Functionalization of Silicon Nanoparticles via Silanization: Alkyl, Halide and Ester

The feasibility of using silanization as a general tool to functionalize the surface of silicon nanoparticles (NPs) has been investigated in detail. Silicon NPs were prepared from reduction of silicon tetrachloride with sodium naphthalide. The terminal chloride on the surface of as-synthesized particles was substituted by methanol and water, in sequence. The particles were then silanized by octyltrichlorosilane, 11-bromoundecyltrichlorosilane, or 2-(carbomethoxy)ethyltrichlorosilane. These treatments yielded alkyl-, bromo-, or ester-termini on NP surfaces, respectively. The NPs were characterized by TEM, NMR, FTIR, UV–Vis, and PL spectroscopy. Changes of termination groups brought various functionalities to the NPs, without loss of the photophysics of the original NPs.     

金纳米颗粒的水相法合成及荧光性能

在水溶液中,以PAMAM树形分子为模板,乙醇为还原剂,制备了树形分子包裹的金纳米颗粒,其水溶性好,可以稳定放置1年以上;通过控制Au3+与PAMAM树形分子的摩尔比,可以得到粒径可控的金纳米颗粒,其粒径范围为1～4nm,分别在385和402nm处出现强的共振瑞利光散射峰和荧光峰.室温下,荧光量子产率达到10%以上,比其它文献报道的金纳米颗粒的荧光量子产率高2个数量级以上,这一特性使其在潜指纹识别、光催化等方面具有很大的应用潜力.     

Synthesis of Carbon Quantum Dots Nanoparticles by Cyclic Voltammetry and Its Application as Methanol Tolerant Oxygen Reduction Reaction Electrocatalyst

Carbon quantum dot (CQD) nanoparticles are synthesized by one‐step electrochemical method, cyclic voltammetry (CV), at different potentials using graphite rods and NaOH/EtOH as electrolyte. The electro‐chemically manufactured CQD is characterized by Transmission electron microscopy, Ultra violet absorption, X‐ray diffraction and Fourier transform infrared spectrometry. The morphology and microstructure methods confirm the formation of high quality CQD. Finally, we design a new gas diffusion electrode (GDE) based on CQD pasted on carbon paper for the oxygen reduction reaction at cathode side as methanol tolerance in direct methanol fuel cell and compared it with standard Pt‐C catalysts using cyclic voltammetry and linear sweep voltammetry. The ORR results in presence of methanol indicate that the GDE prepared from CQD exhibits methanol tolerance compared to the GDE prepared from Pt/C (Electrochem).     

硅纳米晶的制备及其在太阳电池中的应用研究

硅纳米晶由于量子限域效应的作用而产生了多种不同于体硅材料的新特性,如荧光效应显著、光学带隙可调等,因而在微电子、光伏、生物医学等领域受到极大的重视。本文介绍了分立的硅纳米晶颗粒和硅纳米晶薄膜的制备方法,并对比了不同方法制备硅纳米晶体的优缺点。着重介绍了硅纳米晶体在太阳电池中应用的几种方式,包括利用纯硅纳米晶薄膜制备太阳电池、硅纳米晶体与有机薄膜基质结合形成复合结构太阳电池、含有硅纳米晶颗粒的硅墨水在太阳电池中的应用等。     

硅量子点支撑钯纳米粒子的可控制备

采用微乳法制备烯丙胺修饰的硅量子点(Si QDs),通过紫外-可见吸收光谱、荧光光谱和红外光谱对其光学性能进行了表征,通过透射电镜(TEM)对其形貌进行了表征,测得其荧光量子产率为10.06%,荧光寿命τ1=3.1982ns,τ2=12.4527ns。依据Si QDs的光学性质,制备了Si QDs支撑Pd纳米粒子材料(Si QDs/Pd)。通过量子点的浓度实现了Pd纳米粒子形貌和尺寸的有效控制。结果表明制备的Pd纳米材料具有较好的分散性,在有机催化和能源转化领域具有潜在的应用价值。     

Photoluminescence as a Function of Aggregated Size from n-Butyl-Terminated Silicon Nanoclusters

Photoluminescence (PL) from alkyl-terminated silicon nanocrystallites as a function of size has been studied. Ultraviolet–blue luminescence (390–410 nm) is observed from as-prepared silicon nanoclusters with diameters from 3 to 8 nm. After 1 h of annealing at 162°C in 2-methoxyethyl ether (diglyme), the _max of PL shifts from 360 to 420 nm. High-resolution transmission electron microscopy (HRTEM) images show that individual silicon nanoparticles are fused to form pairs of nanoparticles. FTIR spectra show that the alkyl groups remain on the surface of silicon nanoparticles. As the temperature is raised to 250°C for 1 h, the PL no longer shows any peak in the visible light region. TEM images show that the silicon nanoparticles are aggregated and fused uniformly in one single dimension, to form a strip, and these strips parallel each other. When the temperature is raised to 350°C these silicon nanoparticles form a large piece of silicon textile network, showing that functionalized alkyl surface does not persist above this temperature. A strong Si–O–Si asymmetric stretching vibration appears between 1000 and 1100 cm^–1 at the expense of the C–H vibrational modes and there is no more change after 3 h of annealing at 250 or 350°C. These results provide strong evidence that the PL originates from quantum confinement.     

