Ultraviolet Diffuse Reflectance Spectroscopy Research Articles

Excellent Dark/Light Dual-Mode Photoresponsive Activities Based on g-C3N4/CMCh/PVA Nanocomposite Hydrogel Using Electron Beam Radiation Method.

Photocatalytic technology for inactivating bacteria in water has received much attention. In this study, we reported a dark-light dual-mode sterilized g-C3N4/chitosan/poly (vinyl alcohol) hydrogel (g-CP) prepared through freeze-thaw cycling and an in situ electron-beam radiation method. The structures and morphologies of g-CP were confirmed using Fourier infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), solid ultraviolet diffuse reflectance spectroscopy (UV-vis DRS), and Brunauer-Emmett-Teller (BET). Photocatalytic degradation experiments demonstrated that 1 wt% g-CP degraded rhodamine B (RhB) up to 65.92% in 60 min. At the same time, g-CP had good antimicrobial abilities for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) within 4 h. The shapes of g-CP were adjustable (such as bar, cylinder, and cube) and had good mechanical properties and biocompatibility. The tensile and compressive modulus of 2 wt% g-CP were 0.093 MPa and 1.61 MPa, respectively. The Cell Counting Kit-8 (CCK-8) test and Hoechst33342/PI double staining were used to prove that g-CP had good biocompatibility. It is expected to be applied to environmental sewage treatment and wound dressing in the future.

Electrospun hydroxypropyl-β-cyclodextrin nanofibers loaded with anti-inflammatory drugs for potential therapeutic wound dressings

Electrospun cyclodextrin nanofibers as innovative drug delivery structures offer efficient, selective, and controlled drug release. In the present work, free-standing nanofibrous webs (NFs) were fabricated from inclusion complexes (ICs) between 2-hydroxypropyl-β-cyclodextrin (HPβCD) and non-steroidal anti-inflammatory drugs (NSAIDs) using an electrospinning technique. The fabricated NSAID-HPβCD-IC-NFs were characterized by field emission scanning electron microscopy, X-ray diffraction, thermogravimetric/differential thermal analysis, ultraviolet diffuse reflectance spectroscopy, and photoluminescence analysis. Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, and computational studies were carried out to characterize the NSAID-HPβCD-IC-NFs and identify the functional groups involved in the binding mechanism. The NFs showed higher thermal stability than the pure drugs due to IC formation. The ultraviolet–visible absorption and fluorescence results indicated strong interactions between the HPβCD and NSAIDs with significant association constants at 1:1 stoichiometry. The efficiency of the NFs in terms of cell biocompatibility was verified, and the NFs exhibited excellent biocompatibility, as determined by in vitro biocompatibility assay. The in vitro scratch assay confirmed that the NFs allow the rapid growth and migration of skin fibroblast cells. These results showed that these NFs could be potential candidates for wound treatment.

Radiation construction and excellent performances of Ag NPs/TiO2/PEG/PVP multifunctional aerogel: Adsorption-photocatalytic degradation, photosensitive antibacterial and cytotoxicity

A cutting-edge method known as photocatalytic antibacterial technology can effectively eliminate drug-resistant bacterial strains and boast a wide-ranging antimicrobial capability. In the study, a novel Ag NPs/TiO2/PEG/PVP (ATPP) aerogel photocatalyst was synthesized by an electron beam in-situ radiation method using polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), AgNO3, and TiO2 as raw materials. ATPP was characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS) and solid ultraviolet diffuse reflectance spectroscopy (UV–Vis DRS). The results demonstrated that silver ions were reduced to silver nanoparticles by electron beam radiation method. At the same time, the doping of silver nanoparticles (Ag NPs) enhanced visible-light adsorption. The degradation rate of methylene blue (MB) on 5% (in mass) ATPP could reach 81% under visible light for 180 min. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used as model bacteria to explore the antimicrobial properties of ATPP by zone of the inhibition method, plate counting method and live/dead bacterial staining. Cyclic antibacterial experiments showed that the antibacterial effect of ATPP was sustainable. Meanwhile, MTT assay and Hoechst33342/PI double staining were used to prove that the composite had good biocompatibility. The aerogel photocatalytic material has the potential to decrease microbial presence in both medical and environmental settings, making it a valuable tool for such applications.

