PL Studies Research Articles

Prompt photocatalytic purification of dye wastewater using zinc doped nickel oxide nanostructures and Artima salina model for acute toxicity screening

Industrial organic contaminates in water bodies are toxic not only to aquatic plants and animals but also to the entire ecosystem. The present study focuses on eradicating these industrial pollutants using zinc ions doped nickel oxide nano photocatalysts. Ultrasonication-aided co-precipitation method was used to synthesize Zn doped NiO nanoparticles which were further analyzed for their structural, optical, morphological, elemental, and photocatalytic abilities. Bragg diffraction patterns of synthesized samples revealed that zinc ions were successfully loaded in the NiO lattice as cubic nano-crystallites with Fm3m, space-group. FTIR study supported the formation of Zn –Ni linkages and Ni-O stretching vibrations. Tauc plot found that optical band gap energy decreases from 3.2 to 2.7 eV. PL study revealed the charge recombination process delayed by an intermediate band to enhance photocatalytic activity. The formation and reduction of clear rectangular rod structures by increasing zinc dopant materials and the composition of Ni, Zn, and O elements were explored in SEM-EDX images. XPS, TEM and SAED patterns corresponded quite well with the XRD results. Pseudo-first-order kinetics of photocatalytic degradation analysis predicted that Zn doped NiO nanostructures show their suitableness for preventing Rhodamine B and 4-Nitrophenol contaminates (up to 95 % and 80 %) in aquatic media under direct sunlight. Further, detox and practical usage of Zn doped NiO were confirmed by the Artemia salina organism’s considerable lifespan in the treated water using a toxicity evaluation model. Based on these observations, it is expected to facilitate an expedited remedy of toxicity screening for regulatory purposes.

Synthesis, characterization and application of MWCNT/TiO2 composite for photocatalytic reduction of benzophenone to benzopinacol

Photocatalytic reactions are widely investigated as a green chemistry approach towards organic molecule synthesis. Herein, we fabricated (MWCNT/TiO2) composite materials which are beneficial in the photocatalytic synthesis of benzopinacol on irradiation with UV–visible light. The precursor-layer-coating (PLC) method was successfully employed to produce a series of composite materials, X%-MWCNT/TiO2, where (X = 2, 4, 6, and 8 % w/w). The XRD confirmed major-anatase and minor-brookite TiO2 along with MWCNT in the composite. FE-SEM, HR-TEM, and EDAX revealed the expected composite microstructure, morphology, and compositional details. The nanosized (10 ̶30 nm), spherically shaped TiO2 particles were seen integrated to the MWCNT surface. The BET-surface area of the mesoporous composites enhanced from 83.77 to 114.39 m2/g as the MWCNT loading increased from 2 % to 8 %. The optical studies indicated a marginal shift in absorption edge towards longer wavelength with % MWCNT loadings. The band gap (Eg) was reduced and the charge pair recombination rate retarded. The PL, Raman and XPS studies supported the heterojunction formation at the interface. The photocatalytic activity was evaluated based on the % conversion efficiency of benzophenone to benzopinacol in the presence of light and composite as a photocatalyst. The 6 %-MWCNT/TiO2 demonstrated the highest photoactivity with an additional 34 % and 25 % yield in UV and sunlight respectively compared to bare TiO2. The effective light absorption, electronic excitation, charge pair separation and transfer mechanism at the MWCNT/TiO2 interface were responsible for enhanced photoactivity. The current investigation provided a promising strategy to produce hybrid photocatalytic material for organic molecule synthesis.

