Nitrogen Doping

氮掺杂
  • 文章类型: Journal Article
    多孔碳材料的氮掺杂是提高电极材料电化学性能的有效途径。在这项研究中,制备了源自花生壳的氮掺杂多孔碳作为超级电容器的电极。三聚氰胺,尿素,磷酸脲,和磷酸二氢铵被用作不同的氮掺杂剂。花生壳制备的优化电极材料PA-1-1,磷酸二氢铵作为氮掺杂剂,表现出3.11%的N含量和602.7m2/g的比表面积。在6MKOH中,PA-1-1电极在1A/g的电流密度下提供208.3F/g的高比电容。此外,PA-1-1电极表现出优异的倍率性能,比电容为170.0F/g(保留率为81.6%),保持在20A/g。在5000次循环后,在20A/g时,它提供了PA-1-1的电容,比电容保持率为98.8%,表明优异的循环稳定性。PA-1-1//PA-1-1对称超级电容器在2467.0W/kg的功率密度下表现出17.7Wh/kg的能量密度。这项工作不仅为超级电容器提供了有吸引力的N掺杂多孔碳材料,而且还提供了对从废物剥离中衍生的生物炭碳的合理设计的新颖见解。
    The doping of porous carbon materials with nitrogen is an effective approach to enhance the electrochemical performance of electrode materials. In this study, nitrogen-doped porous carbon derived from peanut shells was prepared as an electrode for supercapacitors. Melamine, urea, urea phosphate, and ammonium dihydrogen phosphate were employed as different nitrogen dopants. The optimized electrode material PA-1-1 prepared by peanut shells, with ammonium dihydrogen phosphate as a nitrogen dopant, exhibited a N content of 3.11% and a specific surface area of 602.7 m2/g. In 6 M KOH, the PA-1-1 electrode delivered a high specific capacitance of 208.3 F/g at a current density of 1 A/g. Furthermore, the PA-1-1 electrode demonstrated an excellent rate performance with a specific capacitance of 170.0 F/g (retention rate of 81.6%) maintained at 20 A/g. It delivered a capacitance of PA-1-1 with a specific capacitance retention of 98.8% at 20 A/g after 5000 cycles, indicating excellent cycling stability. The PA-1-1//PA-1-1 symmetric supercapacitor exhibited an energy density of 17.7 Wh/kg at a power density of 2467.0 W/kg. This work not only presents attractive N-doped porous carbon materials for supercapacitors but also offers a novel insight into the rational design of biochar carbon derived from waste peelings.
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  • 文章类型: Journal Article
    制造高效且稳健的氧还原反应(ORR)电催化剂是具有挑战性的,但对于实际的Zn-空气电池是理想的。作为一种早期的过渡金属氧化物,二氧化锆(ZrO2)由于其独特的高稳定性特性而成为一种有趣的催化剂,抗毒性,良好的催化活性,和小的氧吸附焓。然而,其固有的差的导电性使得其难以用作ORR电催化剂。在这里,我们报告了嵌入N掺杂多孔碳基质中的超细N掺杂ZrO2纳米颗粒作为ORR电催化剂(N-ZrO2/NC)。N-ZrO2/NC催化剂表现出优异的活性和长期耐久性,其半波电位(E1/2)为0.84V,并且在0.1MKOH中对氧的四电子还原具有选择性。在锌空气电池中就业时,N-ZrO2/NC的功率密度为185.9mWcm-2,比容量为797.9mAhgZn-1,超过了商用Pt/C(122.1mWcm-2和782.5mAhgZn-1)。这种优异的性能主要归功于超细ZrO2纳米颗粒,导电碳基材,以及N掺杂后ZrO2的电子能带结构。密度泛函理论计算表明,通过N原子的p态与氧原子的2p态的杂化,N掺杂可以将ZrO2的带隙从3.96eV降低到3.33eV;这提供了增强的电导率并导致更快的电子转移动力学。这项工作为其他增强型半导体和绝缘体材料的设计提供了一种新的方法。
    Fabricating highly efficient and robust oxygen reduction reaction (ORR) electrocatalysts is challenging but desirable for practical Zn-air batteries. As an early transition-metal oxide, zirconium dioxide (ZrO2) has emerged as an interesting catalyst owing to its unique characteristics of high stability, anti-toxicity, good catalytic activity, and small oxygen adsorption enthalpies. However, its intrinsically poor electrical conductivity makes it difficult to serve as an ORR electrocatalyst. Herein, we report ultrafine N-doped ZrO2 nanoparticles embedded in an N-doped porous carbon matrix as an ORR electrocatalyst (N-ZrO2/NC). The N-ZrO2/NC catalyst displays excellent activity and long-term durability with a half-wave potential (E1/2) of 0.84 V and a selectivity for the four-electron reduction of oxygen in 0.1 M KOH. Upon employment in a Zn-air battery, N-ZrO2/NC presented an intriguing power density of 185.9 mW cm-2 and a high specific capacity of 797.9 mA h gZn -1, exceeding those of commercial Pt/C (122.1 mW cm-2 and 782.5 mA h gZn -1). This excellent performance is mainly attributed to the ultrafine ZrO2 nanoparticles, the conductive carbon substrate, and the modified electronic band structure of ZrO2 after N-doping. Density functional theory calculations demonstrated that N-doping can reduce the band-gap of ZrO2 from 3.96 eV to 3.33 eV through the hybridization of the p state of the N atom with the 2p state of the oxygen atom; this provides enhanced electrical conductivity and results in faster electron-transfer kinetics. This work provides a new approach for the design of other enhanced semiconductor and insulator materials.
