Vis NIR Absorption Research Articles

Symmetry, aggregation and counterion role in tuning NIR absorbance of a Cu(I) coordination complex

A homoleptic Cu(I) coordination complex bearing N^N-bischelating functionalised biquinoline (BQCOOTEG) ligand and weakly coordinating counterions, BF4 or ClO4 respectively, was designed, synthesized and characterized. Hydrophilic tetraethyleneglycol chains functionalizing the ligands help water solubility of these compounds, that show aggregation in water with increasing concentration. Self-assembly behaviour in water was investigated by accurate 1H NMR and UV–Vis-NIR absorption studies, supported by computational studies, highlighting the influence of counterion-metal distance in tuning NIR absorbance of the complex.

Tether-directed regioselective synthesis of new cis-2ʹ azafullerene bisadducts

Embarking into unexplored realms beyond the C1equatorial-face and C1trans-4′ regioisomers, this study delves into the synthesis of cis-2ʹ C59N bisadducts. The synthesis involves a two-step process. Firstly, a Mannich-type reaction between bisazafullerene (C59N)2 and a tether yields a monoadduct. Further Bingel-Hirsch cyclopropanation results in the formation of the desired cis-2ʹ C59N bisadducts. Comprehensive spectroscopic techniques, including polarimetry and X-ray crystallography, confirm the absolute configuration (f,sclockwise or f,santiclockwise) of the enantiomerically pure cis-2ʹ C59N bisadducts. Circular dichroism measurements revealed the extremely high chiroptical activity of these inherently chiral bisadducts. Evaluation of their optoelectronic properties through Vis-NIR absorption, PL emission, and cyclic voltammetry techniques reveals distinctive bandgap and NIR emission, ranging from 1.31 to 1.81 eV and 700–1108 nm, respectively, showcasing promising potential for applications in energy conversion.

Structure and gamma attenuation behavior of copper ions in host glass from the system (P2O5–LiF–CaF2)

Copper-doped lithium calcium fluorophosphate glasses in the compositional system (60−x)P2O5·20LiF·20CaF2·xCuO (x = 0−3 mol%) were prepared using the conventional melt quenching technique. X-ray diffraction confirmed the amorphous, non-crystalline phase of the glasses. Optical absorption spectra indicated the presence of additional broad visible-NIR absorption bands upon CuO doping, attributed to distorted Cu2+ ions. Possible overlaps from Jahn-Teller distorted sites or clustering into nanodomains may contribute to band broadening. The direct optical bandgap was found to reduce from 3.89 eV to 1.17 eV with increasing CuO content. The study of physical parameters showed almost linear variation in density (2.62–2.95 g/cm3) and molar volume (40.45–35.29 cm3/mol) with incremental CuO substitution, explained by changes in structural packing efficiency and formation of Cu–O complexes. FTIR spectra revealed vibrations corresponding to phosphate structural groups. The simulation of radiation shielding parameters displayed steady improvements with higher CuO fractions, which were related to enhanced photon interactions via photoelectric absorption and Compton scattering.

Influence of Co-formers on the radiation shielding properties of zinc incorporated barium borate glasses for radioactive waste storage applications

The primary objective of the current investigation is to explore a novel series of Dy3+ions doped Zinc incorporated barium borate glasses synthesized through the classic melt quenching approach for the application of radiation defending. In this examination, the co-formers TeO2, Bi2O3, V2O5 and one of the glass formers P2O5comprised individually with the glass network. The non-crystalline phase of fabricated glasses symbolized by the empirical formula (64−x) B2O3+xA+15BaO+20ZnF2+1Dy2O3 (where x = 0, 20; A = P2O5, TeO2, Bi2O3, V2O5) and these pristine glasses were characterized by various techniques. Structural investigations were done by XRD, FTIR approach. FTIR analysis reveals the existence of functional group and their corresponding band assignments in the glass samples were recognized. The UV–Visible–NIR absorption spectra elucidates the optical properties including the energy transitions concerned with the trivalent Dysprosium ion, Urbach energy, direct and indirect bandgap energy using Tauc's plot method. The vanadium pentoxide (V2O5) co-former comprised glass network exhibits highly contrary behavior in optical scrutiny compared to other glasses. The Physical, structural attributes along with elastic properties are deliberated for the prepared glasses. The ionicity and covalency estimation validates the fact that the present glass samples exhibit maximum ionic nature. Radiation shielding parameters such as mass attenuation coefficients (MAC), half value layer (HVL) and effective atomic number (Zeff) for the titled glasses have been enumerated, discussed and reported. Among the prepared glasses, Bi2O3 co-former comprised glass exhibit better efficiency than the available concrete shielding materials.

