Dielectric Barrier Discharge Microplasma Research Articles

Construction of self-support three-dimensional nickel iron layered double hydroxide by dielectric barrier discharge microplasma for electrochemical sensing in food, serum and cell

With the development of non-enzyme sensors, non-noble metal catalysts have been widely utilized to construct glucose (Glu) or hydrogen peroxide (H2O2) sensors. However, most of them cannot achieve dual-function detection and are insensitive. In this paper, we prepared a NiFe layered double hydroxide (LDH) with a three-dimensional structure using dielectric barrier discharge microplasma (DBD microplasma) via a simple chemical reaction. The results demonstrate that this sensor exhibits sensitivities of 31591.0 μA·mM−1·cm−2 and 5199.3 μA·mM−1·cm−2 for Glu and H2O2 detection respectively. Additionally, wide linear ranges of 0.0004–2 mM and 0.0006–4 mM were achieved for Glu and H2O2 detection, respectively. Furthermore, we verified the applicability of this catalyst in analyzing human serum samples, cell samples, and food samples which yielded satisfactory results. The constructed sensor possesses advantages such as simplicity, efficient preparation, and high sensitivity.

One-Pot Pretreatment Coupled to Microplasma Optical Emission Spectrometry for Field and Sensitive Determination of Inorganic Mercury and Methylmercury in Fish.

Field and sensitive analysis of mercury species in seafood is helpful to assess the risk of human exposure to mercury, but the cumbersome pretreatment process is time-consuming and laborious. Herein, a simple one-pot pretreatment system is designed for extraction, separation, and enrichment of inorganic mercury (Hg(II)) and methylmercury (MeHg) in fish, and coupled to dielectric barrier discharge (DBD) microplasma optical emission spectrometry (OES). Both Hg(II) and MeHg species in fish can be effectively extracted by tetramethylammonium hydroxide under ultrasound, then separated from the fish matrix by vapor generation and photochemical vapor generation, and finally enriched on the activated carbon electrode tips. Mercury trapped on the activated carbon electrode tips can be rapidly released to produce OES under the DBD microplasma excitation for quantitative analysis. The pretreatment and analysis of a batch of 12 samples are completed within 50 min, and the extraction efficiency of total mercury is up to 90% for 100 mg of freeze-dried fish or 86% for 1 g of fresh fish. Under the optimized conditions, the detection limits are 2 μg kg-1 for Hg(II) and 1.2 μg kg-1 for MeHg in freeze-dried fish, and precisions are 3.2% for Hg(II) and 3.9% for MeHg. The present method is applied to the analysis of the certified reference material and real marine fishes, giving rise to spiked recoveries of 95-103%. The present system hardly leads to MeHg and Hg(II) transforming into each other during extraction, providing a simple, convenient, and low-cost analytical tool to evaluate the risk of mercury species in fish.

Inactivation of Staphylococcus Aureus by Microplasma

Dielectric barrier discharge microplasma has various industry applications such as surface treatment, NOx removal, flow control ore biomedical applications. Transdermal drug delivery procedure could be enhanced by microplasma. Along with this procedure skin treatment in order to remove harmful bacteria is necessary. One of these harmful bacteria which lives on human skin is <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Staphylococcus Aureus</i> . Microplasma was used for the sterilization of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Staphylococcus Aureus</i> . Argon, oxygen and air were used as discharge gases. The sterilization process is mainly carried out by the reactive oxygen species. Thus the highest sterilization rates were obtained by using as discharge gas air or a mixture of argon and oxygen. The applied voltages were sine wave and pulse. In the case of sine wave the ozone generation is higher thus a pulse powered microplasma discharge is preferred.

One-step rapid synthesis of Ni0.5Co0.5-CPO-27 nanorod array with oxygen vacancies based on DBD microplasma: As an effective non-enzymatic glucose sensor for beverage and human serum

The rational design of high-efficiency catalysts for non-enzymatic glucose sensing is extremely important for the timely and effective monitoring of glucose content in beverages and human blood. A 3D bimetallic organic framework (Coordination Polymer of Oslo, CPO) nanorod array with oxygen vacancies was green fabricated on carbon cloth (Ni0.5Co0.5-CPO-27 NRA/CC) using dielectric barrier discharge (DBD) microplasma for the first time. Density functional theory (DFT) calculations demonstrated that the oxygen vacancy of Ni0.5Co0.5-CPO-27 can be effectively induced under DBD microplasma conditions. Based on the 3D nanorod arrays with rich oxygen vacancies and bimetallic synergistic effects, as a non-enzyme glucose sensor, the Ni0.5Co0.5-CPO-27 electrode exhibited a sensitivity of 8499.5 μA L/mmol cm−2 and 3239.2 μA L/mmol cm−2 and a limit of detection (LOD) of 0.16 μmol/L (S/N = 3). It has been successfully applied to the determination of glucose levels in real samples such as cola, green tea and human serum.