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  • 文章类型: Journal Article
    设计并合成了外围掺杂有氮原子的环间亚苯基。大环结构的合成是通过一锅Suzuki-Miyaura偶联以交替方式排列亚苯基环和亚吡啶环实现的。UV-vis光谱分析表明,氮掺杂的光物理性质发生变化,和X射线晶体学分析表明,外围氮原子上存在偏置电荷。
    Cyclo-meta-phenylenes doped with nitrogen atoms at the periphery were designed and synthesized. The syntheses of the macrocyclic structures were achieved with one-pot Suzuki-Miyaura coupling to arrange phenylene rings and pyridinylene rings in an alternating fashion. Analyses with UV-vis spectroscopy showed changes in the photophysical properties with nitrogen doping, and X-ray crystallographic analyses experimentally revealed the presence of biased charges on the peripheral nitrogen atoms.
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  • 文章类型: Journal Article
    在这项研究中,通过制备发光二极管(LED),研究了缺陷对氮掺杂ZnO纳米颗粒(NPs)受体性质的影响。通过电弧放电气体中蒸发法合成了氮掺杂的ZnONP,并在800°C的氧气和氮气气氛中进行了后退火。通过X射线衍射对退火后的ZnONPs进行了表征,扫描电子显微镜,拉曼光谱,和光致发光光谱。发现氮掺杂的ZnONP在氮环境中的退火增加了锌空位的数量,而在氧环境中退火则由于氮解吸而增加了氧空位的数量。用氧退火的NP制造的LED的输出特性下降,而那些氮退火的NP显著提高。从这些结果来看,在实际的pn结器件中,首次证实了锌空位对ZnONP中受体形成的贡献。
    In this study, the effect of defects on the acceptor properties of nitrogen-doped ZnO nanoparticles (NPs) was investigated through the fabrication of light-emitting diodes (LEDs). Nitrogen-doped ZnO NPs were synthesized by an arc discharge in-gas evaporation method and post-annealed at 800 °C in an oxygen and nitrogen atmosphere. The annealed ZnO NPs were characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and photoluminescence spectroscopy. It was found that the annealing of nitrogen-doped ZnO NPs in a nitrogen environment increased the number of zinc vacancies, while annealing in an oxygen environment increased the number of oxygen vacancies due to nitrogen desorption. The output characteristics of LEDs fabricated with oxygen-annealed NPs were degraded, while those with nitrogen-annealed NPs were significantly improved. From these results, the contribution of zinc vacancies to acceptor formation in ZnO NPs was confirmed for the first time in actual pn junction devices.
