Lower Band Gap Energy Research Articles

A series of MgAl layer double hydroxide-based materials intercalated with Clitoria ternatea flower extract as photocatalysts in the ciprofloxacin degradation

The preparation of MgAl Layer Double Hydroxide (LDH) was performed using the coprecipitation method. Pristine MgAl LDH was calcined at 500 °C to produce the MgAl Layer Double Oxide (LDO). The two materials were modified via restacking-delaminating the bioactive compounds from the flower extract of Clitoria ternatea (CT) to produce MgAl LDHCT and MgAl LDOCT. Modifications are performed to enhance the stability of the catalyst structure, allowing its higher photocatalytic activities and regeneration use. The prepared catalysts were characterized using XRD, FT-IR, UV-DRS, BET, and SEM-EDX. The XRD diffraction pattern showed that the three catalysts have typical diffraction patterns commonly observed in LDH-based materials. FT-IR spectra confirmed that MgAl LDHCT and MgAl LDOCT showed combined spectra of its precursor materials. MgAl LDOCT has the lowest bandgap energy with the highest degradation kinetics. BET and SEM-EDX characterization shows uniform surface and pore size on MgAl LDOCT. The prepared catalysts were used in the ciprofloxacin photodegradation under UV light. The optimal catalyst dose was 5 mg, while the optimal pH was 5. MgAl LDOCT, MgAl LDHCT, and MgAl LDH showed ciprofloxacin degradation capacity up to 73.300%, 65.739%, and 71.320%, respectively, within 120 min. Repeated use of the catalyst up to the third cycle resulted in%R reaching 80.871%, 74.003%, and 52.025%, respectively, by MgAl LDHCT, MgAl LDOCT, and MgAl LDH. Compared to pristine MgAl LDH, the CT intercalated catalysts exhibited more excellent stability.

Optimizing the structural, thermal, gas sensing and electrical properties of in-situ polymerized poly(thiophene-co-indole)/silicon carbide nanocomposites for energy storage applications

Conducting copolymer nanocomposites of thiophene and indole incorporated with silicon carbide nanoparticles [poly (thiophene-co-indole-SiC) (PPSiC)] has been developed by in-situ copolymerization and these nanocomposites were characterized by different analytical techniques. The FTIR peak at 865 cm−1 signifies the successful incorporation of SiC nanoparticles in the copolymer matrix. The intensity of the UV-Vis absorbance of the copolymer nanocomposites increased with the nanoparticle concentrations, and PPSiC7 showed the highest intensity. This was in correlation with its low optical bandgap energy (3.032 eV) and high refractive index (2.388) value. XRD revealed the consistent positioning of sharp and distinct crystalline peaks of SiC in the copolymer. SEM revealed the effective dispersion of nanoparticles throughout the matrix and uniform dispersion was obtained for PPSiC7 nanocomposite. HR-TEM images validated the presence of spherical-shaped particles in the nanocomposite with the nano-size distribution of SiC. The surface roughness of the copolymer nanocomposite was evident from AFM analysis. TGA and DSC revealed that PPSiC nanocomposites have better thermal properties than the copolymer. AC conductivity increased with frequency and temperature. The PPSiC7 exhibits a maximum conductivity of 1.5×10−2 S/cm at 106 Hz and an activation energy of 0.064 eV. PPSiC nanocomposites demonstrated excellent results in degrading dye and detecting ammonia gas at ambient temperature. All analyses showed that the PPSiC7 nanocomposite exhibited superior properties than the copolymer. These admirable properties can be exploited in developing optoelectronic devices, energy storage devices and gas sensors.

The investigation of wetting and agglomerating mechanism of short-chain fluorocarbon surfactant suppressing coal dust from macro and molecular scales

This paper carried out a multi-scale investigation on the wetting and agglomerating mechanism of short-chain fluorocarbon surfactant suppressing coal dust. As investigated, FS-50 achieves higher dedusting rate and shorter suppression time than FS-3100, which is attributed to its better wettability and more sufficient agglomeration on coal particles. Simulation indicates that FS-3100 with longer chain length is easier to generate chemical bond rotation, which results in a distorted spatial structure, higher steric hindrance, and poorer ability of FS-3100 in retaining H2O molecules and adsorbing surround the coal particles. The hydrophilic group of FS-50 is dominated by the induced effect and presenting larger charge density and electron-absorbing nature. Higher electrostatic potential difference with coal molecules, more hydrogen bonds, shorter bond length and larger bond angle are key factors to endorse FS-50 a better wetting and agglomerating performance. The C atom connected with the fluorocarbon tail chain of FS-3100 is linked to a carboxyl group with lone pair electrons. This carboxyl group enlarges the LUMO value of FS-3100 and weaken its ability to attract the electrons of coal particles. On the contrary, the lower LUMO value, lower band gap energy, and smoother spatial configuration jointly bring FS-50 better wetting and agglomerating ability.