憎水性单分散粒径小于10 nm复合金属量子点的制备

0引言粒径小于10nm的量子点,具有特殊的物理化学性质。如低电子转换性能、高氧化还原电位,高矫顽力,高催化性能等,金量子点还具有生物识别、生物传感器等性能[1]。纳米颗粒的合成与应用已经引起人们的广泛兴趣[2￣4],二维、三维量子点阵长程有序排布对将来的纳米电子器件及超功能性材料具有重要意义[5,6]。然而,二维、三维量子点阵长程有序排布需要单分散量子点。这就需要人们利用各种方法制备单分散量子点。直接合成法,如Lianos等[7,8],利用反胶束法合成出粒径为5nm量子点,但是单分散性不佳。目前,获得单分散纳米颗粒主要有3种方法,种子增…     

贵金属纳米粒子/硅纳米线复合纳米材料的制备及其催化性能研究

以十二烷基硫酸钠(SDS)作为保护剂, 利用贵金属阳离子(Mⁿ⁺)与HF处理后的硅纳米线(SiNWs)之间的氧化还原反应, 在SiNWs表面负载了贵金属纳米粒子. 通过调控SDS/Mⁿ⁺物质的量比、反应物浓度、反应温度等实验参数, 制备出了金属纳米粒子粒径均一且负载密集的AuNPs/SiNWs, PtNPs/SiNWs复合材料. 将AuNPs/SiNWs复合材料应用在亚甲基蓝的还原反应, 实验结果显示, 60 min内AuNPs/SiNWs可以将55%的亚甲基蓝还原, 表明AuNPs/SiNWs具有良好的催化活性. 这种复合材料易于从反应溶液中分离出来, 可以实现纳米催化剂的循环使用.     

Quantum Size Effects in the Photonics of Semiconductor Nanoparticles

The appearance of quantum size effects in ultradisperse semiconductors, their quantitative analysis, and their effect on the absorption of light and on the photophysical (vibrational relaxation of photogenerated “hot” charge carriers, band-band and “defect” luminescence) and certain primary photochemical processes (the accumulation of excess negative charge by the semiconductor nanoparticles, interphase electron transfer, etc.) are discussed.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 2, pp. 67–87, March–April, 2005.     

Decomposition of SiCl4 and deposition of Si in inductively coupled plasmas of H2+SiCl4

The mechanism of homogeneous reactions in plasmas of H₂+5%SiCl₄ was studied by mass spectrometry and was compared to the mechanism observed in plasmas of Ar+H₂+SiCl₄. Contrary to the behavior with Ar, the results indicate that without argon the SiCl₄ molecule undergoes only fragmentation and the deposition proceeds through SiCl₂. No polymerization was observed. The deposition rates of c-Si were lower and the amounts of chlorine incorporated in the films were higher in the plasma of SiCl₄+H₂ than in the argon-containing plasma.     

表面修饰Ag_2S纳米微粒的制备及其量子尺寸效应研究

采用同阳离子共沉淀法制备了DDP修饰的Ag2 S纳米微粒 ,其紫外—可见吸收光谱和荧光光谱表明DDP修饰的Ag2 S纳米微粒具有显著的量子尺寸效应 ,粒子尺寸分布较窄 ,粒子表面存在多种表面态能级。     

Solid‐State NMR and DFT Combined for the Surface Study of Functionalized Silicon Nanoparticles

Silicon nanoparticles (NPs) serve a wide range of optical, electronic, and biological applications. Chemical grafting of various molecules to Si NPs can help to passivate their reactive surfaces, “fine‐tune” their properties, or even give them further interesting features. In this work, ¹H, ¹³C, and ²⁹Si solid‐state NMR spectroscopy has been combined with density functional theory calculations to study the surface chemistry of hydride‐terminated and alkyl‐functionalized Si NPs. This combination of techniques yields assignments for the observed chemical shifts, including the contributions resulting from different surface planes, and highlights the presence of physisorbed water. Resonances from near‐surface ¹³C nuclei were shown to be substantially broadened due to surface disorder and it is demonstrated that in an ambient environment hydride‐terminated Si NPs undergo fast back‐bond oxidation, whereas long‐chain alkyl‐functionalized Si NPs undergo slow oxidation. Furthermore, the combination of NMR spectroscopy and DFT calculations showed that the employed hydrosilylation reaction involves anti‐Markovnikov addition of the 1‐alkene to the surface of the Si NPs.     