Enhanced white light emission and quantum efficacy of borate-zinc–lithium-aluminium glasses doped with Dy2O3 for potential white light emission applications

The pursuit of efficient and enhanced white light emission in glasses doped with rare earth ions is a noble endeavour, one that has the potential to revolutionise many industries and benefit countless individuals. In view of this, we have prepared the Dy3+ ions doped Borate-Zinc–Lithium-Aluminium glasses via melt-quenching methods and their properties were meticulously studied using XRD, Raman, FTIR, DSC, Luminescence and time decay kinetic studies. To evaluate the influence of Dy2O3 doping, various physical parameters were analysed. The integration of Dy2O3 into the host glass matrix causes significant changes in the numerous physical parameters due to the geometrical structural change, resulting in the formation of non-bridging oxygens (NBOs), resulting in the increased compactness, thus the density and refractive index of the glasses. The DSC profile analysis reveals the thermal stability of the glasses. The UV–visible–NIR absorption spectra reveal the presence of a pronounced peak, owing to a hyperfine transition and other transitions dependent on the host. Furthermore, the Judd-Ofelt theory was applied to support the experimental results and evaluate the radiative parameters and efficiency. It was discovered that the JO parameters are in the following order: Ω2> Ω6> Ω4. The luminescence emission enhancement was observed with Dy2O3, up to 0.75 mol%; beyond that, the concentration quenching effect was observed. The glasses were proficiently fitted to the Inokuti-Hirayama model. Colorimetric parameters such as CIE coordinates, correlated colour temperature, and yellow-to-blue intensity ratios were estimated. It was discovered that, the sample containing 0.75 mol% of Dy2O3 doped glass is capable of white light emission with 72 % efficiency under excitation of 349 nm. Overall, present studies demonstrate that the thermal stability of glasses with phonon energy of 1330 cm−1, when stimulated at 349 nm and capable of producing white light, offers considerable benefits in relevant applications in the field of wLEDs.

Agricultural waste Ipomoea batatas leaves for low-temperature dyeing and functional finishing of polyester fabrics

The increasing focus on eco-friendly textiles and cleaner production manufacturing techniques have made natural pigments for coloring and enhancing the functionality of textiles become a popular trend. This research aimed to extract plant pigment from bio-waste Ipomoea batatas leaves and utilize it for dyeing and functional decoration of polyester fabric at low temperature. The study optimized the parameters for pigment extraction and fabric dyeing and also investigated the stability of the pigment solution. The finding indicated that strong acids and bases, intense light, high temperatures, and oxidants have a greater impact on pigment stability. Observation and analysis using SEM, bio-optical microscope, FTIR, and UV–vis–NIR absorption spectroscopy revealed that chlorophyll pigment entered into the interior of polyester molecular chains through hydrophobic end intercalation and was retained by the physical forces, enabling low-temperature coloring and functional finishing of polyester fabrics. As a result, the polyester fabrics dyed with natural pigment exhibited excellent resistance to rubbing, washing, saliva, and perspiration (rated at level 4 or higher), except for the average light fastness (only grade 4). Additionally, the dyed polyester fabrics demonstrated outstanding UV resistance (UPF of 33.57 for raw polyester and 120.77 for pre-mordant dyed polyester) and antibacterial properties (raw polyester agar plates showed bacterial growth, while the colored polyester agar plates had almost no bacterial growth). Even after 10 wash cycles, the dyed polyester fabrics maintained their UV protection and antibacterial properties. This research is expected to provide a new approach to the valuable utilization of agricultural residues in the textile industry.