The significant role of Z-scheme band alignment at the heterojunction for the enhanced photocatalytic H2 production in TiO2/BiNbO4/rGO nanocomposite

An efficient ternary TiO2/BiNbO4/rGO nanocomposite was prepared by a simple wet impregnation process. PXRD confirmed the tetragonal and orthorhombic crystalline natures of titanium dioxide (TiO2) and bismuth niobate (BiNbO4) respectively. The loading of BiNbO4 and reduced graphene oxide (rGO) shifted the light absorption of TiO2 to a longer wavelength from 400 to 430 nm. The suitable conduction band position of BiNbO4 facilitated a favourable band alignment to suppress the electron/hole (e−/h+) recombination in TiO2 via the Z scheme mechanism at the heterojunction. The excited electrons at the CB of TiO2 were easily transported via the fast electron accepting and conducting rGO matrix for the surface redox reactions with the improved charge transfer efficiency, which was confirmed by EIS and PL studies respectively. BiNbO4 and rGO synergistically improved the specific surface area and solar light absorption. EPR analysis confirmed the presence of increased oxygen vacancies at the heterojunction. Hence, the ternary TiO2/BiNbO4/rGO nanocomposite demonstrated an enhanced hydrogen evolution (8910 μ mol h−1 gcat−1) than bare TiO2 (4820 μ mol h−1 gcat−1), bare BiNbO4 (950 μ mol h−1 gcat−1) and TiO2/BiNbO4 (6730 μ mol h−1 gcat−1) under direct solar light. The optimum of 1 wt % BiNbO4 and rGO loaded TiO2 nanocomposite produced twice the H2 production than the bare TiO2. This also further confirms that rGO played a major role during the photocatalytic process by highlighting the potential of metal oxides combined with carbon material as an efficient photocatalyst which prominently enhances the H2 evolution.

An insight in to microwave induced defects and its impact on nonlinear process in NiO nanostructures under femtosecond and continuous wave laser excitation.

This work demonstrates the impact of microwave (MW) irradiation on third-order nonlinear optical (NLO) processes in chemically deposited NiO nanostructure films. The optical nonlinearity of the NiO nanostructure films was studied using third-harmonic generation (THG) measurements in the pulsed femtosecond laser regime and the Z-scan technique in the continuous wave laser regime. In the ultrafast pulsed regime, THG measurements revealed a significant increase in the THG signal of MW-irradiated NiO nanostructures due to photoexcitation and relaxation processes, resulting from an enhancement in defect concentration. This increase in defect density upon MW irradiation was quantified by PL and XPS studies. Under continuous wave laser irradiation, the Z-scan technique showed an enhanced absorption coefficient of ∼10-1 m W-1 and a nonlinear refractive index of ∼10-7 m2 W-1. The high NLO values in both pulsed and continuous laser regimes indicate that MW-irradiated NiO nanostructure films hold promise for optoelectronic device applications.

Enhanced sonophoto-catalytic and adsorption capabilities of Fe3O4@MC/MWCNT-CuO/Ag for petrochemical organic pollutants degradation from industrial process streams

To address the problem of petrochemical organic pollutants in water, specifically monoethylene glycol (MEG) present in industrial process streams, in this research, we synthesized and evaluated a multifunctional nanocomposite, Fe3O4@MC/MWCNT-CuO/Ag. The nanocomposite was produced by combining magnetic Fe3O4 nanoparticles, methylcellulose (MC), multi-walled carbon nanotubes (MWCNTs), and CuO/Ag nanoparticles by an integrated synthesis process. A consistent dispersion of nanoparticles, with diameters ranging from 30-40 nm, was discovered by FESEM analysis, showing effective integration without aggregation. Effective synthesis was demonstrated by well-doped and evenly dispersed CuO and Ag nanoparticles. Functional groups that improve electrostatic interactions with contaminants hence enhancing catalytic performance and adsorption efficiency, were validated by FTIR analysis. XRD indicated an unchanged crystal structure with an average crystallite size of 8.67 nm. The anticipated elemental composition was verified by EDS & mapping. A VSM study revealed magnetic characteristics (9.33 emu/g) that simplify nanocomposite separation and reuse. TGA proved thermal stability to be up to 600 °C. A BET study showed a highly specific surface area of 67.661 m2/g, enhancing adsorption. According to DRS and PL studies, the bandgap was lowered by 1.31 eV, which led to better optical absorption. The nanocomposite exhibited notable MEG removal efficiency, with 72 % in adsorption, 65 % in photocatalysis, and 56 % in sonocatalysis. This makes it a promising alternative for the remediation of organic pollutants in water treatment.

