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Copper (I) oxide (cuprite) is a material widely used nowadays, and its versatility is further amplified when it is brought to the nanometric size. Among the possible applications of this nanomaterial, one of the most interesting is that in the medical field. This paper presents a cuprite nanopowder study with the aim of employing it in medical applications. With regards to the environmental context, the synthesis used is related to green chemistry since the technique (out-of-phase pulsed electrochemistry) uses few chemical products via electricity consumption and soft conditions of temperature and pressure. After different physico-chemical characterizations, the nanopowder was tested on the Candida albicans to determine its fungicide activity and on human blood to estimate its hemocompatibility. The results show that 2 mg of this nanopowder diluted in 30 µL Sabouraud broth was able to react with Candida albicans. The hemocompatibility tests indicate that for 25 to 100 µg/mL of nanopowder in an aqueous medium, the powder was not toxic for human blood (no hemolysis nor platelet aggregation) but promoted blood coagulation. It appears, therefore, as a potential candidate for the functionalization of matrices for medical applications (wound dressing or operating field, for example). [ABSTRACT FROM AUTHOR]

Copper (I) oxide (cuprite) is a material widely used nowadays, and its versatility is further amplified when it is brought to the nanometric size. Among the possible applications of this nanomaterial, one of the most interesting is that in the medical field. This paper presents a cuprite nanopowder study with the aim of employing it in medical applications. With regards to the environmental context, the synthesis used is related to green chemistry since the technique (out-of-phase pulsed electrochemistry) uses few chemical products via electricity consumption and soft conditions of temperature and pressure. After different physico-chemical characterizations, the nanopowder was tested on the Candida albicans to determine its fungicide activity and on human blood to estimate its hemocompatibility. The results show that 2 mg of this nanopowder diluted in 30 µL Sabouraud broth was able to react with Candida albicans. The hemocompatibility tests indicate that for 25 to 100 µg/mL of nanopowder in an aqueous medium, the powder was not toxic for human blood (no hemolysis nor platelet aggregation) but promoted blood coagulation. It appears, therefore, as a potential candidate for the functionalization of matrices for medical applications (wound dressing or operating field, for example).

Developing effective strategies for the flexible control of fluid is vital for microfluidic electrochemical biosensing. In this study, a gigahertz (GHz) acoustic streaming (AS) based sonoelectrochemical system was developed to realize an on-chip surface modification and sensitive hydrogen peroxide (H2O2) detection from living cells. The flexible and controlled fluid surrounding the electrochemical chip was optimized theoretically and applied in the sonoelectrochemical deposition of Au nanoparticles (AuNPs) first. Under the steady and fast flow stimulus of AS, AuNPs could be synthesized with a smaller and evener size distribution than the normal condition, allowing AuNPs to show an excellent peroxidase-like activity. Moreover, the AS also accelerated the mass transport of target molecules and improved the catalytic rate, leading to the enhancement of H2O2 detection, with an extremely low detection limit of 32 nM and a high sensitivity of 4.34 μA/ (mM·mm2). Finally, this system was successfully applied in tracking H2O2 release from different cell lines to distinguish the cancer cells from normal cells. This study innovatively integrated the surface modification and molecules detection process on a chip, and also proposed a simple but sensitive platform for microfluidic biosensing application.

In this report, the synergetic sonoelectrochemical method was utilized to produce magnetite nanoparticles was doped with MnO2 with the assistance of ultrasound to form nanoarchitectonic magnetic crystals with a mesoporous magnetite @ manganese dioxide (m-Fe3O4@MnO2) hybrid nanostructure. The hybrid nanocomposite was rapidly produced based on the nucleation and growth of pure iron-oxide nanocrystals in the electrochemical system. The nanocomposite was pure, highly amorphous, and mesoporous in nature; the magnetite was spherical in shape, with an average diameter of 45 ± 10 nm and a MnO2-plane length of 420 ± 30 nm. The stability of the pure m-Fe3O4 was enhanced from 89.61 to 94.04% with negligible weight loss after adding manganese dioxide and the stable formation of the hybrid nanostructure. Based on the superior results of the material, it was utilized as an anode material in Li-ion batteries. The m-Fe3O4@MnO2 hybrid nanostructure had a highly active surface area, which enhanced the interfacial interaction between the Li-ion and the metal surface; it delivered 1513 mAh g−1 and 1290 mAh g−1 as the first specific discharge and charge capacity, respectively, with 85% coulombic efficiency, and it showed an excellent cyclic reversibility of 660 mAh g−1 with a coulombic efficiency of almost 99% at current density of 1.0 A g−1. [ABSTRACT FROM AUTHOR]

In this report, the synergetic sonoelectrochemical method was utilized to produce magnetite nanoparticles was doped with MnO2 with the assistance of ultrasound to form nanoarchitectonic magnetic crystals with a mesoporous magnetite @ manganese dioxide (m-Fe3O4@MnO2) hybrid nanostructure. The hybrid nanocomposite was rapidly produced based on the nucleation and growth of pure iron-oxide nanocrystals in the electrochemical system. The nanocomposite was pure, highly amorphous, and mesoporous in nature; the magnetite was spherical in shape, with an average diameter of 45 ± 10 nm and a MnO2-plane length of 420 ± 30 nm. The stability of the pure m-Fe3O4 was enhanced from 89.61 to 94.04% with negligible weight loss after adding manganese dioxide and the stable formation of the hybrid nanostructure. Based on the superior results of the material, it was utilized as an anode material in Li-ion batteries. The m-Fe3O4@MnO2 hybrid nanostructure had a highly active surface area, which enhanced the interfacial interaction between the Li-ion and the metal surface; it delivered 1513 mAh g−1 and 1290 mAh g−1 as the first specific discharge and charge capacity, respectively, with 85% coulombic efficiency, and it showed an excellent cyclic reversibility of 660 mAh g−1 with a coulombic efficiency of almost 99% at current density of 1.0 A g−1.

The hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) occurring at the Raney-Ni mesh electrode in 30 wt.-% aqueous KOH solution were studied in the absence (silent) and presence of ultrasound (408 kHz, ∼54 W, 100% acoustic amplitude) at different electrolyte temperatures (T = 25, 40 and 60 °C). Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) experiments were performed to analyse the electrochemical behaviour of the Raney-Ni electrode under these conditions. Under silent conditions, it was found that the electrocatalytic activity of Raney-Ni towards the HER and the OER depends upon the electrolyte temperature, and higher current densities at lower overpotentials were achieved at elevated temperatures. It was also observed that the HER activity of Raney-Ni under ultrasonic conditions increased at low temperatures (e.g., 25 °C) while the ultrasonic effect on the OER was found to be insignificant. In addition, it was observed that the ultrasonic effect on both the HER and OER decreases by elevating the temperature. In our conditions, it is suggested that ultrasound enhances the electrocatalytic performance of Raney-Ni towards the HER due to principally the efficient gas bubble removal from the electrode surface and the dispersion of gas bubbles into the electrolyte, and this effect depends upon the behaviour of the hydrogen and oxygen gas bubbles in alkaline media.

In electrochemical processes, gas bubbles on the electrode can cause an increase in both overpotential and ohmic voltage drop which leads to higher energy consumption. Applying power ultrasound during water electrolysis can help to reduce the overpotential, enhance mass transfer, and save energy. In this study, we investigated the effect of ultrasound (20 kHz) on the hydrogen evolution reaction (HER) on a stainless steel plate with varying concentrations of NaOH solutions at 298 K, using linear sweep voltammetry (LSV). We especially focused on understanding the bubble behavior on the stainless steel plate during HER using high-speed imaging in ultrasonic field. When ultrasound was applied to solutions with NaOH concentrations of 0.1, 0.5, 1 M, the current density increased by about 9.0, 5.9, 2.8 %, respectively. As the ultrasound irradiation began, the bubbles tended to hover around on the electrode surface, coalescing with other bubbles, rather than rising. When the size of the coalesced bubbles became too large to stay on the surface of the electrode, they were expelled from the ultrasonic field. The repeated collapse and coalescence of these bubbles was observed while they were rising. The velocity increased about 2 times when ultrasound irradiation began, and increased by more than 6 times in the ultrasonic field. More nucleation of bubbles was observed on the electrode in the ultrasonic field. Using ultrasound reduced the critical diameter of bubbles which detached from the electrode, from 58.0 to 15.9 μm, and the residence time of the bubbles, from 533 to 118 ms. Further, when the ultrasound was applied, the mean diameter of bubbles decreased from 71.8 to 17 μm. Hence, bubble coverage on the electrode surface decreased from 8.3 to 1 % despite an increase in the total number of bubbles. As a result, ultrasound was found to be effective for hydrogen production during water electrolysis, increasing current by the faster removal of gas from the stainless steel plate.

The electrochemical CO2 reduction reaction (CO2RR) on polycrystalline copper (Cu) electrode was performed in a CO2-saturated 0.10 M Na2CO3 aqueous solution at 278 K in the absence and presence of low-frequency high-power ultrasound (f = 24 kHz, PT ~ 1.23 kW/dm3) in a specially and well-characterized sonoelectrochemical reactor. It was found that in the presence of ultrasound, the cathodic current (Ic) for CO2 reduction increased significantly when compared to that in the absence of ultrasound (silent conditions). It was observed that ultrasound increased the faradaic efficiency of carbon monoxide (CO), methane (CH4) and ethylene (C2H4) formation and decreased the faradaic efficiency of molecular hydrogen (H2). Under ultrasonication, a ca. 40% increase in faradaic efficiency was obtained for methane formation through the CO2RR. In addition, and interestingly, water-soluble CO2 reduction products such as formic acid and ethanol were found under ultrasonic conditions whereas under silent conditions, these expected electrochemical CO2RR products were absent. It was also found that power ultrasound increases the formation of smaller hydrocarbons through the CO2RR and may initiate new chemical reaction pathways through the sonolytic di-hydrogen splitting yielding other products, and simultaneously reducing the overall molecular hydrogen gas formation.

The influence of ultrasound agitation on the properties of electrodeposited Zn-Co coatings was analysed and compared with coatings deposited by using magnetic stirring. The morphology and chemical composition of the deposits were analysed by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. X-ray diffraction was used in examining the crystallographic orientation and phase composition of the coatings. It was found that utilising ultrasound during deposition enhanced the compactness, homogeneity and corrosion resistance of the coatings compared to deposition with magnetic stirring of the plating solution. Magnetically stirred coatings were dendritic and porous, whereas coatings produced under ultrasound agitation were more homogeneous and dense. The higher the ultrasound intensity applied the higher the cobalt content in the coating. The corrosion resistance of Zn-Co coatings was improved by ultrasound agitation, with the best results obtained at 20 W cm−2 of ultrasound intensity. [ABSTRACT FROM AUTHOR]

In this work, discoloration of basic yellow 28 using sonoelectrochemical method in presence of titanium dioxide nanoparticles was investigated. The respond surface methodology (RSM) was applied for optimization of discoloration. The influence of different factors such as applied potential, amount of titanium dioxide nanoparticles, time and solution pH was evaluated on discoloration. A mathematical model was presented to prediction of discoloration with RSM. The results shown that time has highest effect on discoloration efficiency, pH, applied potential and amount of titanium dioxide nanoparticles has also effective factors. The sonoelectrochemical route in presence of TiO2 nanoparticles has better performance on discoloration comparing with other methods including sonoelectrochemistry, sonochemistry in presence of hydrogen peroxide, sonochemistry in presence of hydrogen peroxide/TiO2 nanoparticles and electrochemistry in presence of TiO2 nanoparticles at optimum condition, i.e. pH= 8.0, 1.1 V applied potential, 0.96 g/L TiO2 nanoparticles and 119 min.

