Dielectric barrier discharge plasma for nanomaterials: Fabrication, modification and analytical applications

A review of non-thermal plasma -catalysis: The mutual influence and sources of synergetic effect for boosting volatile organic compounds removal

This review is aimed at researchers in air pollution control seeking to understand the latest advancements in volatile organic compound (VOC) removal. Implementing of plasma-catalysis technology for the removal of volatile organic compounds (VOCs) led to a significant boost in terms of degradation yield and mineralization rate with low by-product formation. The plasma-catalysis combination can be used in two distinct ways: (I) the catalyst is positioned downstream of the plasma discharge, known as the "post plasma catalysis configuration" (PPC), and (II) the catalyst is located in the plasma zone and exposed directly to the discharge, called "in plasma catalysis configuration" (IPC). Coupling these two technologies, especially for VOCs elimination has attracted the interest of many researchers in recent years. The term "synergy" is widely reported in their works and associated with the positive effect of the plasma catalysis combination. This review paper investigates the state of the art of newly published papers about catalysis, photocatalysis, non-thermal plasma, and their combination for VOC removal application. The focus is on understanding different synergy sources operating mutually between plasma and catalysis discussed and classified into two main parts: the effect of the plasma discharge on the catalyst and the effect of the catalyst on plasma discharge. This approach has the potential for application in air purification systems for industrial processes or indoor environments.

The mutagenic effect of cold plasma on Medicago sativa L

To explore the feasibility of using cold plasma as a mutagenesis breeding technology for forage crops, in this study we used the Medicago sativa L. cultivar, Zhongcao No. 3, as the experimental material. The effects of plasma treatments on Medicago sativa L. were analyzed through the use of plasma and activated water. Treatments with plasma and activated water inhibited plant height but promoted root growth. By creating a closed environment, adding a dielectric barrier plate, and combining these two treatment methods, the greatest impact can be had on the growth of Medicago sativa L. seeds. After treatment, the plant heights were approximately half those of the control group, and the root lengths were approximately 1.6 times those of the control group. Through emission spectroscopy, it was found that active particles such as O, NO2, and N2* were present and could be considered to have produced plasma-activated water through contact with the water surface, thus affecting the survival and growth of the seeds. Whole-genome resequencing (WGRS) was performed on the wild-type and selected mutants after treatment, with an average sequencing depth of 115.93×, an average genome alignment rate of 91.72 %, and an average genome coverage rate of 91.85 %. Various types of mutations were detected and annotated. After filtering, 7,822,324 SNP (single nucleotide polymorphisms) sites, 2,161,917 indel sites, 200,544 SV sites, 238 CNV (copy number variation) sites. The SNPs, indels (insertions/deletions), and SVs (structural variations) were mainly heterozygous, with heterozygosity rates of 87.13 %, 92.16 %, and 83.49 %, respectively. The CNVs were dominated by low copy numbers, accounting for 53.77 %. These results indicate that plasma treatment has significant effects on plant growth and genome of Medicago sativa L.

Multifunctional bimetallic MOF with oxygen vacancy synthesized by microplasma for rapid total antioxidant capacity assessment in agricultural products

The assessment of total antioxidant capacity (TAC) is crucial for evaluating overall antioxidant potential, predicting the risk of chronic diseases, guiding dietary and nutritional interventions, and studying the effectiveness of antioxidants. However, achieving rapid TAC assessment with high sensitivity and stability remains a challenge. In this study, Ce/Fe-MOF with abundant oxygen vacancies was synthesized using microplasma for TAC determination. The microplasma synthesis method was rapid (30 min) and cost-effective. The presence of oxygen vacancies and the collaboration between iron and cerium in Ce/Fe-MOF not only enhanced the catalyst's efficiency but also conferred multiple enzyme-like properties: peroxidase-like, oxidase-like, and superoxide dismutase mimetic activities. Consequently, a simple colorimetric assay was established for TAC determination in vegetables and fruits, featuring a short analysis time of 15 min, a good linear range of 5-60 μM, a low detection limit of 1.3 μM and a good recovery of 91 %-107 %. This method holds promise for rapid TAC assessment in agricultural products.

