Lower Band Gap Energy Research Articles

Innovative ternary bismuth oxychloride/bismuth oxide/carbon nanotubes induced excellent solar light-driven activity toward photomineralisation of diclofenac: Impact of metastable β-Bi2O3 inserted and electron-hole separation

Solar energy-utilizing photocatalysts for water purification remain essential for environmental sustainability. This report presents new concepts in bismuth oxychloride/oxide/carbon nanotubes. (BiOCl/Bi2O3/CNT) composites, synthesized through a chemical deposition method involving BiOCl in a carbon nanotube bath, followed by surface reduction/oxidation steps. The impact of nanotube ratio and calcination temperature were explored. Characterization involved ultraviolet–visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), elemental mapping, N2 adsorption/desorption analysis, and electrochemical impedance spectroscopy (EIS). XRD analysis revealed in-situ formation of α and β-Bi2O3 phases, rendering the composite more responsive to visible light at 200 °C. Carbon nanotubes reduced the band gap of ternary composites, yielding lower band gap energies in the visible range compared to BiOCl and Bi2O3. XPS analysis identified metallic Bi0 particles, enhancing electron mobility and charge separation. The synergy of BiOCl/Bi2O3/CNT-200 material significantly improved diclofenac degradation under solar simulator irradiation. Total organic carbon (TOC) analysis demonstrated 81 % mineralization with the BiOCl/Bi2O3/CNT-200 material. Active species trapping revealed the crucial roles of HO• radicals and h+ holes in pollutant degradation. The presence of the normally metastable β-Bi2O3 phase at 200 °C enhanced solar simulation efficiency, while carbon nanotubes acted as electron reservoirs, aided by Bi0 particles. The present study sets out an efficient composite synthesis approach for the photomineralization of complex pharmaceutical compounds.

Magnetic self-doped TiO2-x /Fe3O4@g-C solar-driven photocatalytic composite for water decontamination.

Declining water resources and their contamination with chemicals risk the aquatic environment. Therefore, this work was devoted to designing a magnetically recyclable photocatalyst suitable for water treatment, namely, a TiO2-x /Fe3O4@g-C composite. Different preparation conditions were investigated together with the corresponding characteristics. The pure defective anatase TiO2-x phase of low band gap energy was detected through XRD and DRS analyses. Low charge recombination after the formation of defects was confirmed. The performances of the prepared photocatalysts in phenol degradation under solar light were evaluated, revealing the superior efficiency of TiO2-x prepared hydrothermally at 200 °C/24 h relative to intact TiO2. This best sample was incorporated with Fe3O4@g-C to facilitate its recovery and reuse. This successful combination was confirmed using XRD, Raman and XPS tools. TiO2-x /Fe3O4@g-C 2 : 1 formulation was found to be the most photoactive and could be reused up to five times without significant loss in its efficiency. Therefore, the precisely developed magnetic photocatalyst is promising for application in the water-treatment process.

Photocatalytic conversion of carbon dioxide to methanol over different precursors of graphitic carbon nitride supported on fibrous silica iron

In this study, the graphitic carbon nitride (g-C3N4) was successfully synthesized through thermal polymerization under three different g-C3N4 precursors such as urea (U-gC3N4), melamine (M-gC3N4) and dicyandiamide (D-gC3N4) and then doped into the fibrous silica iron (FSFe), denoted as U-gC3N4/FSFe, MgC3N4/FSFe, and D-gC3N4/FSFe, respectively. The synthesized catalysts were characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectrometer (FTIR), and UV-Vis Diffuse Reflectance Spectroscopy (UV-Vis/DRS) and also tested for photocatalytic conversion of carbon dioxide (CO2) to methanol (CH3OH). The study indicated that altering the precursors had a substantial impact on the physicochemical features of the FSFe, which in turn increased the catalytic performance of the conversion of CO2 to CH3OH. U-gC3N4/FSFe exhibits the highest CH3OH yield (2.3 x 104 µmol gcat−1) compared to bare FSFe, D-gC3N4/FSFe and M-gC3N4/FSFe under visible light irradiation within 240 min. The higher CH3OH yield over U-gC3N4/FSFe is mostly owing to the lower bandgap energy of U-gC3N4/FSFe, as well as the advantageous interaction between g-C3N4 and FSFe.