Prompt antibacterial activity of silver nanoparticle decorated on HAp embedded NiFe2O4 nanocomposite (NiFe2O4@HAp-Ag) against pathogenic strains and investigation of its photocatalytic activity towards degradation of antibiotics

Local bacterial infection in clinics is still a difficult task and poses serious health threats to human. Systemic antibiotic administration typically results in negative side-effects and bacterial resistance and only has transient antibacterial activity. Several biomedical applications immensely prefer modified hydroxyapatite with excellent biocompatibility and antibacterial characteristics. Herein, we fabricate hydroxyapatite-embedded NiFe2O4 using in situ hydrothermal method and used as a support for silver nanoparticle onto its surface to achieve an effective biological response. The properties of the as-synthesized materials were characterized using several spectroscopic techniques which include X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–diffuse reflectance spectroscopy spectroscopy, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy. In addition, the magnetic behavior of these nanocomposites was examined using the vibrating sample magnetometer technique. This ternary nanocomposite exhibits potent antimicrobial activity against both Gram-negative bacteria (Pseudomonas aeruginosa and klebsiella pneumoniae) as well as Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus). The MIC or minimum inhibitory concentration, MBC or minimum bactericidal concentration, the disc diffusion, bacterial growth rate, and inhibition rate tests were utilized for the examination of the antimicrobial effect of this synthesized nanocomposite against pathogenic strains. Along with this, we have also investigated its photocatalytic activity toward degradation of cefixime antibiotic under solar light and it shows excellent photodegradation performance. The fabricated nanocomposite demonstrated high reusability with good photostability. Notably, using magnetic decantation this prepared nanocomposite can be easily eliminated from the disinfected medium.

Synergistic effect of ZnO nanoparticles with Cu2+ doping on antibacterial and photocatalytic activity

The nanoparticles (NPs) of ZnO and Cu-doped ZnO samples were prepared using a chemical precipitation method specifically aimed at enhancing photocatalytic and antibacterial activity. The structural, morphological, phase constitutional, functional, elemental, and optical properties have been studied using Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM), Ultra Violet diffused reflectance spectroscopy (UV-DRS), Fourier-transform infrared (FTIR) spectroscopy, and Thermogravimetric analysis (TGA). The crystallite size was calculated by using Debye Scherrer formula and the obtained average crystallite size of pure ZnO, ZnO-Cu2.5%, ZnO-Cu5%, and ZnO-Cu10% sample is 24.31 ± 0.12 nm, 25.72 ± 0.47 nm, 26.83 ± 0.39 nm, and 26.94 ± 0.29 nm, respectively. High-resolution Transmission Electron Microscope (HR-TEM) was used to calculate the d-spacing. The values of d-spacing for ZnO, ZnO-Cu2.5%, ZnO-Cu5%, and ZnO-Cu10% samples were measured as 0.248 nm, 0.266 nm, and 0.273 nm, respectively and corresponds to (101), (002) and (100) planes of ZnO, respectively which are well associated with the PXRD data (JCPDS card no. 36–1451). It was found that the doping concentration affects the crystallinity of the ZnO nanoparticles. The average grain size of ZnO, ZnO-Cu2.5%, ZnO-Cu5%, and ZnO-Cu10% is 35.75 ± 1.91 nm, 38.55 ± 2.31 nm, 45.39 ± 1.78 nm, and 50.65 ± 2.23 nm, respectively as determined from TEM images by using the ImageJ software. Further, photo-catalytic dye degradation was studied to understand the photocatalytic behavior of synthesized nanoparticles. The UV–Vis adsorption study has revealed that optimum doping of Cu is mandatory to get the highest degradation of methylene blue (MB) dye. It was observed that 5% Cu-doped ZnO NPs have the optimum photocatalytic activity. Furthermore, the antibacterial activity of various formulations on the gram-negative, facultative anaerobic, coliform bacterium Escherichia coli (E. coli) was studied to establish zone of inhibition (ZOI) values for ZnO and Cu-doped ZnO NPs. The current research indicated that 5% Cu-doped ZnO NPs have shown maximum inhibition and may be used for various antibacterial applications.