Sustainable synthesis of levulinic acid using waste derived silica-alumina-hydroxyapatite supported nano ZrO2 photo-acidic catalyst under synergistic UV-FIR irradiations

A novel nano-photocatalyst has been prepared using hydroxyapatite (HAp) derived from waste fish scale and fly ash-derived aluminosilicate (SiO2-Al2O3) grafted with zirconium oxide (ZrO2) active sites by innovative photo-hydrothermal protocol. The physiochemical properties of the prepared photocatalyst have been characterized by different analyses like TGA, XRD, FTIR, XPS, UV–VIS–NIR, BET, NH3-TPD, HRTEM, and DLS. The optimal catalyst has a zirconium loading of 20 wt% and has a low bandgap energy of 2.15 eV as confirmed by UV–VIS–NIR spectroscopy. The optimal catalyst also depicted a high acidity of 1.52 mmol NH3/g and a specific surface area of 62.872 m²/g. Owing to the high acidity, specific surface area, and low band gap energy the photocatalyst has led to achieving an elevated yield of 76.6% levulinic acid (LA) from glucose in hybrid irradiation reactor (HIR) deploying UV and FIR radiations at appreciably low temperature and reaction time of 115 ℃ and 2 h respectively. Under the same reaction conditions, the conventionally heated reactor (CHR) gave a very low yield of 23.7%. Individual radiation effects on LA yield evinced the synergistic advantageous effect of the hybrid irradiation technique. The catalyst reusability and regenerative study confirmed the high stability of the prepared catalyst. Also, a comparative LCA study has been conducted between HIR and CHR systems which revealed that HIR was more environmentally sustainable than CHR. HIR -based process demonstrated a reduction in 59% global warming potential, 70.66% forest resource scarcity, and 65% lower terrestrial ecotoxicity while being 120% more energy efficient than CHR-based reaction making HIR more environmentally sustainable as well as economically feasible.

Band gap opening of metallic single-walled carbon nanotubes via noncovalent symmetry breaking

Covalent bonding interactions determine the energy-momentum (E-k) dispersion (band structure) of solid-state materials. Here, we show that noncovalent interactions can modulate the E-k dispersion near the Fermi level of a low-dimensional nanoscale conductor. We demonstrate that low energy band gaps may be opened in metallic carbon nanotubes through polymer wrapping of the nanotube surface at fixed helical periodicity. Electronic spectral, chiro-optic, potentiometric, electronic device, and work function data corroborate that the magnitude of band gap opening depends on the nature of the polymer electronic structure. Polymer dewrapping reverses the conducting-to-semiconducting phase transition, restoring the native metallic carbon nanotube electronic structure. These results address a long-standing challenge to develop carbon nanotube electronic structures that are not realized through disruption of π conjugation, and establish a roadmap for designing and tuning specialized semiconductors that feature band gaps on the order of a few hundred meV.

Green fabrication of tinospora cordifolia-derived MgO nanoparticles: Potential for diabatic control and oxidant protection