Fibrous silica bismuth sulfide: An advanced material towards promising photoelectrochemical water-splitting

The emission of greenhouse gaseous to the atmosphere as a consequence of the utilization of fossil fuels has significantly contributed to global warming and sudden climax change which aroused a lot of concerns. This occurrence has indirectly spurred interest in hydrogen energy as a future alternative energy due to its environmentally friendly, high efficiency and long-term energy storage. Photoelectrochemical (PEC) water-splitting is a top-notch approach that can efficiently produce hydrogen. Moreover, semiconductor materials like bismuth sulfide have often been used as photoanode material in the PEC water-splitting study due to their narrow bandgap, high optical absorption coefficient, appropriate band alignment and low toxicity. Yet, Bi2S3 photoanode suffers from the rapid recombination of charge carriers which ultimately leads to sluggish water oxidation kinetics and poor charge transfer. Interestingly, the fabrication of fibrous silica bismuth sulfide (FSBS) not only demonstrated a low bandgap energy level but also effectively separated the photoproduced charges. In addition, the FSBS photoanode also showed a photocurrent density of 47.9 mA/cm2 at 1.23 VRHE which is 1.78 times greater than the commercial BS photoanode (26.9 mA/cm2). These findings indirectly exposed the potential of FSBS photoanode towards a sustainable PEC water-splitting application.

Exploring Acceptor Modification in Helicene‐Phenylamine‐Based Small Molecules for Organic and Perovskite Solar Cells

The current quantum mechanical study is focused on the fabrication of eight helicene‐phenylamine‐based molecules (MPAM1–MPAM8) to investigate their photovoltaic (PV) and optoelectronic properties for photovoltaic cells (PVCs). The outcomes revealed that fabricated chromophores showed deeper highest occupied molecular orbital levels, higher solubility, low exciton binding energy, greater hole mobility with low band gap energy than the model compound (MPAR). Moreover, the reorganization energy values interpret that newly fabricated compounds possess high charge mobility compared to the representative molecule (MPAR) which encourages their usage as HTM in PSCs. All the freshly designed molecules revealed greater estimated open circuit voltage values contrasted to the reference molecule (MPAR) which ensures their prominent working efficacy. The results signify the competence of this strategic approach, paving a new path for the fabrication of hole transport material (HTM) for perovskite solar cells (PSCs) and donor molecules for organic solar cells (OSCs).

Nano Fe(IO3)3 as a heterogenous catalyst for the photo-Fenton reaction

The Fenton reaction is a powerful method of degrading pollutants. The rate of the reaction is improved in an acidic environment, which limits its application. To overcome this drawback, the reaction can be performed under visible light irradiation at a neutral pH. In this condition, a photo-Fenton catalyst is required. For this purpose, Fe(IO3)3 was synthesized by precipitation method. X-ray diffractometry revealed that the prepared product was amorphous and the presence of the Fe-O stretching mode in Fe(IO3)3 was confirmed by Fourier-transform infrared spectroscopy. The X-ray photoelectron spectrum of Fe(IO3)3 showed peaks corresponding to I5+ and Fe3+. Energy-dispersive X-ray spectroscopy confirmed that the Fe-to-I atomic ratio was 1:3. Due to its low bandgap energy, Fe(IO3)3 exhibited photo-Fenton properties when exposed to visible light irradiation. As a result, Fe(IO3)3 could effectively degrade rhodamine B (RhB), reactive orange 16 (RO), and tetracycline hydrochloride (TC). Trapping experiments confirmed that the hydroxyl radical was the dominant oxidizing agent responsible for degrading the three pollutant models. The ability of Fe(IO3)3 to degrade the three pollutant models decreased as the pollutant model concentrations and initial pH values increased. Conversely, the degradation activity of Fe(IO3)3 increased as the catalyst loading was increased. The degradations of all pollutant models were confirmed by mass spectrometry. When the reaction was completed, the parent peaks of the pollutant models were no longer detected, and peaks representing phenolic compounds, sulfonate compounds, and carboxylic acids were observed.

