以煅烧三聚氰胺后形成的C3N4材料为氮源,柠檬酸为碳源,六水合三氯化铁为铁源,通过两步法合成FeN/C催化剂,并考察该催化剂对氧还原反应的电催化能力。采用XRD、SEM、Raman、XPS等表征手段对Fe-N/C催化剂的晶体结构和元素化学状态进行综...以煅烧三聚氰胺后形成的C3N4材料为氮源,柠檬酸为碳源,六水合三氯化铁为铁源,通过两步法合成FeN/C催化剂,并考察该催化剂对氧还原反应的电催化能力。采用XRD、SEM、Raman、XPS等表征手段对Fe-N/C催化剂的晶体结构和元素化学状态进行综合评价;以CV和LSV等电化学测试手段探究Fe-N/C催化剂的氧还原电催化能力。研究结果表明,Fe-N/C催化剂具有管状形貌、较高的石墨氮含量和较佳的氧还原电催化能力。通过对电化学性能关键参数进行分析发现,Fe-N/C催化剂的起始电位是1.071 V vs. RHE,半波电位是0.911 V vs. RHE,极限电流密度是5.943 mA/cm2。展开更多
An environmentally friendly precursor, adenosine, has been used as a dual source of C and N to synthesize nitrogen-doped carbon catalyst with/without Fe. A hydrothermal carbonization method has been used and water is ...An environmentally friendly precursor, adenosine, has been used as a dual source of C and N to synthesize nitrogen-doped carbon catalyst with/without Fe. A hydrothermal carbonization method has been used and water is the carbonization media. The morphology of samples with/without Fe component has been compared by HRTEM, and the result shows that Fe can promote the graphitization of carbon. Further electro-chemical test shows that the oxygen reduction reaction（ORR） catalytic activity of Fe-containing sample（C–Fe N） is much higher than that of the Fe-free sample（C–N）. Additionally, the intermediates of C–Fe N formed during each synthetic procedure have been thoroughly characterized by multiple methods,and the function of each procedure has been discussed. The C–Fe N sample exhibits high electro-catalytic stability and superior electro-catalytic activity toward ORR in alkaline media, with its half-wave potential 20 mV lower than that of commercial Pt/C（40 wt%）. It is further incorporated into alkaline polymer electrolyte fuel cell（APEFC） as the cathode material and led to a power density of 100 m W/cm;.展开更多
The N and C doping effects on the crystal structures, electronic and optical properties of fluorite structure CeO2 have been investigated using the first-principles calculation. Co-doping these two elements results in...The N and C doping effects on the crystal structures, electronic and optical properties of fluorite structure CeO2 have been investigated using the first-principles calculation. Co-doping these two elements results in the local lattice distortion and volume expansion of CeO2. Compared with the energy hand structure of pure CeO2, some local energy levels appear in the forbidden band, which may facilitate the light absorption. Moreover, the enhanced photo-catalytic properties of CeO2 were explained through the absorption spectra and the selection rule of the band-to-band transitions.展开更多
以TiCl_3(3THF)为原料合成脒基钛(Ⅲ)配合物1,将其作为前驱体通过LPCVD沉积N/C-TiO_2薄膜。利用1HNMR、元素分析以及热重分析(TGA)探究配合物1的结构和热化学性质。结果表明,配合物1具有良好的热稳定性和合适的挥发性,满足CVD的要求。通...以TiCl_3(3THF)为原料合成脒基钛(Ⅲ)配合物1,将其作为前驱体通过LPCVD沉积N/C-TiO_2薄膜。利用1HNMR、元素分析以及热重分析(TGA)探究配合物1的结构和热化学性质。结果表明,配合物1具有良好的热稳定性和合适的挥发性,满足CVD的要求。通过EDS和UV-Vis吸收光谱表征了薄膜的成分及光学性能,结果表明,当沉积温度为350℃时,N/C-TiO_2薄膜的N、C质量分数最高,其禁带宽度降低为2. 82 e V,对可见光的吸收最强。与纯的二氧化钛薄膜相比,N/C-TiO_2薄膜对亚甲基蓝的降解率显著提高到90%。展开更多
文摘以煅烧三聚氰胺后形成的C3N4材料为氮源,柠檬酸为碳源,六水合三氯化铁为铁源,通过两步法合成FeN/C催化剂,并考察该催化剂对氧还原反应的电催化能力。采用XRD、SEM、Raman、XPS等表征手段对Fe-N/C催化剂的晶体结构和元素化学状态进行综合评价;以CV和LSV等电化学测试手段探究Fe-N/C催化剂的氧还原电催化能力。研究结果表明,Fe-N/C催化剂具有管状形貌、较高的石墨氮含量和较佳的氧还原电催化能力。通过对电化学性能关键参数进行分析发现,Fe-N/C催化剂的起始电位是1.071 V vs. RHE,半波电位是0.911 V vs. RHE,极限电流密度是5.943 mA/cm2。
文摘研制高活性的Fe/N/C氧还原催化剂对于降低燃料电池成本、实现商业化应用有重要意义.为实现Fe/N/C催化剂的理性设计,需要深入研究其活性位结构.本文发展一种研究活性位结构的新策略,以预先合成好的聚间苯二胺基Fe/N/C催化剂(Pm PDA-Fe Nx/C)为起始物,对其在1000~1500 o C高温下再次进行热处理并使其失活,通过关联催化剂热处理前后的结构变化与氧还原催化性能来揭示活性位结构.实验结果表明,随着热处理温度升高,活性中心结构被破坏,铁原子析出团聚并形成纳米颗粒,氮元素挥发损失,导致催化剂失活.XPS分析显示,低结合能含氮物种的含量与催化剂的ORR活性呈良好的正相关性,表明活性中心很可能是由吡啶N和Fe-N物种构成的.
