Visible light induced photodegradation of organic pollutants on nitrogen and fluorine co-doped TiO_2 photocatalyst

The nitrogen and fluorine co doped TiO 2 polycrystalline powder was synthesized by calcinations of the hydrolysis product of tetra butyl titanate with ammonium fluoride. Nitrogen and fluorine co doping causes the absorption edge of TiO 2 to shift to a lower energy region. The photocatalytic activity of co doped TiO 2 with anatase phases was found to be 2 4 times higher than that of the commercial TiO 2 photocatalyst Degussa P25 for phenol decomposition under visible light irradiation. The co doped TiO 2 powders only contain anatase phases even at 1000℃. Apparently, ammonium fluoride added retarded phase transformation of the TiO 2 powders from anatase to rutile. The substitutional fluorine and interstitial nitrogen atoms in co doped TiO 2 polycrystalline powder were responsible for the vis light response and caused the absorption edge of TiO 2 to shift to a lower energy region.

Preparation of nitrogen and sulfur co-doped ultrathin graphitic carbon via annealing bagasse lignin as potential electrocatalyst towards oxygen reduction reaction in alkaline and acid media

Renewable lignin used for synthesizing materials has been proven to be highly potential in specific electrochemistry.Here,we report a simple method to synthesize nitrogen and sulfur co-doped carbon nanosheets by using bagasse lignin,denoted as lignin-derived carbon(LC).By adjusting the ratio of nitrogen source and annealing temperature,we obtained the ultrathin graphitic lignin carbon(LC-4-1000)with abundant wrinkles with high surface area of 1208 m2g_1 and large pore volume of 1.40 cm3g_1.In alkaline medium,LC-4-1000 has more positive half-wave potential and nearly current density compared to commercial Pt/C for oxygen reduction reaction(ORR).More importantly,LC-4-1000 also exhibits comparable activity and superior stability for ORR in acid medium due to its high graphitic N ratio and a direct four electron pathway for ORR.This study develops a cost-effective and highly efficient method to prepare biocarbon catalyst for ORR in fuel cells.

Nitrogen and Sulfur Co-doped Porous Carbon Derived from ZIF-8 as Oxygen Reduction Reaction Catalyst for Microbial Fuel Cells

Nitrogen and sulfur co-doped porous nanocarbon (ZIF-C-N-S) catalyst was successfully synthesized derived from ZIF-8 and thiourea precursors.The electrochemical measurements indicate that the as-obtained ZIF-C-N-S catalyst exhibits higher electrocatalytic activity for oxygen reduction reaction (ORR) in alkaline electrolyte and superior durability-longer than commercial Pt/C catalyst.The enhancment of electrocatalytic activity mainly be come from the open pore structure,large specific surface area as well as the synergistic effect resulted from the co-doping of N and S atoms.In addition,the ZIF-C-N-S catalyst is also used as the air cathode catalyst in the microbial fuel cell (MFC) device.The maximum power density and stable output voltage of ZIF-C-N-S based MFC are 1315 mW/m2 and 0.48 V,respectively,which is better than that of Pt/C based MFC.

Controllable active sites and facile synthesis of cobalt nanoparticle embedded in nitrogen and sulfur co-doped carbon nanotubes as efficient bifunctional electrocatalysts for oxygen reduction and evolution reactions

Development of efficient and promising bifunctional electrocatalysts for oxygen reduction and evolutionreactions is desirable. Herein, cobalt nanoparticles embedded in nitrogen and sulfur co-doped carbonnanotubes(Co@NSCNT) were prepared by a facile pyrolytic treatment. The cobalt nanoparticles and co-doping of nitrogen and sulfur can improve the electron donor-acceptor characteristics of the carbon nan-otubes and provide more active sites for catalytic oxygen reduction and evolution reactions. The preparedCo@NSCNT, annealed at 900℃, showed excellent electrocatalytic performance and better durability thancommercial platinum catalysts. Additionally, Co@NSCNT-900 catalysts exhibited comparable onset poten-tials and Tafel slopes to ruthenium oxide. Overall, Co@NSCNT showed high activity and improved dura-bility for both oxygen evolution and reduction reactions.