Efficient Photocatalytic Reduction of Hexavalent Chromium by BiVO4-Decorated MXene Photocatalysts and Their Charge Carrier Dynamics.

The synergistically MXene (Ti3C2Tx) co-catalyst-decorated BiVO4-based heterostructured photocatalysts have been synthesized by a hydrothermal approach with varied loading concentrations of MXene (Ti3C2Tx) to drive the hexavalent chromium reduction efficiently. The formation of the heterostructured photocatalyst was confirmed by the appearance of X-ray diffraction (XRD) peaks corresponding to the monoclinic BiVO4 phase and MXene (Ti3C2Tx) and also the antisymmetric (834 cm-1) and symmetric stretching (715 cm-1) of tetrahedral VO4 and D (1330 cm-1) and G (1570 cm-1) bands corresponding to MXene (Ti3C2Tx) in the Raman spectrum. The worm-like structures of BiVO4 nanocrystals grew onto the lamellar sheets of MXene (Ti3C2Tx), as shown by field emission scanning electron microscopy (FESEM), and has an increased surface area of 15.62 m2g-1 in the case of BVO-20-TC. X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of V5+ and Ti3+states, and the uniform distribution of BiVO4 nanocrystals over lamellar sheets of MXene (Ti3C2Tx) is evident from energy-dispersive X-ray (EDX) analysis. The ultraviolet-diffuse reflectance spectroscopy (UV-DRS) spectra suggest a decrease in the band gap energy of BVO-20-TC to 2.335 eV, promoting a higher degree of visible light harvesting. Upon optimization, by varying the pH, the amount of the photocatalyst, and the concentration of Cr(IV), BVO-20-TC exhibits the highest photocatalytic efficiency (96.39%) while using a Cr(VI) concentration of 10 ppm at pH 2 and 15 mg of the photocatalyst, and the photoreduction of Cr(VI) to Cr(III) follows the pseudo-first-order reaction. The decrease in the PL intensity in BVO-20-TC reveals a faster transfer of electrons from MXene (Ti3C2Tx) to BiVO4. Further, the higher degree of band bending at the BiVO4/MXene (Ti3C2Tx) heterojunction, revealed from the Mott-Schottky analysis, facilitates efficient charge transfer and eventually faster and efficient photoreduction of Cr(VI) to Cr(III). The reusability and stability test undertaken for BVO-20-TC reveals that even after five cycles, the Cr (VI) photoreduction efficacy is retained. This work provides insights into photoreduction of Cr (VI) by using such heterostructures.

Probing the effect of precursor concentration on the growth and properties of titanium dioxide nanocones for environment safe solar cells.

Environment friendly third-generation solar cells sensitized by dyes, quantum dots, and perovskites are seen as promising energy alternatives. Among the various strategies, employing one-dimensional nanostructures that exemplify the smallest dimension for efficient carrier transport rate from the active layer to electron transport layer (ETL) in photovoltaic devices is attempted in this work. We herein report the synthesis of well-aligned 1-D TiO2 nanocones as ETL for photovoltaic thin films by varying the precursor concentration (0.03M, 0.04M, 0.05M) to track the evolution of growth. The hydrothermal approach is exploited to grow oriented rutile TiO2 nanocones on fluorine doped tin oxide (FTO) under neutral conditions. The examination of phase, crystallinity, morphology, and opto-electronic properties of the well-structured nanocone arrays is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), ultra violet diffuse reflectance spectroscopy (UV-DRS), Brunnauer-Emmett-Teller (BET) surface area analysis, and field-dependent dark and photoconductivity analysis. The XRD pattern confirms the formation of the tetragonal rutile phase. SEM micrographs and UV-DRS spectroscopy reveals that the length of the nanocones and the energy gap is found to be maximum for 0.04M concentration with a well-defined excitation band at 316nm. Significantly, a strong light-trapping effect that decreases the incident light reflections and correspondingly increases the light absorption is unveiled through photoconductive studies for the TiO2 nanocones at 0.04M having a surface area of 81.767 m2/g. The investigation essentially suggests that the as-prepared one-dimensional nanostructures would serve as efficient photoanodes in environment safe third-generation solar cells.

