Synthesis and Characterization of Hyperbranched RuO2 Nanostructures

RuO₂ nanostructures were synthesized by heating Ru nanoparticles in air at 280°C using Cu as catalyst. The Ru nanoparticles were prepared by the pyrolysis of ruthenium precursors in a vacuum using multi-walled carbon nanotubes as templates. The RuO₂ nanostructures grew radically with diameters of 50–150 nm, and lengths of 0.5–2.0 μm. The growth of nanostructure mainly depends on the dispersivity of Ru nanoparticles on MWNTs. The electrochemical property of these nanostructures was studied by cyclic voltammetry. Electronic Supplementary Material Supplementary material for this article is available at and is accessible for authorized users.     

Self-assembly of a hexagonal boron nitride nanomesh on Ru(0001)

Hexagonal boron nitride (h-BN) nanostructures were grown on Ru(0001), and are very similar to those previously reported on Rh(111). They show a highly regular 12 x 12 superstructure, comprising 2 nm wide apertures with a depth of about 0.1 nm. Valence band photoemission reveals two distinctly bonded h-BN species, and X-ray photoelectron spectroscopy indicates an h-BN monolayer film. The functionality of the h-BN/Ru(0001) nanomesh is demonstrated by using this structure for the assembly of gold nanoclusters.     

Spontaneous formation and electrogenerated chemiluminescence of tris(bipyridine) Ru(II) derivative nanobelts

The single crystalline nanobelts were successfully fabricated with an ionic compound by a simple reprecipitation method. The compound used is the water-insoluble derivative of tris(bipyridine) Ru(II), [Ru(bpy)2(4,4'-(CH3(CH2)14COO)2-bpy)](ClO4)2. The prepared nanobelts show an enhanced fluorescence emission and relatively strong electrogenerated chemiluminescence (ECL), that have potential analytical applications. More interesting, ECL of a single nanobelt deposited on an ultramicroelectrode was observed. The observation of ECL in such nanostructures leads to the development of a new class of ECL systems that may prove useful for a variety of purposes.     

Ruthenium Nanoparticles on Nano‐Level‐Controlled Carbon Supports as Highly Effective Catalysts for Arene Hydrogenation

The reaction of three types of carbon nanofibers (CNFs; platelet: CNF‐P, tubular: CNF‐T, herringbone: CNF‐H) with [Ru₃(CO)₁₂] in toluene heated at reflux provided the corresponding CNF‐supported ruthenium nanoparticles, Ru/CNFs (Ru content=1.1–3.8 wt %). TEM studies of these Ru/CNFs revealed that size‐controlled Ru nanoparticles (2–4 nm) exist on the CNFs, and that their location was dependent on the surface nanostructures of the CNFs: on the edge of the graphite layers (CNF‐P), in the tubes and on the surface (CNF‐T), and between the layers and on the edge (CNF‐H). Among these Ru/CNFs, Ru/CNF‐P showed excellent catalytic activity towards hydrogenation of toluene with high reproducibility; the reaction proceeded without leaching of the Ru species, and the catalyst was reusable. The total turnover number of the five recycling experiments for toluene hydrogenation reached over 180 000 (mol toluene) (mol Ru)^?1. Ru/CNF‐P was also effective for the hydrogenation of functionalized benzene derivatives and pyridine. Hydrogenolysis of benzylic C? O and C? N bonds has not yet been observed. Use of poly(ethylene glycol)s (PEGs) as a solvent made possible the biphasic catalytic hydrogenation of toluene. After the reaction, the methylcyclohexane formed was separated by decantation without contamination of the ruthenium species and PEG. The insoluble PEG phase containing all of the Ru/CNF was recoverable and reusable as the catalyst without loss of activity.     

Towards Electrochemiluminescence Microscopy Exploration of Plasmonic-Mediated Phenomena at the Single-Nanoparticle Level

The rational design of functional plasmonic metasurfaces and metamaterials requires the development of high-throughput characterization techniques compatible with operando conditions and capable of addressing single-nanostructures. In their work, Wei et al. demonstrate the use of electrochemiluminescence microscopy to investigate the mechanism behind plasmon-enhanced luminescence induced by gold nanostructures. The use of gold plasmonic arrays was exploited to achieve the rapid spectroscopic evaluation of all the individual nanostructures, and the correlation of the results with high- resolution electron microscopy analysis, guaranteeing a strict one-to-one correspondence. The authors were able to identify two different mechanisms for the enhancement of [Ru(bpy)₃]²⁺-tri-n-propylamine electrochemiluminescence mediated by single gold nanoparticles and by small plasmonic clusters. In the future, the proposed characterization could be used for the rapid and in situ spectroscopic analysis of more complex plasmonic nanostructures and metasurfaces.     