Pure and encapsulated magnesium oxide (MgO) nanoparticles were synthesized using a hydrothermal method with Tinospora Cordifolia (TC) leaf extract. XRD analysis revealed a face-centered cubic structure for both types of nanoparticles, with an average crystallite size of 26.94 nm and 36.48 nm. The pure and encapsulated MgO nanoparticles were confirmed by UV-Visible spectrophotometer, the encapsulated MgO nanoparticles had a lower optical energy band gap of 5.304 eV compared to pure MgO nanoparticles at 5.506 eV. FTIR and BET results confirmed the presence of phytochemicals such as phenolic and flavonoid groups encapsulated over the surface of MgO nanoparticles. HRTEM analysis showed nearly spherical shaped encapsulated MgO nanoparticles with a thickness of 8.1 nm. Histogram represents the average particle size of encapsulated MgO NPs was found to be 37.08 ± 4.70 nm. In vitro analysis revealed that these nanoparticles exhibited anti-diabetic and anti-oxidant properties that were comparable to commercially available Metformin drug. The antidiabetic and antioxidant ability of encapsulated MgO NPs was shown by effective inhibition against carbohydrate digestive enzymes such as α- amylase and α-glucosidase with IC50 values of 48.71 µg/ml and 46.29 µg/ml respectively and DPPH radical with IC50 value of 48.012 µg/ml. Encapsulated MgO nanoparticles exhibited higher efficacy in vitro against carbohydrate digestive enzymes and DPPH free radicals than pure MgO nanoparticles due to the presence of phenolic and flavonoid groups. The spectral analysis indicates that the use of Tinospora Cordifolia extract to synthesize MgO nanoparticles results in a green method that shows promise for various biomedical applications.

Rational construction of defect-enriched α-Fe2O3/Bi2S3 composites for high-effective photocatalytic degradation of p-nitrophenol

Herein, the high-activity α-Fe2O3 (PSNF) was obtained first, and defect-enriched PSNF/Bi2S3 composites were prepared via a one-step hydrothermal process. The obtained PSNF had abundant oxygen vacancies (OV) and low bandgap energy, showing enhanced visible-light catalytic activity. Compared with PSNF and Bi2S3, the PSNF/Bi2S3 composites presented superior adsorption capacity and photocatalytic degradation activity for p-nitrophenol (p-NP). The p-NP degradation process followed the BMG model. The PSNF/Bi2S3-2 exhibited the highest photocatalytic activity, as 90.5% of the p-NP was degraded within 30 min. A tight heterojunction was formed between PSNF and Bi2S3 by the S–O bond, which effectively inhibited the recombination of photoproduced carriers and promoted the generation of OV defects. Under the synergistic effect of OV detects, photo-Fenton, and heterojunction, the generation of active species was promoted in the composite degradation system, thereby resulting in the rapid degradation of p-NP.

DFT and electrochemical determination of Hg2+ and Pb2+ in water using polyaniline–quinoxaline composite modified GCE electrode

In this study, we designed and synthesized a new class of donor–acceptor conjugated polymers containing the polyaniline-quinoxaline [Acenaptho [1, 2 -b] quinoxalin-9-amine] (PAni-QUA) composite, and we subsequently utilized it as an electrochemical sensor to detect Hg2+ and Pb2+ ions with good selectivity and sensitivity. Energy dispersive X-ray analysis spectroscopy (EDAX), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and UV–Vis spectroscopy (UV–Vis) were employed to analyze the structural and morphological characteristics of the resulting composite. The electrochemical characteristics of the electrode modifiers were analyzed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Several sensitivity-influencing factors, including chemical and electrochemical parameters like pH and the impact of the supporting electrolyte medium, were also identified to improve the efficiency of the developed sensor. In the presence of different hazardous metal ion species, the interference ability of the proposed sensor was also examined. They were also used to conduct individual and simultaneous sensing studies of various metal ions in different supportive electrolyte media utilizing the differential pulse voltammetry technique (DPV). The PAni-QUA composite modified GCE sensor shows remarkable selectivity and sensitivity towards Hg2+ and Pb2+ ions over the other heavy metal ions in 1 to 20 µM ranges, respectively. The detection limits (3σ/m) were 1.28 nM and 5.91 nM for Hg2+ and Pb2+ ions. Density Functional Theory (DFT) was used in the present study to accomplish the adsorption mechanism of the suggested sensors. The DFT calculation demonstrated that the PAni-QUA composite was formed with a lower band gap energy than QUA and DD PAni. These results showed that the suggested sensor (PAni-QUA) had the lowest detection limit in the acetate buffer medium compared to the specified electrolyte media. Based on these findings, it is possible to use this technology to identify harmful metal ions (Hg2+ and Pb2+) with high sensitivity in real water samples.