ZnO-based Cu metal-organic framework (MOF) nanocomposite for boosting and tuning the photocatalytic degradation performance.

Although metal-organic frameworks (MOFs) are a viable choice for photocatalysts with large surface area and tunable pore structure, the rapid recombination of excited photogenerated charges results in low activity towards photodegradation. Aiming at improving the photocatalytic activities of MOFs, different strategies to incorporate MOF with light-harvesting semiconductors have been developed. In this research, we report an effective photocatalyst designed by incorporating Cu-MOF with ZnO for the photocatalytic degradation of Rose Bengal exhibiting excellent degradation efficiency of 97.4% in 45min under natural sunlight with catalyst dosage of 320mg/L. The optical, morphology and surface characteristics of the prepared nanocomposite were studied using scanning electron microscopy (SEM-EDX), high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (PXRD), Brunauer-Emmett-Teller (BET) analysis, thermogravimetric (TGA) analysis, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and ultraviolet diffused reflectance spectroscopy (UV-DRS) techniques. Further studies showed that the degradation followed first-order kinetics with a rate constant of 0.077869min-1. The degradation mechanism was investigated by photoluminescence (PL) study, XPS, zeta potential and quenching experiment in presence of different scavengers. Meanwhile, the fabricated composite displayed good recovery and reuse properties up to 5 cycles as revealed by XRD analysis proving itself a potential MOF-based photocatalyst towards environmental remediation process.

Polyoxometalate Intercalated M2+/Al (M2+=Ni, Mg) Layered Double Hydroxide for Degradation of Methylene Blue

The synthesis and characterization of M2+/Al (M2+=Ni, Mg) layered double hydroxide (LDH) and intercalated polyoxometalate is presented. We have reported the growth of polyoxometalate on Ni/Mg layered double hydroxide for degradation methylene blue (MB). By considering variables such as pH of dye solution, dye concentration, and time as degradation variables, the efficiency of organic dye degradation and degradation parameters of M2+/Al (M2+ = Ni, Mg) LDH and both composite LDH-polyoxometalate has been identified. X-Ray Diffraction (XRD), Fourier Transform Infra Red (FTIR), Scanning Electron Microscope (SEM), and Ultra Violet Diffuse Reflectance Spectroscopy (UV-DRS) spectroscopy confirmed the layered double hydroxide structure. XRD and FTIR analysis confirmed the single-phase of the as-made and polyoxometalate intercalated LDH. SEM images show the formation of aggregates of small various sizes. The material’s photodegradation was assessed through methylene blue (MB) degradation process. The result showed that NiAl-Si has a good degradation capacity for MB as compared to NiAl-Pw, MgAl-Si, and MgAl-PW. The result shows that LDH composite presents stability and has good photocatalytic activities toward the reduction of methylene blue. The FTIR measurement confirming the LDH composite structure reveals the materials used in the fifth regeneration. The activity of MB photodegradation pristine were NiAl (45%), MgAl (43%), NiAl-Pw (78%), NiAl-Si (85%), MgAl-Pw (58%), and MgAl-Si (75%), respectively. The LDH-polyoxometalate composite material’s capacity to successfully photodegrade, as measured by the percentage of degradation, revealed an increase in photodegradation catalysis and the ability of the LDH to regenerate. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Enhanced magnetic, electrochemical and gas sensing properties of cobalt substituted nickel ferrite nanoparticles prepared by hydrothermal route