Multilayered Pt/Ru nanorods with controllable bimetallic sites as methanol oxidation catalysts

A physical synthesis of multilayered Pt/Ru nanorods with controllable bimetallic sites as methanol oxidation catalysts is reported for the first time. The novel nanorods were synthesized via the oblique angle deposition method, deposited prior to the formation of each individual noble metal layer, in a sequential fashion. It has been shown that the oblique angle deposition controls the morphology and electrochemical properties of the resultant nanostructures. Sequentially the multilayered nanorods comprising Pt and Ru segments exhibited superior electrocatalytic activity when compared to equivalent monometallic Pt nanorods with respect to methanol electrooxidation reaction in an acidic medium. Moreover, it has been established that the electrochemical process takes place at the Pt/Ru nanorods followed the bifunctional mechanism. The relative rates of reaction, recorded using chronoamperometry, show a linear relationship between the long-time current density and the number of Pt/Ru interfaces. Interestingly, the best catalyst for methanol oxidation was found to the surface of bimetallic Pt/Ru nanorods produced by the heat treatments via the so-called electronic effect. This reflects the fact that the ensemble effects of combined bifunctional and electronic effects via second elements could be expected in methanol oxidation reactions. Electrocatalytic activities correlate well with bimetallic pair sites and electronic properties analyzed by X-ray photoemission spectroscopy and X-ray absorption near-edge structure.     

Self‐organized Ruthenium–Barium Core–Shell Nanoparticles on a Mesoporous Calcium Amide Matrix for Efficient Low‐Temperature Ammonia Synthesis

A low‐temperature ammonia synthesis process is required for on‐site synthesis. Barium‐doped calcium amide (Ba‐Ca(NH₂)₂) enhances the efficacy of ammonia synthesis mediated by Ru and Co by 2 orders of magnitude more than that of a conventional Ru catalyst at temperatures below 300 °C. Furthermore, the presented catalysts are superior to the wüstite‐based Fe catalyst, which is known as a highly active industrial catalyst at low temperatures and pressures. Nanosized Ru–Ba core–shell structures are self‐organized on the Ba‐Ca(NH₂)₂ support during H₂ pretreatment, and the support material is simultaneously converted into a mesoporous structure with a high surface area (>100 m² g⁻¹). These self‐organized nanostructures account for the high catalytic performance in low‐temperature ammonia synthesis.     

Sonochemical nanosynthesis at the engineered interface of a cavitation microbubble

This work demonstrates the potential of sonochemistry to become a most valuable tool for nanotechnology if the underlying complex processes are understood and controlled. It is shown that control of cavitation requires controlling of interfaces at the microsec time scale and thus a diversity of phenomena are observed using different surfactants. By means of concrete examples it is shown that non-equilibrium nanostructures, e.g. Ru/Pt core-shell nanoparticles can be prepared. Hollow microbubbles with nanoparticles in the wall, which may contain gases over weeks, can be constructed by sonication of the corresponding colloid solutions.     

Synthesis of Silver Nanowires and Other Metal Nanostructures in Dialkylimidazolium Ionic Liquid

Room temperature ionic liquids have attracted much research attention for the preparation of nanoparticles owing to their nonvolatile nature, thermally stable properties and inflammability. In this contribution, we have made an effort to fabricate the late transition metal — Ru, Rh, Ir, Ni, Pd, Pt, Ag, and Au — nanostructures by thermal decomposition of the corresponding organometallic precursors in the presence of various surfactants in ionic liquid [Omim][PF₆]. Silver nanowires can be specifically generated by heating the mixture of (hfac)Ag(PMe₃) and 1‐hexadecylamine with the mole ratio of 1:10 in [Omim][PF₆] at 140 °C for 3 h. Characterization of these metal nanostructures were carried out by transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X‐ray powder diffraction analysis.     

