Nitrogen cold plasma treatment stabilizes Cu^(0)/Cu^(+) electrocatalysts to enhance CO_(2) to C2 conversion

Cu-based materials are ideal catalysts for CO_(2) electrocatalytic reduction reaction(CO_(2)RR) into multicarbon products.However,such reactions require stringent conditions on local environments of catalyst surfaces,which currently are the global pressing challenges.Here,a stabilized activation of Cu^(0)/Cu^(+)-onAg interface by N_(2) cold plasma treatment was developed for improving Faradaic efficiency(FE) of CO_(2)RR into C2 products.The resultant Ag@Cu-CuN_x exhibits a C2 FE of 72% with a partial current density of-14.9 mA cm^(-2) at-1.0 V vs.RHE(reversible hydrogen electrode).Combining density functional theory(DFT) and experimental investigations,we unveiled that Cu^(0)/Cu^(+) species can be co ntrollably tu ned by the incorporation of nitrogen to form CuN_x on Ag surface,i.e.,Ag@Cu-CuN_x.This strategy enhances ^(*)CO intermediates generation and accelerates C-C coupling both thermodynamically and kinetically.The intermediates O^(*)C^(*)CO,^(*)COOH,and ^(*)CO were detected by in-situ attenuated total internal reflection surface enhanced infrared absorption spectroscopy(ATR-SEIRAS).The uncovered CO_(2)RR-into-C2 products were carried out along CO_(2)→^(*)COOH→^(*)CO→O^(*)C^(*)CO→^(*)C_(2)H_(3)O→^(*)C_(2)H_(4)O→ C_(2)H_(5)OH(or ^(*)C_(2)H_(3)O→^(*)O+C_(2)H_(4)) paths over Ag@Cu-CuN_x electrocatalyst.This work provides a new approach to design Cu-based electrocatalysts with high-efficiency,mild condition,and stable CO_(2)RR to C2 products.

Cold plasma-activated Cu-Co catalysts with CN vacancies for enhancing CO_(2)electroreduction to low-carbon alcohol

Electrocatalytic CO_(2)reduction reaction to low-carbon alcohol is a challenging task,especially high selectivity for ethanol,which is mainly limited by the regulation of reaction intermediates and subsequent C–C coupling.A Cu-Co bimetallic catalyst with CN vacancies is successfully developed by H_(2)cold plasma toward a high-efficiency CO_(2)RR into low-carbon alcohol.The Cu-Co PBA-V_(CN)(Prussian blue analogues with CN vacancies)electrocatalyst yields methanol and ethanol as major products with a total low-carbon alcohol FE of 83.8%(methanol:39.2%,ethanol:44.6%)at-0.9 V vs.RHE,excellent durability(100 h)and a small onset potential of-0.21 V.ATR-SEIRAS(attenuated total internal reflection surface enhanced infrared absorption spectroscopy)and DFT(density functional theory)reveal that the steric hindrance of V_(CN)can enhance the CO generation from*COOH,and the C–C coupling can also be increased by CO spillover on uniformly dispersed Cu atoms.This work provides a strategy for the design and preparation of electrocatalysts for CO_(2)RR into low-carbon alcohol products and highlights the impact of catalyst steric hindrance to catalytic performance.

Properties enhancement of antimicrobial chitosan-deposited polylactic acid films via cold plasma treatment

The present study aimed to understand the effect of dielectric barrier discharge cold plasma(DBD-CP)technology on the antimicrobial chitosan deposition and the properties enhancement of polylactic acid(PLA)films.The results indicated that DBD-CP was an effective method for improving the adhesion and surface hydrophilicity of PLA,facilitating the deposition of chitosan coating.This modification was attributed to the increased surface roughness,as well as the presence of polar functional groups observed through atomic force microscopy,surface free energy and Fourier transform infrared spectroscopy analysis.The study further revealed that both water resistance and mechanical properties were significantly improved after DBD-CP treatment,which was positively correlated with the amount of chitosan deposited on the PLA surfaces.Following comprehensive evaluation,the treatment at 75 W was determined as the optimal condition for enhancing the properties.Additionally,the modified film exhibited strong antimicrobial activity against Staphylococcus aureus.Consequently,the DBD-CP technology could be a promising tool for better utilization of PLA-based materials in the antibacterial food packaging industry.