Ultrasonic Nebulization-Accelerated Gas-Phase Enrichment Following In Situ Microplasma Desorption for Analysis of Trace Heavy Metals by Optical Emission Spectrometry.

Despite the great potential of microplasma optical emission spectrometry (OES) for on-site analysis, it remains a challenge to achieve the fast, sensitive, batch, and multielement analysis of trace heavy metals in a complex matrix. Herein, a novel ultrasonic nebulization-accelerated gas-phase enrichment (GPE) following in situ microplasma desorption sampling approach is employed for the determination of trace heavy metals by a miniature dielectric barrier discharge (DBD)-OES device. The volatile heavy metal species obtained by hydride generation (HG) can be quickly separated from the complex matrix under the action of ultrasonic nebulization, adsorbed on the surface of the activated carbon electrode tip for GPE, and then in situ desorbed and excited by DBD microplasma to achieve multielement OES analysis. With an array nebulizer plate, a batch of 10 samples can be handled for GPE in 40 s, and DBD-OES analysis is maintained at a rate of 6 s per sample. Under the optimized conditions, the detection limits for simultaneous determinations of Hg, Cd, Cu, and Sn are 0.005, 0.01, 0.03, and 0.04 μg L-1, respectively, and the detection sensitivities are about 164, 157, 132, and 91-fold improved with respect to those of the conventional HG-DBD-OES mode, respectively. The accuracy and practicability are verified by measuring several certified reference materials. This fast GPE plus in situ DBD-OES analysis strategy possesses the features of simple operation, time-savings, and low cost, contributing to volatile species transport, matrix interference elimination, and device miniaturization for field applications.

Microplasma-enabled carbon dots composited with multi-walled carbon nanotubes for dopamine detection

Composited carbon nanomaterials have attracted wide attention and are used for high-sensitivity biological assays due to their low toxicity, good biocompatibility, and excellent electrical conductivity. To further promote electron transfer and enhance electrocatalytic activity to detect dopamine (DA), this study proposed carbon dots (CDs) based on glycerol synthesized by liquid dielectric barrier discharge (DBD) microplasma. Combined with the multi-walled carbon nanotubes (MWCNTs) with excellent electrical conductivity, a composited carbon nanomaterial electrode of CDs/MWCNTs was constructed. As a DA biosensor, the interaction and electron exchange between MWCNTs, CDs, and DA can be enhanced thanks to the π-π stacking force, thereby facilitating the sensitive electrochemical detection of DA. The sensor exhibits good sensing performance toward DA detection with a linear range of 2.0–100 μM, a limit of detection (LOD) of 11.08 nM (S/N = 3), and a sensitivity of 29020 μA cm−2 mM−1. The proposed electrode successfully detected DA levels in human serum samples with satisfactory selectivity and recovery rate. The microplasma-enabled synthesized method provides a promising path for preparing and applying carbon-based nanomaterials.

Analysis of trace phytoavailable heavy metals in saline soil extract by one-step electroextraction coupled with in situ desorption microplasma optical emission spectrometry

On-site and sensitive analysis of phytoavailable heavy metals is the key to fast evaluate the pollution incidents, while the development of convenient and efficient sample introduction approaches against matrix interference is crucial to improve the performances of field-deployable instruments. Herein, trace phytoavailable heavy metals in soil are first extracted by 0.1 M NaNO3, afterwards adsorbed onto an activated carbon tip via electroextraction (EE), and finally analyzed by dielectric barrier discharge (DBD) microplasma optical emission spectrometry (OES) via in situ desorption. The activated carbon tip is not only able to extract heavy metals from alkali metals/alkaline earth metals matrix, resisting the interference of coexisting anions and non-electroactive species in saline soil extract, but also significantly improves the detection sensitivity of subsequent DBD-OES analysis by increasing loading amounts of analytes. Taking the key heavy metals pollution as model, the detection limits of Cd, Zn, Cu and Pb reach 0.8, 2.3, 6.0 and 4.5 μg kg−1, respectively, and precisions are within 2.7–4.6%. The accuracy and practicability of the present miniaturized EE-DBD-OES device have been verified by measuring several certified reference materials and real soil samples, providing a promising tool for convenient and sensitive analysis of trace phytoavailable heavy metals in soil.

