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.

中心电极结构DBD等离子体辅助煤炭池火燃烧特性

为研究块状煤的高效燃烧,论文搭建了以氧化铝陶瓷作为介质的中心电极结构助燃装置;针对不规则块状煤炭燃烧的放电独特环境,研究了激励源参数和装置结构在特殊工质气体氛围下的系统匹配和介质阻挡放电等离子体辅助煤炭池火燃烧时的放电特性及对燃烧的影响。结果表明:外施峰值电压在12~16k V范围内装置实现稳定放电,放电功率大小与外施电压大小正相关;装置内径为30~60mm,增大内径且电压保持不变,放电功率先增大后减小。介质阻挡放电等离子体介入后煤炭池火燃烧面逐步扩大,燃烧极限得到了拓展,燃烧温度和质量衰减得到明显提升,并与电压大小正相关,助燃前期温度和质量随电压变化明显。

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.

Synthesis of Cu-Doped Mixed-Phase TiO_2 with the Assistance of Ionic Liquid by Atmospheric-Pressure Cold Plasma

An atmospheric-pressure dielectric barrier discharge （DBD） gas-liquid cold plasma was employed to synthesize Cu-doped TiO~ nanoparticles in an aqueous solution with the assistance of [C2MIM]BF4 ionic liquid （IL） and using air as the working gas. The influences of the discharge voltage, IL and the amount of copper nitrite were investigated. X-ray diffraction, N2 adsorption-desorption measurements and UV-Vis spectroscopy were adopted to characterize the samples. The results showed that the specific surface area of TiO2 was promoted with Cu-doping （from 57.6 m^2.g^-1 to 106.2 m^2.g^-1 with 3% Cu-doping）, and the content of anatase was increased. Besides, the band gap energy of TiO~ with Cu-doping decreased according to the UV-Vis spec- troscopy test. The 3%Cu-IL-TiO2 samples showed the highest eificiency in degrading methylene blue （MB） dye solutions under simulated sunlight with an apparent rate constant of 0.0223 min-1, which was 1.2 times higher than that of non-doped samples. According to the characterization results, the reasons for the high photocatalytic activity were discussed.

利用DBD等离子体处理技术制备Fe3O4/云南松磁性复合材料

采用空气介质阻挡放电(DBD)冷离子体处理云南松木材表面,然后浸泡在带有负电荷的Fe3O4纳米材料溶液中,研究了不同沉积次数对松木表面Fe3O4纳米材料沉积量的影响。采用扫描电镜和红外光谱测试了沉积5次的松木表面的形貌和化学成分变化,并测试其电磁屏蔽效果。结果表明:经空气DBD冷等离子体处理后的松木表面可以沉积Fe3O4纳米材料,松木表面Fe3O4纳米材料的沉积量与沉积次数有关,本研究中沉积5次,每次20 min,效果较好,沉积了Fe3O4纳米材料的松木具有明显的电磁屏蔽效果。

低温等离子活化水对猕猴桃溃疡病菌抗菌活性及机制

为了探究低温等离子体活化水(cold plasma activated water,PAW)对丁香假单胞杆菌猕猴桃致病变种(Pseudomonas syringae pv.actinidiae,PSA)的抗菌活性和潜在机制。该研究通过介质阻挡放电(dielectric barrier discharge,DBD)低温等离子体发生装置制备不同激活时间的PAW,考察放电时间与杀菌效果之间的关系。此外,通过评估PSA形态特征,细胞粒径、DNA、细胞膜损伤情况和胞内活性氧积累(reactive oxygen species,ROS)情况探究PAW对PSA的杀菌机制。结果表明:PAW对PSA的杀灭效果与PAW激活时间呈依赖性,与对照相比PAW处理120 s后,PSA显著(P<0.05)减少了4.38 lg CFU/mL。扫描电子显微镜(field emission scanning electron microscope,FESEM)结果清楚地表明,由于PAW处理,PSA细胞发生了明显的质壁分离。荧光染色结果显示,PSA细胞DNA、膜渗透屏障被破坏程度、内容物泄漏量和ROS积累量与PAW激活时间表现为正相关关系。因此,推测PAW由于自身酸性、较高的氧化还原电位(oxidation-reduction potential,ORP),以及水性活性物质导致细胞的氧化损伤,而且这可能是杀灭PSA的主要原因。研究结果可为PAW控制猕猴桃细菌性溃疡病提供参考。