Prominent ferroelectric properties in multilayered TiO2 Mn-doped BiFeO3 spin-coated thin films

The study investigates the effects of doping on the leakage current and ferroelectric properties of bismuth ferrite (BiFeO3) thin film-based heterostructures. The spin coating method has been employed to deposit thin films of BiFeO3 and heterostructures of TiO2/BiFeO3 and TiO2/BiFe0.95Mn0.05FeO3 on fluorine-doped tin oxide substrates. The ferroelectric behavior of the TiO2/BiFe0.95Mn0.05FeO3 films exhibited better ferroelectric hysteresis loop compared to the other prepared films. The ferroelectric behavior reveals the TiO2/BiFe0.95Mn0.05FeO3 heterostructure showed a significantly lower leakage current density compared to both the BiFeO3 thin film and TiO2/BiFeO3 heterostructure, and the TiO2/BiFe0.95Mn0.05FeO3 heterostructures are likely suitable for solar cell applications. Highlights FTO/TiO2/BiFe0.95Mn0.05FeO3/Au heterostructure thin films prepared by spin coating method. Structure and optical properties of TiO2/BiFe0.95Mn0.05FeO3 heterostructure thin films were investigated. TiO2/BiFe0.95Mn0.05FeO3 heterostructure thin films showed a low optical energy band gap of 2.25 eV. Enhanced ferroelectric property in TiO2 thin film composited with BiFe0.95Mn0.05FeO3 thin films.

Sonochemically assisted fabrication of highly photoactive novel ZnO/MoO3 binary nanotubes anchored with Bi2O3 nanosheet for solar light-driven photocatalytic activity

In this work, we present the fabrication of a direct Z-scheme photocatalyst, ZnO/MoO3/Bi2O3 by using a sonochemical-assisted biochemical (leaf extract of Moringa oleifera) process. The structural, surface and morphological characteristics of the manufactured composite were comprehensively studied by using various techniques including UV–Visible spectroscopy, X-ray diffraction, FTIR, SEM/EDX analysis, HRTEM imaging, XPS for chemical composition investigation, and BET surface area analysis. Our findings reveal that the nanotubes of ZnO/MoO3 are exquisitely aligned and interconnected well with Bi2O3 sheets which can be ascribed to the effective prevention of photoinduced electron-hole (e−-h+) pairs recombination. Moreover, the ternary hybrid possesses low band gap energy of 2.26 eV which suggest that sensitivity toward visible light and a large surface area, thereby increasing the active sites on its surface. ZnO/MoO3 with Bi2O3 enhances interfacial electron translocation efficiency, leading to a slower recombination rate of hole-electron pairs. Consequently, the one-pot combinative synthesis demonstrates a synergistic effect on the separation rate of active charge carriers, resulting in improved production and transmission of photo-excited electrons consequently enhancing its photocatalytic activity. In contrast to ZnO, MoO3, Bi2O3 and ZnO/MoO3, the ZnO/MoO3/Bi2O3 composite exhibited an impressive 98.8 % degradation efficiency of malachite green (MG) dye within 48 min under direct sunlight radiation, under optimized conditions (pH 13, 75 mg photocatalyst dose). The photocatalytic degradation process exhibited a rate constant of 0.090 min−1, following first-order reaction kinetics. Additionally, inhibitor studies allowed us to propose a mechanism that highlights the significant contributions of h+ (holes) and •O2− in the photocatalytic process.

Optical properties and electric modulus studies of TSP: CH3COONa based biopolymer electrolytes

The research of biopolymers for the creation of solid polymer electrolytes (SPE) for electrochemical devices has resulted from the green revolution. Various strategies have been used to build and characterise biopolymer-based membranes for proton and lithium-ion conduction. However, research on biopolymers based on sodium ions is uncommon in the literature. The solution cast approach is used in this work to create a SPE based on the biopolymer Tamarind Seed Polysaccharide (TSP) incorporated with sodium acetate (CH3COONa). UV–visible optical absorption spectroscopy in the wavelength range of 200–800 nm was used to investigate the optical characteristics. From the studies of optical absorption, optical transmission, optical absorption coefficient, refractive index spectrum, extinction coefficient spectra, direct energy bandgap, indirect energy bandgap, optical absorption edge, Urbach – energy, and optical dielectric loss were calculated. The comparative study of the optical dielectric loss to the optical bandgap showed that the direct allowed transition was the most probable electronic transition for the prepared films. The calculated optical bandgap (Direct allowed) was decreased for 80:20 film from 5.51 eV (for pure TSP) to 4.88 eV. The direct, indirect, and absorption edges for pure TSP were all high, and when the salt concentration of CH3COONa increased, the above characteristics progressively decreased. For 80 % TSP: 20 % CH3COONa concentration, a low direct and indirect energy bandgap value was obtained. Tangent loss and electric modulus experiment results were then presented using AC Impedance data. For the 80:20 film, the tangent energy loss revealed a minimum and the electric modulus spectra exhibited the zeroth tail is at its maximum.

