Biomimetic synthesis of CuInS2 nanoparticles: Characterization,cytotoxicity, and application in quantum dots sensitized solar cells

CuInS₂ (CIS) nanoparticles have unique chemical, toxicological and optoelectronic properties that favor their technological applications. In the present work we report a novel one step biomimetic method for the aqueous synthesis of CIS nanoparticles, that is also low cost and environmentally friendly. This biomimetic method uses only CuSO₄ and InCl₃ as precursor salts, and the biological molecule glutathione as sulfur donor and stabilizer of the nanoparticles (NPs). The reaction is performed at low temperatures, under aerobic conditions and atmospheric pressure. CIS nanoparticles produced by our biomimetic method exhibit fluorescence emission between 650 and 700 nm when excited at 500 nm. A size between 10 and 15 nm was determined by Dynamic light scattering (DLS) and corroborated by electron transmission microscopy. X-ray diffraction analysis (XRD) confirmed the crystalline structure of the CIS NPs produced. Energy Dispersive X-Ray Spectroscopy (EDX) analyses revealed the presence of Cu, In, and S in a 0.6: 1.4: 2 ratio, which has been reported for other CIS NPs in literature. No cytotoxicity of CIS NPs was observed in human OKT6/TERT2 cells and bacteria. Besides, the potential application of biomimetic CIS NPs as photosensitizers in quantum dots sensitized solar cells (QDSSCs) was confirmed. The biocompatibility, spectroscopic properties, and energy harvesting performance in solar cells of the CIS NPs produced by our biomimetic method make them suitable for their use in different biotechnological applications.     

Growth of CuInS2 Nanotubes from Cu2S-CuInS2 Heterostructures as a Potential Photovoltaic Material

Chemically synthesized nanostructures possess well-defined domains with an interconnected network, which helps the carriers to bypass the other material in the solar cell while moving to their respective electrodes. In this work, CuInS₂ films constituting CuInS₂ nanotubes and nanoparticles were fabricated using a hot-injection chemical technique, followed by sulfurization. Structural and microstructural investigations reveal Cu₂S nanoparticle formation at an early stage of growth of nanotubes, serving as possible catalyst sites for the subsequent anisotropic growth of the heterostructured hexagons. The crossover takes place over a number of intermediate stages. This sharing of the heterostructure by the hexagonal Cu₂S and chalcopyrite CuInS₂ minimizes the lattice distortion. The Cu₂S- CuInS₂ interface in the heterostructure acts as the nucleation center for CuInS₂ nanotubes. Optical absorption and Raman spectroscopy studies reveal better optical properties for CuInS₂ nanoparticles as compared to CuInS₂ nanotubes. Compared to all other nanostructures, nanowires or nanotubes tend to provide single-crystalline nanograins for direct characterization. These nanoparticles, especially the nanotubes, can be used to form an interconnected network structure of p- and n-type materials in bulk heterojunctions providing the key to improve solar cell efficiencies.     

SILAR法制备化学计量CuInS2薄膜

在室温下，以不同c_Cu/c_In的CuCl₂和InCl₃混合溶液作为阳离子前驱体，Na₂S水溶液为硫源，利用连续离子层吸附反应法(SILAR)在玻璃基底上制备了CuInS₂薄膜。XRD结果表明，当c_Cu²⁺/c_In³⁺在1～1.5范围内均可形成具有黄铜矿结构的CuInS₂薄膜。SEM观察到随c_Cu²⁺/c_In³⁺的升高，薄膜表面颗粒长大并出现团簇聚集。通过XPS测定薄膜表面的化学组成证明当c_Cu²⁺/c_In³⁺=1.25时，CuInS₂薄膜接近其标准的化学计量组成。此时薄膜的吸收系数大于>10⁴ cm^-1，禁带宽度E_g为1.45 eV。     