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  • 文章类型: Journal Article
    生物质残余物的碳化以及随后的活化具有成为生产用于各种应用的各种碳材料的安全方法的巨大潜力。生物质基碳材料的商业使用需求在先进技术中快速增长,包括能源部门,作为催化剂,电池和电容器电极。在这项研究中,用两种碳化方法从硬木中合成了碳材料,然后用H3PO4、KOH和NaOH活化并用氮掺杂。它们的化学成分,多孔结构,研究了样品的热稳定性和结构有序性。事实证明,尽管存在差异,合成的碳材料是氧还原反应的活性催化剂。在研究的碳材料中,NaOH活化的样品表现出最低的Tafel斜率值,-90.6和-88.0mVdec-1,非常接近商业Pt/C在-86.6mVdec-1的值。
    Carbonization of biomass residues followed by activation has great potential to become a safe process for the production of various carbon materials for various applications. Demand for commercial use of biomass-based carbon materials is growing rapidly in advanced technologies, including in the energy sector, as catalysts, batteries and capacitor electrodes. In this study, carbon materials were synthesized from hardwood using two carbonization methods, followed by activation with H3PO4, KOH and NaOH and doping with nitrogen. Their chemical composition, porous structure, thermal stability and structural order of samples were studied. It was shown that, despite the differences, the synthesized carbon materials are active catalysts for oxygen reduction reactions. Among the investigated carbon materials, NaOH-activated samples exhibited the lowest Tafel slope values, of -90.6 and -88.0 mV dec-1, which are very close to the values of commercial Pt/C at -86.6 mV dec-1.
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  • 文章类型: Journal Article
    虽然二氧化钛(TiO2)具有广泛的潜在应用,TiO2的光催化性能受到其有限的光响应范围和光生电荷载流子的快速复合的限制。在这项工作中,通过以尿素为N源的简单退火处理,可以制备氮(N)掺杂的TiO2并引入氧空位(Vo)。在退火处理期间,尿素的存在不仅实现了TiO2的N掺杂,而且在N掺杂的TiO2(N-TiO2)中产生了Vo,这也适用于商业TiO2(P25)。出乎意料的是,N掺杂抑制了退火处理引起的N-TiO2比表面积的降低,因此,保持更活跃的网站。因此,N掺杂和Vo的形成以及增加的活性位点都有助于N-TiO2在可见光照射下的优异光催化性能。我们的工作为通过尿素退火处理制备具有Vo的N-TiO2提供了一种简便的策略。
    Although titanium dioxide (TiO2) has a wide range of potential applications, the photocatalytic performance of TiO2 is limited by both its limited photoresponse range and fast recombination of the photogenerated charge carriers. In this work, the preparation of nitrogen (N)-doped TiO2 accompanied by the introduction of oxygen vacancy (Vo) has been achieved via a facile annealing treatment with urea as the N source. During the annealing treatment, the presence of urea not only realizes the N-doping of TiO2 but also creates Vo in N-doped TiO2 (N-TiO2), which is also suitable for commercial TiO2 (P25). Unexpectedly, the annealing treatment-induced decrease in the specific surface area of N-TiO2 is inhibited by the N-doping and, thus, more active sites are maintained. Therefore, both the N-doping and formation of Vo as well as the increased active sites contribute to the excellent photocatalytic performance of N-TiO2 under visible light irradiation. Our work offers a facile strategy for the preparation of N-TiO2 with Vo via the annealing treatment with urea.
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  • 文章类型: Journal Article
    每到深秋,飘扬的杨树叶子散落在校园和城市街道上。在这项工作中,以杨树叶为原料,而H3PO4和KOH用作活化剂并且尿素用作氮源来制备基于生物质的活性炭(AC)以捕获CO2。孔隙结构,官能团和形态学,和解吸性能的制备ACs进行了表征;CO2吸附,再生,和动力学也进行了评估。结果表明,H3PO4和尿素明显促进孔结构和吡咯氮(N-5)的发育,而KOH和尿素更有利于羟基(-OH)和醚(C-O)官能团的形成。在最佳操作条件下,H3PO4和KOH活化杨树经尿素处理后对CO2的吸附量分别达到4.07和3.85mmol/g,分别,在室温下;经过十个吸附-解吸循环后,两者均显示出稳定的再生行为。
    Every late autumn, fluttering poplar leaves scatter throughout the campus and city streets. In this work, poplar leaves were used as the raw material, while H3PO4 and KOH were used as activators and urea was used as the nitrogen source to prepare biomass based-activated carbons (ACs) to capture CO2. The pore structures, functional groups and morphology, and desorption performance of the prepared ACs were characterized; the CO2 adsorption, regeneration, and kinetics were also evaluated. The results showed that H3PO4 and urea obviously promoted the development of pore structures and pyrrole nitrogen (N-5), while KOH and urea were more conductive to the formation of hydroxyl (-OH) and ether (C-O) functional groups. At optimal operating conditions, the CO2 adsorption capacity of H3PO4- and KOH-activated poplar leaves after urea treatment reached 4.07 and 3.85 mmol/g, respectively, at room temperature; both showed stable regenerative behaviour after ten adsorption-desorption cycles.