The cobalt doped nickel ferrite nanoparticles were successfully synthesized via hydrothermal method at low reaction temperature. X-ray diffraction analysis confirmed the cubic spinel structure with an average crystallite size of 41 nm for pure nickel ferrite (NF) and in the range (38–33) nm for substituted samples. High resolution transmission electron microscope observations revealed the cubic-like shaped nanosized particles. Ultraviolet diffuse reflectance spectroscopy indicated an increase in the energy bandgap with increasing Co content. X-ray photoelectron spectroscopy confirmed the oxidation states of constituents, +2 for Ni, +2 for Co, and +3 for Fe. The AC conductivity was enhanced with increasing frequency. The observed higher value of saturation magnetization and coercivity, manifests its suitability in high density recording media. Besides, the ratio of Hcr/Hc confirmed the pseudosingle domain nature of the synthesized nanoparticles. The valency and occupancy of the Fe ion in tetrahedral-A and octahedral-B sites within the spinel cubic structure were elucidated by Mossbauer spectroscopy analysis. The cyclic voltammetry (CV) studies revealed the pseudocapacitance behaviour with high specific capacitance value at low scan rates. The sensor activity towards liquified petroleum gas (LPG) at 100 ppm showed the response and recovery time as 52 and 13s respectively.

The Al3+ doped modified ZnO sensor material: Fabrication, characterization and gas sensing characteristics of some environmental pollutant and greenhouse gases

The current study examines the gas sensing properties of the fabricated material Al3+ modified ZnO. The material was fabricated by using co-precipitation technique. Here, sodium hydroxide was used as precipitating material to precipitate zinc as zinc hydroxide to convert it finally into ZnO. The insitu doping method was adapted to doped aluminum through ZnO lattice. The material was characterized by means of several characterization techniques. The X-ray diffraction (XRD) instrument utilized for structural investigation of the prepared material. The mean particle size estimated 28 nm using the Debye-Scherer equation. Scanning electron microscopy (SEM) was utilized for surface and topographic properties of the prepared material, while energy dispersive x-ray spectroscopy (EDX) was utilized to get atomic weight percentage of elements. The ultra violet diffuse reflectance spectroscopy (UV-DRS) was used to find the energy band gap of modified ZnO. The hexagonal crystal lattice of the materials was confirmed from transmission electron microscopy (TEM) analysis. Thick films of Al3+ doped ZnO made using a screen printing technology. The developed thick film sensor of Al3+ doped ZnO was utilized to sense certain harmful gases such as toluene vapors (TV), LPG, petrol vapors, CO2 and CO. The material showed considerable response for CO and LPG at 500 ppm gas concentration with 85.20% and 76.23% gas response at 90°C and 120°C respectively. The other gas sensing characteristics of the materials was also examined for the fabricated Al3+ doped ZnO sensor such as response and recovery, reusability, ppm variation and gas response. From overall study it was observed that fabricated sensor Al3+ doped ZnO is reliable, and very rapid to detect the carbon monoxide vapors and liquefied petroleum gas vapors (LPG) at moderately high temperature and low gas concentration. The built sensor’s gas sensing mechanism was assessed to detect CO and LPG.

Unveiling the Photocatalytic Activity of Carbon Dots/g-C3N4 Nanocomposite for the O-Arylation of 2-Chloroquinoline-3-carbaldehydes

Visible-light-active, organic, heterogeneous photocatalysts offer an ecologically friendly and sustainable alternative to traditional metal-based catalysts. In this work, we report the microwave synthesis of nanocarbon dots (CDs), loaded with graphitic carbon nitride (g-C3N4). The fabricated nanocomposite was shown to exhibit various properties, such as the Schottky heterojunction. The optical properties, functional group analysis, surface morphology, crystallinity, chemical stability, electronic properties, and pore size distribution of the synthesized nanocomposite were analyzed by Ultraviolet-Diffuse Reflectance Spectroscopy (UV-DRS), Photoluminescence (PL), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Zeta potential, X-Ray Photoelectron Spectroscopy (XPS), and Brunauer–Emmett–Teller (BET). Until now, to the best of our knowledge, there have been no reports published on the light-assisted synthesis of O-arylation of 2-chloroquinoline-3-carbaldehyde. Therefore, we explored the photocatalytic activity of the fabricated nanocomposite in the production of the O-arylated 2-chloroquinoline-3-carbaldehyde. This facile technique uses a blue LED light source as a non-conventional source and operates under moderate conditions, resulting in useful O-arylated products. The experimental data shows the good recyclability of the catalyst for up to five cycles without a loss in catalytic activity, a simple operational protocol, easy recoverability of the catalyst, and good product yields (65–90%) within 12–24 h. Additionally, the preliminary mechanistic investigations are discussed. The results show that the phenoxy and quinoline-3-carbaldehyde radicals generated upon blue LED irradiation during the course of the reaction are responsible for C-O bond formation, which results in O-arylation. The present study clearly indicates that 0D/2D nanocomposites have a bright future as metal-free, heterogeneous photocatalysts suitable for organic reactions.