等离激元增强上转换发光及其分子检测应用

针对荧光分子检测普遍灵敏度低和检测范围窄的问题,制备了具有等离子激元共振特性的重掺杂半导体纳米结构Cu_2-xS和典型的稀土掺杂上转换发光纳米颗粒NaYF₄：Yb,Er,通过三相界面自组装方法获得了Cu_2-xS/NaYF₄：Yb,Er薄膜基底。结合有限元模拟,计算了不同摆放情况下Cu_2-xS周围的局域电场分布,研究了在实际薄膜中Cu_2-xS纳米盘之间产生的等离激元耦合对上转换发光性能以及对拉曼信号增强的影响。结果表明,Cu_2-xS等离激元层与NaYF₄：Yb,Er发光层的耦合,不仅得到了上转换3个数量级的提高,还实现了分子检测10^-7 mol·L^-1的检测极限,并且获得了10^-3~10^-7 mol·L^-1的宽线性响应,从而达到高灵敏度的定性和定量双功能的精确检测。     

Crystal structure and Raman scattering characterization of Cu2Fe1-xCoxSnS4 chalcogenide compounds

This work reports the synthesis by solid–state reaction of Cu₂Fe_1-xCo_xSnS₄ solid solutions. Crystal structures of Cu₂Fe_0.8Co_0.2SnS₄ and Cu₂Fe_0.6Co_0.4SnS₄ were investigated by single crystal X-ray diffraction. Both phases crystallize in the tetragonal stannite-type structure. The volume of the tetrahedral [MS₄] (M = Fe, Co) presented the highest distortion, with Edge-Length Distortion (ELD) indices ∼2% from the ideal tetrahedron. The powder X-ray diffraction (XRD) patterns of Cu₂Fe_1-xCo_xSnS₄ (x = 0.2, 0.4, 0.6 and 0.8) has been refined by Rietveld method. No secondary phases were detected in XRD patterns. An analysis of the vibrational properties of Cu₂Fe_1-xCo_xSnS₄ was performed using Raman scattering measurements. The Raman peaks were analyzed by fitting of the spectra and subsequently identifying the vibrational modes by comparison with experimental and theoretical data from Cu₂FeSnS₄ (CFTS) and Cu₂CoSnS₄ (CCTS) end-members. The spectra from Cu₂Fe_1-xCo_xSnS₄ show that there is a variation in the frequency of the main A₁ peak at ∼320 cm⁻¹ together with a decrease in the secondary mode intensity at ∼285 cm⁻¹. Full Width at Half Maximum (FWHM) and the intensity of the Raman peaks reflect the high crystallinity of Cu₂Fe_1-xCo_xSnS₄ solid solutions. The oxidation states of the metals were confirmed by temperature-dependent magnetization measurements performed in the antiferromagnetic Cu₂Fe_1-xCo_xSnS₄ solid solutions.     

Metal Cation Valency Dependence in Morphology Evolution of Cu2−xS Nanodisk Seeds and Their Pseudomorphic Cation Exchanges

A crucial parameter in the design of semiconductor nanoparticles (NPs) with controllable optical, magnetic, electronic, and catalytic properties is the morphology. Herein, we demonstrate the potential of additive metal cations with variable valency to direct the morphology evolution of copper-deficient Cu_2−xS nanoparticles in the process of seed-mediated growth. In particular, the djurleite Cu_1.94S seed could evolve from disk into tetradecahedron in the presence of tin(IV) cations, whereas they merely formed sharp hexagonal nanodisks with tin(II) cations. In addition to djurleite Cu_1.94S, the tin(IV) cations could be generalized to direct the growth of roxbyite Cu_1.8S and covellite CuS nanodisk seeds into tetradecahedra. We further perform pseudomorphic cation exchanges of Cu_1.94S tetradecahedra with Zn²⁺ and Cd²⁺ to produce polyhedral zinc sulfide (ZnS) and cadmium sulfide (CdS) NPs. Moreover, we achieve Cu_1.8S/ZnS and Cu_1.94S/CdS tetradecahedral heterostructures via partial cation exchange, which are otherwise inaccessible by traditional synthetic approaches.     