Sunlight-driven charge separation for a heterojunction of nano-pyramidal CuWO4-MOF modified TiO2 nanoflakes for photocatalytic degradation of ciprofloxacin

The study presents a breakthrough of a balanced charge separation for heterojunction CuWO4-TiO2 cocatalyst to efficiently enhance visible light photocatalytic degradation of ciprofloxacin (CIP). A solvothermal-synthesized nanopyramid-like CuWO4 semiconductor was assembled before sol–gel treatment with TiO2 precursors to generate CuWO4-TiO2 nanocomposites. The optical, structural, and morphological properties of CuWO4-TiO2 were elucidated using UV–Vis DRS, XRD, FTIR, Raman spectroscopy, and TEM/SEM techniques. The UV–Vis DRS spectroscopy of as-synthesized CuWO4-TiO2 cocatalyst demonstrated enhanced visible light absorbance. The XRD patterns of CuWO4-TiO2 revealed a triclinic phase nanocrystal. The O-Ti–O functionality was confirmed by FTIR spectroscopy. The photoactive bands corresponding to anatase redshift were observed from Raman spectroscopy of CuWO4-TiO2 nanocomposite. The PL studies attributed this redshift to the elevated extra energy bands that aid electron/hole pair charge separation in a co-catalyst heterojunction CuWO4-TiO2 nanocomposite afforded by embedding CuWO4-MOF within TiO2 crystalline. The TEM showed that un-sintered CuWO4.MOF mimicked a pyramidal shape and converted to nanoflakes upon sintering, while TiO2 and CuWO4-TiO2 retained a tetragonal shape. The photocatalytic activity of CuWO4-TiO2 cocatalyst was studied using CIP, as a model pollutant. The innovative design of 5CuWO4-TiO2 charge separation nanocomposite completely degraded 10 mg L−1 CIP solution at pH = 6.31 (natural pH) and 9 under 120 min of sunlight irradiation.

Investigating the physicochemical, optical and microstructural properties of sodium doped CdO nano powders fabricated by co-precipitation technique for blue emission and antimicrobial applications

A series of cubic structured pristine and sodium doped CdO nanoparticles (Cd1-xNaxO NPs) with varying dopant concentrations have been synthesized using simple Co-precipitation process. Crystal structure and the connection between various structural parameters are evidenced using powder XRD diffractograms. The crystallite size is evaluated with different models and the mean crystallite size was reduced with Na ions doping concentration due to severe lattice distortion. The existence of various vibrational modes and functional groups were demonstrated through FTIR characterization. The signature of Cd–O and Na–O stretching modes were confirmed with FTIR. Raman spectra also confirmed the formation of metal–oxygen bond and the second order vibration features. The direct bandgap of the CdO material increased from 2.132 to 2.40 eV with an increase in the Na dopant content which presents the appearance of a blue shift as probed through UV–Vis spectroscopy. The surface morphology and microstructure of the samples were studied using FESEM and HRTEM images, respectively. EDAX measurements revealed the presence of Cd, and O in the host lattice and Cd, O and Na in the doped CdO constructions. The SAED concentric ring pattern of Cd1-xNaxO nanoparticles demonstrated the polycrystalline nature of the samples. PL study revealed the impression of intrinsic defects and the photoluminescence colour emission of the Cd1-xNaxO materials shifted more towards bright blue region as the Na doping concentration increased. CIE color coordinates of Na-doped CdO NPs shows intense bluish color and extending its applications in commercial UV lighting, blue LEDs and Fluorescent biological labelling and tagging. Cd1-xNaxO nanoparticles exhibited enhanced antibacterial activity with increasing Na doping content towards gram-positive, and gram-negative bacteria. Further, the antifungal analysis against C. albicans, and A. niger authenticate that Na+ substituted CdO nanoparticles shows excellent antifungal activity. The mechanism of the above observed results is examined in detail in this article.

