Ultrasonic-assisted synthesis of porous S-doped carbon nitride ribbons for photocatalytic reduction of CO2

A series of porous S-doped carbon nitride ribbons (PSCN) were prepared by one-pot hydrothermal and sonochemical synthesis techniques. The morphologies and nanostructures of the catalysts were characterized by SEM, XRD and IR, which confirmed the pristine graphitic structures of carbon nitrides retained in the products. Due to sonication treatment, PSCN has porous structures in the thin ribbon and larger specific surface areas (PSCN 43.5 m²/g, SCN 26.6 m²/g and GCN 6.5 m²/g). XPS and elemental mappings verified that sulfur atoms were successfully introduced into the carbon nitride framework. Diffuse reflectance spectroscopy (DRS) results showed S-doping in the carbon nitride reduced the bandgap energy and enhanced their capability of the utilization of visible light, which contributed to higher photo-generated current. Photoluminescence (PL) analysis indicates the recombination of photogenerated carriers was suppressed in PSCN. Moreover, the photocatalytic performance showed that S-doping and porous and thin ribbon nanostructures may effectively boost the CO₂ reduction rate (to as much as 5.8 times of GCN) when illuminated byvisible light (>420 nm) without the need of sacrificial materials. The preliminary mechanisms of the formation of PSCN and its applications in photocatalytic CO₂ reduction are proposed. It highlights the potential of the current technique to produce effective, nonmetal-doped carbon nitride photocatalysts.

Ultrasonic-assisted preparation and characterization of magnetic ZnFe2O4/g-C3N4 nanomaterial and their applications towards electrocatalytic reduction of 4-nitrophenol

Nanoball-structured ferromagnetic zinc ferrite nanocrystals (ZnFe₂O₄ NPs) entrapped with graphitic-carbon nitride (g-C₃N₄) was produced via straightforward and facile sonochemical synthetical technique (titanium probe; 100 W/cm² and 50 KHz). The morphological (SEM), elemental (EDS), diffraction (XRD), XPS, and electrochemical studies (CV) have been carry out to verify the nanostructure and shape of the materials. The ZnFe₂O₄ NPs/g-C₃N₄ electrode (GCE) was constructed which displayed outstanding electrochemical ability towards toxic 4-nitrophenol (NTP). A sensitive, selective, reproducible, and durable electrochemical NTP sensor was developed by ZnFe₂O₄ NPs/g-C₃N₄ modified electrode. The modified sensor exhibited a high sensitivity and 4.17 nanomolars of LOD. It's greater than the LOD of previously reported NTP modified sensors. The real-time experiments of the modified electrochemical (ZnFe₂O₄ NPs/g-C₃N₄ electrode) sensor were successfully explained in various water (river and drinking) samples and its showed high standard recoveries. Therefore, sonochemical synthetical method and fabrication of modified electrode were developed this work based on environmental analysis of NTP sensor.

Highly sensitive determination of cancer toxic mercury ions in biological and human sustenance samples based on green and robust synthesized stannic oxide nanoparticles decorated reduced graphene oxide sheets

This work proposes the conventional sonochemical synthesis of nanoparticles of tin (IV) oxide on reduced graphene oxide (rGOS@SnO₂) influencing the formation of a composite with enhanced properties. The combination of SnO₂ nanoparticles with rGOS weakens the accumulation in layered structures of the latter system, which leads to better exposure of SnO₂ active sites and thus increases the conductivity of rGOS@SnO₂ composite. This validates the improved electro-catalytic activity of the composite based on previous reports for its successful utilization in the electrochemical determination of toxic contaminants. The quantitative determination of mercury ions, through the use of the electrochemical sensor based on rGOS@SnO₂ manifests several advantages such as simple operator, promptness, cost effectiveness and time independency when compared to other traditional techniques. The fabricated sensor displays two wide linear responses in the range of 0.25-705.3 μM for mercury ions, with a rapid response time about 1 s, and with a high sensitivity of 10.18 μA μM^-1 cm^-2 under optimized conditions. The accumulation of traces of mercury in the bodies of fish in the marine eco system marks the significance of its detection in real samples. The satisfactory results of the proposed sensor establish the supreme efficacy of layered nanomaterials in conjunction with nanoparticles for the simple, rapid and efficient detection of pollutants in food and biological samples.