Sulfur Precursor Reactivity Affecting the Crystal Phase and Morphology of Cu2−xS Nanoparticles

For plasmonic copper-deficient Cu_2−xS nanoparticles (NPs), accurate control of the crystal phase and morphology is highly desirable as both of which are known to determine the localized surface plasmon resonance (LSPR) wavelength and amplitude. Here, how the sulfur precursor reactivity in the synthesis of Cu_2−xS NPs affects the resulting crystal phase and morphology is examined. Djurleite Cu_1.94S, roxbyite Cu_1.8S, digenite Cu_1.8S as well as covellite CuS nanodisks were synthesized by using 1-dodecanethiol, N,N-dibutylthiourea, and crystal sulfur 1-octadecene/oleylamine solutions and their crystal phase dependent LSPR properties were exhaustively discussed. In addition, crystal phase interconversion between covellite CuS and djurleite/roxbyite Cu_2−xS was realized in the presence of the above sulfur precursors. On the other hand, djurleite Cu_1.94S nanorods rather than nanodisks were prepared by replacing 1-dodecanethiol with more reactive tert-dodecanethiol. The structural and morphological Cu_2−xS NPs here holds great promise in the application of photothermal therapy, photocatalysis, surface-enhanced Raman scattering (SERS), and many others.     

Subsolidus phase relations and crystal structures of R-Ca-Cu-O (R=Nd, Sm, Gd, Tm) systems

The subsolidus phase relations of R₂O₃-CaO-CuO ternary systems (R=Nd, Sm, Gd, Tm) have been investigated by X-ray powder diffraction. All samples were synthesized at about 950° in air. There exists a ternary compound Ca_14−xR_xCu₂₄O₄₁ (x = 4 for R=Nd, Gd and x = 5 for R = Sm) and a ternary solid solution Ca_2+xR_2−xCu₅O₁₀ (R=Nd, Sm, Gd, Tm) with a wide composition range Δx of about 0.6. The compound Ca_14−xR_xCu₂₄O₄₁ possesses a layered orthorhombic structure and is isostructural to Sr_14−xCa_xCu₂₄O₄₁. The lattice parameters a and c of the compound are basically independent of the ionic radius of R, while the lattice parameter b and unit-cell volume V decrease substantially with the decrease of the ionic radii of R. The Ca_2+xR_2−xCu₅O₁₀ solid solution is isostructural to Ca_2+xY_2−xCu₅O₁₀, the structure of which is based on an orthorhombic “NaCuO₂-type” subcell containing infinite one-dimensional chains of edge-shared square planar cuprate groups crosslinked by the layered cations Ca and R that locate in the inter-chain tunnels.     

Synthesis, structure and electrical properties of Cu3.21Ti1.16Nb2.63O12 and the CuOx-TiO2-Nb2O5 pseudoternary phase diagram

Subsolidus phase relations in the CuO_x-TiO₂-Nb₂O₅ system were determined at 935 °C. The phase diagram contains one new phase, Cu_3.21Ti_1.16Nb_2.63O₁₂ (CTNO) and one rutile-structured solid solution series, Ti_1−3xCu_xNb_2xO₂: 0<x<0.2335 (35). The crystal structure of CTNO is similar to that of CaCu₃Ti₄O₁₂ (CCTO) with square planar Cu²⁺ but with A site vacancies and a disordered mixture of Cu⁺, Ti⁴⁺ and Nb⁵⁺ on the octahedral sites. It is a modest semiconductor with relative permittivity ∼63 and displays non-Arrhenius conductivity behavior that is essentially temperature-independent at the lowest temperatures.     