Developing a new multi-featured chitosan-quinoline Schiff base with potent antibacterial, antioxidant, and antidiabetic activities: design and molecular modeling simulation

A new chitosan Schiff base was developed via the reaction of chitosan (CH) with 2-chloro-3-formyl-7-ethoxy quinoline (Q) derivative. The alteration in the chemical structure and morphology of CHQ derivative was confirmed by 1H NMR, FT-IR spectroscopy and SEM analysis. The antibacterial activity was considerably promoted with increasing quinoline concentration up to 1 M with maximal inhibition reached 96 and 77% against Staphylococcus haemolyticus and Escherichia coli, respectively. Additionally, CHQ derivative afforded higher ABTS·+ radical scavenging activity reached 59% compared to 13% for native chitosan, approving its acceptable antioxidant activity. Moreover, the developed CHQ derivative can stimulate the glucose uptake in HepG-2 and yeast cells, while better inhibition of α-amylase and α-glucosidase was accomplished with maximum values of 99.78 and 92.10%, respectively. Furthermore, the molecular docking simulation clarified the binding mode of CHQ derivative inside the active site of α-amylase and α-glucosidase, suggesting its potential use as diabetes mellitus drug. The DFT calculations indicated an improvement in the electronic properties of CHQ with a lower energy band gap reached 4.05eV compared to 5.94eV for CH. The cytotoxicity assay revealed the safety of CHQ towards normal HSF cells, hypothesizing its possible application as non-toxic antibacterial, antioxidant, and antidiabetic agent for biomedical applications.

Solar light driven photocatalytic degradation of methylene blue dye over Cu doped α-MnO2 nanoparticles

Cu-α-MnO2 nanoparticles were synthesized by hydrothermal method and their potential application in the aqueous-based degradation of organic contaminants was examined under solar light. Cu doping increases the particle size and affects the morphology of MnO2. The Cu-doped α-MnO2 XRD pattern showed a tetragonal crystalline structure with a crystal size of ∼30nm. When compared to α-MnO2, which has a band gap energy of 1.58eV, the 6% Cu-doped α-MnO2 photocatalyst has a lower band gap energy (1.23eV). As a result, the light absorption was increased towards the visible spectrum. The considerable change in PL intensity of MnO2 observed after Cu doping. The findings show that a 6% Cu- α-MnO2 sample degrades methylene blue dye completely within 2 h. The improvement of the photocatalytic activity of the Cu-α-MnO2 nanoparticles was significantly influenced by the expanded light absorption range and effective charge separation. A variety of scavengers were employed to identify the active species by capturing the radicals and holes generated upon the photocatalytic degradation process.

Enhancing perovskite solar cells: Tailoring the properties of Ti-doped MAPbBr3 for reduced recombination and improved efficiency

By using the sol-gel method, (0 %, 4 % and 6 %) Ti-doped MAPbBr3 films were deposited on FTO-glass substrates. XRD confirmed cubic structure of all films and the 4 % Ti-doped film has a large grain size of 80 nm. UV–Vis spectroscopy analysis confirmed that the 4 % Ti-doped film has low band gap energy of 2.36 eV, and a high refractive index of 2.62. The tuning of the conduction and valence band edges speeds up the movement of charges between the layers. The solar cells of these films have been fabricated with the geometry of glass/TiO2/Ti-MAPbBr3/spiro-OMeTAD/Au. The 4 % Ti-MAPbBr3 based cell showed high current density (9.15 mA/cm2), open circuit voltage (1.03 V), fill factor (0.7407), and efficiency (6.9804 %). EIS showed that the 4 % Ti-MAPbBr3 cell has an increased electron transfer rate and lowers the possibility of recombination at the TiO2/perovskite interface.