Sonochemical approach to the synthesis of metal tungstate/nafion composite with electrocatalytic properties and its electrochemical sensing performance

High-intensity ultrasound can be used to produce novel materials, offering an atypical pathway to recognized products without high bulk temperatures, high pressures, or long reaction times. A highly sensitive and selective robust modified sensor was developed using a composition of electrochemically active strontium metal (Sr) based tungstate interconnected with nafion polymer through a facile sonochemical approach. In addition, multiple parameters are important for sonochemical methods and specifically nanomaterial or electrocatalyst development during the ultrasonic irradiation. Moreover, high-intensity ultrasonic probe (Ti-horn) was used to synthesis of nanomaterial at 50 kHz and 200 W. The SrWO₄/nafion was characterized via FESEM, EDX and XRD methods. 8-HD-guanosine (8-hydroxydeoxyguanosine) is one of the major byproduct of deoxyribonucleic acid (DNA) oxidation. The concentrations of 8-HD-guanosine within a cell are a measurement of oxidative stress in body and however its excess level in body causes carcinogenic threats. Therefore, the quantification of 8-HD-guanosine in biological samples with high sensitivity is of great significance. The SrWO₄/nafion modified sensor displayed low detection of 14.36 nM and wide linear range (0.025-398.6 µM), compare to previous reports.

Sonochemical preparation of carbon nanosheets supporting cuprous oxide architecture for high-performance and non-enzymatic electrochemical sensor in biological samples

Copper (Cu) based metal oxides have high electrocatalytic ability. In this work, we are synthesized stone-like cuprous oxide particles (Cu₂O SNPs) covered on acid functionalized graphene oxide (GOS) sheets using ultrasonic process (50 kHz and 100 W). Besides, the chemical structural and crystalline analyses of Cu₂O SNPs@GOS composites were characterized by transmission electron microscopy, X-ray crystallography and energy-dispersive X-ray spectroscopy. The Cu₂O SNPs@GOS nanomaterials were tested towards detection of 8-hydroxydeoxyguanosine (8-OHdG) in biological samples. As expected Cu₂O SNPs@GOS catalyst modified electrodes performed an outstanding catalytic ability on 8-hydroxydeoxyguanosine oxidation. 8-OHdG is oxidative stress biomarker. Further, it is noted that the detection performance of Cu₂O SNPs@GOS coated electrodes and it's highly enhanced due to the synergistic effect of Cu₂O SNPs and GOS. Besides, the modified materials provide more electro-active faces and as well as rapid electron transport pathway and shorten diffusion. Moreover, oxidation of 8-OHdG sensor is exploring a long linear or working range of 0.02-1465 µM and high sensitivity (8.75 nM). The viability of the Cu₂O SNPs@GOS proposed electrochemical methods have tested, to find out 8-OHdG concentrations in biological fluids (blood serum and urine) with a satisfying recovery ranges.

A nanocomposite consisting of cuprous oxide supported on graphitic carbon nitride nanosheets for non-enzymatic electrochemical sensing of 8-hydroxy-2'-deoxyguanosine

Graphitic carbon nitrides supported cuprous oxide architecture is reported as an efficient electrode material for supercapacitors, especially due to its high charge-transfer conductivity of the electrochemical devices. Herein, we present an electrochemical sensor to specifically detect 8-hydroxy-2'-deoxyguanosine (8-HDG) oxidative stress biomarker using graphitic carbon nitrides that decorate a cuprous oxide cubes modified electrode. The fabricated electrochemical sensor was characterized and proved by electrochemical methods, EDX, FESEM, and amperometry (i-t). In the presence of 8-hydroxy-2'-deoxyguanosine (8-HDG), the effective interaction between graphitic carbon nitrides and 8-HDG favors the accumulation on the Cu₂O/g-C₃N₄/GCE, which increases the electrocatalytic property and amperometric response. The proposed electrochemical sensor exhibits a wide linear range for 8-HDG in 0.1 M phosphate buffer (pH 7.0) from 25 nM to 0.91 mM, and the limit of detection (LOD) is 4.5 nM. The stability of the Cu₂O/g-C₃N₄/GCE is improved when stored at 4 °C. The repeatability and reproducibility of this electrochemical sensor is good and the sensor retains its  current response for 8-HDG detection also after long time storage. The modified sensor proved high selectivity and sensitivity for 8-HDG, which made it possible to determine 8-HDG in biological samples. Furthermore, the Cu₂O/g-C₃N₄/GCE offered a favorable electron transfer between the Cu₂O/g-C₃N₄ and the electrode interface compared to Cu₂O/GCE, g-C₃N₄/GCE, and unmodified GCE. Graphical abstract Electrochemical detection of oxidative stress marker based on Cu₂O@g-C₃N₄ materials modified electrode.