Engineered praseodymium sulfide nanocarrier and supramolecular association of anticancer drug for effective delivery to breast cancer cells

Metal sulfide nanoparticles are synthesized for their biomedical applications, including cancer drug targeting. This paper reports a novel nanocomposite made of praseodymium sulfide nanoparticles and poly-cyclodextrin. The praseodymium sulfide nanoparticles were synthesized hydrothermal, autoclaving the nitrate precursors at 150 °C for 18 hours. The material is characterized using XRD and shows an orthorhombic crystal system with high crystallinity. The size and morphology of the nanomaterial were optimized. The material shows a rod-shaped morphology, as seen in the TEM image, with 150 ± 3 nm length and 25 ± 5 nm width. Particle size analysis supports this size range. The colloidal particles were stable in the aqueous medium without precipitation at neutral pH. The elements in the material in the polymer-coated form and their electronic states are studied by X-ray photoelectron spectroscopy. Thermogravimetry confirms that the material contains about 18.5% of the weight of the polymer. The material has an observable magnetic property at room temperature due to the praseodymium element. The UV–vis–NIR absorption spectrum of the material shows a long absorption range that extends to 1200 nm. The drug 5-fluorouracil is encapsulated in the nanoparticles through host: guest association, and its release profile is analyzed. The release is modulated at a slightly acidic pH, indicating the pH-tunability. The nanoparticles and 5-fluorouracil were taken in the w/w ratio of 2:1 (2/1 mg in 1 mL of deionized water). Further, the in vitro anticancer activity of the drug-encapsulated material is screened on breast cancer and non-cancerous cell lines. The IC50 values are reported, and the advantageous properties of the material as drug carriers are discussed.

Synthesis of cobalt doped nickel titanate nanomaterials for enhanced photocatalytic reduction of chromium

A series of cobalt doped nickel titanate nanomaterials where cobalt % is varied from 1 to 10% have been successfully synthesized by solvothermal method followed by calcination at 600 °C. Synthesized materials are characterized by XRD, FE-SEM, HR-TEM, BET surface area, DRS UV-Vis-NIR, XPS and PL spectroscopy. XRD and HR-TEM confirm the existence of NiTiO3 ilmenite structure with crystallite size in the range of 20–30 nm. HR-TEM of cobalt doped NiTiO3 shows the presence of tiny single atom cobalt metal sitting on NiTiO3, surface which induces the surface plasmon resonance effect. XPS of the doped NiTiO3 exhibits Ti3+ formation accompanied with oxygen vacancies resulting in the extended light absorption in the Vis-NIR region. The photocatalytic efficiency is studied monitoring the photoreduction of carcinogenic Cr (VI) under visible light. 3% cobalt doped NiTiO3 achieves 100% reduction of 30 ppm Cr (VI) solution within 60 min whereas pristine NiTiO3 shows only 50% efficiency under identical conditions. The trapping experiment shows the direct transfer of photogenerated electrons for the reduction of Cr (VI) following a first order kinetics. The two-fold enhanced activity of cobalt doped NiTiO3 is due to the collective effect of oxygen vacancies, efficient Vis-NIR absorption and surface plasmon resonance effect.

Judd-Ofelt analysis and NIR spectroscopy properties of Nd3+-doped Na2O/NaF-Al2O3-Y2O3-P2O5 glass and transparent glass-ceramics containing NaYP2O7 crystals

In the present work, the Nd3+-doped Na2O/NaF-Al2O3-Y2O3-P2O5 glass and transparent glass-ceramics were fabricated by conventional melting-quenching and subsequent heat treatment. The glass structure was studied by XRD, DSC, and FTIR spectrum, the fluorophosphate glass exhibits a more compact cross-link network. The UV–Vis–NIR absorption spectra, Judd-Ofelt theory, and photoluminescence spectra were used to explore the absorption and NIR spectroscopic features of the Nd3+-doped phosphate and fluorophosphate glasses. Under the excitation of 582 nm, the intense NIR emission in the Nd3+-doped glasses originating from the internal transition 4F3/2 → 4IJ/2 (J = 13, 11 and 9) was observed, and the transition 4F3/2 → 4I11/2 (1053 nm) is the most dominate. The transparent glass-ceramics (GC) was fabricated via heat treating on the precursor glass (PG) at Tg+100 °C, and the precipitation of NaYP2O7 crystals in GC was confirmed by XRD and SEM. With the benefit of the existence of the NaYP2O7 crystals, the Nd3+-doped GC exhibits higher NIR emission intensity, higher quantum efficiency (72.85% and 84.11%), larger σ(λp) values of 4.24×10-20 cm2 and 4.86×10-20 cm2, larger σ × Δλeff values of 10.22×10-26 cm3 and 11.67×10-26 cm3 than that of PG. These results indicate that the Nd3+-doped phosphate and fluorophosphate glasses and glass-ceramics may be used as a gain medium for 1053 nm laser emission.