A novel Ag2O/Bi2WO6 composite with enhanced piezocatalytic performance for ciprofloxacin removal

Bi2WO6, an important semiconductor material, has been widely used in the catalytic degradation of organic wastewater in recent years. However, Bi2WO6 owns the low band gap energy, the recombination of the produced e−-h+ pairs expected to be fast, which leads to undesirable degradation effects. In order to improve its piezocatalytic ability, this paper combined the semiconductor material Bi2WO6 with Ag2O to form Ag2O/Bi2WO6 piezoelectric catalysts, which was characterized and its removal effect on ciprofloxacin (CIP) was discussed. According to the analyses, the reaction rate constant for the piezocatalytic removal of CIP in the company of 5 % composite ratio of Ag2O/Bi2WO6 was about 1.40 and 4.87 times higher than it was when Bi2WO6 and piezocatalytic technology were used alone. By exploring the experimental principle, the increased piezocatalytic activity of Ag2O/Bi2WO6 was found to be due to the creation of Z-scheme heterojunction, which could efficiently separate the e−-h+ pairs. Reuse experiments were also carried out, and the results showed that it has good reusability and stability in piezocatalysis. In summary, Ag2O/Bi2WO6 has good piezocatalytic activity for the removal of CIP.

Hydrothermal syntheses of d10-based Zn(II) and Cd(II) metal–organic frameworks for the catalysis of the Knoevenagel condensation

Metal–organic frameworks (MOFs) are compounds that feature metal clusters coordinated with organic ligands, forming impressive structures and properties. In this study, two MOFs of Zn(II) and Cd(II) were synthesized using the organic compound 5‑hydroxy-2-pyrazinecarboxylic acid, forming Zn-MOF and Cd-MOF. To better understand the intricate structures of these MOFs, single-crystal X-ray crystallography was used to characterize their respective structures. The results showed that both MOFs have complex three-dimensional supramolecular structures that are highly symmetric and contain water molecules. Additionally, topological analysis of the MOFs indicated that they have a zeolite-like structure. The Hirshfeld surfaces analysis revealed that both crystal structures could preferentially interact with other molecules through hydrogen bonds. The MOFs were found to have a direct band gap, with the energy observed to be 2.44 and 2.71 eV for the Zn-MOF and Cd-MOF systems, respectively. The hydrogen bond formation ability of the MOFs, in combination with their low band gap energy, make them highly suitable for use in the Knoevenagel condensation reaction in water. Overall, the results of this study provide important insights into the unique properties and potential applications of MOFs in diverse fields.

Synthesis of Graphene Based Graphitic Carbon Nitride Hybrid Nanocomposite Photocatalysts for Hydrogen Generation: A Mini Review

The discovery of visible active photocatalysts for H2 evolution via water splitting is the most awaited and critical goal of many researchers in recent years. Novel polymeric graphitic carbon nitride (GCN/g-CN) has emerged as a versatile material which has attracted the scientific community and industrialist because of its distinctiveness and outstanding electronic properties. g-CN is a metal free semiconductor as well as non-toxic, biodegradable polymeric material with low band gap energy which makes it a promising candidate as a photocatalyst and its efficiency as a catalyst can be modified by forming a hybrid nanocomposite with other semiconducting materials. Reduced graphene oxide, another metal free 2D material is a very good choice for this purpose. This review is an outlook for the synthesis processes and various properties of both g-CN and graphene. Further, it gives the approaches attempted towards the modifications required and done towards the development of a metal-free nano-hybrid material which is cost-effective, eco-friendly, and highly active visible light catalyst for the water- splitting process.

Synthesis, spectroscopy, band gap energy and electrical conductivity of poly(dopamine–co–aniline) copolymer