Hyphenated liquid electrode glow discharge-dielectric barrier discharge molecular emission spectrometry for determination of dithiocarbamates

A hyphenated liquid electrode glow discharge (LEGD)-dielectric barrier discharge (DBD) molecular emission spectrometer was constructed and used as a novel liquid chromatography (LC) detector for dithiocarbamates (DTC) determination. The LEGD was used as an acidolysis reactor for the in-situ transformation of DTCs into CS2 with high efficiencies of 74.11-97.98%. The DBD was used to excite CS2 gas to generate a specific molecular emission at 257.94 nm. The linear correlation coefficient of the method was > 0.99 from 1 to 200 μg mL-1. The detection limits ranged from 0.1 to 0.3 μg mL-1 with 76-119% recovery and relative standard deviations of 0.2-8.5%. Moreover, the hyphenated microplasma spectrometer achieved low power consumption, low temperature, immediate acidolysis, and high transformational efficiency, and can detect each DTC when combined with LC.

Rapid cold plasma synthesis of cobalt metal-organic framework/reduced graphene oxide nanocomposites for use as supercapacitor electrodes

Metal-organic frameworks (MOFs) are recognized as a desirable class of porous materials for energy storage applications, despite their limited conductivity. In the present study, Co-MOF-71 was fabricated as a high-performance supercapacitor electrode at ambient temperature using a fast and straightforward, one-pot cold plasma method. A supercapacitor electrode based on Co-MOF@rGO was also synthesized by adding reduced graphene oxide (rGO) during processing to increase the capacitance retention and stability after 4000 cycles from 80 to 95.4%. The Co-MOF-71 electrode provided a specific capacitance (Cs) of 651.7 Fg-1 at 1 Ag-1, whereas the Co-MOF@rGO electrode produced a Cs value of 967.68 Fg-1 at 1 Ag-1. In addition, we fabricated an asymmetric device (Co-MOF@rGO||AC) using Co-MOF-rGO as a high-rate positive electrode and activated carbon (AC) as a negative electrode. This hybrid device has a remarkable specific energy and power density. The combination of MOFs with reduced graphene oxide (rGO) in a cold plasma environment resulted in the formation of a three-dimensional nanostructure composed of nanosheets. This nanostructure exhibited an increased number of electroactive sites, providing benefits for energy storage applications.

A chemiluminescence method induced by microplasma jet for nitrites detection and the miniature detection system using smartphone

A method of luminol-diazonium chemiluminescence (CL) induced by microplasma for hazardous substance detection is proposed. The luminol-diazonium CL is caused by microplasma jet, rather than hydrogen peroxide reagent or other oxidizing agents. The CL intensity is increased by the concentration of nitrites. Based on the process of microplasma generation and CL mechanism, the optimal work conditions of the method are obtained. The linear range for nitrites detection is 0.03-1 mmol L^-1 with the limit of detection (LOD) of 0.01 mmol L^-1. Furthermore, a miniature system using test paper and smartphone is designed for nitrites detection in emergency. The detection system is confined in the custom-tailored shell which is only 28 cm in length, 18 cm in width and 10 cm in height. After microplasma jet treatment, the color of the test paper changes with the NO₂^- concentration. The photographs of the test paper are taken by the built-in camera of smartphone and analyzed by visiting the website via smartphone. The LOD is 1 mmol L^-1 obtained by the CL miniature detection system based on test paper and smartphone. The accuracy, reliability and practicability of the proposed method is verified in this paper.

Review of Plasma Processing for Polymers and Bio-Materials Using a Commercial Frequency (50/60 Hz)-Generated Discharge

This manuscript introduces the properties and diverse applications of plasma generated using commercial frequencies of 50/60 Hz. Commercial frequency (CF) derived plasma exhibits characteristics similar to DC discharge but with an electrical polarity and a non-continuous discharge. Due to the low-frequency nature, the reactor configurations usually are capacitively coupled plasma type. The advantages of this method include its simple power structure, low-reaction temperature, and low substrate damage. The electrical polarity can prevent charge buildup on the substrates and deposited films, thereby reducing substrate damage. The simple, low-cost, and easy-to-operate power structure makes it suitable for laboratory-scale usage. Additionally, the various applications, including plasma-enhanced vapor deposition, sputtering, dielectric barrier discharge, and surface modification, and their outcomes in the CF-derived plasma processes are summarized. The conclusion drawn is that the CF-derived plasma process is useful for laboratory-scale utilization due to its simplicity, and the results of the plasma process are also outstanding.

Synthesis and real-time monitoring of the morphological evolution of luminescent Eu(TCPP) MOFs

Real-time acquisition of the morphological information of nanomaterials is crucial to achieving morphological controllable synthesis, albeit being challenging. A novel device was designed, which integrated dielectric barrier discharge (DBD) plasma synthesis and simultaneous in situ spectral monitoring of the formation of metal-organic frameworks (MOFs). Important dynamic luminescence behaviors such as coordination induced emission (CIE), antenna effect (AE), and red-blue shift were continuously captured to reveal the spectral emission mechanism and energy transfer progress and verify the correlation with the morphological evolution of the MOFs. The prediction and control of morphology were successfully achieved with Eu(TCPP) as a model MOF. The proposed method will shed new light on exploring the spectral emission mechanism, energy conversion and in situ morphology monitoring of other luminescent materials.