Syntheses, structures and photophysical properties of Ni/Co[sbnd]Ln coordination polymers

The new Ni/Co-Ln coordination polymers (CPs), {[LnNi0.5(2,5-pydc)(ox)(H2O)x]·yH2O}n (Ln = Pr 1, Nd 2, x = 4, y = 2; Gd 3, Tb 4, Dy 5, x = 3, y = 1; 2,5-H2pydc = pyridine-2,5-dicarboxylic acid, H2ox = oxalic acid); {[Er2Ni(2,5-pydc)3(ox)(H2O)4]·2H2O}n6; {[LnCo0.5(2,5-pydc)(ox)(H2O)x]·yH2O}n (Ln = Pr 7, Nd 8, x = 4, y = 2; Tb 9, x = 3, y = 5) were successfully synthesized by the hydrothermal methods, and their crystal structures were characterized by single-crystal X-ray diffraction. With the participation of the auxiliary ligands (ox2−), the main ligands (2,5-pydc2−) adopt four coordination modes and make these polymers exhibit three kinds of crystal structures. CPs 1, 2, 7 and 8 are isomorphous and exhibit 2D layers which are further connected to form the 3D structure by hydrogen bonds. The other four CPs are bridged into the 3D network structure by 2,5-pydc2- and ox2−. All the polymers are characterized by IR spectro, Roman spectro, thermogravimetric analysis and X-ray powder diffraction. The UV–vis–NIR absorption spectra and Vis fluorescence excitation and emission spectra of nine coordination polymers are measured and analyzed. All the CPs show ligand-to-metal charge transfer (LMCT) transition emission of NiII/CoII–ligands, while some of the CPs show weak characteristic luminescence of LnIII ions.

Enhanced performance of self-powered CuS photodetectors with Al doping and dark current suppression

In this study, un- and aluminum (Al)-doped copper sulfide (CuS) nanostructures were synthesized using the sonochemical method and employed as a photodetector. The physical properties were characterized through X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) patterns, energy-dispersive X-ray (EDX) spectroscopy, X-ray photoelectron spectroscopy (XPS), UV–Vis-NIR absorption, photoluminescence (PL), and Raman spectroscopies. The CuS nanostructures exhibited a polycrystalline covellite structure. Al doping, at different concentrations, influenced the crystallite size, with a reduction at lower concentrations and an increase at higher concentrations. Transmission electron microscope images revealed that Al doping led to an increase in the average size of CuS nanostructures. Elemental analysis indicated Cu-poor stoichiometry, which was intensified with higher Al concentrations. Evaluation of electrical properties showed that all samples exhibited dominant hole (p-type) electrical conductivity. Moreover, in Al-doped CuS nanostructures, both the carrier density and diode coefficient increased compared to the undoped sample. Photodetectors fabricated with CuS nanostructures demonstrated that Al doping suppressed dark current and enhanced photocurrent.

Hybrid Zn-β-Aminoporphyrin–Carbon Nanotubes: Pyrrolidine and Direct Covalent Linkage Recognition, and Multiple-Photo Response