Copolymerization is used to improve the solubility and processability of polymers and copolymers includes the individual properties of homopolymer. In this study, the poly(dopamine-co-aniline) (poly(DA-co-ANI) copolymer was synthesized and the UV–vis. absorption, optical band gap energy, fluorescence, FT-IR, SEM-EDS, MALDI-TOF-MS, XRD and electrical conductivity have been investigated. The obtained results for the poly(DA-co-ANI) copolymer were compared with the PDA and PANI homopolymers. It was observed that the poly(DA-co-ANI copolymer is soluble easily in NMP and DMF solvents. The optical band gap energy of the poly(DA-co-ANI) copolymer film were calculated. as 1.00 eV with favorable indirect transition. The poly(DA-co-ANI) copolymer showed the FL emission maximum bands at 390 and 533 nm wavelengths. It was observed from the SEM images that the poly(DA-co-ANI) has 0–1500 nm crystalline rectangular particles prepared in acidic media and 0–600 nm amorphous particles prepared in basic media. The electrical conductivity of the poly(DA-co-ANI) was 1.35 × 10−6 S/cm. In the MALDI-TOF-MS measurements, the number-average molecular weight of the copolymer was found as 2628 Da with a distribution up to 5500 Da. The poly(DA-co-ANI) copolymer, soluble in NMP and DMF solvents and with a low optical band gap energy can be utilized as optical, fluorescent, and semi-conductive material in biomedical applications.

Synthesis of p-CuO/n-ZnO heterostructure by microwave hydrothermal method and evaluation of its photo and bio-catalytic performance

The use of photocatalysts without noble metals is of great interest in the industrial field for the degradation of organic pollutants. In this study, a CuO/ZnO heterostructure was synthesized using the microwave hydrothermal method and characterized using various analytical techniques. The synthesized CuO/ZnO photocatalyst exhibited a low bandgap energy of 2.4 eV, enabling efficient visible light absorption. The photocatalytic activity of the CuO/ZnO heterostructure was evaluated for the degradation of Methyl Orange (MO) dye and showed a high degradation efficiency of 99 % due to its excellent electron-hole charge separation. The biological activity of the synthesized CuO/ZnO catalyst was further investigated through protein docking studies, which showed promising results. The CuO/ZnO was also evaluated for its anticancer and antibacterial properties. It exhibited effective anticancer activity against prostate cancer cells (PC-3) in a dose-dependent manner, with an IC50 value of 6.87 ± 8. In addition, it demonstrated potent antibacterial activity against Escherichia coli, Staphylococcus aureus, Bacillus cereous and Pseudomonas aeruginola. The results of this study demonstrate the potential of CuO/ZnO heterostructures as promising materials for various applications in the fields of photocatalysis, biomedicine and antimicrobial materials. Future research in this area will focus on further optimizing the properties of the CuO/ZnO heterostructure to enhance its performance in these applications.

Vibrational spectra, molecular level solvent interaction, stabilization, donor- acceptor energies, thermodynamic, non-covalent interaction and electronic behaviors of 6-Methoxyisoquinoline- anti tubercular agent

The present research is a theoretical examination of 6-methoxyisoquinoline implementing Density Functional Theory quantum mechanical approach. Structural optimization was performed to achieve a stable molecular structure with the least amount of energy. Several protic and aprotic solvent interactions were performed using the IEF polarization continuum model to examine the reactivity and stability of the molecules. Molecular interactions with solvents were investigated using UV–Visible, HOMO-LUMO, MEP, NBO, and NLO properties, which shows some changes in the compound activity at solvent phases against gas phase. The molecular interaction of π*C1–N2 to π*C5 - C10 shows the higher stabilizing energy. DMSO solvent exhibits a very low band gap energy, favors the molecule's high stability. Molecular reactivity, interactions, and optical behavior were all readily apparent. The chemical reactivity of the compound was found good in water. The percentage of PED contributions was evaluated for each mode of vibrations using vibrational spectral investigation. Topological surface analysis was used for better understanding of molecular electron density, reactive center, and steric effect. ELF, LOL, and RDG was generated for compounds with different solvents. The distance of transition and the overlapping of electron and hole were calculated using electron hole analysis. Pharmacological assessments include drug likeness, ADME, toxicity, and a pre-ADMET online tool, which supports the biological capability of the compound. Finally, molecular docking with anti-tubercular protein was performed, and a Ramachandran plot of chosen protein was shown to explore stability.

