贵金属纳米粒子及其复合物的非线性光学性能和应用研究进展

具有非线性光学特性的贵金属纳米粒子受到广泛的关注,因为这类金属纳米粒子及其复合物不仅具有重要的理论研究意义而且在非线性光学器件方面具有重要的潜在应用价值.对这类金属纳米粒子的主要制备方法、光学特性以及在激光防护等非线性光学器件方面的应用研究进展进行了综述,并对未来的研究和尚存在的问题进行了分析和展望.     

Synthesis of Zirconia Nanoparticles in Distilled Water Solution by Laser Ablation Technique

Pulsed laser ablation in liquid （PLAL） has become an increasingly important technique for metals production and metal oxides nanoparticles （NPs） and others. This technique has its many advantages compared with other conventional techniques （physical and chemical）. This work was devoted for production of zirconia （ZrO2） nanoparticles via PLAL technique from a solid zirconium target immersed in a wet environment in order to study the effect of this environment on the optical properties and structure of ZrO2 nanoparticles. The solutions which used for this purpose is distilled water （D.W）. The produces NPs were characterized by mean of many tests such as UV-visible （UV-Vis.）, transmission electron microscope （TEM） and Z-Potential. The UV-Vis. A spectrum has atwavelength is 271 nm. The TEM test shows less than 10 nm average particle sizes with spherical and irregular shapes. Z-Potential test shows value about ＋56.1 mV which indicate for NPs stability with extremely low agglomeration solution.     

Nonspherical Noble Metal Nanoparticles: Colloid‐Chemical Synthesis and Morphology Control

Metal nanoparticles have been the subject of widespread research over the past two decades. In recent years, noble metals have been the focus of numerous studies involving synthesis, characterization, and applications. Synthesis of an impressive range of noble metal nanoparticles with varied morphologies has been reported. Researchers have made a great progress in learning how to engineer materials on a nanometer length scale that has led to the understanding of the fundamental size‐ and shape‐dependent properties of matter and to devising of new applications. In this article, we review the recent progress in the colloid‐chemical synthesis of nonspherical nanoparticles of a few important noble metals (mainly Ag, Au, Pd, and Pt), highlighting the factors that influence the particle morphology and discussing the mechanisms behind the nonspherical shape evolution. The article attempts to present a thorough discussion of the basic principles as well as state‐of‐the‐art morphology control in noble metal nanoparticles.     

相转移过程中贵金属纳米颗粒的自组装行为

采用湿化学法制备了系列贵金属纳米颗粒（Ag、Au、Pt和Rh）,并通过相转移过程实现了贵金属纳米颗粒的自组装,首先将水相中制备的贵金属溶胶与十二胺的乙醇溶液混合,然后将十二胺稳定的金属颗粒从极性的水相中转移到非极性的有机相中。这种方法不仅能实现金属纳米颗粒在基底上的自组装,而且有望应用于纳米颗粒自组装膜的制备中。     

Properties and Applications of Colloidal Nonspherical Noble Metal Nanoparticles

Nanoparticles of noble metals belong to the most extensively studied colloidal systems in the field of nanoscience and nanotechnology. Due to continuing progress in the synthesis of nanoparticles with controlled morphologies, the exploration of unique morphology‐dependent properties has gained momentum. Anisotropic features in nonspherical nanoparticles make them ideal candidates for enhanced chemical, catalytic, and local field related applications. Nonspherical plasmon resonant nanoparticles offer favorable properties for their use as analytical tools, or as diagnostic and therapeutic agents. This Review highlights morphology‐dependent properties of nonspherical noble metal nanoparticles with a focus on localized surface plasmon resonance and local field enhancement, as well as their applications in various fields including Raman spectroscopy, fluorescence enhancement, analytics and sensing, photothermal therapy, (bio‐)diagnostics, and imaging.     

Pulsed Laser Modulated Shock Transition from Liquid Metal Nanoparticles to Mechanically and Thermally Robust Solid–Liquid Patterns

In this work, a general mechanism is discovered to form liquid‐metal‐based, stable and stretchable conductive patterns on rigid and soft substrates. It is discovered that pulsed laser irradiation of liquid metal nanoparticles (LMNPs) with tunable conditions can induce transformation to stable and stretchable solid–liquid (S–L) dual phases on various surfaces. Formation of this unique solid–liquid composite phase is the key to change the wetting behavior of the conductive patterns on various substrates and enables mechanically stable patterns on various substrates. Pulsed‐laser‐driven thermo‐mechanical shock momentum is important for rupture and joining of the LMNPs, providing much better control than the traditional mechanical sintering. The solid nanophase forms a nanoporous matrix filled with and wetted by the LM, thereby providing a stabilization mechanism for the S–L composite patterned thin film. The mechanical and thermal reliability of the solid–liquid patterns is investigated. The S–L patterns can stretch up to 30% strain and cycle stably for 7000 cycles. It can be heated up to 177 °C with an input power of 0.58 W. The solid–liquid composite film provides great opportunity for various applications as a flexible conductor with unique mechanical and physics properties and further inspires design of LM devices for completely exposed applications.     