Enhancing and broadening the photoresponse of CdS nanowire by constructing core–shell heterostructure

Limited by the severe surface recombination and large bandgap, it is still a challenge to achieve a high-performance broad-spectrum photodetector based on CdS nanowires (NWs). In this work, the CdS/GeS core–shell heterostructure is constructed to enhance and broaden the photoresponse of CdS NWs. The CdS/GeS core–shell heterostructure NWs are prepared by the chemical vapor deposition method, exhibiting smooth surfaces, controlled shell thicknesses, and compositions. From the UV-Vis-near-infrared (NIR) diffuse reflectance spectrum, PL, and time-resolved photoluminescence studies, it is found that the surface recombination is weakened and the light absorption range is widened after the constructing core–shell heterostructure. When configured into photodetectors, the responsivity of the CdS/GeS core–shell heterostructure NWs is up to 76.8 A W−1, which is 10 folds higher than that of pristine CdS NWs. Furthermore, the photoresponse wavelength of the CdS/GeS core–shell heterostructure NWs is extended from 405 to 850 nm. The improved photodetection performance is attributed to the effective separation of photogenerated carriers at the heterostructure interface, weakened surface recombination, and excellent light absorption of the GeS shell. All results imply that constructing core–shell heterostructures is an effective strategy for constructing high-performance photodetectors.

Carbon dot enhanced electrodeposited coatings for advanced early-stage corrosion sensing

This work explores a novel approach for metal corrosion by integrating carbon dots (CDs) into electrodeposited (ED) coatings. We detail the synthesis and properties of CDs, making them suitable for corrosion detection. Characterization techniques like Fourier Transform Infrared Spectroscopy (FTIR), Scanning electron microscope (SEM), Energy Dispersive X-ray Analysis (EDX), Fluorescent Microscopy and Photoluminescence Spectroscopy (PL).A Design of Experiment (DOE) optimized parameters like CD concentration, curing temperature, and voltage for improved coating performance. The optimized conditions (0.4 wt% M-CDots, 165 °C curing, and 36.2 V) resulted in enhanced adhesion and corrosion resistance.CD-infused coatings demonstrated superior adhesion and mechanical stability compared to controls. Electrochemical tests confirmed a 10 % improvement in corrosion resistance and PL study demonstrated an approximately 60 % enhancement in emission intensity. The adhesion was not affected by introducing carbon dots to the coating. Monitoring the onset of metal corrosion on samples in salt spray cabinets was achieved through the use of a UV source. The photoluminescence of M-CDs offered real-time, non-destructive monitoring of early-stage corrosion through quenching in the presence of exposed metal surfaces.This research presents a significant advancement by integrating CD-based sensing into corrosion-resistant coatings, holding promise for various industries and leading to improved safety, reduced maintenance costs, and extended equipment lifespans. Notably, the biocompatible and disposable nature of CD-based sensors further enhances their practical application.

Ultra-fast switching of energy efficient electrochromic nickel oxide thin films for smart window applications

In today's modern world, energy consumption continues to escalate. In such cases, smart windows play a crucial role in reducing energy consumption and enhancing the quality of life. Electrochromic devices (ECDs) -based smart windows rely profoundly on nickel oxide (NiO) thin films, which act as a counter electrode in ECDs. This work aims to fabricate NiO thin films, with the intention of achieving ultrafast ECD. Through the sputtering technique, energy-efficient ECD is obtained with the highest optical modulation of 60 % at a rapid switching speed of 0.55s for bleaching and 0.95s for coloration. We have also investigated the structural, morphological, vibrational, and optical properties of NiO thin films. XRD analysis revealed the less crystalline or near amorphous nature of NiO thin film. XPS, PL, and Raman studies confirm the existence of defects in the film. The favourable, less crystalline nature, along with the presence of defects, facilitates ultra-fast ion intercalation and de-intercalation process. We believe that prepared NiO film can be used as a promising anodic colourant in electrochromic smart windows with applications in energy-efficient buildings.