Highly Efficient Photocatalytic Remediation of Carcinogenic Anthracene and Phenanthrene by green Synthesized N‐doped Prussian blue Analogues

AbstractPolycyclic aromatic hydrocarbons (PAHs) are classified as priority pollutants because of their persistent nature, carcinogenicity, and mutagenicity; therefore, they must be eliminated. Herein, synthesis of nitrogen‐doped metal hexacyanoferrate nanoparticles (N−MHCF; M=Cu, Zn) was achieved using the green protocol in co‐precipitation techniques for the oxidative removal of PAH pollutants, namely, anthracene (ANT) and phenanthrene (PHE). PXRD and XPS analysis confirmed the doping of Nitrogen in MHCF nanocomposite. The optimum conditions, concentration of PAHs (10 mg L−1), and catalyst dose (20 mg) at neutral pH under sunlight to eliminate PAHs were reported. The degradation followed the Langmuir model and Ist‐order kinetics. The highest photodegraFdation was found for N−CuHCF (ANT: 95 %; PHE: 93 %), as compared to N−ZnHCF (ANT: 90 %; PHE: 87 %), which might be due to a high negative zeta charge (−30.3 mV), surface area, and lower band gap energy (1.7 eV). The GC‐MS technique showed that photocatalysts (N−MHCF) break down PAH contaminants into minor metabolites in exposure to solar irradiation. Up to eight consecutive cycles of use were possible with nanocomposites without any appreciable decrease in activity. Largely because of favorable surface characteristics, N−MHCF nanostructure fabricated via the green method is of great importance with a bright future in industries.

An electrochemical voltammetric response of Hg2+ and Pb2+ ions using polyaniline-benzothiazole composite modified GCE electrode: Synthesis, characterization and quantum chemical calculation

An efficient electrochemical sensor based on polyaniline-benzothiazole [(3,5-bis (benzo[d]thiazol-2-yl)-[1,1–biphenyl]-4-ol)] (PAni-BEN) composite was designed and synthesized in this study, and it was employed as an electrochemical sensor to detect Hg2+ and Pb2+ ions with good selectivity and sensitivity. Fourier transform-infrared spectroscopy, UV–Vis spectroscopy, scanning electron microscopy, and energy dispersive X-ray analysis spectroscopy were employed to examine the morphology and structure of the produced composite. The electrochemical characteristics of the electrode modifiers were evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Also, they were employed to perform both individual and simultaneous sensing studies of various metal ions using the differential pulse voltammetry technique (DPV) in a different supporting electrolyte (acetate buffer (pH 5), phosphate buffer (pH 7), and 0.1 M HCl) mediums. The PAni-BEN composite modified GCE sensor shows remarkable selectivity and sensitivity towards Hg2+ and Pb2+ ions over the other heavy metal ions in 1 to 24.84 µM, respectively. The limits of detection (S/N = 3) were 1 nM and 4.6 nM for Hg2+ and Pb2+ ions. Density Functional Theory (DFT) was used in the present study to accomplish the adsorption mechanism of the suggested sensors. The DFT calculation demonstrated that the PAni-BEN composite was formed with a lower band gap energy than BEN and DD PAni. These findings showed that the suggested sensor (PAni-BEN), which may used to detect Hg2+ and Pb2+ ions, had the lowest detection limit in the acetate buffer medium compared to the proposed electrolyte medium.