To unveil and shape the molecular connectivity in (metallo)porphyrin–carbon nanotube hybrids are of main relevance for the multiple medicinal, photoelectronic, catalytic, and photocatalytic applications of these materials. Multi-walled carbon nanotubes (MWCNTs) were modified through 1,3-dipolar cycloaddition reactions with azomethine ylides generated in situ and carrying pentafluorophenyl groups, followed by immobilization of the β-amino-tetraphenylporphyrinate Zn(II). The functionalities were confirmed via XPS and FTIR, whereas Raman spectroscopy showed disruptions on the graphitic carbon nanotube surface upon both steps. The functionalization extension, measured via TGA mass loss and corroborated via XPS, was 0.2 mmol·g−1. Photophysical studies attest to the presence of the different porphyrin–carbon nanotube connectivity in the nanohybrid. Significantly different emission spectra and fluorescence anisotropy of 0.15–0.3 were observed upon variation of excitation wavelength. Vis-NIR absorption and flash photolysis experiments showed energy/charge transfer in the photoactivated nanohybrid. Moreover, evidence was found for direct reaction of amino groups with a carbon nanotube surface in the presence of molecular dipoles such as the zwitterionic sarcosine amino acid.

Spectroscopic studies on Sm3+ ions doped modifiers incited calcium phospho-silicate glasses for photonic and optoelectronic applications

In order to learn the effect of incorporating the alkaline modifiers into the network of Sm3+ ions incorporated calcium-phospho silicate glass matrices, the glasses were synthesized by the usual melt-quench procedure with the novel compositional matrix 40P2O5+11SiO2+(30‒X) CaO+XMgO+6Sr2F+6LiF+6BaF+1Sm2O3 where (X=0, 5, 10, 15, 20, 25). The impact of concentration variation in alkaline modifiers (CaO and MgO) is carried out by several spectroscopic scrutinize such as UV–Vis-NIR absorption, and luminescence spectra on Sm3+ doped glasses. Incremental trend of absorption intensity is observed while decreasing the MgO's concentration and similarly, luminescence intensity gets increased. The trend of Judd-Ofelt (Ω6˃Ω4˃Ω2) parameters casts the ionic temperament of Sm−O bond and rigid binding between Sm3+ and chosen host. The ionic nature is further justified by the negative significance of the bonding parameter (δ) and also the provision of symmetric character of the Sm3+ ions by the calcium-phospho silicate host. Through Ω6, Ω4, and Ω2 parameter values, vital characteristics like emission cross-sections (σPE), effective bandwidth (Δλeff) or FWHM (full-width half maximum), branching ratio (βR), transition probabilities (A), and experimental lifetime (τexp) were calculated for the grading of lasing potential. Glass with 30% of CaO exhibits about 57% of branching ratio deliberated for 4G5/2→ 6H7/2 transition, shorter bandwidth, and higher transition probability are the disclosure of potential for lasing and LED applications. Quantum efficiency (η) is observed to be on the higher side for the glass with equal wt% of both CaO and MgO. The decay of 4G5/2 states was monitored, showing a non-exponential manner and it is consistent with all the prepared glasses. Along with color purity, Color coordinates (x, y) suggested that the emission wavelength of all other glasses is located at the reddish-orange region except for the glass with 30% of CaO. The emission line shifted nearer to the white light region.

Evaluating the Phosphorescence duration of Zn2P2O7 glass–ceramic activated by Dy3+/Pr3+ for LED applications

The present study focuses on investigating the phosphorescence efficiency of binary zinc–phosphate glasses co-doped with dysprosium and/or praseodymium oxides together with their corresponding glass ceramics. The studied glass series was prepared directly by the conventional melting and quenching method. Differential thermal analysis (DTA) indicated an exothermic peak at 550 °C that was applied to yield glass-ceramic samples. The major monoclinic phase of Zn2P2O7 was detected by X-ray diffraction (XRD). FTIR and SEM–EDAX were applied to identify the structural morphology of the prepared samples. The optical efficiency was characterized through UV–Visible–NIR absorption spectra and photoluminescence analysis. Both light emissions and their corresponding lifetimes were enhanced significantly in glass–ceramic. These samples display high CRI, low color temperature, and CIE values comparable to those expected for pure white-light and warm yellow emitting diodes.