Effect of Cold Plasma Treatment on Seed Germination and Growth of Wheat

This study investigated the effect of cold helium plasma treatment on seed germina- tion, growth and yield of wheat. The effects of different power of cold plasma on the germination of treated wheat seeds were studied. We found that the treatment of 80 W could significantly improve seed germination potential （6.0%） and germination rate （6.7%） compared to the control group. Field experiments were carried out for wheat seeds treated with 80 W cold plasma. Com- pared with the control, plant height （20.3%）, root length （9.0%） and fresh weight （21.8%） were improved significantly at seedling stage. At booting stage, plant height, root length, fresh weight, stem diameter, leaf area and leaf thickness of the treated plant were respectively increased by 21.8%, 11.0%, 7.0%, 9.0%, 13.0% and 25.5%. At the same time, the chlorophyll content （9.8%）, nitrogen （10.0%） and moisture content （10.0%） were higher than those of the control, indicating that cold plasma treatment could promote the growth of wheat. The yield of treated wheat was 7.55 t-ha-1, 5.89% more than that of the control. Therefore, our results show that cold plasma has important application prospects for increasing wheat yield.

The Interactions of Two Cold Atmospheric Plasma Jets

This paper presents the interactions between two cold atmospheric plasma jets. By changing the experimental conditions including the gas flow rate, the applied voltage, the power supply frequency and the inter-electrode distance d, three different interaction modes, attraction, repulsion and combination, were observed. It is shown that the interaction modes of the two jets are principally affected by the electrodes, the gas flow rate, the plasma jets and the power supply frequency.

Effects of cold plasma treatment on alfalfa seed growth under simulated drought stress

The effect of different cold plasma treatments on the germination and seedling growth of alfalfa（Medicago sativa L.） seeds under simulated drought stress conditions was investigated.Polyethyleneglycol-6000（PEG 6000）with the mass fraction of 0%（purified water）, 5%, 10%,and 15% were applied to simulate the drought environment. The alfalfa seeds were treated with15 different power levels ranged between 0–280 W for 15 s. The germination potential,germination rate, germination index, seedling root length, seedling height, and vigor index were investigated. Results indicated significant differences between treated with proper power and untreated alfalfa seeds. With the increase of treatment power, these indexes mentioned above almost presented bimodal curves. Under the different mass fractions of PEG 6000, results showed that the lower power led to increased germination, and the seedlings presented good adaptability to different drought conditions. Meanwhile, higher power levels resulted in a decreased germination rate. Seeds treated with 40 W resulted in higher germination potential,germination rate, seedling height, root length, and vigor index. Vigor indexes of the treated seeds under different PEG 6000 stresses increased by 38.68%, 43.91%, 74.34%, and 39.20%respectively compared to CK_（0-0）, CK_（5-0）, CK_（10-0）, and CK_（15-0）（the control sample under 0%, 5%,10%, and 15% PEG 6000）. Therefore, 40 W was regarded as the best treatment in this research.Although the trend indexes of alfalfa seeds treated with the same power were statistically the same under different PEG 6000 stresses, the cold plasma treatment had a significant effect on the adaptability of alfalfa seeds in different drought environments. Thus, this kind of treatment is worth implementing to promote seed growth under drought situations.

Preparation of novel Ni-Ir/γ-Al_2O_3 catalyst via high-frequency cold plasma direct reduction process

The novel Ni-Ir/γ-Al2O3 catalyst, denoted as NIA-P, was prepared by high-frequency cold plasma direct reduction method under ambient conditions without thermal treatment, and the conventional sample, denoted as NIA-CR, was prepared by impregnation, thermal calcination, and then by H2 reduction method. The effects of reduction methods on the catalysts for ammonia decomposition were studied, and they were characterized by XRD, N2 adsorption, XPS, and H2-TPD. It was found that the plasma-reduced NIA-P sample showed a better catalytic performance, over which ammonia conversion was 68.9%, at T = 450℃, P = 1 atm, and GHSV = 30, 000 h^-1. It was 31.7% higher than that of the conventional NIA-CR sample. XRD results showed that the crystallite size decreased for the sample with plasma reduction, and the dispersion of active components was improved. There were more active components on the surface of the NIA-P sample from the XPS results. This effect resulted in the higher activity for decomposition of ammonia. Meanwhile, the plasma process significantly decreased the time of preparing catalyst.

Cold Plasma Surface Modification of NiTi for Biomedical Applications

Surface-grafted poly(ethylene glycol) (PEG) molecules are known to prevent protein adsorption to the surface. Nitinol samples were coated under tetraglyme ECR cold plasma conditions to enhance its biocompatibility. The modified Nitinol surfaces were characterized by high resolution ESCA and contact angle, it was demonstrated that the deposited PEG-like coatings were built up mainly of-CH2-CH2-O- linkages in surfaces. The surface wettability of the modified Nitinol was increased compared with the control surface. Human plasma protein was adsorbed on Nitinol evaluated by SEM, the protein adsorption on modified surfaces decreased rapidly. Thus, the potential benefits of cold plasma technique will be of use to the biomedical industries improving the biocompatibility of metals.