Nickel deficiency in RENi2-xP2 (RE=La, Ce, Pr). Combined crystallographic and physical property studies

Large single crystals from RENi_2-xP₂ (RE=La, Ce, Pr) were synthesized from the pure elements using Sn as a metal flux, and their structures were established by X-ray crystallography. The title compounds were confirmed to crystallize in the body-centered tetragonal ThCr₂Si₂ structure type (space group I4/mmm (No. 139); Pearson's symbol tI10), but with a significant homogeneity range with respect to the transition metal. Systematic synthetic work, coupled with accurate structure refinements indicated strong correlation between the degree of Ni-deficiency and the reaction conditions. According to the temperature dependent dc magnetization measurements, LaNi_2-xP₂ (x=0.30(1)), as expected, is Pauli-like paramagnetic in the studied temperature regime, while the Ce-analog CeNi_2-xP₂ (x=0.28(1)) shows the characteristics of a mixed valent Ce³⁺/Ce⁴⁺ system with a possible Kondo temperature scale on the order of 1000 K. For three different PrNi_2-xP₂ (x?0.5) samples, the temperature and field dependence of the magnetization indicated typical local moment 4f-magnetism and a stable Pr³⁺ ground state, with subtle variations of T_C as a function of the concentration of Ni defects. Field-dependent heat capacity data for CeNi_2-xP₂ (x=0.28(1)) and PrNi_2-xP₂ (x=0.53(1)) are discussed as well.     

Cuprous oxide nanospheres as probes for light scattering imaging analysis of live cells and for conformation identification of proteins

A facile solution-phase synthesis route of highly uniform Cu₂O nanospheres (Cu₂O NPs) with the size of 57.7 ± 4.7 nm was developed, and then the nanoparticles were applied to live cell imaging under a common dark-field microscope. Starting from copper(II) salts, the synthesis of Cu₂O NPs was made in the presence of cetyltrimethylammonium bromide (CTAB) by reducing the copper(II) with sodium borohydride (NaBH₄) in aqueous medium and by aging process in the air. Monitoring of morphology evolution process of Cu₂O NPs with scanning electron microscopy (SEM) and measuring of the UV-visible spectra showed that the synthesis of Cu₂O NPs follows the reduction-oxidation coupled process of Cu²⁺ into Cu⁰ species at first and then the resulted Cu⁰ species into Cu₂O NPs in the air. Light scattering (LS) features have been measured with a common spectrofluorometer and a common dark-field microscope, and it was found that the as-prepared Cu₂O NPs display strong blue scattering light and can be applied for cell imaging. If incubated with human bone marrow neuroblastoma, transferrin-conjugated Cu₂O NPs can get into the cells and show strong pure blue light in cytoplasm. Further investigations showed that the Cu₂O NPs could be applied for probes for conformation of proteins.     

Structural and electrical changes in NdSrNiO4−δ by substitute nickel with copper

A novel series of the formula NdSrNi_1−xCu_xO_4−δ were synthesized for various values of x ranging from 0 to 1 in 1 atm of O₂ gas flow using conventional solid-state methods and were characterized by powder X-ray diffraction and electrical resistivity measurements. The compounds have been shown to adopt the K₂NiF₄-type structure. The oxygen stoichiometry of the compounds was determined from thermo-gravimetric analysis (TGA). An analysis of the micro-structure of the neodymium strontium nickel copper oxide is described. All the samples were semi-conducting from room temperature down to 77 K. The effect of Cu²⁺ incorporation on the structural and electrical properties of NdSrNi_1−xCu_xO_4−δ, 0?x?1, are discussed in terms of Jahn-Teller distortion of the (Ni/Cu)O₆ octahedra and mixed valence character of copper.     

Chiral CuxCoyS Nanoparticles under Magnetic Field and NIR Light to Eliminate Senescent Cells

In the present study, chiral Cu_xCo_yS nanoparticles (NPs) were developed to selectively induce apoptosis of senescent cells using both an alternating magnetic field (AMF) and near infrared (NIR) photon illumination. The chiral effects on living cells were investigated, and d ‐Cu_xCo_yS NPs showed about 2.5 times higher of internalized ability than l ‐NPs. By modifying beta 2 macroglobulin (MG), senescent cells were effectively eliminated by d ‐Cu_xCo_yS NPs without damaging the activities of normal cells under AMF and photon illumination. Compared to the individual application of NIR illumination and AMF, their synergistic effect induced the production of caspase‐3 with a much shorter treatment time and higher efficiency due to the more serious photon‐induced cellular redox and mechanical damage of cellular skeleton. Moreover, the developed strategy was successfully used to remove senescent cells in vivo. This study developed a controllable way of regulating cell activities using chiral NPs, which will provide a valuable way for treating diseases and promoting health.     