A combination of electrochemistry and ultrasound (i.e., sonoelectrochemistry) is one of the advanced oxidation processes for decolorization of color wastewaters. In this method, ultrasound is generally produced by an ultrasonic bath in which an electrochemical cell is immersed. The physicochemical effects of ultrasound improve the electro-oxidation of dye solutions and the rate of their decolorization. This study evaluates the effect of the sonoelectrochemical process on the decolorization of anthraquinone C.I Reactive Blue 49. The effects of various experimental parameters in this process were investigated using response surface methodology (RSM) with a central composite design. The optimization results pointed to a maximum decolorization efficiency rate of more than 95% achieved in optimum conditions (pH = 8.3, concentration of dye = 10 mg L−1, voltage = 0.7 V and treatment time = 80.6 min). The corresponding synergistic effect was determined through a comparison of the decolorization percentage of the sonoelectrochemistry process and the sum of the decolorization percentages of electrochemistry and ultrasound methods. The maximum COD removal for sonochemistry, electrochemistry, sonochemistry/H2O2 and sonoelectrochemistry in optimum conditions was 4.0, 53.4, 40.6 and 91.0%, respectively. According to the optimization results, the maximum decolorization efficiency could be achieved in optimum conditions by the sonoelectrochemical process. [ABSTRACT FROM AUTHOR]

Abstract Most of the observations seen in the application of power ultrasound in electrochemistry or also known as sonoelectrochemistry are due to enhanced mass-transport of electroactive species from the bulk solution to the electrode surface caused by efficient stirring, acoustic streaming and cavitation. However, fundamental studies on the effect of ultrasound on electrode kinetics i.e. on the electron-transfer are scarce. The main question still remains to be answered: Does power ultrasound affect heterogeneous electron transfer kinetics? This opinion paper discusses the effect of ultrasonic frequency and intensity upon the electrode kinetic parameters such as the half-wave potential (E 1/2) and the apparent heterogeneous rate constant (k o). A few sonoelectrochemical studies have highlighted changes in half-wave potential and in apparent heterogeneous rate constant for both quasi-reversible and irreversible systems when the data were compared to silent conditions. These observations are thought to be due to the contribution of mass-transport and macroscopic temperature effects, as well as the continuous cleaning of the electrode surface caused by the collapse of high-energy cavitation bubbles and the production of high velocity jets of liquid. However, there still remains mechanistic controversy in assigning whether these findings could also be due to localised temperature increases, the contribution of sonolysis products or solely due to enhanced mass-transport at the electrode surface. Thus, the effect of stirring, macroscopic temperature and sonication time upon these electrode kinetic parameters is also shown to be important factors in comparing the validity of any sonoelectrochemical effects. [ABSTRACT FROM AUTHOR]

Highlights • Sonicated water produces hydrogen. • Ultrasonically-assisted water electrolysis enhances hydrogen yield. • Ultrasound improves water electrolysis efficiency. • Ultrasound reduces cell voltages, electrode potentials and overpotentials. • Hydrogen yield depends upon the ultrasonic frequency and power. Abstract Reserves of fossil fuels such as coal, oil and natural gas on earth are finite. The continuous use and burning of these fossil fuel resources in the industrial, domestic and transport sectors has resulted in the extremely high emission of greenhouse gases, GHGs (e.g. CO 2) and solid particulates into the atmosphere. Therefore, it is necessary to explore pollution free and more efficient energy sources in order to replace depleting fossil fuels. The use of hydrogen (H 2) as an alternative fuel source is particularly attractive due to its very high specific energy compared to other conventional fuels and its zero GHG emission when used in a fuel cell. Hydrogen can be produced through various process technologies such as thermal, electrolytic, photolytic and biological processes. Thermal processes include gas reforming, renewable liquid and biooil processing, biomass and coal gasification; however, these processes release a huge amount of greenhouse gases. Production of electrolytic hydrogen from water is an attractive method to produce clean hydrogen. It could even be a more promising technology when combining water electrolysis with power ultrasound to produce hydrogen efficiently where sonication enhances the electrolytic process in several ways such as enhanced mass transfer, removal of hydrogen and oxygen (O 2) gas bubbles and activation of the electrode surface. In this review, production of hydrogen through sonochemical and sonoelectrochemical methods along with a brief description of current hydrogen production methods and power ultrasound are discussed. [ABSTRACT FROM AUTHOR]

In this paper, electrooxidation of methyl paraben (MeP) is studied by electrolysis only and electrolysis coupled with sonolysis, using a diamond electrode. Complete mineralization of MeP was achieved for both processes, in chloride and sulfate media. Results showed that, although the oxidation of pollutant is faster in the presence of chloride, the mineralization is favored in sulfate medium. Ultrasound irradiation enhanced the removal of organic matter due to the activation of oxidant species in both supporting electrolytes. Moreover, the formation of chlorine gas in the chloride containing medium improves the ultrasound cavitation effect, promoting faster depletion of the total organic carbon in the first hour of treatment. Regarding the formation of more toxic products, all possible organochlorinated intermediates were removed, since complete mineralization was attained in less than 5 hours. Ultrasonic coupling to the electrolysis process accelerates the destruction of the intermediates and delays the formation of perchlorate, which only begins after the complete removal of the total organic carbon. Low and high ultrasound frequencies were evaluated and were found to produce different effects of cavitation, which affect the electrolysis in different ways. The final result will be a balance between these effects and thus, an optimum frequency can be established for different systems. How ultrasound affects electrolysis? Enhancement of electrolysis by the coupling to sonolytic process for wastewater treatment results in the complete mineralization of a pollutant (methyl paraben) in sulfate and chloride media. Low frequency ultrasound promotes the activation of persulfate, which favors the TOC removal in the presence of sulfate. Cavitation effects of low and high intensities of ultrasound are balanced in an optimal frequency. [ABSTRACT FROM AUTHOR]