多孔硅上银纳米粒薄膜的制备及其表面增强红外光谱

通过简便的化学沉积法在多孔硅上制备银纳米粒薄膜用于表面增强红外光谱检测。通过Ag⁺与多孔硅表面的SiHx发生氧化还原反应将银纳米粒子沉积在多孔硅表面。红外探针分子溶解于无水乙醇中进而被均匀分散在多孔硅表面,实验结果显示：对氨基苯硫酚、对氨基苯甲酸和对氟苯硫酚3个探针分子的红外峰分别最大增强了10、85和21倍。银纳米粒的大小和形状等物理特性、探针分子是否有与银表面进行强结合的基团和芳烃结构、以及表面选律等因素影响表面增强红外的吸收效应。     

Magnetic NiFe2O4 Nanoparticles Prepared via Non-Aqueous Microwave-Assisted Synthesis for Application in Electrocatalytic Water Oxidation

Phase-pure spinel-type magnetic nickel ferrite (NiFe₂O₄) nanocrystals in the size range of 4 to 11 nm were successfully synthesized by a fast and energy-saving microwave-assisted approach. Size and accessible surface areas can be tuned precisely by the reaction parameters. Our results highlight the correlation between size, degree of inversion, and magnetic characteristics of NiFe₂O₄ nanoparticles, which enables fine-tuning of these parameters for a particular application without changing the elemental composition. Moreover, the application potential of the synthesized powders for the electrocatalytic oxygen evolution reaction in alkaline media was demonstrated, showing that a low degree of inversion is beneficial for the overall performance. The most active sample reaches an overpotential of 380 mV for water oxidation at 10 mA cm⁻² and 38.8 mA cm⁻² at 1.7 V vs. RHE, combined with a low Tafel slope of 63 mV dec⁻¹.     

2-Aminobenzenethiol-Functionalized Silver-Decorated Nanoporous Silicon Photoelectrodes for Selective CO2 Reduction

A molecularly thin layer of 2-aminobenzenethiol (2-ABT) was adsorbed onto nanoporous p-type silicon (b-Si) photocathodes decorated with Ag nanoparticles (Ag NPs). The addition of 2-ABT alters the balance of the CO₂ reduction and hydrogen evolution reactions, resulting in more selective and efficient reduction of CO₂ to CO. The 2-ABT adsorbate layer was characterized by Fourier transform infrared (FTIR) spectroscopy and modeled by density functional theory calculations. Ex situ X-ray photoelectron spectroscopy (XPS) of the 2-ABT modified electrodes suggests that surface Ag atoms are in the +1 oxidation state and coordinated to 2-ABT via Ag−S bonds. Under visible light illumination, the onset potential for CO₂ reduction was −50 mV vs. RHE, an anodic shift of about 150 mV relative to a sample without 2-ABT. The adsorption of 2-ABT lowers the overpotentials for both CO₂ reduction and hydrogen evolution. A comparison of electrodes functionalized with different aromatic thiols and amines suggests that the primary role of the thiol group in 2-ABT is to anchor the NH₂ group near the Ag surface, where it serves to bind CO₂ and also to assist in proton transfer.     

石墨烯量子点负载银纳米粒子制备及氧还原电催化活性

银基氧还原电催化剂具有较高的电催化活性且价格相对低廉,因而受到广泛关注. 本文采用简单、预先合成的石墨烯量子点作为载体和还原剂,制得了负载于石墨烯量子点、且无保护剂和表面活性剂的表面洁净银纳米粒子（Ag NPs/GQDs）. 电化学研究表明,Ag NPs/GQDs复合电催化剂的氧还原有较高的电催化活性,氧在碱性溶液中可经4电子途径还原为水. 与商业铂碳电极（Pt/C）相比,AgNPs/GQDs电极具有高催化电流密度、良好稳定性和极佳抗甲醇性能. 该银纳米粒子对开发高性能和低成本的非铂氧还原电催化剂有潜在的应用前景.     

巯基乙胺稳定的水溶性CdTe纳米粒子的合成与表征

用巯基乙胺(cysteamine，CA)作为稳定剂，在水相中合成了发光可调的CdTe半导体纳米粒子。这些巯基乙胺稳定的CdTe纳米粒子表面带有大量的正电荷。实验结果表明，稳定剂与Cd的比例以及pH等实验条件对CdTe纳米粒子体系的荧光发射强度影响较大。在pH为6.1时，纳米粒子体系在橙红波段的荧光量子产率达到了9%左右。控制实验条件，合成了各种尺寸的CdTe纳米粒子，荧光发射光谱在520～600 nm范围连续可调。分别用X射线光电子能谱(XPS)，透射电子显微镜(TEM)，X射线衍射仪(XRD)，红外吸收     

Photocatalytic Reduction of Zn(II) with Participation of ZnS Nanoparticles

We have studied the photochemical processes occurring in colloidal ZnS solutions containing zinc chloride and sodium sulfite as additives. Irradiation of such systems leads to reduction of Zn(II), the rate of which increases as the size of the ZnS nanoparticles decreases. Based on analysis of the kinetic curves for the reaction, we hypothesize that photoreduction of Zn(II) is a two-electron process. __________ Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 4, pp. 231–235, July–August, 2005.