Controlled crystallinity of LiTaO3 surface layer for single-crystalline Ni-rich cathodes for lithium-ion batteries and all-solid-state batteries

Various functional materials have been explored as surface-coating layers for Ni-rich cathode materials used in lithium-ion batteries (LIBs) aiming to enhance their long-term cycling performance and electrochemical stability under high-voltage operation. In particular, lithium tantalate (LiTaO3) has received considerable attention as a promising candidate due to its distinct physicochemical properties, including high ionic conductivity, wide voltage window, low band-gap energy, and excellent mechanical strength. These characteristics are beneficial for effective surface stabilization of Ni-rich cathode materials, which currently suffer from poor cycling performance, mainly due to issues related to structural instability with elevated Ni concentrations. In this respect, we report the benefits of surface coating with LiTaO3 on the electrochemical properties of single-crystalline Ni-rich cathode materials (SNCM) for successful implementation in high-energy LIBs. The controlled crystallinity of the LiTaO3 surface layer directly affects the reversibility as well as interfacial stability of the SNCM cathode under various operating conditions. The tailored crystallinity of LiTaO3 surface layer is mainly responsible for enhancing the cycle performance of SNCM cathodes under high-temperature (60 °C) and high-voltage (4.5 V vs. Li/Li+) operations. Our findings will significantly contribute to the development of robust and reliable cathode materials for high-energy LIBs.

Biochar/α‐Fe2O3/γ‐Fe2O3 Heterjunction Composite for Photocatalytic Removal of Amino Black

AbstractHerein we synthesized biochar/iron oxide composite (C/α‐Fe2O3/γ‐Fe2O3) by two‐step calcination method. The prepared C/α‐Fe2O3/γ‐Fe2O3 had a highly pure and a concentration ratio of α‐Fe2O3 and γ‐Fe2O3 about 1 : 1. The optical properties of as‐synthesized C/α‐Fe2O3/γ‐Fe2O3 show a lower bandgap energy (1.90 eV) than that of pure C/α‐Fe2O3 (2.02 eV). The effects of different biochar composite catalysts on the removal of amino black were investigated. Upon illumination, the total removal rate of amino black dye by C/α‐Fe2O3/γ‐Fe2O3 catalyst reached 98 %, which was about 1.7 times that of C/α‐Fe2O3. In addition, the coercivity and the remanence intensity of C/α‐Fe2O3/γ‐Fe2O3 is respectively 1.81 times and 7.17 times that of C/α‐Fe2O3. The catalyst could be magnetically separated and reused for five times with a slight loss of its reactivity. The study of biochar composite provides a new direction for the removal of toxic organic dye in wastewater.

Enhanced mechanical, electrical, thermal, and optical properties of poly(methyl methacrylate)/copper oxide nanocomposites for flexible optoelectronic devices via in‐situ polymerization technique

AbstractPolymethyl methacrylate (PMMA) with varied compositions of copper oxide (CuO) nanoparticles was synthesized using in‐situ free radical polymerization. UV–visible, FT‐IR, XRD, FE‐SEM, DSC, and TGA were employed to examine their structure, morphology, and thermal properties. The broadening and intensification of UV absorption, as well as the shift in IR peaks of PMMA with the addition of CuO, confirm their interactions. The reduction in optical bandgap values with the reinforcement of nanofillers confirms the existence of intermediate energy bands in nanocomposites. XRD indicated that polymerization with CuO reduced the amorphous nature of PMMA. The FE‐SEM image revealed that the dispersion of CuO altered the nonporous, rough surface of PMMA into a homogeneous shape. The reinforcement of CuO enhanced the thermal stability and glass transition temperature of PMMA. The mechanical strength, modulus, impact strength, and rigidity of PMMA were significantly improved through in‐situ polymerization. The electrical property analysis revealed that the AC conductivity increased with frequency, temperature, and filler content. The reduction in activation energy of AC conductivity with temperature points toward their semiconducting nature. PMMA/CuO nanocomposites with higher tensile strength, lower bandgap energy, higher conductivity, and thermal properties can be used to make flexible optoelectronic devices.Highlights A series of PMMA/CuO nanocomposites were synthesized and characterized. Enhanced optical property, thermal stability, and glass transition temperature. Possess excellent dielectric constant and AC conductivity. Mechanical strength and impact resistance of PMMA were greatly enhanced. A promising material for flexible optoelectronic and power storage applications.

Visible-Light-Driven Mentha spicata L.-Mediated Ag-Doped Bi2Zr2O7 Nanocomposite for Enhanced Degradation of Organic Pollutants, Electrochemical Sensing, and Antibacterial Applications.