CuO Nanosheets Prepared by Dielectric Barrier Discharge Microplasma as Catalysts for the Oxygen Evolution Reaction

CuO Nanosheets Prepared by Dielectric Barrier Discharge Microplasma as Catalysts for the Oxygen Evolution Reaction

Development of a miniaturized hydride generation-dielectric barrier discharge atomic absorption spectrometer

A miniaturized atomic absorption spectrometer (AAS) was proposed with a planar dielectric barrier discharge (DBD) microplasma as an atomizer, a charge coupled device (CCD) spectrometer as a spectral detector, and a hydride generation (HG) unit as a sampler, and the potential analytical capability was evaluated through the determination of cadmium. Auxiliary hydrogen was added to enhance the atomic absorption signals and the potential mechanism of enhancement effect was studied by use of various techniques. The HG-DBD-AAS was further applied to the determination of Cd, yielding a 1.7-fold enhancement in AAS response with added hydrogen and a limit of detection (LOD) of 0.3 μg L−1 under optimized conditions. Good agreement with the certified values, and desirable spike recoveries ranging between 98% and 108%, were obtained for two certified reference materials and several real water samples, respectively. It can be useful in field analysis of many trace elements with high detectability.

Constructing a defect-rich hydroxide nanoenzyme sensor based on dielectric barrier discharge microplasma etching for sensitive detection of thiamine hydrochloride and hydrogen peroxide

In this work, a novel approach was designed to fabricate a defect-rich hydroxide nanoenzyme sensor based on transition metal cobalt derived from metal-organic framework (MOF). Facile preparation was realized by room-temperature reaction and chemical etching via dielectric barrier discharge (DBD) microplasma, which possesses great chemical reactivity to obtain defect-rich and ultrathin structures. The prepared cobalt hydroxide (Co(OH)2) emerges with superior catalytic activity for thiamine hydrochloride (TCL) and hydrogen peroxide (H2O2) assay. The linear ranges were 0.0006 mM to 2.75 mM for TCL detection and 0.001 mM to 5.5 mM for H2O2 detection with low limit of detections (LODs) of 14 nM and 93 nM, respectively. Meanwhile, the as-prepared sensor provides excellent long-term durability (>25 days), as well as high sensitivity (12730 μA mM−1cm−2 and 5199.3 μA mM−1 cm−2) for TCL and H2O2 assay. TCL in serum samples has been detected with satisfactory results by the proposed material, while the H2O2 in Hela cells was also successfully measured. The developed sensor provides several advantages including simplicity, high sensitivity, and efficient preparation.

One-step rapid synthesis of NiMoO4·xH2O nanowires by dielectric barrier discharge micro-plasma method for high-efficiency non-enzymatic glucose sensing

One-step rapid synthesis of NiMoO4·xH2O nanowires by dielectric barrier discharge micro-plasma method for high-efficiency non-enzymatic glucose sensing

Rapid Preparation of 3D Ultra-Thin CuO Nanosheets by Dielectric Barrier Discharge Microplasma for Non-Enzymatic Detection of Glucose

Rapid Preparation of 3D Ultra-Thin CuO Nanosheets by Dielectric Barrier Discharge Microplasma for Non-Enzymatic Detection of Glucose

Microplasma-assisted synthesis of a mixed-valence Ce-MOF with enhanced oxidase-like activity for colorimetric sensing of dopamine.

Due to their high catalytic activity, stability and low cost, nanozymes with oxidase-like activity have attracted widespread interest in the fields of analytical detection and colorimetric sensing. To further promote the catalytic activity and the sensitivity of dopamine (DA) sensing, herein, a mixed valence Ce-MOF (MVCM) with enhanced oxidase-like activity was synthesized by the dielectric barrier discharge (DBD) microplasma method. Compared with hydrothermal synthesis, the prepared MVCM synthesized using a microplasma showed a higher catalytic activity, which benefits from a low Ce3+/Ce4+ ratio. Due to the spontaneous redox properties of Ce3+/Ce4+ in a MVCM, the MVCM-based colorimetric sensing of dopamine was established and showed a limit of detection of 0.74 μM over a linear range of 5-100 μM with high selectivity and stability and has been applied for the detection of dopamine in sweat. The proposed study provides an effective synthesis method for nanozymes with enhanced activity and shows great promise in widespread analytical and sensing applications.