Ultrasound induced cleaning of polymeric nanofiltration membranes

Cleaning of the flat sheet nanofiltration membranes, using backflushing, chemical cleaning, and ultrasonication operated individually as well as in combination with chemicals, has been studied in the present work. Identical hydrophilic polyamide membranes were fouled individually using an aqueous solution containing a single dye, an aqueous solution containing a mixture of dyes, and a synthetically prepared petroleum refinery effluent. Effect of different parameters such as the concentration of cleaning solution, contact time, frequency, and power of ultrasound on the efficacy of membrane cleaning has been studied. Optimal cleaning was achieved under sonication conditions of frequency of 24 kHz and power dissipation of 135 W. It was demonstrated that application of sonication under optimum conditions without chemical agents, gave about 85% water flux recovery. In the case of combined chemical and ultrasonic treatment, it was clearly observed that the use of chemical agent increased the efficacy of ultrasonic cleaning. The hybrid method recovered the initial water flux to almost 90% based on the use of 1.0 M aqueous NaOH and 4 min of sonication. Overall, the use of aqueous NaOH in combination with sonication showed a better efficiency for cleaning than the individual processes thus demonstrating a new avenue for membrane cleaning.

Facile sonochemical synthesis of rutile-type titanium dioxide microspheres decorated graphene oxide composite for efficient electrochemical sensor

In this reports the facile and green synthesis of rutile-type titanium dioxide nanoparticles decorated graphene oxide nanocomposite via the ultrasonication process (frequency: 50 kHz, Power: 100 W/cm² and Ultrasonic type: Ti-horn). Because, the sonochemical synthesis method is simple, non-explosive and harmless method than other conventional technique. Furthermore, the synthesized material was characterized by various analytical techniques including FESEM, EDX, XRD, EIS and electrochemical methods. Then, the synthesized TiO₂ MPs@GOS composite was applied for the electrocatalytic detection of theophylline (TPL) using CV and amperometric (current-time) techniques. Captivatingly, the modified sensor has excellent electrocatalytic performance with the wider linear range from 0.02 to 209.6 µM towards the determination of theophylline and the LOD and sensitivity of the modified sensor was calculated as 13.26 nM and 1.183 μA·µM^-1·cm^-2, respectively. In addition, a selectivity, reproducibility and stability of the TiO₂ MPs@GOS modified GCE were analyzed towards the determination of theophylline molecule. Finally, the real time application of TiO₂ MPs@GOS modified theophylline sensor was established in serum and drug samples.

Sonochemical synthesis and physical properties of Co0.3Ni0.5Mn0.2EuxFe2-xO4 nano-spinel ferrites

Nanoparticles (NPs) of composition Co_0.3Ni_0.5Mn_0.2Eu_xFe_2-xO₄, where 0.00 ≤ x ≤ 0.10 (hereafter called CNMEuF) were synthesized by sonochemical approach using UZ SONOPULS HD 2070 ultrasonic homogenizer (frequency of 20 kHz and power of 70 W). As-synthesized samples were characterized thoroughly to determine the effects of europium ions (Eu³⁺) substitution on their structure, morphology and magnetic traits. Structural analyses of the synthesized NPs confirmed their high purity and crystalline cubic phases. Percent diffuse reflectance (%DR) data and Kubelka-Munk theory were exploited to evaluate the optical band gap energies of the studied CNMEuF NPs. Values of optical band gap energies obtained from the Tauc plots were observed in the range of 1.47-1.58 eV. The hysteresis loops (at room temperature and 10 K) of synthesized NPs were analyzed to determine their magnetic properties. These NPs disclosed superparamagnetic and hard ferrimagnetic character at room temperature and 10 K, respectively. With exception, the sample with x = 0.10 revealed soft ferrimagnetic behavior at 10 K. Eu³⁺ doping was shown to have significant influence on the structure and magnetic attributes of the proposed CNMEuF NPs. Values of various magnetic parameters of proposed compositions were reduced with the increase in Eu³⁺ dopant contents.

