sensitized solar cells (DSSCs) were analyzed. The ZnO nanorods provide high specific surface area for dye adsorption and the pathway is efficient for electron transportation.

Utilising the interface interaction on tris(hydroxymethy)aminomethane-capped carbon dots to enhance the sensitivity and selectivity towards the detection of Co(II) ions

In this paper, a facile and green thermal carbonisation approach was adopted for the synthesis of carbon dots (CDs) from α-cellulose. The conditions during the synthesis have been optimised to produce CDs with highest fluorescence intensity. Later, tris(hydroxymethy)aminomethane (TRIS) was introduced to the isolated CDs as capping agent on the interface of the CDs. TRIS was chosen due to the well reported capability to interact with various metal ions to form complexes. Particularly in this study, TRIS has enhanced the specificity and sensitivity features of CDs to detect cobalt (II) ions, (Co(II) ions). The UV–vis absorption spectroscopy study performed has found that the CDs can effectively interact with TRIS, while the assembled CDs/TRIS system later can form complex with Co(II) ions. In this case, TRIS has acted as the bridge to bring CDs and Co(II) ions to a close proximity in distance, which subsequently promoted the energy transfer due to the good overlapping in the emission of the CDs with the absorbance of the Co(II) ions. The process was observed clearly by the concentration dependent fluorescence quenching in the presence of increasing amount of Co(II) ions. This has been demonstrated for the first time and the system has been suggested to be used as a single shot detection probe for Co(II) ions in aqueous media. The probe was found to be effective for the detection of Co(II) ions with a linear response up to 1.87 mM and a limit of detection of 16.84 μM. This study has presented some new insights on the surface interface interaction between CDs and its capping agent and demonstrated its potential application for metal ions sensing.