An effective method for size-controlled gold nanoparticles synthesis with nonthermal microplasma

A simple, effective and interesting method for gold nanoparticles (AuNPs) synthesis with nonthermal microplasma is developed in this study. The device of dielectric barrier discharge (DBD) microplasma generator with a spray portion is designed and fabricated for uniform AuNPs synthesis. The AuNPs can be synthesized effectively in situ by the DBD microplasma generated on the nozzle of the pneumatic micro-nebulizer. The mechanism of the AuNPs formation under microplasma, the effect of nebulization for uniform AuNPs synthesis and other significant parameters are investigated in the experiment. The morphology and optical properties of the synthesized gold nanoparticles are also characterized. The minimum particle size in average obtained by the proposed method is 4.9 ± 1.1 nm. The particle size of AuNPs can be controlled in the range of 4.9–16.8 nm by the various aqueous solution conditions.

Miniaturized TOC analyzer using dielectric barrier discharge for catalytic oxidation vapor generation and point discharge optical emission spectrometry

Total organic carbon (TOC) is an important parameter describing organic pollution degree of waters. Due to the increasing need of field analysis and drawbacks of conventional TOC analytical instruments, miniaturized TOC analyzers are still demanding. In this work, a dielectric barrier discharge (DBD) microplasma was utilized for catalytic oxidation vapor generation (COVG) of organic compounds into CO2, and a point discharge (PD) microplasma was employed to excite the carbon atomic emission spectra for quantification. Sample solution with phosphoric acid and persulfate solution was injected into the DBD-COVG reactor by a syringe to convert organic compounds into CO2 efficiently and quickly, which was subsequently transported into the point discharge optical emission spectrometer (PD-OES) for detecting carbon at 193.09 nm. Under optimal experimental conditions, high oxidation efficiencies for several organic compounds were achieved, i.e., 96.4%, 95.1% and 94.3% for 50 mg L−1 potassium hydrogen phthalate (KHP), sodium laurylsulfonate and phenol, respectively. A limit of detection (LOD) of 0.02 mg L−1 (as C) was obtained, with a precision of 3.9% (relative standard deviation, RSD) at 15 mg L−1 TOC standard (as C). The possible catalytic oxidation mechanism was proposed with the characteristic results of electron paramagnetic resonance (EPR). Its potential environmental application was demonstrated by successfully analyzing TOC in underground water, surface river water and surface sedimentary water samples from oil fields, with analytical results agreed well with those obtained by the commercial high-temperature combustion coupled nondispersive infrared absorption (HTC-NDIR) technique.

Flow injection hydride generation and on-line W-coil trapping for electrothermal vaporization dielectric barrier discharge atomic emission spectrometric determination of trace cadmium

A fast, low-cost and sensitive method for the determination of trace cadmium was developed by using a miniaturized dielectric barrier discharge microplasma atomic emission spectrometer coupled with a tungsten coil (W-coil) for on-line hydride generation trapping-electrothermal vaporization. Total sample throughput can be greatly improved through the adoption of a horizontally fixed W-coil and the flow injection mode. In addition, the horizontally fixed W-coil and an inserted quartz capillary for on-line trapping contributed to stable and good signal even at a high gas flow rate when volatile cadmium species were trapped, and less sample-consuming and time-saving can be realized in this work. Compared to direct injection, the sensitivity and the LOD were improved by 29- and 38-fold, respectively. The proposed method provides a promising approach to develop a miniaturized instrumentation for highly sensitive detection of trace elements.

In-site and solvent-free exfoliation of porous graphene oxide from pencil lead fiber for solid-phase microextraction of cadmium ion before GF-AAS determination.

Graphene oxide (GO)-functionalized pencil lead fiber was prepared for the first timeby in situ oxidation and exfoliation of graphite contained in pencil lead fiber to porous graphene oxide structure via a one-step solvent-free dielectric barrier discharge (DBD) microplasma treatment. This new fiber was demonstrated as a highly efficient and low-cost solid-phase microextraction (SPME) fiber for the determination of toxic metal ions. The fiber extraction performance was evaluated by using cadmium as a model analyte in a direct immersing SPME mode. Unlike mostcommercially available and other lab-built fibers, the preparation of the graphene oxidized pencil lead fiber is environmentally friendly, low cost, and non-toxic without using any organic solvents. The fiber is robust due to its coating-free configuration. Furthermore, high extraction efficiency and high sensitivity for cadmium can be obtained due to the abundant oxygen-containing functional groups on the surface of the novel fiber. After extraction, the cadmium adsorbed on the fiber was desorbed to 150-μL solution. Graphite furnace atomic absorption spectrometry (GF-AAS) with low sample consumption was used to determine cadmium. The calibration curve for cadmium ions was linear in a range 0.04-0.26μgL-1 with a detection limit of 0.005μgL-1. A relative standard deviation (RSD, n = 5) of 2.1% was obtained at 0.1μgL-1 of cadmium. The sensitivity enhancement factor (EF) value of the proposed SPME method was 25. The SPME fiber was successfully applied to determinecadmium in tap water, river water, and pond water with spike recoveries ranging from 94 to 105%. Pipe network water samples were also analyzed to evaluate the cadmium release to drinking water due to the corrosion of tubes.