One-step sonochemical synthesis of 1D β-stannous tungstate nanorods: An efficient and excellent electrocatalyst for the selective electrochemical detection of antipsychotic drug chlorpromazine

In the modern world, the contamination of ecosystem by human and veterinary pharmaceutical drugs through the metabolic excretion, improper disposal/industrial waste has been subjected to a hot issue. Therefore, exploitation of exclusive structured material and reliable technique is a necessary task to the precise detection of drugs. With this regards, we made an effort for the fabrication of novel one-dimensional (1D) stannous tungstate nanorods (β-SnW NRs) via simple sonochemical approach and used as an electrochemical sensor for the detection of antipsychotic drug chlorpromazine (CPZ) for the first time. The crystallographic structure, surface topology, elemental compositions and their distributions and ionic states were enquired by different spectroscopic techniques such as XRD, FTIR, SEM, EDS, elemental mapping and XPS analysis. The developed β-SnW NRs/GCE sensor exhibits a rapid and sensitive electrochemical response towards CPZ sensing with wide linear response range (0.01-457 µM), high sensitivity (2.487 µA µM^-1 cm^-2), low detection limit (0.003 µM) and excellent selectivity. Besides, the as-proposed electrochemical sensor was successfully applied to real sample analysis in commercial CPZ drug and biological fluids and the acquired recovery results are quite satisfactory. The proposed sonochemical method for the preparation of β-SnW NRs is low cost, very simple, fast and efficient for sensor applications.

Sonochemical synthesis and characterization of a new nano Ce(III) coordination supramolecular compound; highly sensitive direct fluorescent sensor for Cu2

Micro and nano-structures of a new Ce(III) Coordination supramolecular compound, [Ce (1,5-NDS)_1.5(H₂O)₅]_n,1, (1,5-Naphthalenedisulfonic acid), were prepared using hydrothermal and sonochemical approaches, respectively. These new micro and nano structures were characterized by elemental analysis, IR spectra, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and powder X-ray diffraction. The X-ray single crystal structure determination of 1 shows that it features a neutral 2D framework based on the [Ce₂H₂₀O₁₆S₂] clusters as a secondary building unit (SBU) which shows a sql/Shubnikov tetragonal plane net. Moreover by considering the H-bonds, the final structure can be considered as 3D supramolecular network. The influence of ultrasound irradiation time on the morphology and size of the nanostructure 1 was investigated. The results indicated that by increasing the time of ultrasonic radiation, smaller nanostructures form and morphological changes occur. Fluorescent properties of the nanoparticles of 1 were also investigated. Coordination polymer 1 shows high fluorescence intensity and good tendency to copper ion that can be used as an optical sensor for selective and sensitive determination of Cu²⁺ in aqueous media with detection limit of 3.0μM.

Sonochemical synthesis of two nanostructured silver(I) coordination polymers based on semi-rigid bis(benzimidazole) ligands

Nanoparticles of two silver(I) coordination polymers (CPs), [Ag₂(L1)₂(DCTP)]_n (1) and [Ag₂(L2)(DCTP)]_n (2) (L1=1,3-bis(5,6-dimethylbenzimidazol-1-ylmethyl)benzene, L2=1,4-bis(benzimidazol-1-yl)-2-butene, H₂DCTP=2,5-dichloroterephthalic acid), were synthesized by the sonochemical approach and hydrothermal method. Both CPs were characterized by elemental analysis, IR spectra, single-crystal X-ray diffraction, scanning electron microscopy (SEM), and thermogravimetric analyses (TGA). CP 1 exhibits a 2D 4-connected sql net with the point symbol {4⁴.6²}. While CP 2 displays a 2D 3,4-connected 3,4L13 net with the point symbol {4.6²}₂{4².6².8²}. The structural diversity indicates that semi-rigid bis(benzimidazole) co-ligands play important roles in tuning the structures of the mixed Ag(I) CPs. The ultrasound irradiation time, temperature, and power showed significant effects on the morphology and growth process of the nanoparticles of two silver(I) CPs. The luminescence and photocatalytic properties of the nanoparticles of CPs 1-2 on the degradation of methyl blue (MB) were also investigated in detail.