Improving Seed Germination and Peanut Yields by Cold Plasma Treatment

This study explored the effects of cold plasma treatment on seed germination, plant growth, and peanut yield. Cold plasma treatment improved germination and seedling growth, and the 120 W treatment produced the best effect. Germination potential and germination rate were markedly raised by 150% and 21%, respectively. Germination was accelerated and the uniformity of emergence improved. The apparent contact angle was decreased by 53%. Seedling shoot and root dry weights increased by 11% and 9%. Leaf area, leaf thickness, leaf nitrogen concentration, chlorophyll contents, and dry weight at the fruiting stage, together with plant height, stem diameter, and root dry weight at the mature stage were all markedly raised by the cold plasma treatment. The cold plasma treatment enhanced yield components, such as branch numbers per plant, pod numbers per plant, and 100 pod weights by 8%, 13%, and 9%, respectively, compared to the control. Furthermore, the yield improved by 10%. These results suggested that cold plasma treatment improved germination, plant growth, and yield, which might be due to the cold plasma increasing the leaf area, nitrogen concentrations, and chlorophyll contents.

Effects of low-vacuum helium cold plasma treatment on seed germination,plant growth and yield of oilseed rape

The effects of low-vacuum helium cold plasma treatment on the seed germination,plant growth and yield of oilseed rape（Brassica napus L.cv.Zhongshuang 9） were investigated.Seeds were exposed to low-vacuum helium cold plasma ranging from 0-120 W for 15 s.Cold plasma increased the germination,plant growth and yield of oilseed rape,and the treatment of 100 W provided the best result.The germination rate,germination and vigor indices,and uniformity of emergence were improved by cold plasma treatment.Cold plasma raised the relative conductivity and water uptake,and reduced the apparent contact angle.The characteristics of plant growth,including plant height,stem diameter,dry weights of shoot and root at the seedling,bolting and flowering stages were increased by the cold plasma treatment.Yield components,including pod numbers per plant and 1000 seed weights were increased by the cold plasma treatment.Furthermore,the yield per plant increased by 28.20%.These results suggest that cold plasma treatment has the potential to improve the yield of oilseed rape through the enhancement of permeability,wettability and capacity of water uptake of the seeds,seed germination and plant growth.

Effect of cold plasma treatment on seedling growth and nutrient absorption of tomato

The effects of cold plasma(CP) treatment on seed germination, seedling growth, root morphology, and nutrient uptake of a tomato were investigated. The results showed that 80 W of CP treatment significantly increased tomato nitrogen(N) and phosphorus(P) absorption by12.7% and 19.1%, respectively. CP treatment significantly improved the germination potential of tomato seed by 11.1% and the germination rate by 13.8%. Seedling growth characteristics,including total dry weight, root dry weight, root shoot rate, and leaf area, significantly increased after 80 W of CP treatment. Root activity was increased by 15.7% with 80 W of CP treatment,and 12.6% with 100 W of CP treatment. CP treatment(80 W) markedly ameliorated tomato root morphology, and root length, surface area, and volume, which increased 21.3%, 23.6%, and29.0%, respectively. Our results suggested that CP treatment improved tomato N and P absorption by promoting the accumulation of shoot and root biomass, increasing the leaf area and root activity, and improving the length, surface area, and volume of root growth. Thus, CP treatment could be used in an ameliorative way to improve tomato nutrient absorption.

Effect of Cold Plasma Treatment on the Mechanical Properties of RTM Composites

Cold plasma technology was used to treat the surface of carbon fibers braided by PET in this paper and SEM was used to analyze the fracture microstructure of composite interlaminar shear stress (ILSS). The result shows that the surface polarity of carbon fibers was modified by cold plasma treatment, which increases the impregnation of PET braided carbon fibers during the process of resin flowing, improves the interfacial properties of RTM composites, and therefore enhances the mechanical properties of the KTM composites.