"Insert-and-Go" Activated Carbon Electrode Tip for Heavy Metal Capture and In Situ Analysis by Microplasma Optical Emission Spectrometry.

The miniaturized optical emission spectrometry (OES) devices based on various microplasma excitation sources provide reliable tools for on-site analysis of heavy metal pollution, while the development of convenient and efficient sample introduction approaches is essential to improve their performances for field analysis. Herein, a small activated carbon electrode tip is employed as solid support to preconcentrate heavy metals in water and subsequently served as an inner electrode of the coaxial dielectric barrier discharge (DBD) to generate microplasma. In this case, heavy metal analytes in water are first adsorbed on the surface of the activated carbon electrode tip via a simple liquid-solid phase transformation during the sample loading process, and then, fast released to produce OES during the DBD microplasma excitation process. The corresponding OES signals are synchronously recorded by a charge-coupled device (CCD) spectrometer for quantitative analysis. This activated carbon electrode tip provides a new tool for sample introduction into the DBD microplasma and facilitates "insert-and-go" in subsequent DBD-OES analysis. With a multiplexed activated carbon electrode tip array, a batch of water samples (50 mL) can be loaded in parallel within 5 min. After drying the activated carbon electrode tips for 5 min, the DBD-OES analysis is maintained at a rate of 6 s per sample. Under the optimized conditions, the detection limits of 0.03 and 0.6 μg L-1 are obtained for Cd and Pb, respectively. The accuracy and practicability of the present DBD-OES system have been verified by measuring several certified reference materials and real water samples. This analytical strategy not only simplifies the sample pretreatment steps but also significantly improves the sensitivity of the DBD-OES system for heavy metal detection. By virtue of the advantages of high sensitivity, fast analysis speed, simple operation, low cost, and favorable portability, the upgraded DBD-OES system provides a more powerful tool for on-site analysis of heavy metal pollution.

Fast and facile synthesis of carbonate-modified NiFe layered double hydroxide nanosheets by dielectric barrier discharge microplasma: mechanism and application in enhanced water oxidation

A fast and facile approach was designed to fabricate carbonate (Ci)-modified NiFe layered double hydroxide (LDH) nanosheets array on carbon cloth (CC) by dielectric barrier discharge (DBD) microplasma. The whole synthetic process can be completed within 1 h at ambient temperature and pressure. The prepared NiFe LDH-Ci/CC emerges a superior catalytic activity for oxygen evolving reaction in alkaline media, which only demands an overpotential of 240 mV at 20 mA cm−2 with a high stability for at least 90 h, and shows an excellent turnover frequency value of 0.323 mol O2 s−1 at 350 mV. Time-resolved measurements of direct emission spectra for nitrogen second positive system N2(C-B) were measured in the DBD microplasma discharge. And a high vibrational temperature (Tvib, 3100 K) and rotational temperature (Trot, 340 K) were obtained, indicating a great chemical reactivity. In addition, the intermediate products of hydroxyl radicals (·OH) were identified and the possible synthesis mechanism was tentatively proposed. A fast and facile approach was designed to fabricate NiFe LDH-Ci/CC by DBD microplasma.

Synthesis of 3D CoO nanowires supported NiFe layered double hydroxide using an atmospheric pressure microplasma for high-performance oxygen evolution reaction

A novel approach was designed to fabricate three-dimensional (3D) hierarchical-structure cobalt oxide (CoO) supported NiFe layered double hydroxide (LDH) nanosheets array on Ni foam (NF). Facile preparation was realized by dielectric barrier discharge (DBD) microplasma, which owns a great chemical reactivity to obtain 3D open structures. The prepared 3D CoO@NiFe LDH/NF emerges a superior catalytic activity for oxygen evolving reaction (OER) in alkaline media, which only demands an overpotential of 225 mV at 20 mA cm−2. The as-prepared electrocatalyst provides excellent long-term durability (>80 h) and a high turnover frequency (TOF) of 0.59 mol O2 s−1 at 350 mV. Compared to the 2D NiFe LDH/NF, the overpotential of CoO@NiFe LDH/NF can be directly reduced 52 mV at 20 mA cm−2. The intermediate products of hydroxyl radicals (OH) were identified and the possible synthesis mechanism was tentatively proposed. We believe the present work could provide new insight for the rational design of other efficient OER electrocatalysts by DBD microplasma.