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1.
采用阳极极化的方法在铜电极表面形成氧化铜纳米粒子,然后采用循环伏安法将羧基化石墨烯电沉积到上述电极表面,成功制备了石墨烯/氧化铜纳米粒子/铜电极,用于碱性溶液中亚叶酸钙的检测.采用循环伏安法对亚叶酸钙在修饰电极上的催化氧化行为进行了研究,阳极扫描极化反向催化伏安法应用于亚叶酸钙的检测.在2.0×10-7~2.0×10-5 mol/L范围内,该电极显示出良好的线性关系,灵敏度为22.0 μA·μL/(μmol/cm2),检测限达到7.6×10-8 mol/L(S/N=3),成功应用于实际样品的检测.  相似文献   

2.
利用经典的循环伏安法制备出普鲁士蓝/离子液体-聚苯胺/多壁碳纳米管(PB/IL-PANI/MWNTs)复合膜.离子液体为润滑剂,能够显著增强聚苯胺链的电子去极化度并减少其链的结构缺陷.离子液 体的引入使该复合膜在H2O2检测中呈现出更优异的特性,线性范围为2.5~5.0 mmol/L,灵敏度为736.8 μA·(mmol/L)-1·cm-2,复合膜比纯PB 膜在中性溶液中稳定性好;传感器在12.5~1.75 mmol/L对葡萄糖也呈现很好的线性关系,检测限为1.1 μmol/L(信噪比为3),灵敏度为94.79 μA·(mmol/L)-1·cm-2.该传感器还用于检测未经过任何预处理的人血清中的血糖含量,结果和医院提供的值吻合较好.  相似文献   

3.
通过一步电沉积制备了石墨烯-金纳米复合膜修饰玻碳电极,并以此修饰电极为工作电极,采用差分脉冲阳极溶出伏安法测定环境水中痕量汞. 这种纳米复合膜结合了金纳米粒子和石墨烯两者的优势,能够增加异相电子转移速度和修饰电极对汞的富集能力,从而显著提高了电极的灵敏度和选择性. 这种修饰电极具有良好的分析性能:Hg(II)的分析曲线覆盖了0.2~5.0和5.0~30 μg/L两个线性范围,Hg(II)检测限(S/N=3)为0.030 μg/L. 此外,该修饰电极还表现出良好的稳定性和抗干扰性能,还被成功地应用于实际水样中Hg(II)的测定.  相似文献   

4.
赵理  刘东洋  刘东梅  陈平  赵毅  刘式墉 《物理学报》2012,61(8):88802-088802
通过采用4,4′,4″-三(N-3-甲基苯基-N-苯基氨基)三苯胺 (m-MTDATA)掺入MoOx作为器件的空穴传输层来提高酞菁铜(CuPc)/C60小分子 有机太阳电池的效率. 采用真空蒸镀的方法制备了一系列器件, 其中结构为铟锡氧化物 (ITO)/m-MTDATA:MoOx(3:1)(30 nm)/CuPc(20 nm)/C60(40 nm)/4,7-二苯 基-1,10-菲罗啉 (Bphen)(8 nm)/LiF(0.8 nm)/Al(100 nm)的器件, 在AM1.5 (100 mW/cm2)模拟太阳光的照射条件下, 开路电压Voc=0.40 V, 短路电流Jsc=6.59 mA/cm2, 填充因子为0.55, 光电转换效率达1.46%, 比没有空穴传输层的器件ITO/CuPc(20 nm)/C60(40 nm)/Bphen(8 nm)/LiF(0.8 nm)/Al(100 nm) 光电转换效率提高了38%. 研究表明, 加入m-MTDATA:MoOx(3:1)(30 nm)空穴传输层减小了有机层和ITO电极之间的接触电阻, 从而减小了整个器件的串联电阻, 提高了器件的光电转换效率.  相似文献   

5.
制备了金(核)铂(壳)结构纳米粒子(Au@Pt-NPs)及其Au@Pt-NPs/PVP膜修饰电极,考察该修饰电极在酸性介质中对甲醛的电催化氧化行为,研究表明金和铂之闻存在协同催化作用.使Au@Pt纳米粒子比单独铂和金纳米粒子具有更高的催化活性.循环伏安行为显示修饰电极的氧化峰电流与溶液中甲醛浓度有良好的线性关系,线性范围为0.01-0.4mg/g、检出限为4ug/g,可作为甲醛的一种灵敏而快速的电化学检测方法.  相似文献   

6.
利用一种简单的方法制备不含任何表面活性剂并具有高甲醇氧化活性的Pt和PtRu纳米电催化剂. 以CO为还原剂, CO和多壁碳纳米管(MWCNTs)为保护剂和载体,通过一步反应得到沉积在多壁碳纳米管上Pt纳米粒子,在制备过程中无需使用任何有机溶剂或表面活性剂. 利用循环伏安法和计时电流法表征了所合成催化剂的甲醇氧化活性,甲醇氧化的峰电位(ca. 0.9 V vs. RHE)处的电流密度和比质量电流高达11.6 mA/cm2 和860 mA/mgPt. 在Pt/MWCNTs表面电沉积Ru后,催化剂在低电位处的甲醇氧化活性得到提高,其在0.5和0.6 V的稳态比质量电流分别达到了20和80 mA/mg.  相似文献   