Ultrasonic synthesis of two nanostructured cadmium(II) coordination supramolecular polymers: Solvent influence, luminescence and photocatalytic properties

Two nanoparticles of cadmium(II) coordination polymers (CPs) formulated as [Cd(L)(DCTP)]_n (1) and [Cd(L)₂(DCTP)·2H₂O]_n (2) (L=1,2-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H₂DCTP=2,5-dichloroterephthalic acid) were prepared by the sonochemical approach in different solvents and characterized by elemental analysis, IR spectra, scanning electron microscopy (SEM), and powder X-ray diffraction. Structural determination reveals that CP 1 displays a 2D four-connected sql net layer, Whilst CP 2 exhibits a 1D "V"-like chain structure. Luminescence properties, thermal behavior, and photocatalytic activities of the nanoparticles of CPs 1 and 2 on the degradation of methylene blue were investigated. The photocatalytic mechanism is carried out by introducing t-butyl alcohol (TBA) as a widely used OH scavenger. Furthermore, the influence of solvents, reaction time, and ultrasound irradiation temperature on the morphology and size of the nanostructure CPs 1 and 2 were investigated. The results indicated that an increase of time and ultrasound irradiation temperature decreased the nanostructured size.

Ultrasound assisted simultaneous reduction and direct functionalization of graphene oxide with thermal and cytotoxicity profile

The new sonochemical approach for simultaneous reduction and direct functionalization of graphene oxide (GrO) has been developed. The GrO was functionalized with 2-Aminobenzoxazole (2-ABOZ) in twenty min with complete deletion of hazardous steps. The significance of ultrasound was exemplified with the comparative conventional methods. The newly prepared f-(2-ABOZ)GrO was extensively characterized with near edge X-ray absorption fine structure (NEXAFS) spectroscopy, ¹³C solid state NMR, XPS, XRD, HRTEM, SAED, AFM, Raman, UV-vis, FTIR and TGA. The thermal stability of f-(2-ABOZ)GrO was confirmed with total percentage weight loss in TGA. The biological activity of f-(2-ABOZ)GrO was explored with MCF-7 and Vero cell lines. The inherent cytotoxicity was evaluated with SRB assay at 10, 20, 40 and 80μgmL^-1. The estimated cell viabilities were >78% with f-(2-ABOZ) GrO. A high cytocompatibility of f-(2-ABOZ)GrO was ensured with in vitro evaluation on living cell lines, and low toxicity of f-(2-ABOZ)GrO was confirmed its excellent biocompatibility. The morphological effect on Vero cell line evidently supports the formation of biocompatible f-(2-ABOZ)GrO. Therefore, f-(2-ABOZ)GrO was emerged as an advanced functional material for thermally stable biocompatible coatings.

Ultrasound irradiation: a robust approach for direct functionalization of graphene oxide with thermal and antimicrobial aspects

Sonochemical waves as mechanochemical energy was employed to exfoliate graphite oxide and functionalized graphene oxide (GrO), through a reaction of solvent and accountable for top-down and bottom-up approach respectively. The in situ formation of ester intermediate was inferred and a polymeric surface of GrO was further functionalized with 6-Aminoindazole (6-AIND) through sonochemical nucleophilic substitution reaction. As compared to conventional method the effect of ultrasound was verified for the direct functionalization of GrO. The conventional hazardous acylation step for functionalization of GrO was deleted in ultrasound assisted formation of f-(6-AIND) GrO nanocomposite, prepared by stereoselective exploitation of carboxyl groups at edges of GrO. The characterization has ascertained a covalent attachment of 6-AIND onto GrO surface with ATR-FTIR, XPS, SSNMR, TGA, DSC, XRD, AFM, RAMAN, EDX, SEM, BET and elemental analyzer. A weight loss in TGA depicts enhanced thermal stability of f-(6-AIND) GrO and a thermally sensitive behavior. The f-(6-AIND) GrO was studied for in vitro antimicrobial activity to ensure health and environmental safety. Antibacterial activity was identified against human pathogenic gram-positive (Staphylococcus aureus; ATCC 25923) and gram-negative bacteria (Escherichia coli; ATCC 25922). The antifungal activity was observed against Candida albicans (ATCC 10231).