Influence of gadolinium doped in nickel nanoferrites on structural, optical, electrical, and magnetic properties

The sonochemical reaction approach was used to make NiGdxFe2-xO4 nanoferrites (x = 0.01, 0.03, 0.05, 0.07, and 0.09). X-ray diffraction (XRD), ultra violet-diffuse reflectance spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, vibrating sample magnetometer, and electrochemical impedance spectroscopy were used to investigate the optical, magnetic, electrical, and structural properties of NiGdxFe2-xO4 nanoferrites. The creation of a cubic spinel structure was confirmed by analyzing the XRD pattern of these NiGdxFe2-xO4 nanoferrites. The average crystallite diameters of the nanoparticles for the compositions x = 0.01, 0.03, 0.05, 0.07, and 0.09 were 57, 53, 48, 45, and 41 nm, respectively. To investigate the dielectric behavior of the produced nanoferrites, an impedance study was performed. The addition of Gd to NiFe2-xO4 nanoparticles increased the dielectric characteristics of the produced nanoferrites, according to characterization experiments. A cation distribution has been proposed for the determination of various important theoretical parameters for these samples. The addition of Gd3+ nanoparticles has shown the ferromagnetic behavior at room temperature confirmed by VSM analysis. A specific correlation between magnetic interaction and lattice strain was observed in Gd3+ substituted nickel ferrite. An increase in Gd concentration in the manufactured nanoferrites resulted in a rise in saturation magnetization and a decrease in coercivity.

Simultaneous Quantitation of Lead and Cadmium on an EDTA-Reduced Graphene Oxide-Modified Glassy Carbon Electrode.

Cadmium (Cd) and lead (Pb) are classified as category one toxicants. The provisional guideline values, according to the World Health Organization (WHO), for Cd and Pb are 3 and 10 ppb, respectively. An easy, quick, and cheap analytical technique is in demand for the determination of these toxic heavy metals in water. Hence, a novel electrochemical sensing platform is developed by modifying the glassy carbon electrode with ethylenediaminetetraacetic acid (EDTA)-functionalized reduced graphene oxide (ErGO) for the low-cost simultaneous quantitation of toxic heavy-metal ions, lead and cadmium, in real water samples. EDTA is grafted to the surface of graphene oxide, via amine linkage, and the oxygen functionality is reduced by a green agent, tyrosine. Various physical and electrochemical characterizations of the as-prepared electrocatalytic material were performed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), ζ-potential, ultraviolet diffuse reflectance spectroscopy (UV-DRS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), etc. The glassy carbon electrode (GCE) is modified with ErGO by a simple drop-casting method for simultaneous metal-ion quantitation by differential pulse voltammetry (DPV). EDTA functionalization of graphene oxide and its further reduction using the green agent enhance the stability and sensitivity of the electrode substrate. The limits of detection for cadmium and lead ions calculated for ErGO/GCE are 1.02 and 2.52 ppb, while the limits of quantification for lead and cadmium ions are 3.41 and 8.4 ppb, and their sensitivities are 0.8 and 0.6 nA/ppb, respectively. Real river water contains 200.2 ± 0.38 ppb of Pb2+ ions (mean ± stdev, n = 3) by the DPV technique, which is validated by ICP-OES analysis.