A General and Straightforward Route to Noble Metal‐Decorated Mesoporous Transition‐Metal Oxides with Enhanced Gas Sensing Performance

Controllable and efficient synthesis of noble metal/transition‐metal oxide (TMO) composites with tailored nanostructures and precise components is essential for their application. Herein, a general mercaptosilane‐assisted one‐pot coassembly approach is developed to synthesize ordered mesoporous TMOs with agglomerated‐free noble metal nanoparticles, including Au/WO₃, Au/TiO₂, Au/NbO_x, and Pt/WO₃. 3‐mercaptopropyl trimethoxysilane is applied as a bridge agent to cohydrolyze with metal oxide precursors by alkoxysilane moieties and interact with the noble metal source (e.g., HAuCl₄ and H₂PtCl₄) by mercapto (? SH) groups, resulting in coassembly with poly(ethylene oxide)‐b‐polystyrene. The noble metal decorated TMO materials exhibit highly ordered mesoporous structure, large pore size (≈14–20 nm), high specific surface area (61–138 m² g^?1), and highly dispersed noble metal (e.g., Au and Pt) nanoparticles. In the system of Au/WO₃, in situ generated SiO₂ incorporation not only enhances their thermal stability but also induces the formation of ε‐phase WO₃ promoting gas sensing performance. Owning to its specific compositions and structure, the gas sensor based on Au/WO₃ materials possess enhanced ethanol sensing performance with a good response (R_air/R_gas = 36–50 ppm of ethanol), high selectivity, and excellent low‐concentration detection capability (down to 50 ppb) at low working temperature (200 °C).     

Photocatalytic Activity of Protein‐Conjugated CdS Nanoparticles

Colloidal CdS nanoparticles are conjugated with a variety of proteins, including enhanced yellow fluorescent protein, tobacco etch virus protease (TEV), lysozyme, and bacterial cytochrome P450 CYP152A1, and the photochemical properties of the resulting conjugates are analyzed by EPR spectroscopy and hydroxyl radical‐specific fluorimetric assay. While irradiation of bare CdS colloids leads to photogeneration of hydroxyl and superoxide radicals, it is surprisingly observed that coating of the CdS particles with proteins effectively suppresses the production of these radical species and instead leads to increased formation of a long‐lived reactive oxygen species, most likely H₂O₂. A mechanism for the observed results is suggested. The empirical results are capitalized on for the assembly of a CdS–TEV nanohybrid, which shows significantly higher performance as a photocatalytic mediator for fatty acid hydroxylation by CYP152A1 than bare CdS nanoparticles.     

Enhancing Tungsten Oxide Gasochromism with Noble Metal Nanoparticles: The Importance of the Interface

Crystalline tungsten trioxide (WO₃) thin films covered by noble metal (gold and platinum) nanoparticles are synthesized via wet chemistry and used as optical sensors for gaseous hydrogen. Sensing performances are strongly influenced by the catalyst used, with platinum (Pt) resulting as best. Surprisingly, it is found that gold (Au) can provide remarkable sensing activity that tuned out to be strongly dependent on the nanoparticle size: devices sensitized with smaller nanoparticles display better H₂ sensing performance. Computational insight based on density functional theory calculations suggested that this can be related to processes occurring specifically at the Au nanoparticle-WO₃ interface (whose extent is in fact dependent on the nanoparticle size), where the hydrogen dissociative adsorption turns out to be possible. While both experiments and calculations single out Pt as better than Au for sensing, the present work reveals how an exquisitely nanoscopic effect can yield unexpected sensing performance for Au on WO₃, and how these performances can be tuned by controlling the nanoscale features of the system.     

Size control and vacuum-ultraviolet fluorescence of nanosized KMgF3 single crystals prepared using femtosecond laser pulses

We fabricated nanosized KMgF₃ single crystals via a dry pulsed laser ablation process using femtosecond laser pulses. The sizes, shapes, and crystallographic properties of the crystals were evaluated by transmission electron microscopy (TEM). Almost all of the particles were spherical with diameters of less than 100 nm, and they were not highly agglomerated. Selected-area electron diffraction and high-resolution TEM analyses showed that the particles were single crystals. Particle diameter was controlled within a wide range by adjusting the Ar ambient gas pressure. Under low gas pressures (1 and 10 Pa), relatively small particles (primarily 10 nm or less) were observed with a high number density. With increasing pressure, the mean diameter increased and the number density drastically decreased. Vacuum-ultraviolet cathodoluminescence was observed at 140–230 nm with blue shift and broadening of spectrum.     