Investigating the effect of nitrogen and chlorine Co–doped carbon quantum dots in phenazine and quinoxaline sensitized solar cells

We investigated five dyes for dye-sensitized solar cells (DSSCs) relying upon derivatives of phenazine and quinoxaline and also studied their optical characteristics and the influence of functional groups such as (-CH3, -NO2, -C = O, -CN, and -OH) on these characteristics. When the prepared dyes are directly used at DSSCs, 9-Nitrobenzo[a]phenazin-5-ol (3b) dye device showed an improved Jsc (0.288 mA cm−2), Voc (0.437 V), FF (0.446), and η (0.056 %) than the sensitized solar cells by other dyes. In the following, nitrogen-doped carbon quantum dot and nitrogen, chlorine co-doped carbon quantum dot are used to improve the performance of DSSCs. The results showed that the device sensitized using the sensitizer (5-hydroxybenzo[α]phenazin-9-yl)(phenyl) methanone (3c)/NCQD has the highest photovoltaic efficiency with Jsc (0.979 mA cm−2), Voc (0.465 V), FF (0.370), and η (0.168 %). The N and Cl co-doped carbon dots were synthesized with a green approach to improve the performance of solar cells by the co-sensitization method. This approach is improving the efficiency of DCSSs with a simple, eco-friendly, and low-cost technique. Among the prepared sensitizers, (5-hydroxybenzo[α]phenazin-9-yl)(phenyl) methanone (3c)/N, Cl-CQD demonstrates the highest photovoltaic efficiency with Jsc (1.31 mA cm−2), Voc (0.495 V), FF (0.466), and η (0.303 %). FT-IR, XRD, 13C NMR, 1H NMR, TEM, EDS-Map, AFM, DLS, and PL studies were used to confirm the structure of the synthesized dyes and quantum dots.

A Comparative Study on the Degradation of Methylene Blue and Methyl Orange Dyes Under the Irradiation of Visible Light Using GO–CdO Nanocomposites

Cadmium oxide nanoparticles synthesized from alcoholic method using cadmium chloride monohydride and the composites with GO by simple dispersion method. Two nanocomposites with 5 Wt% and 10 Wt% loading of CdO over GO were prepared and named as GC1 and GC2 respectively. From XRD the CdO nanoparticles were of crystalline nature and were indexed to JCPDS card no: 05-0640 corresponding to Cubic lattice system. The particle like morphology of the CdO was confirmed by SEM and TEM. The decoration of monolayer GO sheets by CdO nanoparticles was unveiled through these studies. The Raman analysis reveals the presence of D and G peaks in the composites with an increased ID/IG ratio. UV-Vis study displays the absorption edge of CdO and a redshift is observed for GC2. From PL study, emission peak occurs at 358 nm for composites along with a quenching of intensity for GC2. The TG-DT analysis reveals the thermal stability of pristine and nanocomposites. Photocatalytic degradation of the as synthesized samples was studied for Methylene orange and Methylene blue dye using a Xenon lamp with 500 W. The degradation of the GC2 happens in 90 minutes with degradation efficiency 73% of was achieved for Methyl Orange dye. For Methylene blue the GC2 sample degrades only in 30 minutes with an efficiency of 94% was achieved.