Excellent Photocatalytic Activity of a Novel Hydroxyapatite Based Composite (ZnFe2O4/HAp‐Sn2+) Towards Degradation of Ofloxacin and Norfloxacin Antibiotics

AbstractAntibiotic contamination in wastewater has become a matter of great concern due to the rapid industrial progress. The majority of antibiotic pollution in the environment occurs due to the waste from animal farms, aquaculture, sewage from antibiotic factories and hospitals. Therefore, it is vital to develop efficient and ecologically friendly photocatalysts for the degradation of such pollutants. In this paper, we report synthesis of ZnFe2O4/HAp‐Sn2+, a novel nanocomposite by three‐step processes using hydrothermal treatment followed by calcination. The as‐synthesized composite was characterized by Fourier transform infrared spectroscopy (FT‐IR), ultraviolet diffused reflectance spectroscopy (UV‐DRS), polycrystalline (or power) X‐ray diffraction (PXRD), scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDS), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA) and X‐ray photoelectron spectroscopy (XPS). The as‐prepared composite exhibited excellent photocatalytic activity in the degradation of two antibiotics namely ofloxacin (OFL) and norfloxacin (NFL) under natural sunlight without use of any oxidizing or reducing agents. Scavenger studies were also carried out to ascertain the active radicals such as superoxide and hydroxyl radical during the photodegradation process.

Synthesis and characterization of SbSI modified g-C3N4 composite for photocatalytic and energy storage applications

Two dimensional carbon related materials with superior charge separation and excellent transport properties have been highly used in the field of photocatalytic and electrochemical applications. The hydrothermally synthesized antimony sulfoiodide (SbSI) doped g-C3N4 composite (CSI) has excellent charge storage and charge transport properties. The physio-chemical properties of the synthesized SbSI doped g-C3N4 materials are examined by X-ray diffraction (XRD), transmission electron microscopy (TEM) energy dispersive x-ray spectroscopy (EDS), Fourier transform-infra red spectroscopy (FT-IR), Ultraviolet-diffuse reflectance spectroscopy (UV-DRS), X-ray photoelectron spectroscopy (XPS) and photoluminescence spectroscopy (PL) techniques. The photocatalytic examination of the synthesized catalyst materials is carried out in presence of visible light irradiation using Rhodamine B (RhB), Bromophenol blue (BPB) and mixed dye effluents. The synthesized photocatalyst material CSI shows excellent photocatalytic activity of 94%, 80% and 92% against BPB, RhB and mixed dye effluent and the stability of the prepared material was 95% even after four consecutive photocatalytic performances. In addition, the electrochemical properties of the synthesized CSI composite is examined by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) analysis and electrochemical impedance spectroscopy (EIS) investigations. The synthesized composite material depicts good specific capacitance of 212 F/g at 0.5 A/g current density and retains 96% of the stability after 1000 consecutive GCD performance. The experimental finding confirms that the CSI composites have enhanced photocatalytic and electrochemical performance than the synthesized SbSI and g-C3N4 materials.

Effect of Ni2+ substitution on structural, magnetic and electrical traits of Ba1-xNixFe2O4

Nickel substituted Barium ferrites is synthesized by citrate gel method. Nickel which is transition metal used to tailor the properties of the Ba spinel ferrites. The characterization techniques such as thermogravimetry–differential thermal analysis (TG-DTA), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), ultra-violet diffuse-reflectance spectroscopy (UV-DRS), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), transmission electron microscopy (TEM), Raman analysis and direct current (DC) electrical conductivity are used to investigate various properties. XRD and rietveld refinement confirmed the existence of orthorhombic as well as cubic phase with the decrease in lattice parameters in orthorhombic phase. FTIR spectra confirmed the presence of absorption bands for tetrahedral and octahedral sites. Tauc’s plots accredited the increase in band gap with increase in Ni content. The magnetic hysterisis loop exhibited large variation in coercivity and remanence. Increased Yafet-Kittel (Y-K) angle indicated redistribution of ions amongst the sites strenthening the A-B exchange interactions. DC electrical conductivity observed the conductive switching from n-type to p-type. Thermally activated charge carriers and hopping of electrons boost drift mobility. The activation energy of conduction is observed in the range of 0.40 to 0.85 eV. Raman peaks confirmed formation of orthorhombic as well as cubic phase.