Enhanced visible light-driven photocatalytic activity of green synthesized cobalt ferrite nanoparticles

Cobalt ferrite nanoparticles were synthesized through green synthesis using Erythrina variegata leaf extract. The presence of phytonutrients in the Erythrina variegata leaf extract was confirmed by phytonutrient screening analysis. The thermal, structural, optical, functional, chemical, morphological, and compositional properties of prepared nanoparticles were analysed. The crystal violet (CV) and congo red (CR) dyes eliminated from water using CoFe2O4 NPs as an adsorbent, has been reported. The thermal stability of as-prepared samples was studied by TG-DTA and powder XRD analysis exhibits a cubic inverse spinel structure. By using UV–Vis spectroscopy, the lower band gap energy of CoFe2O4 NPs was found to be around 1.86 eV. The relevant FTIR and Raman spectra indicated Fe–O (tetrahedral site) and Co–O (Octahedral site) band, which attributed to the stretching vibration modes. The cubic-shaped and irregular agglomerated particles was examined from SEM images. The existence of all required elements in prepared CoFe2O4 NPs were confirmed by EDX and XPS analysis. Leaching experiment using the seed germination method for CoFe2O4 catalyst was evaluated. Moreover, the effective photocatalytic performance of crystal violet (CV) and congo red (CR) dye adsorption using CoFe2O4 catalyst within 120 min on the effect of pH, dye dosage, exposure time, and kinetic studies under visible light were investigated. The maximum dye removal efficiency of 85.18 % and 79.58 % was observed using 25 mg/L at pH 9 for CV and CR dyes, respectively. Trapping experiments revealed that O2•− is the major active species in the dye degradation. Recycling experiments revealed good stability after three cycles for CoFe2O4 catalyst. As a result, the prepared CoFe2O4 NPs can be utilized as an effective adsorbent for wastewater treatment.

Easy separation dual-function Cu2O@LDH@Fe3O4 adsorbent for the removal of Cr(VI) under dark conditions: Experimental and mechanistic study

Designing a magnetic adsorbent material that is both reducible and has strong adsorption properties is significant in reducing Cr(VI) ion pollution. Herein, a 3D multifunctional composite adsorbent for Cr(VI) ions was obtained by using Fe3O4 surface-arrayed magnesium iron layered double hydroxides (Mg/Fe-LDH) micro sheets as a substrate with in situ growth of Cu2O nanoparticles (Cu2O NPs) on their surfaces. Under dark conditions, adsorption capacity of the Cu2O@LDH@Fe3O4 for Cr(VI) was up to 218.82 mg·g−1, surpassing that of Cu2O, Mg/Fe-LDH@Fe3O4, and Mg/Fe-LDH by factors of 1.39, 4.41, and 8.32 respectively. Surprisingly, the removal of Cr(VI) was as high as 76.16 % by the Cu2O@LDH@Fe3O4 (Cinitial = 200 mg/L, pH = 3). Kinetic, isotherm, and thermodynamic results reveal that the removal of Cr(VI) by the Cu2O@LDH@Fe3O4 is consistent with the pseudo-second-order kinetic model of spontaneous monomolecular layer chemisorption. Density functional theory (DFT) calculations show that HCrO4- has a lower energy band gap and is more easily reduced by Cu2O. Therefore, the reason for the adsorbent having more removal effect under acidic conditions was revealed. The XPS and FT-IR experimental mechanism analysis results indicated that Cr(VI) is immobilized on the Cu2O@LDH@Fe3O4 surface through electrostatic interactions, followed by reduction to Cr(III) by Cu2O NPs, which is subsequently adsorbed on the surface of the Cu2O@LDH@Fe3O4. This novel adsorbent structure and unique Cr(VI) removal mechanism provide new ideas for the design of future adsorbents.

Lattice Mie resonances and emissivity enhancement in mid-infrared iron pyrite metasurfaces.