原位包覆金属纳米粒子的规模化制备及应用

介绍激光感应复合加热制备金属纳米粒子的方法,以及基于该技术原位制备碳包覆金属纳米粒子和有机物包覆金属纳米粒子,概括了原位包覆金属纳米粒子的应用。根据实际应用条件选择合适的包覆方法和包覆材料,可以极大地提高金属纳米粒子的产品性能和适用性,获得更高的应用价值。     

Toxicity of Metal Oxide Nanoparticles: Mechanisms,Characterization, and Avoiding Experimental Artefacts

Metal oxide nanomaterials are widely used in practical applications and represent a class of nanomaterials with the highest global annual production. Many of those, such as TiO₂ and ZnO, are generally considered non‐toxic due to the lack of toxicity of the bulk material. However, these materials typically exhibit toxicity to bacteria and fungi, and there have been emerging concerns about their ecotoxicity effects. The understanding of the toxicity mechanisms is incomplete, with different studies often reporting contradictory results. The relationship between the material properties and toxicity appears to be complex and diifficult to understand, which is partly due to incomplete characterization of the nanomaterial, and possibly due to experimental artefacts in the characterization of the nanomaterial and/or its interactions with living organisms. This review discusses the comprehensive characterization of metal oxide nanomaterials and the mechanisms of their toxicity.     

Amorphous Bimetallic Oxide–Graphene Hybrids as Bifunctional Oxygen Electrocatalysts for Rechargeable Zn–Air Batteries

Metal oxides of earth‐abundant elements are promising electrocatalysts to overcome the sluggish oxygen evolution and oxygen reduction reaction (OER/ORR) in many electrochemical energy‐conversion devices. However, it is difficult to control their catalytic activity precisely. Here, a general three‐stage synthesis strategy is described to produce a family of hybrid materials comprising amorphous bimetallic oxide nanoparticles anchored on N‐doped reduced graphene oxide with simultaneous control of nanoparticle elemental composition, size, and crystallinity. Amorphous Fe_0.5Co_0.5O_x is obtained from Prussian blue analog nanocrystals, showing excellent OER activity with a Tafel slope of 30.1 mV dec^?1 and an overpotential of 257 mV for 10 mA cm^?2 and superior ORR activity with a large limiting current density of ?5.25 mA cm^?2 at 0.6 V. A fabricated Zn–air battery delivers a specific capacity of 756 mA h g_Zn^?1 (corresponding to an energy density of 904 W h kg_Zn^?1), a peak power density of 86 mW cm^?2 and can be cycled over 120 h at 10 mA cm^?2. Other two amorphous bimetallic, Ni_0.4Fe_0.6O_x and Ni_0.33Co_0.67O_x , are also produced to demonstrate the general applicability of this method for synthesizing binary metal oxides with controllable structures as electrocatalysts for energy conversion.     

核壳式无机-高分子纳米复合粒子的形成机理与表征技术

简要介绍了一种制备核壳式无机－高分子纳米复合粒子的方法－乳液聚合，概述了核壳式无机－高分子纳米复合粒子的形成机理及其表征技术。     

Low‐Cost Manufacturing of Bioresorbable Conductors by Evaporation–Condensation‐Mediated Laser Printing and Sintering of Zn Nanoparticles

Currently, bioresorbable electronic devices are predominantly fabricated by complex and expensive vacuum‐based integrated circuit (IC) processes. Here, a low‐cost manufacturing approach for bioresorbable conductors on bioresorbable polymer substrates by evaporation–condensation‐mediated laser printing and sintering of Zn nanoparticle is reported. Laser sintering of Zn nanoparticles has been technically difficult due to the surface oxide on nanoparticles. To circumvent the surface oxide, a novel approach is discovered to print and sinter Zn nanoparticle facilitated by evaporation–condensation in confined domains. The printing process can be performed on low‐temperature substrates in ambient environment allowing easy integration on a roll‐to‐roll platform for economical manufacturing of bioresorbable electronics. The fabricated Zn conductors show excellent electrical conductivity (≈1.124 × 10⁶ S m^?1), mechanical durability, and water dissolvability. Successful demonstration of strain gauges confirms the potential application in various environmentally friendly sensors and circuits.