Abstract We established an efficient method to trap the hydroxyl radicals (OH) derived from the sonoelectrochemical system, the model compound crystal violet was used as a scavenger. Parameters affecting the trapping reaction, such as reaction time, electrolyte, applied voltage, power, and solution pH, were investigated. The dynamics model was used to analyze the reaction kinetics and the origin of OH. The detection method is stable and accurate, comparing with the single electrochemical and ultrasonic systems, more OH could be trapped in the sonoelectrochemical system; the higher the concentration of the scavenger, the more OH is captured; the OH is promoted to generate in the alkaline conditions; appropriate electrolyte concentration and voltage will enhance the OH yields by increasing the current efficiency; inhibitors can significantly reduce the yields of OH, inorganic inhibitors have better removal effect than organic inhibitors on the OH; the enhancement of power is beneficial to the generation of cavitation effect increasing free radical production, it is not conducive to generate OH when the power is strengthened to a certain degree; the OH may be produced by the decomposition of water molecules and the oxidation of OH− in the system; the process follows first-order reaction kinetics with good linearity. Highlights • A method for indirectly capturing free radicals in the sonoelectrochemical is proposed. • Indirectly characterize the amount of free radicals in the system by the color change of the dye capture agent • In the sonoelectrochemical system, stainless steel is chosen as the electrode with a unique mechanism of action. [ABSTRACT FROM AUTHOR]

Abstract Sonoelectrochemistry is a technique that allows studying the effects of ultrasonic radiation on electrochemical systems. This technique is clean, inexpensive, improves the activation of the electrode surface and enables short synthesis times. In this context, this study uses sonoelectrochemistry to produce nickel oxide nanostructures, which will be proposed as an efficient and reliable glucose sensing device enzyme-free. For this, nickel oxide nanostructures have been electrochemically grown by ultrasound-assisted anodization of nickel foils in a solution composed of: ethylene glycol, ammonium chloride (0.5 wt% of NH 4 Cl) and 5.0 wt% of H 2 O solution. The anodization experiments were carried out using ultrasonic waves (37 kHz, 60 W) at different potentials (50 and 75 V), different temperatures (50 °C and 75 °C) and 900 s as anodization time. The process was carried out using a two-electrode system. The nanostructured NiO layers obtained were analyzed SEM, XRD and EDX for morphology, crystalline structure and chemical composition, respectively. The electrocatalytic activity of nanostructured NiO in the glucose oxidation reaction was studied by linear sweep voltammetry (LSV). From this technique, it was possible to determine the kinetic parameters that allow proposing a mechanism by which the glucose oxidation process takes place. The sensitivity (206.9 μA mM−1 cm−2), the limit of detection (LOD, 1.16 μM), the limit of quantification (LOQ, 3.87 μM), the linear working range of the proposed electrode (0.1 mM ≤ [Glucose] ≤ 10 mM) and the response time (6 s), were determined. Finally, it was established that the nanostructured NiO electrode doesn't respond to different interferences (e.g. ascorbic, uric acid and dopamine acid), confirming the selectivity of NiO nanostructures for glucose. So, the electrode proposed in this study, is a good candidate for to be used as a non-enzymatic amperometric glucose sensor due to the good merit figures and its simple synthesis by ultrasound-assisted anodization. Highlights • The NiO nanostructures have been electrochemically grown by ultrasound-assisted anodization of nickel foils. • NiO electrode shows a good: sensitivity, LOD, LOQ, linear working range, response time, selectivity and stability. • NiO electrode is a good candidate for to be used as a nonenzymatic amperometric glucose sensor for its good merit figures. [ABSTRACT FROM AUTHOR]

Ultrasounds has a wide range of active applications spreading in solid, liquid and gaseous mediums, embedded in new methods and technologies for preventing, reducing and removing of existing pollution. This paper deals with the sonochemistry reactors and their combinations with photocatalysis and electrochemistry. Various parameters such as ultrasound frequency, power, number of ultrasound sources, lab-scale or large-scale equipment used for environmental applications of sonochemical reactors have been analysed using examples available in the literature. [ABSTRACT FROM AUTHOR]

Sonoelectrochemistry is the combination of ultrasound and electrochemistry which provides many advantages in electrochemistry, such as fast reaction rates, surface cleaning and activation, and increased mass transport at an electrode. Due to the advantages, some efforts have been made in order to benefit sonoelectrochemistry in the field of energy and environmental engineering. This review paper highlights the developed progress of the application of sonoelectrochemistry in the production of hydrogen, electrocatalyst materials and electrodes for fuel cells and semiconductor photocatalyst materials. This review also provides the experimental methods that are utilized in several sonoelectrochemical techniques, such as different set-ups generally used for the synthesis of energy-related materials. Different key parameters in the operation of sonoelectrochemical synthesis including ultrasonication time, ultrasound frequency and operation current have been also discussed. There are not many research articles on the sonoelectrochemical production of materials for supercapacitors and water electrolyzers which play crucial roles in the renewable energy industry. Therefore, at the end of this review, some articles which have reported the use of ultrasound for the production of electrocatalysts for supercapacitors and electrolyzers have been reviewed. The current review might be helpful for scientists and engineers who are interested in and working on sonoelectrochemistry and electrocatalyst synthesis for energy storage and energy conversion.

In thin layer sonoelectrochemistry (TLS), constructive interference is established in a thin layer of electrolyte with a low power, ultrasonic quartz crystal oscillator (QCO). No cavitation, no temperature increase, and no impacts on mass transport are observed. In this first report of TLS experiments without cavitation, voltammetric morphologies are not disrupted. Interfacial electron transfer for three transition metal species are evaluated with established cyclic voltammetric diagnostics. For Ru(bpy) 3 2 + with inherently fast (reversible) interfacial electron transfer, voltammograms are unchanged on sonication at 41 kHz. For Fe3＋ with slow heterogeneous electron transfer, interfacial rate increases with sonication, where increases in rate persist without diminution for minutes postsonication. For a cobalt phenanthroline probe, changes in voltammetric morphology at higher QCO intensity are consistent with chemical changes of ligand loss. Constructive interference in TLS imparts sound pressure to the electrode solution interface to increase electron transfer rates without mass transport disruption. TLS may provide means to electrocatalyze interfacial rates. [ABSTRACT FROM AUTHOR]