Electrocatalytic reduction of NAD+ at glassy carbon electrode modified with single-walled carbon nanotubes and Ru(III) complexes

A simple procedure was developed to prepare a glassy carbon electrode modified with carbon nanotubes and Ruthenium (III) complexes. First, 25 μl of dimethyl sulfoxide–carbon nanotubes solutions (0.4 mg/ml) was cast on the surface of the glassy carbon electrode and dried in air to form a carbon nanotube film at the electrode surface. Then, the glassy carbon/carbon nanotube-modified electrode was immersed into a Ruthenium (III) complex solution (direct deposition) for a short period of time (10–20 s for multiwalled carbon nanotubes and 20–40 s for single-walled carbon nanotubes). The cyclic voltammograms of the modified electrode in aqueous solution shows a pair of well-defined, stable, and nearly reversible redox couple, Ru(III)/Ru(II), with surface-confined characteristics. The attractive mechanical and electrical characteristics of carbon nanostructures and unique properties and reactivity of Ru complexes are combined. The transfer coefficient (α), heterogeneous electron transfer rate constants (k _s), and surface concentrations (Γ) for the glassy carbon/single-walled carbon nanotubes/Ru(III) complex-, glassy carbon/multiwalled carbon nanotubes/Ru(III) complex-, and glassy carbon/Ru(III) complex-modified electrodes were calculated using the cyclic voltammetry technique. The modified electrodes showed excellent catalytic activity, fast response time, and high sensitivity toward the reduction of nicotinamide adenine dinucleotide in phosphate buffer solutions at a pH range of 4–8. The catalytic cathodic current depends on the nicotinamide adenine dinucleotide concentration. In the presence of alcohol dehydrogenase, the modified electrode exhibited a response to addition of acetaldehyde. Therefore, the main product of nicotinamide adenine dinucleotide electroreduction at the Ru(III) complex/carbon nanotube-modified electrode was the enzymatically active NADH. The purposed sensor can be used for acetaldehyde determination.     

Ultrafine PtRu Dilute Alloy Nanodendrites for Enhanced Electrocatalytic Methanol Oxidation

Dilute alloy nanostructures have been demonstrated to possess distinct catalytic properties. Noble-metal-induced reduction is one effective synthesis strategy to construct dilute alloys and modify the catalytic performance of the host metal. Herein, we report the synthesis of ultrafine PtRu dilute alloy nanodendrites (PtRu NDs, molar ratio Ru/Pt is 1:199) by the reduction of Ru^III ions induced by Pt metal. For the methanol oxidation reaction, PtRu NDs showed the highest forward peak current density (2.66 mA cm⁻², 1.14 A/mg_Pt) and the best stability compared to those of pure-Pt nanodendrites (pure-Pt NDs), commercial PtRu/C and commercial Pt/C catalysts.     

Using Si and Ge nanostructures as substrates for surface-enhanced Raman scattering based on photoinduced charge transfer mechanism

The possibility of utilizing the Si and Ge nanostructures to promote surface-enhanced Raman scattering (SERS) is discussed. The vibronic coupling of the conduction band and valence band states of Si or Ge with the excited and ground states of the target molecule during the charge transfer (CT) process could enhance the molecular polarizability tensor. Using H-terminated silicon nanowire (H-SiNW) and germanium nanotube (H-GeNT) arrays as substrates, significant Raman enhancement of the standard probes, Rodamine 6G (R6G), dye (Bu(4)N)(2)[Ru(dcbpyH)(2)-(NCS)(2)] (N719), and 4-aminothiophenol (PATP), are demonstrated. The abundant hydrogen atoms terminated on the surface of SiNW and GeNT arrays play a critical role in promoting efficient CT and enable the SERS effect.     

Efficient Noble‐Metal‐Free γ‐Fe2O3@NiO Core–Shell Nanostructured Photocatalysts for Water Oxidation

Flowerlike noble‐metal‐free γ‐Fe₂O₃@NiO core–shell hierarchical nanostructures have been fabricated and examined as a catalyst in the photocatalytic oxidation of water with [Ru(bpy)₃](ClO₄)₂ as a photosensitizer and Na₂S₂O₈ as a sacrificial electron acceptor. An apparent TOF of 0.29 μmols^?1 m^?2 and oxygen yield of 51 % were obtained with γ‐Fe₂O₃@NiO. The γ‐Fe₂O₃@NiO core–shell hierarchical nanostructures could be easily separated from the reaction solution whilst maintaining excellent water‐oxidation activity in the fourth and fifth runs. The surface conditions of γ‐Fe₂O₃@NiO also remained unchanged after the photocatalytic reaction, as confirmed by X‐ray photoelectron spectroscopy (XPS).     