板-板电极结构的介质阻挡放电等离子体辅助煤炭池火燃烧特性研究

基于板-板电极在煤炭燃烧环境下,建立了以氧化铝陶瓷为放电燃烧腔体,烟煤作为介质的板-板电极介质阻挡放电燃烧装置。实验对比了不同激励源参数变化后放电特性与池火燃烧特性变化,结果表明:当外施激励源电压在32kV-40kV范围内时能形成稳定的DBD放电环境,恒压激励下板-板电极的间距对放电电流及功率有显著影响。与未施加放电燃烧的煤炭相比,DBD等离子体可以显著提升煤炭池火燃烧效能;当外施脉冲电压幅值逐渐增大时,煤炭的质量衰减速率和温度变化率逐渐提升,最大燃烧温度明显提高,燃烧极限得到拓展。实验最后对比了板-板电极燃烧装置中煤炭在等离子体介入前后燃烧状态,池火燃烧效果显著提升。

纳米二氧化钛/竹材复合材料制备初探——基于空气介质阻挡放电冷等离子体技术

[目的]基于空气介质阻挡放电(DBD)冷等离子体技术制备纳米二氧化钛(TiO2)/竹材复合材料,为扩大竹材的使用范围提供参考.[方法]采用DBD冷等离子体处理竹皮表面,并浸泡在带有负电荷的不同含量(0.5%和1%,质量分数,下同)纳米TiO2溶液中,沉积一定时间(5,10 min)后取出,用蒸馏水冲洗掉表面游离的TiO2,然后在103℃干燥箱中烘干至与空气含水率平衡,将烘干后的竹皮再次经DBD冷等离子体处理,并浸泡TiO2溶液,再次干燥,如此循环,分别制备沉积1,3,5次样品,研究TiO2溶液含量、沉积次数、沉积时间对纳米TiO2/竹材复合材料表面TiO2负载量的影响.[结果]竹皮表面沉积TiO2纳米材料的负载量与TiO2溶液含量、沉积次数、沉积时间有关.采用空气DBD冷等离子体处理竹皮表面后,在1% TiO2溶液中沉积5次,每次5 min,效果较好,TiO2纳米材料负载量可达4.11 g/m2.[结论]成功制备了纳米TiO2/竹材复合材料,竹皮表面可以负载较多的TiO2纳米材料.

Preparation of Copper Nanoparticles Using Dielectric Barrier Discharge at Atmospheric Pressure and its Mechanism

Dielectric barrier discharge （DBD） cold plasma at atmospheric pressure was used for preparation of copper nanoparticles by reduction of copper oxide （CuO）. Power X-ray diffraction （XRD） was used to characterize the structure of the copper oxide samples treated by DBD plasma. Influences of H2 content and the treating time on the reduction of copper oxide by DBD plasma were investigated. The results show that the reduction ratio of copper oxide was increased initially and then decreased with increasing H2 content, and the highest reduction ratio was achieved at 20% H2 content. Moreover, the copper oxide samples were gradually reduced by DBD plasma into copper nanoparticles with the increase in treating time. However, the average reduction rate was decreased as a result of the diffusion of the active hydrogen species. Optical emission spectra （OES） were observed during the reduction of the copper oxide samples by DBD plasma, and the reduction mechanism was explored accordingly. Instead of high-energy electrons, atomic hydrogen （H） radicals, and the heating effect, excited-state hydrogen molecules are suspected to be one kind of important reducing agents. Atmospheric-pressure DBD cold plasma is proved to be an efficient method for preparing copper nanoparticles.