Influence of nitrogen doping on thermal stability of fluorinated amorphous carbon thin films

Nitrogen doping fluorinated amorphous carbon (a-C∶F) films were deposited using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) and annealed in Ar environment in order to investigate their thermal stability. Surface morphology and the thickness of the films before and after annealing were characterized by AFM and ellipsometer. Raman spectra and FTIR were used to analyze the chemical structure of the films. The results show that the surface of the films becomes more homogeneous either by the addition of N2 or after annealing. Deposition rate of the films increases a little at first and then decreases sharply with the increase of N2 source gas flux. It is also found that the fraction of aromatic rings structure increases and the thermal stability of the films is strengthened with the increase of N2 flux. Nitrogen doping is a feasible approach to improve the thermal stability of a-C∶F films.

Photocatalytic Destruction of Nitrogen Monoxide over La^(3+) and N Co-doped SrTiO_3 Powders under Visible Light Irradiation

Lanthanum and nitrogen co-doped SrTiO_3 was prepared by a mechanochemical reaction using SrTiO_3, urea and La_2O_3 as the raw materials. The samples were characterized by X-ray diffraction, X-ray photoelectron spectrometer, transmission electron microscopy, and nitrogen adsorption-desorption isotherm measurements. Lanthanum doping could increase the doping content of nitrogen in the sample. The sample prepared with 0.2 mol% La_2O_3, 22 mol% urea and 77.8 mol% SrTiO_3 by mechanochemical reaction, which has nearly the same nitrogen and lanthanum doping fractions, exhibited high photocatalytic activities. Under the irradiation of light with wavelength larger than 400, and 290 nm, the photocatalytic activity of nitrogen and lanthanum co-doped SrTiO_3 were 2.6 and 2 times greater than that of pure SrTiO_3.

Effects of nitrogen content on structure and electrical properties of nitrogen-doped fluorinated diamond-like carbon films

Nitrogen-doped fluorinated diamond-like carbon(FN-DLC)films were prepared on single crystal silicon substrate by radio frequency plasma enhanced chemical vapor deposition(RF-PECVD)under different deposited conditions with CF4,CH4 and nitrogen as source gases.The influence of nitrogen content on the structure and electrical properties of the films was studied.The films were investigated in terms of surface morphology,microstructure,chemical composition and electrical properties.Atomic force microscopy(AFM)results revealed that the surface morphology of the films became smooth due to doping nitrogen.Fourier transform infrared absorption spectrometry(FTIR)results showed that amouts of C=N and C≡N bonds increased gradually with increasing nitrogen partial pressure r(r=p(N2)/p(N2+CF4+CH4)).Gaussian fit results of C 1s and N 1s in X-ray photoelectron spectra (XPS)showed that the incorporation of nitrogen presented mainly in the forms ofβ-C3N4 and a-CNx(x=1,2,3)in the films.The current-voltage(I-V)measurement results showed that the electrical conductivity of the films increased with increasing nitrogen content.

Promotion of activation ability of N vacancies to N2 molecules on sulfur-doped graphitic carbon nitride with outstanding photocatalytic nitrogen fixation ability

Nitrogen vacancies and sulfur co-doped g-C3N4 with outstanding N2 photofixation ability was synthesized via dielectric barrier discharge plasma treatment. X-ray diffraction, ultraviolet–visible spectroscopy, N2 adsorption, scanning electron microscopy, X-ray photoelectron spectroscopy, photoluminescence spectroscopy, and temperature-programmed desorption were used to characterize the as-prepared catalyst. The results showed that plasma treatment cannot change the morphology of the as-prepared catalyst but introduces nitrogen vacancies and sulfur into g-C3N4 lattice simultaneously. The as-prepared co-doped g-C3N4 displays an ammonium ion production rate as high as 6.2 mg·L^-1·h^-1·gcat^-1, which is 2.3 and 25.8 times higher than that of individual N-vacancy-doped g-C3N4 and neat g-C3N4, respectively, as well as showing good catalytic stability. Experimental and density functional theory calculation results indicate that, compared with individual N vacancy doping, the introduction of sulfur can promote the activation ability of N vacancies to N2 molecules, leading to promoted N2 photofixation performance.