On the influence of the metal loading on the structure of carbon-supported PtRu catalysts and their electrocatalytic activities in CO and methanol electrooxidation

PtRu (1:1) catalysts supported on low surface area carbon of the Sibunit family (S(BET) = 72 m(2) g(-1)) with a metal percentage ranging from 5 to 60% are prepared and tested in a CO monolayer and for methanol oxidation in H(2)SO(4) electrolyte. At low metal percentage small (<2 nm) alloy nanoparticles, uniformly distributed on the carbon surface, are formed. As the amount of metal per unit surface area of carbon increases, particles start coalescing and form first quasi two-dimensional, and then three-dimensional metal nanostructures. This results in a strong enhancement of specific catalytic activity in methanol oxidation and a decrease of the overpotential for CO monolayer oxidation. It is suggested that intergrain boundaries connecting crystalline domains in nanostructured PtRu catalysts produced at high metal-on-carbon loadings provide active sites for electrocatalytic processes.     

氧化铈负载钌催化剂中钌表面密度对氨合成活性和氢中毒的影响

氨是关系国计民生的大宗化学品,也是氢能源的重要载体.目前,世界合成氨工业每年消耗约2％的世界总能源,并排放超过1％的CO2,节能降耗需求十分迫切,其中的关键在于高性能氨合成催化剂的开发.传统观点认为,B5活性位是钌催化剂上氮解离和氨合成的活性位,当钌粒子尺寸在1.8～2.5 nm时催化剂的B5活性位数量最多,而钌尺寸较小(0.7～0.8 nm)的催化剂几乎没有氨合成活性.本文通过改变钌负载量调变了氧化铈负载钌催化剂的钌表面浓度,证实钌粒子尺寸低于2.0nm时,氧化铈负载钌催化剂也具有较高的氨合成活性.XPS等表征结果证实:钌表面密度低于0.68 Ru nm-2时,钌主要以层状形式存在于氧化铈表面,层状钌与氧化铈紧密接触,电子从氧化铈的缺陷位传递给钌物种,在这种情况下,Ru 3d5/2的结合能有所下降,氮解离能力增强,这有利于提高催化剂的氨合成活性;当钌表面密度约为0.68 Ru nm-2时,钌金属传递电子给氧化铈,此时Ru 3d5/2结合能有所增加;当钌表面密度高于1.4 Ru nm-2后,钌物种优先在层状钌表面聚集成大尺寸钌纳米粒子,此时催化剂中同时存在钌团簇和钌纳米粒子,氧化铈载体对钌粒子电子性质的影响减弱,因此大尺寸钌金属颗粒Ru 3d5/2结合能又有所下降.另一方面,氢分子会在氧化铈表面形成均裂产物(两个OH基团)或异裂产物(Ce-H和OH).同时氢分子还会在0价钌金属表面解离形成氢原子,并进一步溢流到氧化铈表面与氧原子作用形成羟基.钌活性位上的氢物种比氧化铈中的氢更容易脱附,因此氧化铈中钌的存在不仅可以增强其氢吸附量,还降低了氢物种的吸附强度.当钌表面密度低时,氧化铈与钌的相互作用较强,催化剂中的氢物种容易溢流到氧化铈中形成羟基基团,此时催化剂的氢吸附能力增强,氢中毒问题较显著.当钌表面密度较高时,氢原子在大尺寸钌颗粒上移动、反应和脱附,因此催化剂的氢中毒问题也得到显著缓解.总之,对于氧化铈负载钌催化剂,氧化铈与钌金属之间的电子相互作用以及其吸附性质都会影响催化剂的氨合成活性,因此钌表面密度低于0.31 Ru nm-2以及约为2.1 Ru nm-2时,催化剂都展现出了较高的氨合成活性.本文将为设计制备高性能钌基氨合成催化剂提供理论指导.     

CO在担载Ru催化剂上的吸脱附作用及其表面加氢反应

研究了担载于Al_2O_3和ZrO_2上的以Ru_3(CO)_(12)为前体的[Ru]和以RuCl_3为前体的Ru催化剂的TPR特性、CO吸脱附行为及其表面加H_2反应。担载于Al_2O_3上的[Ru]和Ru催化剂上部分物相较担载于ZrO_2上者难于还原。CO在氧化[Ru]催化剂上主要以Ru(CO)yO_2表面络合物形式存在,在还原[Ru]和Ru、以及氧化Ru催化剂上CO以吸附物种形式存在。在Ru离子上的CO比在Ru原子上者难于脱附。以ZrO_2为载体的[Ru]和Ru催化剂上的CO加H_2生成CH_4的性能显著优于以Al_2O_3为载体者,担载[Ru]催化剂上的CO加H_2性能略优于担载Ru催化剂。     

Synthesis, anticancer and antibacterial activity of some novel mononuclear Ru(II) complexes

