Combination of ultrasound-treated 2D g-C3N4 with Ag/black TiO2 nanostructure for improved photocatalysis

Herein, nanosheets of g-C₃N₄ (CN), prepared using a green ultrasonication process under various conditions, were combined with Ag/black TiO₂ nanocomposites (AgBT) to create two-dimensional (2D) CN/Ag/black TiO₂ tri-composites (CNAgBT). The thickness of the CN sheets varied with the ultrasonication conditions. The CNAgBT sample prepared using ultrasound-treated CN exhibited the highest average photocatalytic efficiencies for the degradation of two model pollutants, followed in decreasing order by AgBT, black TiO₂ (BT), sheet CN, bulk CN, and TiO₂. The order of pollutant degradation efficiencies by the photocatalysts was consistent with that of the charge carrier separation efficiencies. The degradation efficiency of the CNAgBT increased as the CN-to-AgBT ratio increased from 0.05 to 0.1, but decreased gradually for higher ratios between 0.15 and 0.20, indicating a lower optimal CN-to-AgBT ratio. A plausible photocatalytic degradation mechanism for the CNAgBT nanocomposites was proposed. Additionally, CNAgBT with a CN-to-AgBT ratio of 0.1 displayed a higher hydrogen generation rate with a maximum value of 21.5 mmol g⁻¹ over 5 h than those of the AgBT and BT. Overall, the CNAgBT prepared using ultrasonication-treated CNs showed enhanced photocatalytic performance for both pollutant degradation and hydrogen generation.     

Preparation of NiO decorated CNT/ZnO core-shell hybrid nanocomposites with the aid of ultrasonication for enhancing the performance of hybrid supercapacitors

Supercapacitor (SC) electrodes fabricated with the combination of carbon nanotubes (CNTs) and metal oxides are showing remarkable advancements in the electrochemical properties. Herein, NiO decorated CNT/ZnO core-shell hybrid nanocomposites (CNT/ZnO/NiO HNCs) are facilely synthesized by a two-step solution-based technique for the utilization in hybrid supercapacitors. Benefitting from the synergistic advantages of three materials, the CNT/ZnO/NiO HNCs based electrode has evinced superior areal capacity of ~67 µAh cm⁻² at a current density of 3 mA cm⁻² with an exceptional cycling stability of 112% even after 3000 cycles of continuous operation. Highly conductive CNTs and electrochemically active ZnO contribute to the performance enhancement. Moreover, the decoration of NiO on the surface of CNT/ZnO core-shell increases the electro active sites and stimulates the faster redox reactions which play a vital role in augmenting the electrochemical properties. Making the use of high areal capacity and ultra-long stability, a hybrid supercapacitor (HSC) was assembled with CNT/ZnO/NiO HNCs coated nickel foam (CNT/ZnO/NiO HNCs/NF) as positive electrode and CNTs coated NF as negative electrode. The fabricated HSC delivered an areal capacitance of 287 mF cm⁻² with high areal energy density (67 µWh cm⁻²) and power density (16.25 mW cm⁻²). The combination of battery type CNT/ZnO/NiO HNCs/NF and EDLC type CNT/NF helped in holding the capacity for a long period of time. Thus, the systematic assembly of CNTs and ZnO along with the NiO decoration enlarges the application window with its high rate electrochemical properties.     

Ultrasonically tuned surface tension and nano-film formation of aqueous ZnO nanofluids

Nanofluids’ thermophysical properties and heat transfer performance has been investigated for many years, while research on their surface tension (ST) and wetting behavior is very limited. To assess nanofluids potential as industrial products, a complete picture is required to prove their performance in a specific application. Boiling heat transfer, microfluidics and drug development are among the applications where ST is a variable. ST of water-based ZnO nanofluids were measured in the presence and absence of direct ultrasonication. The experiments covered variation of ST with ZnO concentration (0.05–0.4 vol%), ultrasonication amplitude (40% and 100%) and duration. To the best of the authors’ knowledge, this is the first report of ST– ultrasonication process relation for a nanofluid. Results showed that after direct ultrasonication, nanofluids ST is strongly affected by the temperature raise, and in those cases relative ST may provide a clearer picture. A nano-film over individual and agglomerated nanoparticles spotted via TEM imaging was affected from the ultrasonication. Such a nano-film can play a key role in the anomalous thermal transport and wettability of nanofluids. Statistical analyses revealed that changes in ultrasonication amplitude resulted in a statistically significance difference on nanofluid ST and relative ST. Changes in nanoparticle concentration caused a significant difference on the nanofluid ST while the difference in relative ST was insignificant. Variation of ultrasonication duration caused significant variations on the relative ST while the difference in nanofluid ST was not significant. This work highlights that based on specific applications ST and other related features of any nanofluid can be adjusted employing proper ultrasonication conditions.     