• Sonochemistry has demonstrated the ability alter chemical reactions and change physical properties under mild reaction conditions. • Ultrasound has found its way into diverse industries but limitedly in the biomedical field. • In the (bio-)medical field ultrasonic cleaning and imaging are most established but use in sonodynamic therapy (SDT) and drug delivery systems is emerging. • To pave the way for sonochemically application-driven advancements, various fundamental aspects need to be addressed. Sonochemistry, although established in various fields, is still an emerging field finding new effects of ultrasound on chemical systems and are of particular interest for the biomedical field. This interdisciplinary area of research explores the use of acoustic waves with frequencies ranging from 20 kHz to 1 MHz to induce physical and chemical changes. By subjecting liquids to ultrasonic waves, sonochemistry has demonstrated the ability to accelerate reaction rates, alter chemical reaction pathways, and change physical properties of the system while operating under mild reaction conditions. It has found its way into diverse industries including food processing, pharmaceuticals, material science, and environmental remediation. This review provides an overview of the principles, advancements, and applications of sonochemistry with a particular focus on the domain of (bio-)medicine. Despite the numerous benefits sonochemistry has to offer, most of the research in the (bio-)medical field remains in the laboratory stage. Translation of these systems into clinical practice is complex as parameters used for medical ultrasound are limited and toxic side effects must be minimized in order to meet regulatory approval. However, directing attention towards the applicability of the system in clinical practice from the early stages of research holds significant potential to further amplify the role of sonochemistry in clinical applications. [ABSTRACT FROM AUTHOR]

• GHz acoustic resonator based microfluidic sonoelectrochemical platform was developed. • Flexibly and accurately controlling the fluid flow in microfluidic channel was achieved. • On-chip sonoelectrochemical deposition of nanoparticles and sensing of H 2 O 2 was improved. • Tracking intracellular H 2 O 2 release to identify the cancer cells from normal cells was evaluated. Developing effective strategies for the flexible control of fluid is vital for microfluidic electrochemical biosensing. In this study, a gigahertz (GHz) acoustic streaming (AS) based sonoelectrochemical system was developed to realize an on-chip surface modification and sensitive hydrogen peroxide (H 2 O 2) detection from living cells. The flexible and controlled fluid surrounding the electrochemical chip was optimized theoretically and applied in the sonoelectrochemical deposition of Au nanoparticles (AuNPs) first. Under the steady and fast flow stimulus of AS, AuNPs could be synthesized with a smaller and evener size distribution than the normal condition, allowing AuNPs to show an excellent peroxidase-like activity. Moreover, the AS also accelerated the mass transport of target molecules and improved the catalytic rate, leading to the enhancement of H 2 O 2 detection, with an extremely low detection limit of 32 nM and a high sensitivity of 4.34 μA/ (mM·mm2). Finally, this system was successfully applied in tracking H 2 O 2 release from different cell lines to distinguish the cancer cells from normal cells. This study innovatively integrated the surface modification and molecules detection process on a chip, and also proposed a simple but sensitive platform for microfluidic biosensing application. [ABSTRACT FROM AUTHOR]

Highlights • A very simple and low cost sonoelectrochemical method for the preparation of highly-oxidized carbon nanosheets (hCNSs). • Excellent electrocatalytic property of the obtained hCNSs. • A sensitive differential pulse voltammetry method based on the hCNSs modified electrode for the determination of pyridoxal. Abstract In this paper, highly-oxidized carbon nanosheets (hCNSs) was prepared with a very simple and low cost sonoelectrochemical method. Compared with the electrochemical method without ultrasonic irradiation, the hCNSs which obtained with ultrasonic irradiation exhibited different ratio of oxygen-containing groups and better electrocatalytic property. The electrochemical behaviour and the electrooxidation mechanism of pyridoxal on the hCNSs modified electrode were investigated in detail. Compare to it on the glassy carbon electrode, the peak current of pyridoxal on the hCNSs modified electrode showed 64-folds enhancement. So a sensitive differential pulse voltammetry method based on the hCNSs modified electrode was proposed for the determination of pyridoxal. Its linear range was 2 × 10−8–1 × 10-6 mol L-1 and the detection limit was 5.4 × 10-9 mol L-1. The method has been applied to the analysis of pyridoxal in the urine and plasma sample. [ABSTRACT FROM AUTHOR]

The optimum conditions for the electrocatalytic hydrogenation of (R)-(+)-pulegone in water, using ultrasound (continuous or pulsed mode) and a nickel sacrificial anode have been determined. The continuous ultrasound (14 W), without temperature control, showed to be a most effective technique if compared with pulses of 0.2 s applied after each second. The sonication of the reaction solution presented a slight stereochemical effect on the product distribution, and its magnitude depends on both the ultrasound power and the mode. Simultaneous ultrasound irradiation during electrochemical process showed a synergetic effect, able to generate H radical from water H O bond rupture, in addition to the H radicals formed by the electrochemical reduction of water on the electrode surface, increasing both current efficiency and conversion yields. Chitosan microspheres were use in the removal of nickel ions of the aqueous medium showing an adsorption efficiency of 64%. [ABSTRACT FROM AUTHOR]

Micropollutants are becoming an increasing problem for the environment and wastewater treatment. One example is Bisphenol A (BPA), an endocrinic disruptor, which is widely used in plastic production. Due to its endocrine disrupting effects on aquatic (micro-)organisms and its ubiquity, in surface- and wastewater alike, adequate treatment techniques are necessary. In this study, the degradation of BPA by a sonoelectrochemical hybrid system was investigated, using a low frequency (24 kHz) ultrasound horn and two boron doped diamond electrodes. It was found that by the combination of the individual processes, i.e. ultrasound and electrochemical oxidation, more than 90% of BPA could be removed within 30 min at an initial concentration of 1 mg L −1 . Moreover, synergistic effects were discovered and a considerable improvement compared to the individual processes could be achieved by using a potential of 5 V, whereas synergistic effects were absent at a potential of 10 V. This study provides investigation of ultrasound amplitude, potential and electrode positioning on BPA degradation. The reaction was found to follow pseudo first order kinetics with a rate constant of 0.089 min −1 . Samples were analysed by high pressure liquid chromatography (HPLC) using a diode array detector. Moreover, the presence and distribution of hydroxyl radicals within the reactor was visualized by using sonochemiluminescence. [ABSTRACT FROM AUTHOR]