Applications of cold atmospheric plasmas(CAPs)in agriculture:a brief review and the novel development of a radio-frequency CAP jet generator for plant mutation

Cold atmospheric plasmas(CAPs)have shown great applicability in agriculture.Many kinds of CAP sources have been studied in agricultural applications to promote plant growth and cure plant diseases.We briefly review the state-of-the-art stimulating effects of atmospheric-pressure dielectricbarrier-discharge(AP-DBD)plasmas,after the direct or indirect treatment of plants for growth promotion and disease control.We then discuss the special demands on the characteristics of the CAP sources for their applications in plant mutation breeding.An atmospheric and room temperature plasma(ARTP)jet generator with a large plasma irradiation area,a high enough concentration of chemically reactive species and a low gas temperature is designed for direct plant mutagenesis.Experimental measurements of the electrical,thermal and optical features of the ARTP generator are conducted.Then,an ARTP-P(ARTP for plant mutagenesis)mutation breeding machine is developed,and a typical case of plant mutation breeding by the ARTP-P mutation machine is presented using Coreopsis tinctoria Nutt.seeds.Physical and agricultural experiments show that the newly-developed ARTP-P mutation breeding machine with a large irradiation area can generate uniform CAP jets with high concentrations of chemically reactive species and mild gas temperatures,and have signiflcant mutagenesis effects on the Coreopsis tinctoria Nutt.seeds.The ARTP-P mutation breeding machine may provide a platform for systematic studies on mutation mechanisms and results for various plant seeds under different operating conditions in future research.

Development of a new atmospheric pressure cold plasma jet generator and application in sterilization

This paper reports that a new plasma generator at atmospheric pressure, which is composed of two homocentric cylindrical all-metal tubes, successfully generates a cold plasma jet. The inside tube electrode is connected to ground, the outside tube electrode is connected to a high-voltage power supply, and a dielectric layer is covered on the outside tube electrode. When the reactor is operated by low-frequency （6 kHz-20 kHz） AC supply in atmospheric pressure and argon is steadily fed as a discharge gas through inside tube electrode, a cold plasma jet is blown out into air and the plasma gas temperature is only 25-30℃. The electric character of the discharge is studied by using digital real-time oscilloscope （TDS 200-Series）, and the discharge is capacitive. Preliminary results are presented on the decontamination of E.colis bacteria and Bacillus subtilis bacteria by this plasma jet, and an optical emission analysis of the plasma jet is presented in this paper. The ozone concentration generated by the plasma jet is 1.0× 10^16cm^-3 which is acquired by using the ultraviolet absorption spectroscopy.

Partially crystallized Pd nanoparticles decorated TiO_2 prepared by atmospheric-pressure cold plasma and its enhanced photocatalytic performance

TiO2 decorated with partially crystallized Pd nanoparticles （Pd/TiO2-P） was successfully prepared by atmospheric-pressure dielectric barrier discharge cold plasma. The XRD and XPS analyses proved that Pd ions were reduced to partially crystallized metallic Pd nanoparticles in Pd/TiO2-P. The XPS spectra also indicated that an enhanced metal-support interaction was formed due to the existence of partially crystallized Pd nanoparticles with lower coordination number in Pd/TiO2-P. Photocatalytic activity of Pd/TiO2-P was much higher than that of TiO2 samples decorated with well crystallized Pd nanoparticles.

In-package cold plasma treatment of braised chicken: voltage effect

This study investigated the effect of different dielectric barrier discharge cold plasma(DBD-CP) treatment voltages on the microbiological growth and quality characteristics of braised chicken during storage at(4 ± 1) ℃. Argon-packed samples were subjected to DBD-CP treatment for 3 min at voltages of 50, 60 and 70 k V. As a result, there was no significant(P > 0.05) difference in L*, a*, b* and p H of braised chicken between control and treatment groups at the same storage time. However, the development of lipid oxidation in DBD-CP treatment samples was slower than that in air-packed samples. Compared to air-packed samples, the reduction of total viable count, yeasts and molds, lactic acid bacteria and Pseudomonads spp. in 70 k V treated samples on day 15 were 3.21, 2.41, 2.44 and 1.96 lg(CFU/g), respectively. The results indicate that DBD-CP treatment could extend the shelf life of braised chicken without negative impacts on quality characteristics.

Tuning Effect of N_2 on Atmospheric-Pressure Cold Plasma CVD of TiO_2 Photocatalytic Films

To deposit TiO2 films through plasma CVD, the partial pressure ratio of O2 to TIC14 should be greater than the stoichiometric ratio （PO2/PTiCl4 〉 1）. However, this may lead to the formation of powder instead of film on the substrate when using volume dielectric barrier discharge （volume-DBD） at atmospheric pressure. In this study, by adding N2 into the working gas Ar, TiO2 photocatalytic films were successfully fabricated in the presence of excess O2 （PO2/PTiC14 = 2.6） by using a wire-to-plate atmospheric-pressure volume-DBD. The tuning effect of N2 on the deposition of TiO2 film was studied in detail. The results showed that by increasing the N2 content, the deposition rate and particle size of the TiO2 film were reduced, and its photocatalytic activity was enhanced. The tuning mechanism of N2 is further discussed.