Microwave-assisted synthesis of Ni-doped europium hydroxide for photocatalytic degradation of 4-nitrophenol

Microwave-assisted synthesis method was used to prepare europium hydroxide (Eu(OH)3) and different percentages of 1, 5, and 10 % nickel-doped Eu(OH)3 (Ni–Eu(OH)3) nanorods (NRs). X-ray diffraction study showed a hexagonal phase with an average crystallite size in the range of 21 – 35 nm for Eu(OH)3 and Ni–Eu(OH)3 NRs. FT-IR and Raman studies also confirmed the synthesis of Eu(OH)3 and Ni–Eu(OH)3. The synthesized materials showed rod-like morphology with an average length and diameter between 27 – 50 nm and 8 – 13 nm, respectively. The band gap energies of Ni–Eu(OH)3 NRs were reduced (4.06 – 3.50 eV), which indicates that the doping of Ni2+ ions has influenced the band gap energy of Eu(OH)3. The PL study exhibited PL quenching with Ni doping. The photocatalytic degradation of 4-nitrophenol (4-NP) by the synthesized materials under UV light irradiation was investigated, in which 10 % Ni–Eu(OH)3 NRs showed the best response. A kinetic study was also conducted which shows pseudo-first-order kinetics. Based on this, Ni–Eu(OH)3 NRs have shown a potential to be a UV-light active material for photocatalysis.

A dual-purpose photocatalytic reaction for hydrogen evolution and simultaneous organic pollutant degradation of V2O5/Ppy based composite photocatalyst

The present work reports for the facile synthesis of novel vanadium oxide/polypyrrole (V2O5/Ppy) nanohybrids using various loadings of the V2O5. This novel hybrid photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, UV–Visible absorption spectra (UV–Vis), photoluminescence spectra (PLS) and N2 adsorption-desorption analysis. XRD and TEM results suggest that V2O5 with individual spherical shaped nanoparticles of around 20–25 nm, which is uniformly wrapped on the surface of the Ppy sheets. A significant reduction in the bad gap energy (3.06–2.13 eV) and prevent the electron-hole recombination process was examined by UV and PL studies. The photocatalytic degradation efficiency was carried out for Reactive Black 31 (RB 31) and 4-chlorophenol (4-CP) dyes under visible light. The results illustrate that the optimal hybrid catalyst could reach 99 % of removal efficiency towards RB31 with visible light irradiation for 60 min. Moreover, the catalyst show high TOC efficiency (88%) high apparent constant (0.9189 min−1), and good stability with multiple cycle experiments. The improved photocatalytic mechanism was also discussed in detail. In comparison to V2O5 (425 μmol−1h−1 of H2) and PPy (151 μmol−1h−1 of H2), the optimised composite, 15 wt% V2O5 incorporated PPy showed a remarkable production rate under visible light (2255 μmol−1h−1 of H2).

Green synthesis of polyoxometalate Cu3Mo2O9 nanoparticles for efficient degradation of organic dyes under visible light irradiation and their photoluminescence

Well-constructed photocatalysts with efficient catalytic activity have attracted much attention due to their efficient visible-light absorption and superior charge separation capability. Visible-light responsive Cu3Mo2O9 nanoparticles are synthesized utilising a simple and environmentally friendly green combustion process with Butea monosperma leaf extract as a reducing agent. X-ray diffraction pattern confirms the formation of orthorhombic crystal structure of Cu3Mo2O9 NPs corresponding to space group Pnma (62). Furthermore, the synthesized NPs were characterized using FTIR, UV-DRS, PL, SEM and TEM studies. It was found that the direct energy band gap was 2.29 eV. Through photodegradation in the presence of visible light, the dye-sorbed photocatalyst exhibited excellent results. The sorbents have also been examined for recycling, and it has been observed that they maintain their effectiveness even after multiple successive runs. These substances therefore appear to have potential as efficient industrial dye wastewater remediators. Moreover, the high intensity emission in the green zone is amply confirmed by the photoluminescence emission spectra and CIE coordinates. The Latent fingerprints (LFP) are visible with the application of the powder dusting process. The synthesized CMO nanoparticles exhibit ridge patterns that are well-resolved and useful for identifying unique LFP.