The purpose of this study is to explore a new synthesis way for the production of iron nanoparticles exploiting the nanometric structure of long ramified iron branches formed by electrodeposition in a Hele-Shaw cell. After the growth, these branches are fragmented by the action of a vibrating element (piezoelectric disk) integrated into the cell. The emphasis is put on the growth of the ramified iron branches which is performed by galvanostatic electrodeposition in a stagnant electrolyte (FeCl 2 ) inside the Hele-Shaw cell (50 μm deep). The competition between the co-formation of H 2 bubbles (H + reduction) and the growth of ramified iron branches (Fe II reduction) is analyzed by varying both the applied current density j and the FeCl 2 concentration. Two regimes, depending mainly on j , are highlighted: below a threshold current density of 8 mA/cm 2 only H 2 bubbles are formed, while above this threshold, iron branches grow accompanied by the formation of H 2 bubbles which nucleate and grow at the top of the branches during their formation. The H 2 bubbles influence the branches growth especially at low j (<24 mA/cm 2 ) when the growth velocity of the branches is low compared to the growth rate of the bubbles. At higher j (>24 mA/cm 2 ), the branches follow a columnar growth with a constant front velocity, well predicted by the theory. Scanning Electron Microscopy (SEM) of the iron branches shows a dendritic structure constituted of nanometric crystallites, whose size depends on the local growth velocity: increasing the growth velocity from 3.6 μm/s to 40 μm/s leads to a decrease in the crystallites size, from ∼1 μm to ∼10 nm. Using the acoustic vibrations (4 kHz) of the piezoelectric disk, these fragile branches are successfully fragmented into submicrometric fragments of dendrites exhibiting high specific surfaces S/V (equivalent to the S/V of nanoparticles of 30 nm diameter). Advantages/Drawbacks compared to other synthesis ways as well as the optimization of the proposed synthesis are discussed. [ABSTRACT FROM AUTHOR]

Simultaneous electrocatalytic Pt-nanoparticle synthesis and decoration of Vulcan XC-72 carbon black substrate was achieved in a novel one-step-process, combining galvanostatic pulsed electrodeposition and pulsed ultrasonication with high power, low-frequency (20 kHz) ultrasound. Aqueous chloroplatinic acid precursor baths, as well as carbon black suspensions in the former, were examined and decoration was proven by a combination of characterization methods, namely: dynamic light scattering, transmission electron microscopy, scanning electron microscopy with EDX-analysis and cyclic voltammetry. In particular, PVP was shown to have a beneficial stabilizing effect against free nanoparticle aggregation, ensuring narrow size distributions of the nanoparticles synthesized, but is also postulated to prevent the establishment of a strong metal-substrate interaction. Current pulse amplitude was identified as the most critical nanoparticle size-determining parameters, while only small size particles, under 10 nm, appeared to be attached to carbon black. [ABSTRACT FROM AUTHOR]

This short review provides the current state-of-the-art of in situ coupling of ultrasound to chemical deposition methods. Synergetic action of ultrasound and light radiation or electrical fields may result in new powerful methodologies, which include sonophotodeposition and sonoelectrodeposition processes. The effect of ultrasound is explained on the basis of different physical mechanisms emerging from cavitation phenomenon. Some possible mechanisms of the interactions between ultrasound and photochemical and electrochemical processes are discussed here. The application of sonophotodeposition and sonoelectrodeposition as green energy sources in the syntheses of different nanomaterials is also reviewed. [ABSTRACT FROM AUTHOR]

The varieties of the methods of nanoparicles synthesis are discussed in this review. Wet and dry chemistry processes, pulse sonoelectrochemistry, methods with use of supercritical CO2, and far from equilibrium systems of two liquids are considered and compared.Possible role of dissipative phenomena during the processes of new nanoparticles creation is under special attention.

This article reviews the nanomaterials that have been prepared to date by pulsed sonoelectrochemistry. The majority of nanomaterials produced by this method are pure metals such as silver, palladium, platinum, zinc, nickel and gold, but more recently the syntheses have been extended to include the preparation of nanosized metallic alloys and metal oxide semiconductors. A major advantage of this methodology is that the shape andsize of the nanoparticles can be adjusted by varying the operating parameters which include ultrasonic power, current density, deposition potential and the ultrasonic vs electrochemical pulse times. Together with these, it is also possible to adjust the pH, temperature and composition of the electrolyte in the sonoelectrochemistry cell.

In this work we present the direct electrodeposition of poly(pyrrole)/Prussian blue composite nanostructures under ultrasonic radiation. Different characterization techniques were employed such as scanning electron microscopy, electrochemical impedance spectroscopy and voltammetric experiments. It was found that the amplitude of the ultrasound highly influences both size and dispersity of PB nanoparticles providing interesting electrochemical features such as the enhancement of mass-transport processes during cycling of the modified electrodes, a good sensitivity in the electrocatalytic reduction of hydrogen peroxide, also the polypyrrole matrix provided an enhanced durability of the Prussian blue, compared with electrodeposited thin films. All these features are probably related to the morphology and distribution of the nanoparticles on the electrode interface which can be tuned by changing the ultrasound amplitude. We believe that this work could be of benefit of different electrochemical devices by presenting a direct and straightforward electrode modification methodology, where the direct electrodeposition of the composite nanostructures assisted by ultrasonic radiation can be applied to many different materials, taken into account the vastly possibilities reached by the combination of conducting polymers and electroactive inorganic materials. [ABSTRACT FROM AUTHOR]