Light‐Induced Chiral Iron Copper Selenide Nanoparticles Prevent β‐Amyloidopathy In Vivo

The accumulation and deposition of β‐amyloid (Aβ) plaques in the brain is considered a potential pathogenic mechanism underlying Alzheimer's disease (AD). Chiral l/d ‐Fe_xCu_ySe nanoparticles (NPs) were fabricated that interfer with the self‐assembly of Aβ42 monomers and trigger the Aβ42 fibrils in dense structures to become looser monomers under 808 nm near‐infrared (NIR) illumination. d ‐Fe_xCu_ySe NPs have a much higher affinity for Aβ42 fibrils than l ‐Fe_xCu_ySe NPs and chiral Cu_2?xSe NPs. The chiral Fe_xCu_ySe NPs also generate more reactive oxygen species (ROS) than chiral Cu_2?xSe NPs under NIR‐light irradiation. In living MN9D cells, d ‐NPs attenuate the adhesion of Aβ42 to membranes and neuron loss after NIR treatment within 10 min without the photothermal effect. In‐vivo experiments showed that d ‐Fe_xCu_ySe NPs provide an efficient protection against neuronal damage induced by the deposition of Aβ42 and alleviate symptoms in a mouse model of AD, leading to the recovery of cognitive competence.     

Light-Induced Chiral Iron Copper Selenide Nanoparticles Prevent β-Amyloidopathy In Vivo

The accumulation and deposition of β-amyloid (Aβ) plaques in the brain is considered a potential pathogenic mechanism underlying Alzheimer's disease (AD). Chiral l/d -Fe_xCu_ySe nanoparticles (NPs) were fabricated that interfer with the self-assembly of Aβ42 monomers and trigger the Aβ42 fibrils in dense structures to become looser monomers under 808 nm near-infrared (NIR) illumination. d -Fe_xCu_ySe NPs have a much higher affinity for Aβ42 fibrils than l -Fe_xCu_ySe NPs and chiral Cu_2−xSe NPs. The chiral Fe_xCu_ySe NPs also generate more reactive oxygen species (ROS) than chiral Cu_2−xSe NPs under NIR-light irradiation. In living MN9D cells, d -NPs attenuate the adhesion of Aβ42 to membranes and neuron loss after NIR treatment within 10 min without the photothermal effect. In-vivo experiments showed that d -Fe_xCu_ySe NPs provide an efficient protection against neuronal damage induced by the deposition of Aβ42 and alleviate symptoms in a mouse model of AD, leading to the recovery of cognitive competence.     

Reactions between YBa2Cu3O7−δ and La2O3 and SrCO3

Solid state reactions at 925°C between the high-T _c ceramic superconductor YBa₂Cu₃O_7?δ and La₂O₃ and SrCO₃, respectively, mixed in various molar ratiosr=MeO_n/YBa₂Cu₃O_7?δ, were studied using X-ray powder diffraction and scanning electron microscopy. The reaction between YBa₂Cu₃O_7?δ and La₂O₃ yielded (La_1?xBa_x)₂CuO_4?δ, withx≈0.075?0.10. La_2?xBa_1+xCu₂O_6?δ, withx≈0.2?0.25 and La-doped (Y_1?xLa_x)₂BaCuO₅, withx≈0.10?0.15. Forr=3.0, Y-doped La₂BaCuO₅ resulted also. The reaction between YBa₂Cu₃O_7?δ and SrCO₃ yielded (Sr_1?zBa_z)₂CuO₃, withz≈0.1, Y₂(Ba_1?zSr_z)CuO₅, withz=0.1?0.15, and a nonsuperconducting compound with an approximate composition of Y(Ba_0.5Sr_0.5)₅Cu_3.5O_10±δ. At values ofr≤2.0, unsubstituted YBa₂Cu₃O_7?delta was found in the reaction products.     