Combining non-thermal plasma technology with photocatalysis: a critical review

Due to the excellent application prospects in the fields of new energy generation and environmental remediation, photocatalysis technology has attracted the increasing attention of researchers. Although significant progress has been made in the past decades, the practical application of this technology is still restricted by the moderate catalytic efficiency. To improve the performance of catalysts, new methods are extremely required for the controllable synthesis of high-efficiency catalysts. To further comprehend the relationship between material structure and catalytic activity, the surface active sites of catalysts should be regulated at the atomic and molecular levels. As the fourth state of matter, plasma can generate diverse active species with low energy consumption. As a subset of plasmas, non-thermal plasma (NTP), defined by the great temperature difference between ions (near room temperature) and electrons (usually hotter than 2 orders of magnitude), contributes to the rapid synthesis of functional nanomaterials under relatively mild conditions. Furthermore, NTP has been widely used for the surface modification of materials. Therefore, the combination of NTP and photocatalysis is expected to provide an ideal approach to synthesize high-performance catalysts and precisely customize their surface structures, which is becoming a new direction in the field of catalysis research. This paper fundamentally reviews the progress in the combination of NTP with photocatalysis for versatile applications. Beginning with the principles of photocatalysis and plasma technology, the application of NTP for catalyst synthesis, the plasma-assisted modification of surface actives sites, and the impact of plasma-involved processes on the catalytic performance are discussed, which will provide useful insights into the performance enhancement of catalysts via plasma-assisted processes.

Fast preparation of Eu(BTB) MOFs in dielectric barrier discharge liquid plasma for luminescent sensing of trace iron

Lanthanide metal-organic frameworks Eu(BTB) MOFs was synthesized in low-temperature plasma produced by dielectric barrier discharge (DBD). This DBD synthesis possesses the characteristics of rapid reaction (within 20 min), mild condition (low temperature and atmospheric pressure) and simple operation compared with many traditional synthesis methods. The prepared Eu(BTB) MOF material exhibits typical red light emitting of europium (Eu³⁺ ) at 617 nm, which can selectively and sensitively be quenched in the presence of trace iron(III) ion (Fe³⁺ ). A simple, fast and sensitive fluorescence sensing strategy of Fe³⁺ was thus constructed, with a limit of detection (LOD) of 0.5 μM. Compared with reported fluorescence probes, Eu(BTB) MOFs have also demonstrated the advantages of low cost, easy and fast preparation, great stability, and excellent optical properties, thus making them a promising fluorescence candidate for trace Fe³⁺ sensing for the potential application in biological systems in the future.

Influences of Plasma Plume Length on Structural, Optical and Dye Degradation Properties of Citrate-Stabilized Silver Nanoparticles Synthesized by Plasma-Assisted Reduction

Citrate-capped silver nanoparticles (Ag@Cit NPs) were synthesized by a simple plasma-assisted reduction method. Homogenous colloidal Ag@Cit NPs solutions were produced by treating a AgNO3-trisodium citrate-deionized water with an atmospheric-pressure argon plasma jet. The plasma-synthesized Ag@Cit NPs exhibited quasi-spherical shape with an average particle diameter of about 5.9−7.5 nm, and their absorption spectra showed surface plasmon resonance peaks at approximately 406 nm. The amount of Ag@Cit NPs increased in a plasma exposure duration-dependent manner. Plasma synthesis of Ag@Cit NPs was more effective in the 8.5 cm plume jet than in the shorter and longer plume jets. A larger amount of Ag@Cit NPs were produced from the 8.5 cm plume jet with a higher pH and a larger number of aqua electrons, indicating that the synergetic effect between plasma electrons and citrate plays an important role in the plasma synthesis of Ag@Cit NPs. Plasma-assisted citrate reduction facilitates the synthesis of Ag@Cit NPs, and citrate-capped nanoparticles are stabilized in an aqueous solution due to their repulsive force. Next, we demonstrated that plasma-synthesized Ag@Cit NPs exhibited a significant degradation of methylene blue dye.

Monitoring nucleic acid amplification process by UiO-66-NH2-based fluorescence sensor

Herein, we developed a nucleic acid amplification process monitoring scheme by use of UiO-66-NH2, in which pyrophosphate ion (PPi) released from the amplification can competitively coordinate with Zr to weaken...