Biologically treated cephalosporin pharmaceutical wastewater is a complex industrial wastewater that is toxic and refractory for further biological treatment. For this purpose, a novel sonoelectrochemical catalytic oxidation-driven process using a nanocoated electrode has been developed to treat such wastewater. In the process, the synergy and mechanism of the sonoelectrochemistry using ultrasound enhancement of the nanocoated electrode activity to treat the wastewater was studied. The nanocoated electrode generated more radicals than the traditional coated electrode did; in the presence of ultrasonic waves, the mass-transfer effects on the nanocoated electrode surface were enhanced, resulting in rapid diffusion of the generated hydroxyl radicals into the solution, and quickly reacted with organic pollutants. Compared with the traditional coated electrode, the effect of the nanocoated electrode used on the wastewater treatment process was more enhanced by ultrasound under the same conditions. The biotoxicity of the wastewater in the sonoelectrochemical catalytic oxidation process was monitored and shown as having first increased and then decreased. The optimum operating conditions resulted in a 94% removal efficiency for COD and consisted of a current of density 8 mA/cm 2 and an ultrasound frequency of 45 kHz. All of the results showed that the sonoelectrochemical catalytic oxidation-driven process was found to be a very efficient method for the treatment of non-biodegradable cephalosporin pharmaceutical wastewater. [ABSTRACT FROM AUTHOR]

This study relates the sonoelectrochemical production of metallic particles and nanoparticles. The emphasis is on the influence of electrode material and roughness on the morphology of iron electrodeposits and their dispersion from the electrode by ultrasonification. Ultrasonification is either applied during cyclic voltammetries with solution stirring or after galvanostatic iron electrodeposition; no dispersion was observed when using a gold electrode, whereas dispersion was always observed when using vitreous carbon (VC) substrates. Scanning Electron Microscopy (SEM) imaging of the electrodeposits shows higher iron coverage on gold than on VC electrodes. Iron spreads more on gold than on VC. The values of both the interfacial energy of the iron/electrode interface and the work of adhesion of iron on the electrode are in agreement with the previous observations. Dispersion kinetics on VC were found to be dependent on the electrode surface roughness. Results suggest that dispersion follows a first order kinetics, which is coherent with the constant action of cavitation bubbles in the vicinity of the electrode surface. Enhancement of mass-transfer by ultrasound has also been observed. [ABSTRACT FROM AUTHOR]

This short review provides the current state-of-the-art of in situ coupling of ultrasound to chemical deposition methods. A synergetic action of the ultrasound and light radiation or electrical fields may result in new powerful methodologies, and these include sonophotodeposition and sonoelectrodeposition processes. The effect of ultrasound is explained on the base of different physical mechanisms emerging from cavitation phenomenon. Some possible mechanisms of the interactions between ultrasound and photochemical and electrochemical processes are discussed here. The application of sonophotodeposition and sonoelectrodeposition as green energy sources in the syntheses of different nanomaterials is also reviewed.

Nanopowders of copper (I) oxide (Cu 2 O, cuprite) were synthesized by out-of-phase pulsed sonoelectrochemical method and characterized by several physico-chemical techniques (X-ray diffraction, transmission electronic miscroscopy, energy-dispersive x-ray spectroscopy, centrifugal liquid sedimentation, zeta potentials and specific area measurements). The same analyses were done on commercial cuprite and copper nanopowders for comparison. Once the chemical nature and morphology of the three materials have been determined, bactericidal assays were performed on methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli) in Trypto-Casein-Soy medium. The results show that sonoelectrochemical Cu 2 O nanopowders are good antibacterial material as compared to the two commercial nanopowders while using a synthesis method that is inexpensive and adaptable to the industrial scale. [Display omitted] • Sonoelectrochemical Cu 2 O nanopowders are efficient bactericide materials in tryptocasein-soy. • Antibacterial activity is better against Staphylococcus aureus than Escherichia coli. • The nanopowder is bactericide at low mass concentration. [ABSTRACT FROM AUTHOR]

[Display omitted] • Sonoelectrochemistry shows promise for removing organic pollutants from water. • This method can rapidly mineralise many persistent organic pollutants in water. • Highly oxidising radicals are the main agents performing mineralisation. • Fundamentals of sonoelectrochemical organic pollutant degradation are reviewed. • An in-depth analysis of recent examples in this field is provided. The combination of electrochemistry and ultrasonic irradiation (sonoelectrochemistry) has gained increasing attention in recent years as a method for removing dissolved pollutants from water. This interest stems from the potential for sonoelectrochemical approaches to completely mineralise dissolved pollutants, converting them into harmless mineral species such as water and carbon dioxide. In many cases, the electrochemical and ultrasonic inputs into a sonoelectrochemical pollutant degradation process are found to be synergistic, producing a faster rate of degradation than that produced by the sum of the purely electrochemical or purely sonochemical inputs on their own. This synergism has several causes, with enhanced production of powerfully oxidising radicals and improved mass transport to and from the electrode surface being the two most often cited. In this review, we first give an overview of the various factors that impact on sonoelectrochemical pollutant degradation studies (including reactor design, sonochemical and electrochemical parameters and reaction conditions), before then discussing in detail examples of sonoelectrochemical processes for the degradation of persistent organic pollutants in water from 2015 onwards. [ABSTRACT FROM AUTHOR]

Cu-Pt nanopowders were prepared by sonoelectrochemistry followed by a displacement reaction. The first method provides pure copper particles. In the second method the surface copper atoms are replaced by platinum atoms. The influence of dissolved oxygen during the conversion reaction was also studied. Nanoparticles (NPs) were observed by transmission electron microscopy (TEM) and their size distribution was determined by centrifugal liquid sedimentation (CLS). The mean diameter of isolated particles was found to be around 8 nm. Their composition was studied by energy dispersive X-ray spectroscopy (EDXS) and X-Ray photoelectron spectrometry (XPS). These analyses and X-ray diffraction (XRD) patterns showed that the particle shell is a solid solution of Cu and Pt. The shell composition is heterogeneous with a richer Pt percentage on its surface. [ABSTRACT FROM AUTHOR]