Novel visible-light-driven Ag (X)-doped Bi2Zr2O7 (BZO) nanocomposites in pudina (P) extract (Mentha spicata L.), X-1, 3, 5, 7, and 9 mol %, were synthesized by the one-pot greener solution combustion method. The as-synthesized nanocomposite materials were characterized by using various spectral [X-ray diffraction (XRD), Fourier transform infrared, UV-visible, UV- diffuse reflectance spectra, X-ray photoelectron spectroscopy], electrochemical (cyclic voltammetry, electrochemical impedance spectroscopy), and analytical (scanning electron microscopy-energy-dispersive X-ray spectroscopy, transmission electron microscopy, Brunauer-Emmett-Teller) techniques. The average particle size of the nanocomposite material was found to be between 14.8 and 39.2 nm by XRD. The well-characterized Ag-doped BZOP nanocomposite materials exhibited enhanced photocatalytic degradation activity toward hazardous dyes such as methylene blue (MB) and rose bengal (RB) under visible light irradiation ranges between 400 and 800 nm due to their low energy band gap. As a result, 7 mol % of Ag-doped BZOP nanocomposite material exhibited excellent photodegradation activity against MB (D.E. = 98.7%) and RB (D.E. = 99.3%) as compared to other Ag-doped BZOP nanocomposite materials and pure BZOP nanocomposite, respectively, due to enhanced semiconducting and optical behaviors, high binding energy, and mechanical and thermal stabilities. The Ag-doped BZOP nanocomposite material-based electrochemical sensor showed good sensing ability toward the determination of lead nitrate and dextrose with the lowest limit of detection (LOD) of 18 μM and 12 μM, respectively. Furthermore, as a result of the initial antibacterial screening study, the Ag-doped BZOP nanocomposite material was found to be more effective against Gram-negative bacteria (Escherichia coli) as compared to Gram-positive (Staphylococcus aureus) bacteria. The scavenger study reveals that radicals such as O2•- and •OH are responsible for MB and RB mineralization. TOC removal percentages were found to be 96.8 and 98.5% for MB and RB dyes, and experimental data reveal that the Ag-doped BZOP enhances the radical (O2•- and •OH) formation and MB and RB degradation under visible-light irradiation.

Molecular engineering of D-π-A-type structures based on nitrobenzofurazan (NBD) derivatives for both organic solar cells and nonlinear optical response

The electronic, photo-physical, and nonlinear optical (NLO) properties of small molecules from nitrobenzofurazan (NBD) derivatives have been fine-tuned through the introduction of various electron-donating groups (OH, OCH3, and N(CH3)2). These designed small molecules follow a donor-linker-acceptor (D-π-A) motif, featuring p-phenylene as the electron donor, thiophene as the π-conjugated bridge, and NBD as the electron acceptor. To achieve this, we conducted density functional theory (DFT) and its time-dependent counterpart, TD-DFT calculations. Our exploration of the structure–property relations among the molecular parameters revealed that the introduction of donor groups has a notable influence on lowering the highest occupied molecular orbital (HOMO) energy levels. Analysis of the absorption–emission spectra showed a prominent π → π* band followed by a weaker n → π* band.Remarkably, three compounds substituted with electron-donor group’s exhibit anti-Stokes fluorescence (ASF) emission. Moreover, the relatively weak emission band associated with the charge transfer n → π* transition of the nitro-functionalized molecules is quenched, similar to the π → π* electronic transition. Consequently, these compounds display a lower bandgap energy, resulting in a broad optical absorption profile with emissions spanning from green to yellow. Notably, when tuning the NLO properties, push-type groups exhibit demonstrate exceptionally high hyperpolarizabilities. Furthermore, our investigation unveiled excellent photovoltaic properties, with these compounds achieving an impressive power conversion efficiency (PCE) of approximately 7 %.Additionally, we conducted complementary topological analyses, including Molecular Electrostatic Potential (MEP), Quantum Theory of Atoms in Molecules (QTAIM), Reduced Density Gradient (RDG), Electron Localization Function (ELF), and the Localized Orbital Locator (LOL), to gain insights into both intra- and intermolecular interactions. These findings strongly underscore the effectiveness of modifying the electron-donating group capability in D-π-A conjugated systems as a strategy for enhancing the optoelectronic properties of organic photovoltaic (PV) devices, as well as their NLO responses.

