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Nanomaterials hold great potential in the development of lithium-ion microbatteries and could assist in developing ever smaller and more reliable power sources to facilitate 21st Century life. Professor Kuan-Jiuh Lin is based in the Department of Chemistry, National Chung Hsing University, Taiwan, and runs the Interfacial Optical-Electronic (IOE) Lab. He and his team leader Dr Wen-Yin Ko are working to address gaps in nanotechnology, including how to conquer the strong interfacial coupling between the porous semiconductor membrane and the electro-plasmon metal-surface film. Their research is expected to have broad applications across electronics and optoelectronics. In a recent project, the researchers are working to develop more efficient lithium-ion microbatteries (micro-LIBs) using active nanostructured anode materials such as carbon nanomaterials composed of porous carbon, graphene and carbon nanotubes (CNTs). The researchers have developed a lightweight and high-rate CNT-based anode system that holds great potential for fast-charging batteries. The team has also created metal-doped MnO2 nanowalls with inter-networked vertically-oriented three-dimensional (3D) porous frameworks directly onto a AgCNT modified current collector, resulting in a superior performance anode material for LIBs. The researchers also created a novel 3D porous scaffold anode material of silicon–porphyrin pearl-chain-like nanowires which was placed onto the surface of a bundled titanium dioxide (TiO2) nanowire. In a world first, Lin and the team were able to achieve dial functionalities of antireflective and electrochemical properties-based anatase TiO2 nanowire devices with a high-porosity cross-linked geometry directly grown onto transparent conductive glass.

Activated carbons with a high mesoporous structure were prepared by a one-stage KOH activation process without the assistance of templates and further used as adsorbents for CO2 capture. The physical and chemical properties as well as the pore structures of the resulting mesoporous carbons were characterized by N2 adsorption isotherms, scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The activated carbon showed greater specific surface area and mesopore volume as the activation temperature was increased up to 600°C, showing a uniform pore structure, great surface area (up to ~815 m2/g), and high mesopore ratio (~55%). The activated sample exhibited competitive CO2 adsorption capacities at 1 atm pressure, reaching 2.29 and 3.4 mmol/g at 25 and 0°C, respectively. This study highlights the potential of well-designed mesoporous carbon as an adsorbent for CO2 removal and widespread gas adsorption applications.

Fabricating flexible/stretchable physical sensors has emerged as a topic of interest owing to the huge market demand for wearable medical devices and electronic skins for the regular and continuous monitoring of human health information. Herein, we report a green and efficient strategy for constructing a sensitive polydimethylsiloxane-derived wearable piezoresistive sensor, based on silver nanoparticle (AgNP)@multi-walled carbon nanotube (CNT) nanocomposite films. The developed sensing material exhibits good flexibility and electrical conductivity because of the interfacial effect between AgNPs and CNTs, leading to excellent sensing performances with good sensitivity, fast response time, low operating voltage, and mechanical stability, as measured under different pressure loading, bending angle, and percentage elongation conditions. In addition, finger movement recognition is sampled by testing the exceptional resistance change, and its practicality was further proven. Thus, the developed material has potential for application in wearable electronics. Notably, the entire sensor fabrication process is low-cost, environment-friendly, scalable, and industrially available, which is beneficial for industrial applications.

A simple and inexpensive method to exfoliate boron nitride powder to form boron nitride nanosheets (BNNSs) with few layers was achieved by using a physically thermal process. The obtained BNNSs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), IR spectroscopy, and Raman spectroscopy. The size distribution of the sheets and average sheet size is in the range of 80–380 nm and 200±62 nm, respectively, and the pure phase h-BN products were confirmed. XPS result showed the B/N atomic ratio to be 0.99. In addition, the BNNSs can well disperse in aqueous solution to form a cloudy suspension and importantly, can remain suspended for 1 month without precipitate, which would have good potential in a wide range of applications.