基金financially supported by the National Natural Science Foundation of China(21573167,21633008,91545205,21125312)National Key Research and Development Program(2016YFB0101203)+2 种基金the National Basic Research Program(2012CB932800,2012CB215500)the Doctoral Fund of Ministry of Education of China(20110141130002)the Fundamental Research Funds for the Central Universities(2014203020207)
文摘An environmentally friendly precursor, adenosine, has been used as a dual source of C and N to synthesize nitrogen-doped carbon catalyst with/without Fe. A hydrothermal carbonization method has been used and water is the carbonization media. The morphology of samples with/without Fe component has been compared by HRTEM, and the result shows that Fe can promote the graphitization of carbon. Further electro-chemical test shows that the oxygen reduction reaction（ORR） catalytic activity of Fe-containing sample（C–Fe N） is much higher than that of the Fe-free sample（C–N）. Additionally, the intermediates of C–Fe N formed during each synthetic procedure have been thoroughly characterized by multiple methods,and the function of each procedure has been discussed. The C–Fe N sample exhibits high electro-catalytic stability and superior electro-catalytic activity toward ORR in alkaline media, with its half-wave potential 20 mV lower than that of commercial Pt/C（40 wt%）. It is further incorporated into alkaline polymer electrolyte fuel cell（APEFC） as the cathode material and led to a power density of 100 m W/cm;.
基金Project supported by the National Natural Science Foundation of China(Grant No.61306098)
文摘The N and C doping effects on the crystal structures, electronic and optical properties of fluorite structure CeO2 have been investigated using the first-principles calculation. Co-doping these two elements results in the local lattice distortion and volume expansion of CeO2. Compared with the energy hand structure of pure CeO2, some local energy levels appear in the forbidden band, which may facilitate the light absorption. Moreover, the enhanced photo-catalytic properties of CeO2 were explained through the absorption spectra and the selection rule of the band-to-band transitions.
文摘以TiCl_3(3THF)为原料合成脒基钛(Ⅲ)配合物1,将其作为前驱体通过LPCVD沉积N/C-TiO_2薄膜。利用1HNMR、元素分析以及热重分析(TGA)探究配合物1的结构和热化学性质。结果表明,配合物1具有良好的热稳定性和合适的挥发性,满足CVD的要求。通过EDS和UV-Vis吸收光谱表征了薄膜的成分及光学性能,结果表明,当沉积温度为350℃时,N/C-TiO_2薄膜的N、C质量分数最高,其禁带宽度降低为2. 82 e V,对可见光的吸收最强。与纯的二氧化钛薄膜相比,N/C-TiO_2薄膜对亚甲基蓝的降解率显著提高到90%。
基金supported by the National Basic Research Program of Chain(973 Program,2015CB932300)the National Natural Science Foundation of China(21373175,21321062,21361140374)Fundamental Research Funds for the Central Universities(20720150109)
文摘燃料电池具有高效、低排放等优势,非常有希望作为未来电动汽车的能源转化装置.目前,燃料电池的商业化受制于昂贵的铂基催化剂,特别是动力学迟缓的阴极氧还原反应（ORR）铂催化剂.Fe/N/C被认为是最有潜力的ORR非贵金属催化剂,但其活性仍远低于Pt催化剂,必须依靠增加载量来弥补其与Pt催化剂的活性差距.然而,较厚的催化层（~100μm）会降低阴极传质速率.因此,改善Fe/N/C阴极的传质是提高电池性能的重要途径.本文选择高N含量的2-氨基苯并咪唑（ABI）为氮源,通过水热聚合包覆在碳黑表面,然后掺入FeCl_3,经高温热解/酸洗制备了Fe/N/C-ABI催化剂,并与基于间苯二胺的微孔型Fe/N/C催化剂（Fe/N/C-Pm PDA）进行比较.Ar等温吸附-脱附结果表明,Fe/N/C-ABI催化剂具有较高的比表面积（662 m2/g）和丰富的双级孔结构（微孔和介孔）;透射电镜表征显示Fe/N/C-ABI催化剂具有中空结构,介孔孔径大约为10–25 nm.而Fe/N/C-Pm PDA催化剂具有相当的比表面积（656 m2/g）,但以微孔为主,基本不含介孔.旋转环圆盘电极（RRDE）测试表明,在0.1 mol/L H2SO4溶液中,Fe/N/C-ABI催化剂的起始还原电位为0.92 V,在0.8 V电位下质量电流密度可达9.21 A/g;而Fe/N/C-Pm PDA催化剂具有相近的起始电位,但具有更高的催化活性,质量电流密度为13.4 A/g.氢氧燃料电池（PEMFC）系统测试结果表明,Fe/N/C-ABI催化剂在1个背压和80 oC测试条件下的最大功率密度达710 m W/cm2,高于Fe/N/C-Pm PDA催化剂（616 m W/cm2）.燃料电池与RRDE测试活性顺序的差异归结于Fe/N/C-ABI的中空球状结构.PEMFC工作时阴极会产生大量的水,很容易堵塞氧气传输通道.Fe/N/C-ABI的介孔结构可以作为水的产生和排除的缓存空间,也有利于提高O_2传质,从而提高燃料电池性能.本文为具有高传质速率的Fe/N/C催化剂研制提供了一种新思路.