The effects of ultrasonication power and time on the dispersion stability of few-layer graphene nanofluids under the constant ultrasonic energy consumption condition

Few-layer graphene (FLG) nanofluids have received widespread interest in recent years due to their excellent thermal and optical properties. However, the low dispersion stability is one of the main bottlenecks for their commercialization. Ultrasonication is an effective method and almost an essential step to improve the stability of nanofluids. This work aimed to determine the optimal ultrasonication process for preparing stable FLG nanofluids, particularly under the constant ultrasonic energy consumption condition. For this purpose, FLG nanofluids were prepared under various amplitudes (20%–80%) and times (33.75–135 min) and evaluated by both sedimentation and optical spectrum analysis techniques. It was found that ultrasonication treatment at 30% amplitude for 90 min was sufficient for proper dispersion of FLG, and a further increase in the ultrasonication power would not benefit the stability enhancement much. However, for FLG nanofluids prepared at amplitudes higher than 30% under the constant ultrasonic energy consumption condition, their stability deteriorated seriously due to the reduced ultrasonication time, while for FLG nanofluids prepared at 20% amplitude for 135 min, they showed the higher stability, which indicates that the stability of FLG nanofluids is more sensitive to ultrasonication time than power. Therefore, a relatively longer ultrasonication time rather than a higher amplitude is recommended to prepare stable FLG nanofluids for practical applications at given ultrasonic energy consumption.     

Sonochemical effects on fabrication,characterization and antioxidant activities of β-lactoglobulin-chlorogenic acid conjugates

The β-lactoglobulin-chlorogenic acid (LG-CA) conjugate was explored to be formed through ultrasonication, redox-pair method and their combination, the ultrasonication used a probe ultrasonic machine with a 6 mm probe at 270 W, and the frequency was 20–25 kHz. The formation of the conjugate was confirmed by SDS-PAGE with a larger molecular weight. Besides, Fourier infrared spectroscopy (FTIR) and Circular dichroism (CD) indicated changes in the secondary structure of the LG-CA conjugate. The α-helix and β-sheet contents of LG decreased and the unordered content increased significantly after the formation of covalent complexes. In addition, both the ultrasonic treatment and its combination with redox-pair method could significantly improve the antioxidant properties of LG. The former increased to 23.16 μmol Trolox/g sample, the latter 82–106 μmol Trolox/g sample. Therefore, ultrasonication could be used both individually and in combination with the redox-pair method to produce LG-CA conjugates with stronger antioxidant activities.     

Ultrasound-assisted Peptide Nucleic Acids synthesis (US-PNAS)

Herein, we developed an innovative and easily accessible solid-phase synthetic protocol for Peptide Nucleic Acid (PNA) oligomers by systematically investigating the ultrasonication effects in all steps of the PNA synthesis (US-PNAS). When compared with standard protocols, the application of the so-obtained US-PNAS approach succeeded in improving the crude product purities and the isolated yields of different PNA, including small or medium-sized oligomers (5-mer and 9-mer), complex purine-rich sequences (like a 5-mer Guanine homoligomer and the telomeric sequence TEL-13) and longer oligomers (such as the 18-mer anti-IVS2-654 PNA and the 23-mer anti-mRNA 155 PNA). Noteworthy, our ultrasound-assisted strategy is compatible with the commercially available PNA monomers and well-established coupling reagents and only requires the use of an ultrasonic bath, which is a simple equipment generally available in most synthetic laboratories.     