Silicon nanowire has been perceived as one of the most promising anodes in the next generation lithium-ion batteries (LIBs) due to its superior theoretical capacity. However, its high-cost and complicated fabrication process presents significant challenges for practical applications. Herein, we propose a simple scalable process, thermal-alkaline treatment followed by sputtering deposition, for preparing a unique self-standing anode of three-dimensional (3D) porous Si–TiO2 web-nanowired nanostructure for micro-LIBs. One-step thermal-alkaline synthesis of TiO2 nanowire scaffolds (TNS) with well-controlled thickness of 600–800 nm is reproducibly obtained onto Cu foils, achieving a 3D porous geometry for further growing Si active materials onto it to form 3D web-nanowired TiO2-Si composite material with interstitial voids. Profiting from the coverage of Si, direct contact of active materials on current collector, and the unique 3D web-nanowired structure, it exhibits high reversible volumetric charge capacity of 2296 mAh cm−3 with a coulombic efficiency of ∼95%, higher capacity retention, better capacity recovery ability and improved rate capability. Importantly, this work paves a simple way to directly build reliable 3D nanostructures or nanowired frameworks on selected current collectors as self-standing anodes for high volumetric capacity microbatteries; thus it is easy to scale up and beneficial for microelectronics industry.

A label- and amplification-free photoelectric immunosensor based on well-defined layer-by-layer sandwich-structured AuNP/TNW/AuNP composite is proposed for direct and ultrasensitive detection of α-fetoprotein (AFP). The AuNP/TNW/AuNP composite is produced by assembling an Au nanoparticle underlayer and anatase TiO2 nanowires (TNW) onto the FTO substrate, followed by decorating Au nanoparticles onto the TNW surface, through a simple sputtering and hydrothermal process. The resulting AuNP/TNW/AuNP electrode exhibits a 14-fold and 2-fold enhancement in photocurrent density under simulated sunlight compared with that of bare TNW and AuNP/TNW, respectively, which benefits from the SPR-induced photoabsorption increment and charge separation improvement in Au nanoparticle and interfacial charge transfer promotion at the TiO2/substrate interface in the Au underlayer. As a proof of concept, the AFP antigen can be quantitatively detected by the proposed AuNP/TNW/AuNP coupled with anti-AFP through the analysis of the photocurrent change. This novel AFP photoelectric immunosensor exhibited sensitive detection of AFP with an ultrahigh sensitivity of 0.001 ng mL−1 and good specific selectivity. Moreover, the practical determination of AFP in human serum is also investigated, demonstrating its applicability and potential attraction for clinical tests and disease diagnosis.

In this study, an anatase/rutile mixed-phase titanium dioxide (TiO2) hierarchical network deposited with Au nanoparticles (Au/TiO2 ARHN) was synthesized using a facile hydrothermal method followed by a simple calcination step. Such a unique structure was designed for improving the light harvest, charge transportation/separation, and the performance of photo-electro-chemical (PEC) cells. The properties of the as-synthesized Au/TiO2 ARHN in PEC cells were investigated by electrochemical measurements using a three-electrode system in a 1 M NaOH electrolyte. Remarkably, a 4.5-folds enhancement of the photocurrent for Au/TiO2 ARHN was observed as compared to that for TiO2 nanowire (NW), under AM1.5G solar illumination, suggesting its potential application in PEC cells. A mechanism has been proposed to explain the high photocurrent of Au/TiO2 ARHN in PEC water splitting.

The green synthesis of nanowired photocatalyst composed of carbon quantum dots-titanium hybrid-semiconductors, CQDs/TiO 2 , are reported. Where graphite-based CQDs with a size less than 5 nm are directly synthesized in pure water electrolyte by a one-step electrochemistry approach and subsequently electrodeposited onto as-prepared TiO 2 nanowires through a voltage-driven reduction process. Electron paramagnetic resonance studies show that the CQDs can generate singlet oxygen and/or oxygen radicals to decompose the kinetic H 2 O 2 intermediate species upon UV light illumination. With the effect of peroxidase-like CQDs, photocurrent density of CQDs/TiO 2 is remarkably enhanced by a 6.4 factor when compared with that of as-prepared TiO 2 .

Three electrode system for fabrication CQDs/TiO2 NW by electrodeposition.; PL spectra of CQD solution on 2016.06 and 2017.03.; HRTEM images of CQDs/TiO2 NW.; EPR signals of hydroxyl radical obtained under irradiation of 365 nm on solution in the presence of DMPO for 90 seconds.

We present a simple and quick procedure for the one-pot synthesis of manganese oxides under a basic solvothermal condition in the presence of cationic surfactants acting as the template in a 2-butanol/water solution. Three-dimensional spinel-type MnO2 microspheres composed of small nanoparticles have been fabricated for the first time using our method. Their corresponding electrochemical performances in the applications of supercapacitor electrodes exhibit a good specific capacitance (SC) value of ∼190 F/g at 0.5 A/g and excellent SC retention and Coulombic efficiency of ∼100% and ∼95% after 1000 charge/discharge cycles at 1 A/g, respectively. This suggests its potential applications in energy storage devices. Further, we demonstrate that this solvothermal technique enables the morphological tuning of manganese oxides in various forms such as schists, rods, fibers, and nanoparticles. This work describes a rapid and low-cost technique to fabricate novel architectures of manganese oxides having the desired crystal phase, which will highly benefit various supercapacitor applications.