A comparative study of Fe (II) doped chiral L/D-methionine carbon dots (MCDs) as a “Turn-on” fluorescent probe for the sensitive detection of L – cysteine

Chiral carbon dots have prominently influenced in the field of chemical, biological, and medicinal research. Comparing to achiral carbon dots, chiral carbon dots exhibit unique characteristics in biosensing application. In this perspective, we have developed bright blue, fluorescent L and d-Methionine Chiral carbon dots (MCDs) using a simple microwave assisted process for effective sensing of l-Cysteine. l-Cysteine plays a vital role in balancing the physiological redox in the body. These MCDs can be complexed with Fe2+ ions to create an energy transfer quenching system due to distinctive N and S functional group distribution on their surface. However, l-Cysteine attaches to Fe2+ ions in a competitive manner, leads to recovery of MCDs fluorescence. As a result, a "turn-on" fluorescent sensing platform based on L and d-Methionine-CDs has been developed for the rapid identification and detection of l-Cysteine. The probe shows good selectivity and sensitivity with coexisting biomolecules and ions. From comparative PL studies, d- MCDs are more responsive than l-Meth CDs towards the detection of l-cysteine with LOD of 0.71 µM and 0.94 µM respectively. The chiroptical properties were evaluated and the probe extends its practical application in paper strip and in biological matrix such as human blood serum with satisfactory recoveries in the range 85–104%.

Spectroscopic investigation and molecular docking analysis of an FRET probe: Trypsin from bovine pancreas@Coumarin 440 dye conjugate

Herein, a systematic investigation of energy transfer from bovine pancreas trypsin to coumarin 440 (C440) dye is presented with an aim to design a FRET probe, as trypsin is an important enzyme for absorption and digestion of nutrients in the small intestine. Conformational changes in trypsin upon interaction with C440 dye are studied by employing both spectroscopic and molecular docking techniques. Steady state and time resolved measurements validate the formation of trypsin-C440 complex via dynamic quenching, that confirms the role of C440 as an inhibitor to suppress the activity of trypsin. Spectral overlap integral, Förster's distance, rate and energy transfer efficiency are calculated from steady state measurements. The observed blue shift in fluorescence suggests conformational changes due to hydrophobicity that arises in trypsin structure on binding with C440 possibly due to their interaction through H-bond (SER195 and GLN192), hydrophobic (GLN192 and HIS57) and π-π stacking bonding (HIS57). The stability of trypsin@C440 bio-conjugate at higher temperature was established from temperature dependent PL studies and the thermodynamic parameters determined agree with second law of thermodynamics. The thermodynamic parameters such as change in enthalpy (ΔH=172.2Jmol−1), change in entropy (ΔS=15.3Jmol−1K−1) and the respective approximately same and unity values of Gibb's free energy (ΔG) and Hill coefficient (n), as well as binding affinities determined from temperature dependent fluorescence studies validate the hydrophobic, spontaneous, exothermic process engaged in trypsin@C440 bio-conjugate.

Synthesis, characterization and luminescent properties of N-donor based samarium-tris-β-diketonate: Tuning optoelectronic characteristics for displays applications

Ternary Sm(III) complexes of general representation [Sm(TFDH)3L] were synthesized to understand influence of different auxiliary moieties on their optoelectronic properties. The synthesized complexes were thoroughly investigated using elemental, IR, NMR, UV and PL studies. In these complexes, the emitting metal ion is bonded with six O atoms from di-ketone 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione and two nitrogen atoms from neutral ligand i.e. 1,10-phenanthroline and its derivatives. Proton NMR spectral data showed that samarium ion induced chemical shift is dipolar in nature. The photoluminescence analysis showed that the complexes show intense orange-red emission due to 4G5/2 → 6H9/2 transition. Moreover, CIE color coordinates supported the results obtained from photoluminescence study, providing additional confirmation of the luminescent properties of prepared complexes within the orange-red region. Their utility in displays and OLED's was confirmed by studying their optical and electronic band gaps.