The effect of oxygen vacancies on the color formation of aquamarine

Oxygen vacancy is an inherent defect of aquamarine crystals. The concentration and properties of this defect have an essential influence on aquamarine crystals and optical properties. This paper reports that blue in aquamarine crystals is due to the interaction between Fe2+ and oxygen vacancy. Infrared and Raman spectra showed that more Fe2+ replaced Al3+ in dark sample A than in light sample B. Oxygen vacancies were found in all samples. Dark sample A strongly absorbed the 830 nm band associated with Fe2+ in the UV–Vis–NIR absorption spectrum. The band gap of dark sample A was smaller than that of light sample B, and the difference in band gap was related to the concentration of oxygen vacancies. X-ray Photoelectron Spectroscopy showed that the oxygen vacancy concentration in sample A was higher than that in sample B, which showed that the oxygen vacancy concentration affected the color depth of aquamarines.

Crystal growth, structural, optical, thermal, DFT and Z-scan analyses of Imidazolium 3,4-dinitrobenzoate crystal

The organic crystal of imidazolium 3,4-dinitrobenzoate single crystal was grown by slow evaporation solution method using methanol as a solvent. The grown crystal structure was confirmed by single crystal X-ray diffraction (SXRD) analysis. The chemical characterization including 1H and 13C NMR was performed. The presence of functional groups is confirmed by FTIR and FT-Raman analyses. The intermolecular interactions of the imidazolium 3,4-dinitrobenzoate molecule are determined using Hirshfeld surface analysis. The UV–Vis-NIR absorption spectrum reveals that there is no absorption peak after 360 nm to 1200 nm. The violet and blue emissions were observed in the photoluminescence (PL) study. The thermal stability of the title crystal is determined using TG/DTG analysis. The DFT study on the imidazolium 3,4-dinitrobenzoate crystal provided additional information on geometrical, electrical, and structural characteristics. The HOMO-LUMO, natural bond orbital analysis (NBO), molecular electrostatic potential (MEP), the density of states (DOS), the crystal's dipole moment, polarizability, and hyperpolarizability analyses are used to find out structural, electrical, and optical properties of the title crystal. The Z-scan technique was used to find out the crystal's third-order nonlinear optical (NLO) characteristics.

Comparative studies on CIELab, thermal and optical characteristics of Dysprosium (Dy3+) incorporated phospho-tellurite glasses for white light generation

Concentration dependence of Dy3+ activated strontium lead phospho-tellurite glass series have been synthesized by melt quenching process. To explore the structural, thermal and optical traits of the present glasses we have investigated XRD, FTIR, DTA, UV–Vis–NIR absorption, optical band gap, excitation band, luminescence emission, decay lifetime and CIE chromaticity diagram, and analysed the Judd-Ofelt intensity parameters Ωλ (λ = 2,4,6) and various radiative parameters in detail. The photoluminescence spectra exhibit highly intense blue and yellow emissions at around 483 and 573 nm. The better values of yellow/blue intensity ratio and branching ratio (βexp) suggest that the proposed glass series are efficient candidates for visible laser media. Emission quenching effect has been observed beyond 1 mol% Dy3+ doping concentration. The luminescence lifetime of the 4F9/2 excited level declines with increasing Dy3+ doping level. The experimental lifetime and quantum efficiency of 1 mol% Dy3+ activated glass are acquired to be 0.75 ms and 81%, respectively. The appearance of chromaticity coordinates as well as CIELab coordinates in the white region highlights that the present glass system could be most promising for white light generation.

Highly efficient near-infrared electrochemiluminescence resonance energy transfer system for biosensing: Nonmetallic plasmon Mediated well-matched energy donor-acceptor pair

Herein, a well-matched energy donor-acceptor pair strategy was designed to construct highly efficient NIR ECL-RET system. In detail, an ECL amplification system consisting of SnS2 quantum dots decorated Ti3C2 MXene nanocomposites (SnS2 QDs-Ti3C2) as the energy donor were developed via a one-pot method, and the nanocomposites exhibited highly efficient NIR ECL emission due to the surface-defect effect generated by the oxygen-containing functional groups in MXene. Nonmetallic plasmon hydrated defective tungsten oxide nanosheets (dWO3•H2O) were utilized as energy acceptors because of its strong surface plasmon resonance effect in Vis-NIR absorption range. Compared with non-defective tungsten oxide hydrate nanosheets (WO3•H2O), the overlapping area between ECL spectrum of SnS2 QDs-Ti3C2 and UV–vis spectrum of dWO3•H2O was increased by 2.1 times, and the results showed that more efficient quenching effect was obtained. As a proof of concept, tetracycline (TCN) aptamer and its complementary chain were served as a bridge to connect the energy donor and acceptor, achieving the successful construction of NIR ECL-RET aptasensor. The as-fabricated ECL sensing platform exhibited a low detection limit of 6.2 fM (S/N = 3) within a wide linear range from 10 fM to 10 μM. Besides, the NIR ECL-RET aptasensor also showed excellent stability, reproducibility and selectivity, providing a promising tool to detect TCN in real samples. This strategy offered a universal and effective method in constructing highly efficient NIR ECL-RET system for developing rapid, sensitive and accurate biological detection platform.