7.
按照团簇的氧化指数,对钒氧化物团簇VxOyq (x≤8, q=0,±1)进行了分类(钒氧化物的氧化指数△=2y+q-5x). 密度泛函理论计算结果表明,氧化指数相同的团簇倾向于具有相似的成键方式、电子结构和反应活性. 根据这一规律,提出了V2O6和V3O6+新的可能的基态构型. 在钒氧化物体系上的成功应用,表明这种分类方法可以有效地  相似文献   

8.
多组分复合体系有利于电荷的有效分离,减少电子空穴对的复合几率。通过低温液相法首次合成Ag-Bi2MoO6/BiPO4三元异质结构光催化剂。利用XRD、SEM、EDX及XPS等技术对样品进行了表征。结果表明,Ag纳米粒子光照积累在Bi2MoO6/BiPO4的表面,通过表面等离子共振增加对可见光的吸收,同时作为电子受体促进了光生电子的转移。Ag、BiPO4和Bi2MoO6形成三元异质结构有效地抑制了光生电子空穴对的复合。Ag-Bi2MoO6/BiPO4表现出优异的光催化性能,其光催化活性较BiPO4、Bi2MoO6和Bi2MoO6/BiPO4样品有较大提高。并且对Ag-Bi2MoO6/BiPO4三元异质结构的光催化机制进行了讨论。光催化过程中反应活性物种捕获实验结果表明h+和O2·-是主要的活性基团.  相似文献   

9.
将介孔TiO2纳米粒子(m-TiO2)多孔膜电极浸入相应的金属硝酸盐的500 oC热处理修饰金属氧化物(如Mg、ZnO、Al2O3或NiO).结果表明,金属氧化物修饰均可形成能垒对m-TiO2膜电极的界面电荷传输过程产生影响,但外加偏压下其膜内电子传输和界面电荷复合均明显依赖于修饰氧化物的种类及其存在形态. 金属氧化物修饰的膜电极在电子传输和界面复合方面的变化与DSSCs的电流-电压特性曲线的变化规律具有明显的相关性,可不同程度地提高电池的光电压,而MgO、ZnO和NiO修饰的电池效率分别提高了23%、13%和6%. 上述结果表明调控电池的本征参数可以改善TiO2-基DSSCs的性能.  相似文献   

10.
本文报道了一种利用简单的两步牺牲模板法,在泡沫铜基底表面完成了三维氧化铜纳米晶阵列的生长. 氧化铜纳米晶阵列具有良好的导电性,稳定性,在碱性溶液中有着优秀的电解水产氧催化性能. 氧化铜纳米晶阵列催化水的电化学氧化只需400 mV的过电势即可达到100 mA/cm2的电流密度,与其它铜基电解水产氧催化剂以及贵金属IrO2相比都有着明显的优势. 氧化铜纳米晶阵列在270 mA/cm2左右的工作电流下连续工作10 h依然可以保持良好的稳定性,是相同的工作电压下IrO2工作电流的10倍(约25 mA/cm2).  相似文献   

11.
The decay constants for D and Ds mesons, denoted fD and fDS respectively, are equal in the SU(3)V limit, as are the hadronic amplitudes for and mixing. The leading SU(3)V violating contribution to (FDS/FD) and to the ration of hadronic matrix elements relevant for and mixing amplitudes are calculated in chiral perturbatiion theory. We discuss the formalism needed to include both meson and anti-meson fields in the heavy quark effective theory.  相似文献   

12.
Most studies on Co-doped TiO2 system were focused on thin films grown by MBE-based methods. In this work we report the ferromagnetism of nanometer-thick-layered TiO2/Co/TiO2/TiN film grown on Si substrate by conventional magnetron sputtering. For the growth of TiO2 on silicon, a non-oxide thermally stable material, TiN, was introduced to prevent Ti penetration into the Si substrate. Structural, magnetic, and transport measurements respectively by Raman, SQUID and Hall effect show that our samples are n-type semiconductors and exchange bias effect due to exchange coupling between Co and interfacial CoO. For the rapid vacuum annealed specimen, we found an enhanced loss and a Perminvar-type constricted hysteresis loop, which attributed to pinning of domain walls due to an induced anisotropy by the pair ordering in the metallic alloy of Co-Ti-Si.  相似文献   

13.
The effects of HfOxNy on the electrical property of HfOxNy-HfO2-HfOxNy sandwich-stack (signed as SS) films were investigated. Excellent electrical performances were achieved in SS films, with a high dielectric constant of 16 and a low leakage current of ∼2 × 10−8 A/cm2 at 1 MV/cm. Schottky (SK) emission and Frenkel-Poole (PF) emission are found to be the dominant mechanisms for the current conduction behavior. After a long time stress, the flat-band voltage shift in the SS film is much smaller than that in a pure HfOxNy film indicating fewer charge traps existed in the SS film. Based on the experiments, the new SS structure is more favorable for the improvement of electrical performances than a pure HfOxNy or HfO2 structure.  相似文献   