Green synthesis of magnetic chitosan composite hydrogel (Fe3O4@CS photocatalyst) for the solar light driven catalytic degradation of organic contaminants

Ecofriendly magnetic chitosan composite hydrogel (Fe3O4@CS photo-catalyst) was prepared by using an aqueous extract of Boerhevia procombens leaves for the solar light mediated catalytic degradation of lethal organic Congo red dye. The prepared composite hydrogel was structurally studied using Fourier transform infrared spectroscopy (FT-IR) which reveals the formation of the Fe3O4@CS photocatalyst. The X-ray diffraction (XRD) investigation of the composite hydrogel signified high crystallinity of photocatalyst and crystallite structure of 53 nm for magnetite nanoparticles (Fe3O4 NPs). The surface investigation suggests multilayered porous photocatalyst owing to the presence of cavities offering more photoactive sites for the photodecomposition of dye molecules. The energy dispersive X-ray (EDX) scanning supports the fabrication of Fe3O4@CS photocatalyst due to the perseverance of carbon, nitrogen, oxygen, and iron. The thermogravimetric analysis (TGA) together with vibrating sample magnetometry (VSM) certifies the preparation of thermally stable and magnetic composite hydrogel. The fabricated Fe3O4@CS photocatalyst possess low bandgap energy of 2.36 eV, supporting the excellent disintegration of dye molecules in the sunlight irradiations. The photocatalyst exhibited a maximum degradation efficacy of 99.1% for Congo red dye in the solar light irradiations with refined states of 70 min radiation time, dye concentration of 20 mg/L, pH 6, and 200 mg photocatalyst amount obeying the second-order kinetic model (R2 = 0.9959). The Fe3O4@CS photocatalyst displayed a little decrease in dissociation efficiency of dye molecules after five repeated cycles owing to the coverage or rupturing of photoactive sites. Conclusively, the results support Fe3O4@ CS to be an economical and biocompatible magnetic catalyst for the catalytic decontamination of Congo red dye molecules and other organic contaminants in domestic and industrial wastewater effluents.

Bio-inspired synthesis of N-doped TiO2/C nanocrystals using jellyfish mucus with high visible-light photocatalytic efficiency.

Non-metal doping of titanium dioxide (TiO2) has been widely investigated, because it can facilely improve the optical response of TiO2 under visible light excitation in environmental pollution treatments. In the ongoing efforts, however, little consideration has been given to the use of harmful marine organisms as dopants. Here, we employed the natural mucus proteins of the large harmful jellyfish Aurelia coerulea and Nemopilema nomurai, which have frequently bloomed in East Asian marginal seas in recent decades, to synthesize mesoporous nitrogen-doped TiO2 nanocrystals modified with carbon (N-TiO2/C) by a simple hydrothermal method. These nanocrystals were composed of predominantly anatase phase and a small amount of brookite phase TiO2. Their mesoporous structures changed with the variation of the volume ratio of jellyfish mucus added to tetrabutyl titanate (TBT). At the same ratio, larger surface area and pore volume but smaller pore size were observed in N-TiO2/C nanocrystals from N. nomurai rather than A. coerulea. Nitrogen was determinately doped into the lattice of the prepared nanocrystals and the carbon species were modified on their surfaces, which narrowed the band gap, facilitated the separation of photogenerated electron-hole pairs and favored the absorption of visible light, thus improving their visible light photocatalytic activity. The photocatalytic degradation efficiency of Rhodamine B (RhB) under visible light irradiation first increased and then decreased with the gradual increase of the volume ratio of jellyfish mucus proteins to TBT. The maximum reached 97.52% in 20 min from N-TiO2/C nanocrystals synthesized using N. nomurai mucus at the volume ratio of 4 : 1, which showed a remarkably strong visible light absorption, lower band gap energy and smaller electron transfer resistance. These N-TiO2/C nanocrystals also had a relatively stable crystal structure in multiple degradation reactions. The main active species including superoxide radicals (˙O2 -), photogenerated holes (h+) and hydroxyl radicals (˙OH) were found to play a major role in the degradation process of RhB. This study highlights the potential high-value reapplication of harmful jellyfish mucus as a natural organic matrix in fabricating advanced materials with optimized functional properties.