The anti-inflammatory drug diclofenac is found worldwide in natural water bodies and toxicological investigations report harmful effects for aquatic species even at low concentrations. Diclofenac is one of the pharmaceutical substances on the first watch list of the European Water Framework Directive. If it will be categorized as a priority substance, emission limits will be established. One of the discussed methods of diclofenac reduction in wastewater are advanced oxidation processes. In this paper, the degradation of diclofenac in water was investigated using a sonoelectrochemical system, consisting of an ultrasound transducer with a frequency of 850 kHz and boron doped diamond electrodes. With the combination of acoustic cavitation and electrochemical oxidation, as advanced oxidation processes, more than 90% of diclofenac could be degraded within 5 min at an initial concentration of 50 μg L −1 . These studies provide optimization of ultrasound density, voltage and electrode positioning on diclofenac degradation. The reaction was found to follow pseudo first order kinetics with a rate constant of 0.505 min −1 . Samples were concentrated with solid phase extraction and analyzed by high pressure liquid chromatography using a diode array detector. The formation of oxidative species was visualized by chemiluminescence of luminol. [ABSTRACT FROM AUTHOR]

The effect that the cathode material has on the electrochemical and high-frequency sonoelectrochemical degradation of TCAA in water samples with no background electrolyte has been studied in the work here presented. For all the cathode materials employed (Ti, AISI 304 stainless steel, carbon and Pb), the high-frequency sonoelectrochemical treatment yielded significantly higher fractional conversions for trichloroacetic acid and a significantly higher degradation efficiency when considering the removal of chlorinated species from the treated solutions. Moreover, differences in fractional conversion, degradation efficiency, current efficiency, C mass balance error and the concentration of the different trichloroacetic acid degradation by-products show how the cathode material has a strong effect on the efficiency of the electrochemical and high-frequency sonoelectrochemical treatments and the degradation mechanisms that may take place. Regarding this, complete dechlorination was virtually achieved in the high-frequency sonoelectrochemical degradation using a Pb cathode, where C mass balance results suggested the mineralization of TCAA. [ABSTRACT FROM AUTHOR]

This study investigated the effect of co-incorporation of a kind of nanomaterials and organic additives in a polymer matrix coating on corrosion performance of St-12 steel. We synthesized sonoelectrochemically the polypyrrole (PPy), polypyrrole/chitosan (PPy-chitosan), polypyrrole/multiwalled carbon nanotubes (PPy/MWCNTs), and polypyrrole/MWCNTs/chitosan (PPy-MWCNTs-chitosan) films on the base alloy. In-situ polymerization carried out in a solution containing 0.1 mol/L oxalic acid, 100 mg/L dodecylbenzen sulfonic acid, and 0.1 mol/L pyrrole in the absence and presence of a certain amount of MWCNTs and chitosan. The corrosion protection behavior of the synthesized coatings in 3.5% NaCl aqueous solution was studied by the evolution of the open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques. The results revealed that PPy-MWCNTs-chitosan nanocomposite coating exhibits significantly better corrosion protection than others. The PPy-MWCNTs-chitosan film acts as a physical barrier against the corrosive species, because it has a very dense and more compact structure. The surface morphology was investigated by scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Amaranth dye is an organic compound largely used in the food and beverage industries with potential toxicity effects on humans. It can be found as a pollutant species in aquatic environments and has been classified as an endocrine disruptor. This study describes amaranth degradation upon ultrasonication associated with an electrochemical system that uses a boron-doped diamond anode BDD, defined as a sonoelectrochemical process. Ninety-minute electrolyses were performed using current densities in the 10–50 mA cm −2 range, and the concentration decay, pH, energy and current efficiencies, as well as the discoloration rate were evaluated. The amaranth concentration decayed as a function of electrolysis time and the reactions obeyed pseudo first-order kinetics, with an apparent constant rate between 10 −1 and 10 −3 min −1 . The electrochemical and sonoelectrochemical processes at 35 mA cm −2 yielded TOC removal values between 92.1% and 95.1% respectively, after 90 min. Current efficiency values obtained for both processes were 18.2% and 23.6%. Exhaustive 5 h electrolysis was performed and the degradation products were identified by HPLC–MS. A mechanism for the degradation of amaranth was proposed based on an analysis of the aromatic and aliphatic intermediates. [ABSTRACT FROM AUTHOR]

This work describes a new sonoelectrochemical synthesis method of novel composite materials based on silicon nitride (SiN) nanoparticles and intrinsically conducting polypyrrole (PPy). The sonoelectrochemical synthesis of polypyrrole coating and polypyrrole-silicon nitride (PPy-SiN) nanocomposite performed and corrosion behavior of these coatings on St-12 steel was studied by electrochemical methods. A design of experiment (DOE) technique using the Taguchi method has been applied to optimize the affecting factors on the sonoelectrochemical synthesis of PPy-SiN nanocomposite such as current density, synthesis time and amount of nanoparticles. The corrosion protection of St-12 steel by polypyrrole and polypyrrole-SiN nanocomposite coatings were investigated by open circuit potential (OCP) time trends, potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS) in NaCl 3.5% solution. The Kramers-Kronig transformation (KK) was applied to evaluate the validity of the experimental impedance data. The results prove that the addition of nanoparticles increased corrosion resistance of coatings and improved the surface morphology. Scanning electron microscopy (SEM) images reveal that the nanocomposite coatings form compact, homogenous and dense films on the St-12 steel surfaces. [ABSTRACT FROM AUTHOR]

In recent years, new advanced oxidation processes based on the electrochemical technology, the so-called electrochemical advanced oxidation processes (EAOPs), have been developed for the prevention and remediation of environmental pollution, especially focusing on water streams. These methods are based on the electrochemical generation of a very powerful oxidizing agent, such as the hydroxyl radical (OH) in solution, which is then able to destroy organics up to their mineralization. EAOPs include heterogeneous processes like anodic oxidation and photoelectrocatalysis methods, in which OH are generated at the anode surface either electrochemically or photochemically, and homogeneous processes like electro-Fenton, photoelectro-Fenton, and sonoelectrolysis, in which OH are produced in the bulk solution. This paper presents a general overview of the application of EAOPs on the removal of aqueous organic pollutants, first reviewing the most recent works and then looking to the future. A global perspective on the fundamentals and experimental setups is offered, and laboratory-scale and pilot-scale experiments are examined and discussed. [ABSTRACT FROM AUTHOR]