14.
Electronic and magnetic structures of zinc blende ZnO doped with V impurities are studied by first-principles calculations based on the Korringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA).Calculations for the substitution of O by N or P are performed and the magnetic moment is found to be sensitive to the N or P content.Furthermore,the system exhibits a half-metallic band structure accompanied by the broadening of vanadium bands.The mechanism responsible for ferromagnetism is also discussed and the stability of the ferromagnetic state compared with that of the paramagnetic state is systematically investigated by calculating the total energy difference between them by using supercell method.  相似文献   

15.
Vibrational and rotational analyses of the near-infrared bands of S2 lying in the region 7440–8085 Å are reported. They form a new band system involving a 3Πgi-3Σu+ transition and arise from the same initial 3Πgi state of the 3Πgi-3Δui band system reported earlier. The analyses of the bands of this system due to the isotopic molecules 32S34S and 34S2 are also reported.  相似文献   

16.
宋杰  许福军  黄呈橙  林芳  王新强  杨志坚  沈波 《中国物理 B》2011,20(5):57305-057305
The temperature dependence of carrier transport properties of AlxGa1-xN/InyGa1-yN/GaN and AlxGa1-xN/GaN heterostructures has been investigated.It is shown that the Hall mobility in Al0.25Ga0.75N/In0.03Ga0.97N/GaN heterostructures is higher than that in Al0.25Ga0.75N/GaN heterostructures at temperatures above 500 K,even the mobility in the former is much lower than that in the latter at 300 K.More importantly,the electron sheet density in Al0.25Ga0.75N/In0.03Ga0.97N/GaN heterostructures decreases slightly,whereas the electron sheet density in Al0.25Ga0.75N/GaN heterostructures gradually increases with increasing temperature above 500 K.It is believed that an electron depletion layer is formed due to the negative polarization charges at the InyGa1-yN/GaN heterointerface induced by the compressive strain in the InyGa1-yN channel,which e-ectively suppresses the parallel conductivity originating from the thermal excitation in the underlying GaN layer at high temperatures.  相似文献   

17.
The magnetic and electrical properties of the Al-doped polycrystalline spinels ZnxCryAlzSe4 (0.13≤z≤0.55) with the antiferromagnetic (AFM) order and semiconducting behavior were investigated. A complex antiferromagnetic structure below a Néel temperature TN≈23 K for the samples with z up to 0.4 contrasting with the strong ferromagnetic (FM) interactions evidenced by a large positive Curie-Weiss temperature θCW decreasing from 62.2 K for z=0.13 to 37.5 K for z=0.55 was observed. Detailed investigations revealed a divergence between the zero-field-cooling (ZFC) and field-cooling (FC) susceptibilities at temperature less than TN suggesting bond frustration due to competing ferromagnetic and antiferromagnetic exchange interactions in the compositional range 0.13≤z≤0.4. Meanwhile, for z=0.55 a spin-glass-like behavior of cluster type with randomly oriented magnetic moments is observed as the ZFC-FC splitting goes up to the freezing temperature Tf=11.5 K and the critical fields connected both with a transformation of the antiferromagnetic spin spiral via conical magnetic structure into ferromagnetic phase disappear.  相似文献   

18.
The branching ratio is calculated for Λ8Li decay to the (2+) 8Be1 states near 17 MeV, using intermediate coupling wave functions for Λ8Li and for the relevant 8Be1 states. It is pointed out that this ratio is sensitive primarily to a mixing angle ? in the Λ8Li wave function. Within one standard deviation, the data allow two ranges (+0.05 to +0.25 rad and +1.10 to +1.25 rad) for the value of ?. The further requirement that there also be acceptable agreement between the angular distribution expected for the subsequent 8Be1 (? 17 MeV → 24He decay and the data, shifts these allowed ranges for ?, to (+0.13 to 0.40) rad and (+0.9 to +1.2) rad. It is predicted that the dominant transition should be to 8Be1 (16.6 MeV), as is observed to be the case, rather than to 8Be1 (16.9 MeV). The interpretation of these values for ? is discussed in some detail and their implications for intermediate coupling shell-model calculations of Λ-hypernuclear wave functions are considered.  相似文献   

19.
At helium temperatures two sharp lines at 9350 and 9510 cm?1 have been observed for the first tune on the low-energy side of the broad double-peaked absorption corresponding to the 5T2g5Eg transition in Fe2+ at the octahedral site in MgO. The lower energy line has a half width of 4 cm?1; Zeeman measurements show that it is of magnetic dipole origin. The Zeeman spectra are consistent with those expected for a pure electronic transition from the (5T2g)T2g ground state to the 5Eg excited state. The second line, with a halfwidth of ~ 35 cm?1, a vibrational sideband.  相似文献   

20.
We present techniques which enable one to calculate quickly the amplitudes for many scattering processes in the high-energy limit. As an illustration of the method, these are applied to the diagrams for ppV + 0, 1 or 2 jets, where V = W± or Z0. The form of the results lends itself to immediate numerical evaluation.  相似文献   

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