Effects of oxygen/nitrogen co-incorporation on regulation of growth and properties of boron-doped diamond films

Regulation with nitrogen and oxygen co-doping on growth and properties of boron doped diamond films is studied by using laughing gas as dopant. As the concentration of laughing gas(N2O/C) increases from 0 to 10%, the growth rate of diamond film decreases gradually, and the nitrogen-vacancy(NV) center luminescence intensity increases first and then weakens. The results show that oxygen in laughing gas has a strong inhibitory effect on formation of NV centers, and the inhibitory effect would be stronger as the concentration of laughing gas increases. As a result, the film growth rate and nitrogen-related compensation donor decrease, beneficial to increase the acceptor concentration(~3.2×10^(19)cm^(-3)) in the film. Moreover, it is found that the optimal regulation with the quality and electrical properties of boron doped diamond films could be realized by adding appropriate laughing gas, especially the hole mobility(~700cm^(2)/V·s), which is beneficial to the realization of high-quality boron doped diamond films and high-level optoelectronic device applications in the future.

多孔氮氟共掺杂碳气凝胶的制备及其在锂硫电池中的应用

锂硫电池以其超高的理论能量密度,已成为最具发展潜力的新一代电化学储能技术,但硫正极存在电导率低、体积膨胀、多硫化物穿梭效应等技术瓶颈问题,制约了其实际应用。通过甲醛和3-氨丙基三乙氧基硅烷的醛胺缩合和溶胶-凝胶化反应合成了席夫碱二氧化硅凝胶,经与聚四氟乙烯乳液冷冻干燥、热处理同步刻蚀二氧化硅以及碳化制备了多孔氮氟共掺杂碳气凝胶(NF-CA)。以NF-CA为载体制备的NF-CA/S正极材料表现出优异的循环性能和倍率性能,0.2 C循环初始放电比容量高达1322 mA∙h/g,1 C循环200圈可逆比容量可保持564 mA∙h/g,2C倍率下可逆比容量高达598mA∙h/g。

Convenient room-temperature synthesis of sulfur and nitrogen co-doped NiCo-LDH coupled with CNTs on NiCo foam as battery-type electrode for high performance hybrid supercapacitor

The convenient synthesis of the composite electrode with high supercapacitance performance plays an important role in practical application but is challenging.Herein,the carbon nanotubes(CNTs)coupled with lowcrystalline sulfur and nitrogen co-doped Ni Co-LDH(denoted as SN-Ni Co-LDH)nanosheets array are grown on Ni Co foam(NCF)substrate by two convenient steps of metal induced self-assembly and corrosion engineering,which present the advantages of operating at roomtemperature and low preparation costs.Benefiting from the S–N co-doping and low-crystallinity of Ni Co-LDH,the prepared SN-Ni Co-LDH@CNTs@NCF electrode presents a topping charge capacity of 2470 C·g^(-1)(4.94 C·cm^(-2))at 5 m A·cm^(-2).Furthermore,the fabricated asymmetry supercapacitor(ASC)achieves an extraordinary energy density of 77 Wh·kg^(-1)(0.617 m Wh·cm^(-2))at a power density of 438 W·kg^(-1)(3.5 m W·cm^(-2))and outstanding stability(91%capacity retention after 5000 cycles at20 m A·cm^(-2)).Impressively,the structure evolution of Ni Co-LDH during the charge/discharge processes has been thoroughly elucidated by in-situ Raman spectra.Therefore,this work verifies a powerful strategy and practical value for preparing composite electrodes with high supercapacitance performance,and also provides guidance for the rational design of the smart electrodes.

Enhanced photocatalytic hydrogen production from Co-MOF/CN by nitrogen and sulfur co-doped coal-based carbon quantum dots

A novel composite photocatalyst for photocatalytic decomposition of water for hydrogen evolution was successfully synthesized by in-situ growth of nitrogen and sulfur co-doped coal-based carbon quantum dots(NSCQDs)nanoparticles on the surface of sheet cobalt-based metal-organic framework(Co-MOF)and graphitic carbon nitride(g-C_(3)N_(4),CN).The structure and properties of the obtained catalysts were systematically analyzed.NSCQDs effectively broaden the absorption of Co-MOF and CN in the visible region.The new composite photocatalyst has high hydrogen production activity and the hydrogen production rate reaches 6254μmol/(g·h)at pH=9.At the same time,NSCQDs synergy Co-MOF/CN composites have good stability.After four cycles of hydrogen production,the performance remains relatively stable.The tran sient photocurrent response and Nyquist plot experimental results further demonstrate the improvement of carrier separation efficiency in composite catalysts.The semiconductor type(n-type semico nductor)of the single-phase catalyst was determined by the Mott-Schottky test,and the band structure was analyzed.The conductive and valence bands of CN are-0.99 and 1.72 eV,respectively,and the conduction and valence bands of Co-MOF are-1.85 and 1.33 eV,respectively.Th e mechanism of the photocatalytic reaction can be inferred,that is,Z-type heterojunction is formed between CN an d Co-MOF,and NSCQDs was used as cocatalyst.