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  • 文章类型: Journal Article
    微生物和新兴有机污染物的增加对环境和生态系统造成有害影响,如疾病,大流行和毒性。这些合成污染物中的大多数是生物顽固的,因此会在环境中持续存在。常规的水处理方法是无效的,因此需要开发先进的技术,例如光催化和膜工艺。在这项研究中,通过将氮掺杂的纳米颗粒固定到聚偏氟乙烯(PVDF)膜上,合成了可见光驱动的光催化膜,并通过大肠杆菌微生物污染物去除进行了性能评估。使用傅里叶变换红外光谱进行表征,X射线衍射(XRD)水接触角,扫描电子显微镜-能量色散X射线(SEM-EDX)。二氧化钛的氮掺杂将光吸收从400nm红移到440nm的可见范围。对于氮掺杂的纳米颗粒,在1420cm-1和1170cm-1处检测到氮掺杂剂,对于氮掺杂的二氧化钛PVDF膜,在1346-1417cm-1处检测到氮掺杂剂。SEM-EDX证实了氮元素组成为0.01wt%的膜表面上氮掺杂的二氧化钛纳米颗粒中存在氮。由于PVA固定了氮掺杂的二氧化钛和戊二醛交联,水接触角从120.14o降低了81.39o至38.75o。氮掺杂导致可见光活性光催化膜具有更好的亲水性和抗污性。8.42E.大肠杆菌对数去除和0.35的相对通量在75分钟内获得。开发的光催化膜能够使用阳光,因此是一种成本较低的废水净化方法。
    The increasing presence of microbial and emerging organic contaminants pose detrimental effects on the environment and ecosystem such as diseases, pandemics and toxicity. Most of these synthetic pollutants are biorecalcitrant and therefore persist in the environment. Conventional water treatment methods are not effective thereby necessitating the development of advanced techniques such as photocatalysis and membrane processes. In this study, visible light-driven photocatalytic membrane was synthesized through the immobilization of nitrogen-doped nanoparticles onto the polyvinylidene fluoride (PVDF) membrane and performance evaluated with E.coli microbial contaminant removal. Characterization was done using Fourier transform infrared spectra, X-ray diffraction (XRD), water contact angle, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX). The Nitrogen-doping of titanium dioxide red-shifted the light absorption to a visible range of 440 nm from 400 nm. Nitrogen dopant was detected at 1420 cm-1and 1170 cm-1 for nitrogen doped nanoparticles and 1346-1417 cm-1 for nitrogen doped titanium dioxide PVDF membrane. SEM-EDX confirmed presences of nitrogen in nitrogen doped titanium dioxide nanoparticles on membrane surface with nitrogen elemental composition of 0.01 % wt. The water contact angle reduced by 81.39o from 120.14o to 38.75o because of PVA immobilization of nitrogen-doped titanium dioxide and glutaraldehyde crosslinking. Nitrogen doping resulted in visible light active photocatalytic membranes with better hydrophilicity and fouling resistance. 8.42 E.coli log removal and a relative flux of 0.35 was obtained within 75 min. The developed photocatalytic membrane enables the use of sunlight hence a less costly method for decontamination of wastewater.
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  • 文章类型: Journal Article
    为了提高生物炭对污染物的吸附效率,制备类石墨烯生物炭(GBC)或氮掺杂生物炭是两种常用的方法。然而,氮掺杂(N掺杂)对原始生物炭(PBC)和GBC吸附污染物的影响差异,以及潜在的机制,还不清楚。以四环素(TC)为例,本研究分析了生物炭(PBC,GBC,N-PBC,N-GBC),在不同的溶液性质下,N掺杂对PBC和GBC吸附TCs的影响存在显著差异。具体来说,N掺杂对PBC的吸附性能有不同的影响,均匀地提高了GBC的吸附性能。为了解释这种现象,QSAR模型揭示了吸附时的N掺杂,这表明孔隙填充(VM)和TC与生物炭(Ead-v)之间的相互作用是最重要的两个因素。此外,密度泛函理论(DFT)结果表明,N掺杂对生物炭的化学反应性略有影响。范德华(vdWs)和静电相互作用是TC-生物炭相互作用的主要力量。此外,N掺杂主要增强了TC-生物炭的静电相互作用,但大多数样品的vdWs相互作用基本上不受影响。总的来说,揭示的N掺杂对生物炭吸附TCs的机理将增强我们对抗生素污染修复的认识。
    To improve the adsorption efficiency of pollutants by biochar, preparing graphene-like biochar (GBC) or nitrogen-doped biochar are two commonly used methods. However, the difference in the nitrogen doping (N-doping) effects upon the adsorption of pollutants by pristine biochar (PBC) and GBC, as well as the underlying mechanisms, are still unclear. Take the tetracycline (TC) as an example, the present study analyzed the characteristics of the adsorption of TCs on biochars (PBC, GBC, N-PBC, N-GBC), and significant differences in the effects of N-doping on the adsorption of TCs by PBC and GBC were consistently observed at different solution properties. Specifically, N-doping had varied effects on the adsorption performance of PBC, whereas it uniformly improved the adsorption performance of GBC. To interpret the phenomenon, the N-doping upon the adsorption was revealed by the QSAR model, which indicated that the pore filling (VM) and the interactions between TCs with biochars (Ead-v) were found to be the most important two factors. Furthermore, the density functional theory (DFT) results demonstrated that N-doping slightly affects biochar\'s chemical reactivity. The van der Waals (vdWs) and electrostatic interactions are the main forces for TCs-biochars interactions. Moreover, N-doping mostly strengthened the electrostatic interactions of TCs-biochars, but the vdWs interactions of most samples remained largely unaffected. Overall, the revealed mechanism of N-doping on TCs adsorption by biochars will enhance our knowledge of antibiotic pollution remediation.