Atmospheric-Pressure DBD Cold Plasma for Preparation of High Active Au/P25 Catalysts for Low-Temperature CO Oxidation

Cold plasma generated by dielectric barrier discharge （DBD） at atmospheric pressure was adopted for preparation of commercial TiO2 Degussa P25 supported Au catalysts （Au/P25- P） with the assistance of the deposition-precipitation procedure. The influences of the plasma reduction time and calcination on the performance of the Au/P25-P catalysts were investigated. CO oxidation was performed to investigate the catalytic activity of the Au/P25 catalysts. The results show that DBD cold plasma for the fabrication of Au/P25-P catalysts is a fast process, and Au/P25-P （4 min） exhibited the highest CO oxidation activity due to the complete reduction of Au compounds and less consumption of oxygen vacancies. In order to form more oxygen vacancies active species, Au/P25-P was calcined to obtain Au/P25-PC catalysts. Interestingly, Au/P25- PC exhibited the highest activity for CO oxidation among the Au/P25 samples. The results of transmission electron microscopy （TEM） indicated that the smaller size and high distribution of Au nanoparticles are the mean reasons for a high performance of Au/P25-PC. Atmospheric- pressure DBD cold plasma was proved to be of great efficiency in preparing high performance supported Au catalysts.

Characteristics of a radio-frequency cold atmospheric plasma jet produced with a hybrid cross-linear-field electrode configuration

Cold atmospheric plasma(CAP)jet has wide applications in various fields including advanced materials synthesis and modifications,biomedicine,environmental protection and energy saving,etc.Appropriate control on the volume,temperature and chemically reactive species concentratio ns of the CAP jet is of great importance in actual applications.In this paper,an radio-frequency atmospheric-pressure glow discharge(RF-APGD)plasma generator with a hybrid cross-linear-field electrode configuration is proposed.The experimental results show that,with the aid of the copper mesh located at the downstream of the traditional co-axial-type plasma generator with a cross-field electrode configuration,a linear field between the inner powered electrode of the traditional plasma generator and the copper mesh can be established.This linerfield can,to some extent,enhance the discharges at the upstream of the copper mesh,resulting in small increments(all less than 12.5%)of the species emission intensities,electron excitation temperatures and gas temperatures by keeping other parameters being unchanged.And due to the intrinsic transparent and conducting features of the grounded copper mesh to the gas flowing,electric current and heat flux of the plasma plumes,a plasma region with higher concentrations of chemically reactive species and larger plasma plume diameters is obtained at the downstream of the grounded copper mesh on the same level of the gas temperature and electron excitation temperature compared to those of the plasma free jet.In addition,the charged particle number densities at the same downstream axial location of the grounded copper mesh decrease significantly compared to those of the plasma free jet.This means that the copper mesh is also,to some extent,helpful for separating the chemically reactive neutral species from the charged particles in side a plasma environment.The preceding results indicate that the cross-linear-field electrode configuration of the plasma generator is an effective approach for tuning the characteristics of the RF-APGD plasma jet in order to obtain an appropriate combination of the plasma jet properties with higher chemically reactive species concentrations,especially relative higher number densities of neutral species,larger plasma volumes and lower gas temperatures.

Influence of low-vacuum helium cold plasma pre-treatment on the rooting and root growth of zoysiagrass(Zoysia Willd.) stolon cuttings

The influence of low-vacuum helium cold plasma treatment on the rooting percentage,root growth and physiochemical properties of zoysiagrass stolon cuttings was studied.Zoysiagrass stolon cuttings were pre-treated with 0,100,200,300 and 400 W of cold plasma for 15 s.The cold plasma positively stimulated rooting and improved the root growth of the zoysiagrass stolon cuttings,and the 300 W treatment produced the best effect.The rooting percentage and root growth parameters,including the root length,total root surface area,total root volume,average root diameter,and root dry weight,significantly improved in response to the cold plasma treatment.In addition,the water uptake and relative conductivity of the stolon cuttings increased significantly in response to the cold plasma treatment.The results revealed that cold plasma-stimulated rooting and root growth appear to be a consequence of the improvement in permeability and water absorbing capacity of zoysiagrass stolon cuttings.The results of the present study will provide inspiration and support for the application of cold plasma in the vegetative propagation of plants.