Decoration of CNTs' surface by Fe3O4 nanoparticles: Influence of ultrasonication time on the magnetic and structural properties

The decoration of CNTs surface by magnetic nanoparticles was achieved by an ultrasonication-assisted hydrothermal method (UAHM). The effect of ultrasonication time on the crystal structure, magnetic performance, and chemical composition of the magnetic CNT composite material was determined. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and vibrating sample magnetometry were used to characterize the physical, chemical, and magnetic properties of the composites. The composites synthesized via the UAHM exhibited superparamagnetic properties. The ultrasonication time was a critical factor that affected the structure and magnetic performance of the composites. By simply controlling the ultrasonication time, the crystal phase structure of Fe oxide could be selectively modulated and the magnetic performance of the MCs could be effectively tuned.     

Ultrasonication promotes extraction of antioxidant peptides from oxhide gelatin by modifying collagen molecule structure

This study primarily explored the internal mechanism underlying the ultrasonication-induced release of antioxidant peptides. An oxhide gelatin solution was treated ultrasonically (power = 200, 300, and 400 W), followed by enzymatic hydrolysis and structural and morphological analysis. The results showed that ultrasonication increased not only the degree of hydrolysis (DH) and protein recovery rate of the oxhide gelatin but also the ABTS radical scavenging, DPPH radical scavenging, ferrous chelating, and ferric reducing activities of its hydrolysate. The oxhide gelatin hydrolysate treated with 300-W ultrasonication had the maximum antioxidant activities. Ultrasonication inhibited hydrogen bond formation, reduced the crosslinking between collagen molecules, transformed part of the folded structure into a helical structure, and lowered the thermal stability of collagen molecules. The micromorphological analysis revealed that ultrasonication caused the gelatin surface to become loose and develop cracks, and as the power of the ultrasonication increased, the repetition interval distance (dÅ) also increased. Moreover, ultrasonication improved the solubilization, surface hydrophobicity, and interface characteristics and increased the content of basic and aromatic amino acids in the hydrolysate. In conclusion, ultrasonication modifies the protein structure, which increases the enzyme’s accessibility to the peptide bonds and further enhances antioxidant peptide release. These findings provide new insights into the application of ultrasonication in the release of antioxidant peptides.     

褐藻酸钠溶液的超声辐照效应及其对分子量参数的影响

观察了超声辐照过程中褐藻酸钠溶液的pH值、温度、表现特性粘度和表现分子量及其分布的变化,发现在超声辐照过程中,褐藻酸钠的表现平均分子量经历了下降→回升→再下降的过程;当超声辐照停止后,表现特性粘度和表观平均分子量又略有回升,因而推测在这一过程中褐藻酸钠的构象可能发生了变化。     

Tuning the type of nitrogen on N-RGO supported on N-TiO2 under ultrasonication/hydrothermal treatment for efficient hydrogen evolution – A mechanistic overview

Efficient hydrogen production through water splitting has been the challenging task to be achieved in the present context of energy crisis. Among the various catalysts employed, nitrogen doped Titanium dioxide/Reduced graphene oxide (N-TiO₂/RGO) nanocomposite has been established to be a promising photocatalytic material for this purpose. However, nuances of doping nitrogen on TiO₂ and the type of nitrogen (pyridinic, pyrrolic and graphitic) stabilized on RGO responsible for facilitating the H₂ production has not yet been addressed mechanistically. In the present investigation, an attempt has been made to synthesise N-Titanium dioxide/N-Reduced graphene oxide (NTNG) nanocomposite under ultrasonication followed by hydrothermal treatment. A stainlesssteel ultrasonic bath, of 6.5 L tank size (LxBxH) 300 × 150 × 150 mm, was used for ultrasonic treatments. The transducers located at the bottom of the ultrasonic bath generate a frequency of 40 kHz with maximum power of 200 W. A mechanism has been proposed including the nuances of formation and the stabilisation of each type of nitrogen on N-RGO as a function of ultrasonication time. The present work supports the stabilization of a given type of nitrogen on RGO through keto enol tautomerism. XPS and FTIR studies have been undertaken to identify the different types of nitrogen doping and the presence of functional groups respectively. XRD, UV–Vis DRS and PL investigations have been made to establish morphological profile and band gap structure of the nanocomposite. It was observed that pyrrolic type nitrogen stabilized on N-RGO augments the efficiency of photocatalytic activity through hydrogen production by water splitting.