The radiation hardness of the nitrogen-fluorine implanted buried oxide layer in silicon-on-insulator materials against higher total dose irradiation

Nitrogen(N) and fluorine(F) ions were sequentially implanted into the buried oxide(BOX) to improve the total dose radiation hardness of the BOX layer in silicon-oninsulator(SOI) materials. The radiation response of the BOX layers modified by the ion implantation was characterized by flat-band voltage shifts and trapped charge changes in the BOX, based on the capacitance-voltage(C-V) measurements on the polysilicon-BOX-semiconductor(PBS) structures fabricated on the SOI materials, before and after irradiation using Co-60 γ rays with various doses range from 0.7 to 1.7Mrad(Si). The experimental results show that a considerably enhanced hardness for the BOX layer can be achieved by this co-implantation of nitrogen and fluorine on proper process conditions, and the radiation responses of the BOX layers are directly associated with the anneal times after nitrogen implantation.In particular, the rebound and fluctuation phenomena of the BOX radiation response were observed with increasing dose, according to the changes in the flat-band voltages, which cannot be explained in terms of the increase in radiation induced interface state density, and the related mechanisms were analyzed and discussed.

氟、氮共掺杂绿色荧光碳点用于替加环素检测的机理研究

通过溶剂热法制备了氟、氮共掺杂的绿色荧光碳点(F,N-CDs)。对所制备的F,N-CDs进行了全面表征和稳定性评估。本文目的是分析TIGE对F,N-CDs的猝灭机制,并构建高效、简便、高灵敏度和高准确性的荧光传感平台。此平台的成功构建为替加环素的检测提供了理论支撑,并为相关领域的研究和应用提供了支持。

氮氟共掺杂蜂窝状多孔炭的制备及超级电容器性能研究

以棉浆为碳前驱体和KOH为活化剂,在没有添加任何含氮和含氟试剂情况下,通过简单的一步法制备出氮氟共掺杂蜂窝状多孔炭,其具有超高的比表面积、高的微孔比表面积、高孔容、较小的平均孔径以及较高的氮和氟掺杂量。在二电极体系中,氮氟共掺杂蜂窝状多孔炭在离子液体中表现出非常高的质量比电容(199 F·g^(-1))、较高的倍率性能(保持率为44.8%)、超高的能量密度(84.6 Wh·kg(-1))以及优异的循环稳定性(保持率为95.1%),在超级电容器中具有较高的实际应用价值。

非金属掺杂改性TiO_2光催化剂的机理

为了扩展TiO2光催化剂对可见光的利用,以非金属元素对其进行掺杂和改性是近年来很活跃的研究内容,文献报道主要有氮、碳、硫、氟等非金属元素的改性结果。各种不同的改性方法如高温气氛还原、脉冲激光沉积、离子溅射、机械化学、溶液湿法等都可以得到非金属元素改性。本文重点探讨了氮改性TiO2光催化剂的结果,氮改性TiO2的方法和改性机理,讨论了氮改性TiO2的结构及其对可见光的利用机理等,对碳、硫、氟等元素掺杂改性也作了简要介绍。

氮氟共掺杂二氧化钛薄膜的制备、表征及杀菌性能

通过溶胶-凝胶法制备了氮氟共掺杂TiO2(N-F-TiO2)溶胶,并利用丝网印刷法在玻璃基底上制备了N-F-TiO2薄膜,通过XRD,XPS及漫反射对N-F-TiO2进行了表征.XRD分析表明制备出的N-F-TiO2以锐钛矿结晶为主;XPS谱显示N元素以N-Ti-O成键的形式掺杂在晶体中,F元素以表面吸附和晶格掺杂的形式存在;紫外-可见漫反射表明与TiO2相比,N-F-TiO2的吸收强度明显增强,光吸收起始位置有明显红移.利用大肠杆菌做为实验菌种,采用可见光与365nm紫外光分别作为激发光源,对其相对存活率及细胞膜损伤程度进行了研究.结果表明:N-F-TiO2薄膜具有较高的杀菌效率,光照60min时紫外光下大肠杆菌相对存活率降低到0,可见光下为10%;细胞损伤实验结果表明在紫外光作为光催化激发光源时,菌悬液中脂质过氧化物(MDA)含量最大值可以达到1.4 nmol/mg干细胞重,可见光下可以达到0.9 nmol/mg干细胞重.