CuInS2量子点敏化太阳能电池中尺寸依赖的电子注入和光电性质

研究了CuInS₂（CIS）量子点敏化太阳能电池（QDSSCs）的电子注入和器件性能与粒子尺寸之间的依赖关系. 首先合成了不同尺寸的CuInS₂量子点（QDs）,制备了CuInS₂量子点敏化的TiO₂薄膜,并组装了量子点敏化太阳能电池. 通过循环伏安法确定了CuInS₂量子点的能级位置. 采用时间分辨荧光光谱分析测量了CuInS₂量子点到TiO₂薄膜的电子转移速率和效率. 结果发现,随着粒子尺寸从4.0 nm减小到2.5 nm,电子注入速率略微增加而电子注入效率减小,同时量子点敏化太阳能电池的开路电压基本不变,而光电转换效率、短路电流和填充因子（FF）均减小. 上述研究结果表明量子点敏化太阳能电池性能的优化可以通过改变量子点的尺寸来实现.     

Copper sulfides and their composites for high-performance rechargeable batteries

Copper sulfides (Cu_xS) are widely used as the promising electrode materials for secondary batteries because of the rich abundance, low cost, excellent capacity (～337/560 mA h/g for Cu₂S/CuS) as well as favorable electrical conductivity (10^?3 S/cm). Moreover, nanostructure designing and compounding with other conductive materials can enhance the electrochemical performance of Cu_xS. In this review, the up-to-date progress in the synthesis method as well as the application for secondary batteries (lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, magnesium-ion batteries, and so on) of Cu_xS and their relevant composites have been discussed detailly. In the end, the challenges, feasible strategies, and application prospects for the Cu_xS are also summarized.     

不同形貌Cu_xCd_(1-x)S光催化剂光腐蚀性能差异研究

利用溶剂热法和水热法,合成出不同形貌的CuxCd1-xS光催化剂,并考察了它们的抗光腐蚀性能。荧光实验表明适量的铜掺杂取代后得到的CuxCd1-xS晶体具有良好的光生电子-空穴对的分离性能,有利于光生载流子的快速转移;不同形貌是导致样品抗光腐蚀性能不同的重要原因;此外铜掺杂量和晶体结晶度都对催化剂光腐蚀性能有重要影响。     

金/氧化亚铜异质球的制备及其可见光催化性能

使用L-半胱氨酸作为连接剂, 利用硼氢化钠原位还原预先吸附在介孔氧化亚铜表面的氯金酸根离子,得到了Au/Cu₂O异质结构. 应用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、X射线光电子能谱(XPS)、紫外-可见(UV-Vis)光谱和N₂物理吸附等手段对催化剂进行表征, 并以λ>400 nm的可见光作为光源, 评价了该催化剂光催化降解亚甲基蓝(MB)的活性. 实验结果表明, 直径为4 nm的金颗粒完好地负载在介孔氧化亚铜的表面, 并且介孔氧化亚铜的细微结构与孔径均未发生变化. 研究表明, 以乙醇作为反应溶剂有效抑制了AuCl₄^-与Cu₂O之间的氧化还原反应, 从而有利于氧化亚铜介孔结构的保持及金颗粒的原位还原. 光催化降解亚甲基蓝的结果表明, Au/Cu₂O异质结构的光催化活性比纯氧化亚铜光催化活性有明显提高. 推测其光催化性能提高的主要原因如下: 一方面, 金颗粒良好的导电性有利于氧化亚铜表面电子的快速转移, 实现电子-空穴分离; 另一方面, 金颗粒可能存在的表面等离子共振现象加速了光生电子的产生.