SnO2-Cu2S nanocomposites: Structural and optical properties with enhanced photocatalytic activities for ciprofloxacin antibiotic and methylene blue dye degradation

Pharmaceutical products and industrial dyes released to water bodies have become major environmental concerns and applications of nanomaterials for their remediation have been receiving a lot of research attention in recent years. In this connection, different SnO2–Cu2S nanocomposites (NCs) have been synthesized by growing Cu2S over previously prepared SnO2 nanocrystals by taking different molarities of copper and sulphur precursors. The pure SnO2 nanocrystals have been prepared by the chemical co-precipitation method combined with calcination of the precipitated materials at 300 °C. X-ray diffraction (XRD) pattern of the pure SnO2 nanocrystals shows the formation of tetragonal crystal structure. UV–visible–NIR absorption spectrum of the pure SnO2 nanocrystals records absorption peak in the UV region, while the Tauc's plot estimates the band gap of SnO2 to be 3.93 eV. Photoluminescence (PL) and electron paramagnetic resonance (EPR) studies reveal the presence of oxygen vacancies in the pure SnO2 nanocrystals. XRD patterns of the NCs comprise of diffraction planes from both tetragonal SnO2 and monoclinic Cu2S. PL studies show presence of both oxygen vacancies and copper vacancies in the NCs. Further, presence of copper vacancies has been evidenced in the EPR signals of the NCs. The NCs show significantly enhanced photocatalytic activities for degradation of ciprofloxacin (CIP) antibiotic and methylene blue (MB) dye under simulated sunlight irradiation, which is attributed to type II heterojunction formation between SnO2 and Cu2S. The NC with the best performance as a photocatalyst degrades 96% of CIP after 120 min and 98% of MB after 210 min of light exposure.

Leveraging visible and near-infrared spectroelectrochemistry to calibrate a robust model for Vanadium(IV/V) in varying nitric acid and temperature levels

Spectroelectrochemistry and optimal design of experiments can be used to rapidly build accurate models for species quantification and enable a greater level of process awareness. Optical spectroscopy can provide vital elemental and molecular information, but several hurdles must be overcome before it can become a widely adopted analytical method for remote analysis in the nuclear field. Analytes with varying oxidation state, acid concentration, and fluctuating temperature must be efficiently accounted for to minimize time and resources in restrictive hot cell environments. The classic one-factor-at-a-time approach is not suitable for frequent calibration/maintenance operations in this setting. Therefore, a novel alternative was developed to characterize a system containing vanadium(IV/V) (0.01–0.1 M), nitric acid (0.1–4 M), and varying temperatures (20–45 °C). Spectroelectrochemistry methods were used to acquire a sample set selected by optimal design of experiments. This new approach allows for the accurate analysis of vanadium and HNO3 concentration by leveraging UV–Vis–NIR absorption spectroscopy with robust and accurate chemometric models. The top model's root mean squared error of prediction percent values were 3.47%, 4.06%, 3.40%, and 10.9% for V(IV), V(V), HNO3, and temperature, respectively. These models, efficiently developed using the designed approach, exhibited strong predictive accuracy for vanadium and acid with varying oxidation states and temperature using only spectrophotometry, which advances current technology for real-world hot cell applications. Additionally, Nernstian analysis of the V(IV/V) standard potential was performed using traditional absorbance methods and multivariate curve resolution (MCR). The successful tests demonstrated that MCR Nernst tests may be valuable in highly convoluted spectral systems to better understand the redox processes' behavior.