Nanospace-confined worm-like BiVO4 in TiO2 space nanotubes (SPNTs) for photoelectrochemical hydrogen production

Titanium dioxide (TiO2) space nanotubes (SPNTs) have attracted considerable attention in the fields of photocatalysis and photoelectrochemical energy conversion because of their large surface area and good physical and chemical stability. However, their large bandgap (3.0–3.2 eV) and poor charge-carrier separation and transport properties lead to unsatisfactory photo-conversion efficiency. To overcome these drawbacks, we performed in vivo and in vitro deposition of BiVO4 (BVO) on SPNTs, obtaining a sophisticated BVO/SPNTs heterojunction via electrochemical anodization and microwave-assisted synthesis. Unlike conventional TiO2 nanotube structures, TiO2 SPNTs possess empty spaces between the tubes (tube-to-tube interface), which can effectively admit BVO particles and generate worm-like BVO, yielding an intimate heterojunction interface and enlarged surface area. The prepared BVO/SPNTs exhibited a narrow bandgap (2.32 eV), small charge-transfer resistance, and accelerated reaction kinetics, as confirmed by incident-photon-to-current conversion efficiency, ultraviolet diffuse reflectance spectroscopy, and electrochemical impedance spectroscopy. These salient features, together with a strong response to visible light, resulted in a photocurrent density of 0.68 mA/cm2 without any co-catalyst at 1.23 V vs. a reversible hydrogen electrode in 0.5 M Na2SO4, which is 14 times higher than that of the pure SPNT electrode film. Thus, this study highlights that the integration of the materials with different dimensions by tailoring the surface properties may yield efficient and stable catalysts for multiple applications, particularly for hydrogen production at a significantly improved rate.

Enhanced Photoelectrochemical Activity of TiO2 Nanotubes Decorated with Lanthanide Ions for Hydrogen Production

Highly ordered TiO2 nanotubes (TNTs) decorated with a series of lanthanide ions (Ln3+ = Ho3+, Tb3+, Eu3+, Yb3+, and Er3+) were prepared through an electrochemical process and anodization. The composition, structure, and chemical bond of the as-prepared photocatalysts were characterized through scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and ultraviolet diffuse reflectance spectroscopy. Furthermore, the electrochemical characteristics of the catalysts were analyzed and photoelectrochemical properties were investigated through water splitting. All samples were prepared in the anatase phase without changing the crystal structure. The holmium-doped TNT photocatalyst exhibited the best performance with a hydrogen evolution rate of 90.13 μmol cm−2h−1 and photoconversion efficiency of 2.68% (0 V vs. RHE). Photocatalytic efficiency increased because of the expansion of the absorption wavelength range attributed to the appropriate positioning of the band structure and reduced electron/hole pair recombination resulting from the unhindered electron movement. This study demonstrated the preparation of high-potential solar-active photocatalysts through the synergetic effects of the work function, band edge, and bandgap changes caused by the series of lanthanide combinations with TNTs.

Enhanced Visible Light-Driven Photoelectrocatalytic Degradation of Paracetamol at a Ternary z-Scheme Heterojunction of Bi2WO6 with Carbon Nanoparticles and TiO2 Nanotube Arrays Electrode.

In this study, a ternary z-scheme heterojunction of Bi2WO6 with carbon nanoparticles and TiO2 nanotube arrays was used to remove paracetamol from water by photoelectrocatalysis. The materials and z-scheme electrode were characterised using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), EDS mapping, ultraviolet diffuse reflection spectroscopy (UV-DRS), photocurrent measurement, electrochemical impedance spectroscopy (EIS), uv-vis spectroscopy and total organic carbon measurement (TOC). The effect of parameters such as current density and pH were studied. At optimal conditions, the electrode was applied for photoelectrocatalytic degradation of paracetamol, which gave a degradation efficiency of 84% within 180 min. The total organic carbon removal percentage obtained when using this electrode was 72%. Scavenger studies revealed that the holes played a crucial role during the photoelectrocatalytic degradation of paracetamol. The electrode showed high stability and reusability therefore suggesting that the z-scheme Bi2WO6-CNP-TiO2 nanotube arrays electrode is an efficient photoanode for the degradation of pharmaceuticals in wastewater.