In search of potential anticancer drug candidates in ruthenium complexes, a series of mononuclear ruthenium complexes of the type [Ru(phen)(2)(nmit)]Cl(2) (Ru1), [Ru(bpy)(2)(nmit)]Cl(2) (Ru2), [Ru(phen)(2)(icpl)]Cl(2) (Ru3), Ru(bpy)(2)(icpl)]Cl(2) (Ru4) (phen=1,10-phenanthroline; bpy=2,2'-bipyridine; nmit=N-methyl-isatin-3-thiosemicarbazone, icpl=isatin-3-(4-Cl-phenyl)thiosemicarbazone) and [Ru(phen)(2)(aze)]Cl(2) (Ru5), [Ru(bpy)(2)(aze)]Cl(2) (Ru6) (aze=acetazolamide) and [Ru(phen)(2)(R-tsc)](ClO(4))(2) (R=methyl (Ru7), ethyl (Ru8), cyclohexyl (Ru9), 4-Cl-phenyl (10), 4-Br-phenyl (Ru11), and 4-EtO-phenyl (Ru12), tsc=thiosemicarbazone) were prepared and characterized by elemental analysis, FTIR, (1)H-NMR and FAB-MS. Effect of these complexes on the growth of a transplantable murine tumor cell line (Ehrlich Ascites Carcinoma) and their antibacterial activity were studied. In cancer study the effect of hematological profile of the tumor hosts have also been studied. In the cancer study, the complexes Ru1-Ru4, Ru10 and Ru11 have remarkably decreased the tumor volume and viable ascitic cell count as indicated by trypan blue dye exclusion test (p<0.05). Treatment with the ruthenium complexes prolonged the lifespan of Ehrlich Ascites Carcinoma (EAC) bearing mice. Tumor inhibition by the ruthenium chelates was followed by improvements in hemoglobin, RBC and WBC values. All the complexes showed antibacterial activity, except Ru5 and Ru6. Thus, the results suggest that these ruthenium complexes have significant antitumor property and antibacterial activity. The results also reflect that the drug does not adversely affect the hematological profiles as compared to that of cisplatin on the host.     

Solid-state Ru-99 NMR spectroscopy: a useful tool for characterizing prototypal diamagnetic ruthenium compounds

The feasibility of (99)Ru NMR spectroscopy as a tool to characterize solid compounds is demonstrated. Results of the first solid-state (99)Ru NMR investigation of diamagnetic compounds are presented for Ru(NH(3))(6)Cl(2), K(4)Ru(CN)(6). xH(2)O (x = 0, 3), LaKRu(CN)(6), and Ru(3)(CO)(12). The sensitivity of the ruthenium magnetic shielding tensor to subtle changes in the local structure about the ruthenium nucleus is highlighted by comparing the (99)Ru isotropic chemical shift of Ru(NH(3))(6)Cl(2) in aqueous solutions and in the solid state. The narrow isotropic (99)Ru NMR peak observed for solid Ru(NH(3))(6)Cl(2) indicates that this compound is an ideal secondary reference sample for solid-state (99)Ru NMR studies. The isotropic (99)Ru chemical shift, (99)Ru nuclear quadrupolar coupling constant, C(Q), and quadrupolar asymmetry parameter of K(4)Ru(CN)(6). xH(2)O (x = 0, 3) are shown to be sensitive to x. For Ru(3)(CO)(12), the magnetic shielding tensors of each of the three nonequivalent Ru nuclei have spans of 1300-1400 ppm, and the (99)Ru C(Q) values are also similar, 1.36-1.85 MHz, and are surprisingly small given that (99)Ru has a moderate nuclear quadrupole moment. Information about the relative orientation of the Ru magnetic shielding and electric field gradient tensors has been determined for Ru(3)(CO)(12) from experimental (99)Ru NMR spectra as well as quantum chemical calculations.     

Oxidation behavior of Ru/TiO2 and metallic Ru fine particles on heating in air

Thermogravimetry (TG) and differential thermal analysis (DTA) were used to investigate the oxidation behavior of Ru/TiO2 and metallic Ru fine particles during heating in air in the range 20-1000 degrees C. Temperature ranges of the oxidation for two samples of Ru/TiO2 with the compositions (92 wt% Ru, 8 wt% TiO2) and (75 wt% Ru, 25 wt% TiO2) and for pure metallic Ru fine particle agglomerates were determined. It was assumed that after the partial oxidation of Ru in the sample containing 75 wt% Ru and 25 wt% TiO2 and in the pure metallic Ru a diffusion barrier was formed, preventing further oxidation of Ru in Ru/RuO2 and Ru/RuO2/TiO2 matrices. XRD and TEM were used for the sample characterization.