High-refractive-index antennas with characteristic dimensions comparable to wavelength have a remarkable ability to support pronounces electric and magnetic dipole resonances. Furthermore, periodic arrangements of such resonant antennas result in narrow and strong lattice resonances facilitated by the lattice. We design iron pyrite antennas operating in the mid-infrared spectral range due to the material's low-energy bandgap and high refractive index. We utilize Kirchhoff's law, stating that emissivity and absorptance are equal to each other in equilibrium, and we apply it to improve the thermal properties of the iron pyrite metasurface. Through the excitation of collective resonances and manipulation of the antenna lattice's period, we demonstrate our capacity to control emissivity peaks. These peaks stem from the resonant excitation of electric and magnetic dipoles within proximity to the Rayleigh anomalies. In the lattice of truncated-cone antennas, we observe Rabi splitting of electric and magnetic dipole lattice resonances originating from the antennas' broken symmetry. We demonstrate that the truncated-cone antenna lattices support strong out-of-plane magnetic dipole lattice resonances at oblique incidence. We show that the truncated-cone antennas, as opposed to disks or cones, facilitate a particularly strong resonance and bound state in the continuum at the normal incidence. Our work demonstrates the effective manipulation of emissivity peaks in iron pyrite metasurfaces through controlled lattice resonances and antenna design, offering promising avenues for mid-infrared spectral engineering.

NiFe2O4/biochar decorated porous polymer membranes for the flow-through photo-Fenton degradation of tetracycline

Herein, coffee grounds derived biochar was used as support for the fabrication of NiFe2O4/biochar composite particles. The composites achieved up to 10x higher turnover frequencies (TOF) in the photo-Fenton degradation of tetracycline (20 mg/L) in batch compared to the pure NiFe2O4 particles. This could be correlated to a decreased agglomeration, lower band gap energy and electronic interaction with the biochar. The hydrophobic support further enabled the incorporation of the NiFe2O4/biochar powders into porous polyethersulfone (PES) membranes via film casting cum phase separation. The resulting about 150 µm thick porous flow-through membrane reactors achieved high degrees of conversion (95–99 %) at a flux of 100 L/m2h in the continuous photo-Fenton degradation of tetracycline (20 mg/L) in water. We could further show that the TOF values are 5-20x times higher in flow-through the catalytic membranes compared to the NiFe2O4/biochar catalyst particles used in batch mode. We also demonstrated that our photocatalytic membranes can remove low concentrations of tetracycline (2 and 0.2 mg/L) toward values below the detection limit of the used mass spectrometry analysis. Monitoring the leaching of Ni and Fe from one membrane over 28 h of flow-through revealed that Ni predominantly leaches from the incorporated NiFe2O4/biochar, which, however, did not lead to any loss of the catalytic activity. Moreover, we found that the residence time in the membrane has a direct influence on the tetracycline degradation pathways and the resulting product profile, which represents a novel approach for tuning Fenton-like reactions towards specific products.

Catalytic action and bactericidal behavior of samarium/carbon spheres-doped manganese oxide nanostructures and their molecular docking analysis

The co-precipitation technique was adapted to synthesize different concentrations (2 % and 4 %) of samarium (Sm) doped constant equates of carbon spheres (Cs) and manganese oxide (MnO2). The principal objective of this investigation is to demonstrate confirmation that Sm/Cs-doped MnO2 nanostructures (NSs) owned antibacterial and catalytic attributes. Reduction in surface area manifested to agglomeration, NSs faces become inaccessible to initiate a reaction, can be overcome upon doping of Sm. Sm has the potential to increase the activity of metal oxide ascribed to its electron trapping effect. The structural morphologies, optical properties, functional groups, elemental composition, and d-spacing were determined by applying various characterizations. With the incorporation of CS and Sm, UV–vis spectra shifted towards lower wavelength and band gap energy (Eg) was reduced. MnO2 possessed orthorhombic structure, according to the XRD pattern and TEM exhibited long Burr-like morphology of undoped MnO2. SAED image illustrated that MnO2 is polycrystalline. 4 % Sm/CS doped MnO2 revealed the highest degradation (91 %) in a neutral environment. Furthermore, 4 % Sm/Cs doped-MnO2 revealed an inhibitory zone of 2.85 mm against Escherichia coli (E. coli). Additionally, an analysis of molecular docking revealed a binding interface with NRs and the functional domains of certain cellular proteins. Results indicated that Cs-doped MnO2 and Cs/Sm-doped MnO2 NRs are the most potent DNA gyrase and FabB enzyme inhibitors.