Strategically tailored double S-scheme heterojunction in h-MoO3 doped Bi7O9I3 decorated with Cr–CdS quantum dots for efficient photocatalytic degradation of phenolics

Phenolic compounds are widely used in various industrial processes, but they can be harmful to the environment if released without proper treatment. In this study, we developed a ternary nanocomposite (NCs) consisting of molybdenum trioxide, bismuth oxoiodide, and chromium-doped cadmium sulphide quantum dots h-MoO3/Bi9O7I3/Cr–CdS QDs (MBC) nanocomposite (NCs) to enhance the photocatalytic degradation of p-chlorophenol (p-CP). The nanomaterial morphology, distribution of depositing material, and heterojunction formation were investigated using SEM, TEM, SAED, and elemental mapping. Further, the structural characterization was done by XRD, XPS, and Raman spectroscopy which confirmed its purity, chemical states, bonding nature, and the presence of oxygen vacancies (OVs) and sulphur defects. The 30-MBC NCs exhibited the highest surface area of 354.5 m2/g and pore volume of 0.76 cm3/g, with the H3 hysteresis loop indicating their mesoporous nature. The Kubelka-Munk plot determined the band gap of the NCs to be 2.22 eV and ensured successful visible-light sensitization. PL and ESR studies revealed that 30-MBC NCs had the lowest charge carrier recombination and highest ROS production. The photocatalytic degradation of p-CP by 30-MBC NCs achieved 94% in 300 min. The highest efficiency was observed at 75 mg/L NCs, 150 mg/L p-CP, and pH 6. Additionally, NCs retained activity in the presence of different ions and degraded 82% p-CP even after six consecutive cycles. •O2− was the dominant ROS involved in the degradation process, while OVs and sulphur defects played a crucial role in ameliorating charge transfer in the 30-MBC NCs. GC-MS/MS analysis identified the possible degradation pathways of p-CP, and ECOSAR showed that less toxic by/end products were produced. Overall, this study highlights the promising potential of 30-MBC NCs for extensive wastewater treatment.

A new approach to the synthesis of CuMoO4 nanoparticles with mechanistic insight into the sunlight-assisted degradation of textile pollutants and antibacterial activity evaluation

CuMoO4 nanoparticles (NPs) were synthesized by a thermal decomposition followed by a precipitation method. Analytical techniques such as SEM, EDS, TEM, XRD, FTIR, UV-visible, PL, and XPS were employed to characterize the structural, optical and photocatalytic properties of CuMoO4. As per XRD analysis, CuMoO4 with different Cu concentrations were consistent, however, their crystallinities were changed. The band gap of CuMoO4 with various concentrations of Cu (0.1, 0.2, and 0.3M) was estimated to be 1.97eV, 1.86eV, and 1.44eV, respectively. The electrical conductivity of 0.3M CuMoO4 NPs was greater than other nanocomposites. Methylene Blue (MB) mineralization in an aqueous medium after 180minutes of exposure to sunlight was investigated to study the photocatalytic activities of all CuMoO4 composites. As per the PL study, the 0.3M CuMoO4 NPs exhibited better photocatalytic efficiency due to their low electron-hole recombination rate. Experimental parameters like the MB concentration, catalyst dosage, and the solution pH were evaluated to optimize the experimental conditions. The in-situ capture analysis proposed a plausible mechanism for the photocatalytic degradation of MB. The two main active species identified for MB degradation were superoxide radical anions and hydroxyl radicals. The repeated photocatalytic MB degradation verified the high level of reusability of 0.3M CuMoO4. The well-diffusion technique was utilized to examine the antibacterial activity of 0.3M CuMoO4 NPs against gram-positive (Salmonella typhi) and gram-negative (Streptococcus mutans) bacterial strains. Optimized CuMoO4 showed excellent promise for application in the field of photocatalysis, electrocatalytic and antibacterial activity.