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  • 文章类型: Journal Article
    无机卤化物钙钛矿CsPbI3因其对紫外和可见光的强吸收而在光催化领域具有广阔的应用前景。在CsPbI3的晶相中,δ相是最稳定的水;然而,直接在水中使用仍然不适用,从而限制了其在水溶液中的染料光降解应用。采用氮掺杂石墨烯量子点(NGQDs)作为表面活性剂制备δ相CsPbI3纳米晶,我们得到了一种水稳定的材料,NGQDs-CsPbI3。这种材料可以很好地分散在水中一个月而没有明显的变质。高分辨率透射电子显微镜和X射线衍射仪表征表明,NGQD涂层后,NGQDs-CsPbI3也是δ相CsPbI3。紫外-可见吸收光谱表明,与δ-CsPbI3相比,NGQDs-CsPbI3对可见光有明显的吸收增强作用,特别是在521nm左右的波长附近。NGQDs-CsPbI3的良好分散性和改善的可见光吸收有利于其水性光催化应用。NGQDs-CsPbI3单独可光降解水中67%的罗丹明B(RhB),与TiO2复合后,NGQDs-CsPbI3/TiO2表现出优异的可见光催化能力,即,它在4h内光降解96%的RhB。NGQDs-CsPbI3在可见光区域的强吸收和光生载流子从NGQDs-CsPbI3到TiO2的有效转移在染料光降解中起关键作用。我们强调NGQDs-CsPbI3是水稳定的卤化物钙钛矿材料和有效的光催化佐剂。
    Inorganic halide perovskite CsPbI3 is highly promising in the photocatalytic field for its strong absorption of UV and visible light. Among the crystal phases of CsPbI3, the δ-phase as the most aqueous stability; however, directly using it in water is still not applicable, thus limiting its dye photodegradation applications in aqueous solutions. Via adopting nitrogen-doped graphene quantum dots (NGQDs) as surfactants to prepare δ-phase CsPbI3 nanocrystals, we obtained a water-stable material, NGQDs-CsPbI3. Such a material can be well dispersed in water for a month without obvious deterioration. High-resolution transmission electron microscopy and X-ray diffractometer characterizations showed that NGQDs-CsPbI3 is also a δ-phase CsPbI3 after NGQD coating. The ultraviolet-visible absorption spectra indicated that compared to δ-CsPbI3, NGQDs-CsPbI3 has an obvious absorption enhancement of visible light, especially near the wavelength around 521 nm. The good dispersity and improved visible-light absorption of NGQDs-CsPbI3 benefit their aqueous photocatalytic applications. NGQDs-CsPbI3 alone can photodegrade 67% rhodamine B (RhB) in water, while after compositing with TiO2, NGQDs-CsPbI3/TiO2 exhibits excellent visible-light photocatalytic ability, namely, it photodegraded 96% RhB in 4 h. The strong absorption of NGQDs-CsPbI3 in the visible region and effective transfer of photogenerated carriers from NGQDs-CsPbI3 to TiO2 play the key roles in dye photodegradation. We highlight NGQDs-CsPbI3 as a water-stable halide perovskite material and effective photocatalytic adjuvant.
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