几种氟化碳材料的结构与电化学性能

氟化碳是一种高储能密度锂原电池的正极材料,材料晶相结构对其电化学性能有重要影响。以NF3为氟化剂对多种碳源进行氟化,制备了不同层间距和比表面积系列的氟化碳材料,并进行表征和电化学测试。结果表明:通过优选碳源,可以增大氟化产物的层间距和比表面积,从而有效减小电极极化,提高电池的工作电压。

施氮对茶园土壤氟和茶树新梢氟含量的影响

通过田间试验研究了不施肥（CK）、施氮360 kg·hm^-2（T1）、施氮720 kg·hm^-2（T2）处理下茶园土壤无机氮、p H、各形态氟含量的动态变化和春、夏、秋茶树新梢一芽四叶、一芽五叶氟含量,探讨茶园施氮对土壤和茶树新梢氟含量的影响。结果表明：1）茶园施氮后短期内（20-30 d）土壤水溶态氟含量显著降低,土壤交换态氟和铁锰结合态氟含量降低;长期（45-50 d）土壤水溶态氟含量的降低作用减弱,土壤交换态氟和铁锰结合态的含量增加;在试验结束时（164 d）,与CK处理相比,T1处理0-20 cm土壤各形态氟含量降低,T2处理0-20 cm土壤各形态氟含量增加。2）0-20 cm茶园土壤水溶态氟、铁锰结合态氟与NH4^＋-N分别呈极显著负、正相关（P〈0.01）,20-40 cm土壤水溶态氟、交换态氟与NO3^--N分别呈极显著正、负相关（P〈0.01）。土壤p H与土壤水溶态氟含量极显著负相关（P〈0.01）,与其他3种形态氟含量相关性不显著。土壤铁锰结合态氟与交换态氟、有机结合态氟呈显著、极显著正相关,但与土壤水溶态氟均无显著相关性。3）春茶前后施氮可以降低春、夏、秋茶树新梢一芽四叶、一芽五叶氟含量,但未达显著水平。T1处理新梢氟含量的降低值为夏茶（25.15-27.95 mg·kg^-1）〉秋茶（21.06-24.31 mg·kg^-1）〉春茶（18.58-21.03 mg·kg^-1）,T2处理的降低值为秋茶（18.64-22.34 mg·kg^-1）〉夏茶（7.79-14.14 mg·kg^-1）〉春茶（3.52-7.30 mg·kg^-1）。春、夏、秋茶树新梢氟含量主要受0-20 cm土壤无机氮和20-40 cm土壤p H的影响。因此推测施氮通过影响茶树根系氟的吸收和氟在叶片中的累积过程调控茶树新梢氟含量,该研究成果为合理利用施氮技术降低茶园土壤和茶树新梢氟含量提供了理论依据。

氮肥对茶园土壤氟赋存形态及转化的影响

为研究不同水平氮肥对茶园土壤氟赋存形态及转化的影响，以皖南十字铺茶场红黄壤茶园0—15cm土壤为对象，设置NOP0K0（CK）、NOP1K1（NO）、N1P1K1（N1）、N2P1K1（N2）、N3P1K1（N3）5个处理，进行了室内盆钵培养试验，通过分析施肥10、20、30、50、70、90d后土壤水溶态氟、交换态氟、铁锰结合态氟、有机结合态氟含量、铵态氮含量、土壤pH值，研究施肥对茶园土壤氟赋存形态及转化的影响。结果表明：与CK相比，氮肥与磷钾混施（N1、N2、N3）在短期内（10d或20d）使土壤水溶态氟含量降低，交换态氟、铁锰结合态氟、有机结合态氟含量增加，20d之后土壤水溶态氟增加，交换态氟、铁锰结合态氟、有机结合态氟含量降低，对水溶态氟、交换态氟的影响效果随时间增加而增加，一般施氮量越大影响效果越明显；土壤水溶态氟含量与氮肥施用量成中度正相关，交换态氟与氮肥施用量成中、高度负相关；土壤水溶态氟含量与pH值成极显著高度负相关，交换态氟含量与pH值成极显著高、中度正相关。因此，氮肥在土壤中的转化过程改变了土壤环境pH值，从而影响土壤氟的形态转化和有效性。