Improved efficiencies in quasi solid-state and liquid state dye-sensitized solar cells (DSSCs) are achieved by constructing TiO2-based photoanodes with nanostructures of nanotubes (NTs) and nanoparticles (NPs). High surface area, high quality, and good crystallinity of TiO2 NTs were synthesized through a simple reflux method by using commercial P25 NPs as a precursor. The highest conversion efficiency was investigated while the composite photoanode composed of the mixture of 10% (v/v) NTs in NPs, where assembled DSSCs exhibited the conversion efficiency of 2.4% in PEGDME-based electrolyte and 10.27% in DMPII-based liquid electrolyte, with TiO2 composite thickness of 6 μm and 12 μm, respectively, which showed improved conversion efficiency by 20.6% and 10.5% as compared to that of pure TiO2 NP DSSC. Electrochemical impedance spectra (EIS) demonstrate that TiO2 NTs are beneficial to improve the electron transport property as well as possess high charge collection and light harvesting and thus lead to the enhancement of the conversion efficiency.

Three-dimensional (3D) spinel-type MnO2 has attracted extensive interest as a potential electrode material for supercapacitors in order to meet cost/performance requirements of power supplies. In t...

To develop environmentally friendly, inexpensive, and high-quality materials for photo-electrodes to be used in dye-sensitized solar cells (DSSCs), nanocrystalline TiO2 with an anatase phase and a high surface area was successfully synthesized through a hydrothermal process. The as-prepared TiO2 was characterized by high-resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), Raman spectroscopy, and the Brunauer–Emmett–Teller (BET) equation. Furthermore, we present a systematic study of its photovoltaic properties based on an as-prepared TiO2 quasi solid-state DSSC device. The quasi solid-state DSSC was compared with a DSSC made with commercial P25. The results demonstrated that electrodes based on anatase TiO2 nanoparticles (NPs) with high surface area are beneficial to improving the dye absorption and electron transport properties. These NPs are also highly efficient in terms of light harvesting and charge collection, which leads to the enhancement of the conversion efficiency. As expected, the results showed that the DSSCs employing the oligo-polyethylene glycol dimethylether (PEGDME) electrolyte have long-term stability.

The use of lightweight and easily-fabricated MnO2/carbon nanotube (CNT)-based flexible networks as binder-free electrodes and a polyvinyl alcohol/H2SO4 electrolyte for the formation of stretchable solid-state supercapacitors was examined. The active electrodes were fabricated from 3D honeycomb porous MnO2 assembled from cross-walled and interconnected sheet-architectural MnO2 on CNT-based plastic substrates (denoted as honeycomb MnO2/CNT textiles).These substrates were fabricated through a simple two-step procedure involving the coating of multi-walled carbon nanotubes (MWCNTs) onto commercial textiles by a dipping-drying process and subsequent electrodeposition of the interconnected MnO2 sheets onto the MWCNT-coated textile. With such unique MnO2 architectures integrated onto CNT flexible films, good performance was achieved with a specific capacitance of 324 F/g at 0.5 A/g. A maximum energy density of 7.2 Wh/kg and a power density as high as 3.3 kW/kg were exhibited by the honeycomb MnO2/CNT network device, which is comparable to the performance of other carbon-based and metal oxide/carbon-based solid-state supercapacitor devices. Specifically, the long-term cycling stability of this material is excellent, with almost no loss of its initial capacitance and good Coulombic efficiency of 82% after 5000 cycles. These impressive results identify these materials as a promising candidate for use in environmentally friendly, low-cost and high-performance flexible energy-storage devices.

Flexible, transparent, and conducting composite thin films, constructed from multi-walled carbon-nanotube-supported silver–platinum alloy nanoparticles (AgPt–MWCNT) on a flexible polyethylene terephthalate (PET) substrate through the combination of a two-step polyol process for synthesizing composites of carbon nanotubes (CNTs) and metallic nanoparticles (NPs) with an ultrasonic atomization-spin coating method for preparing thin films, have been fabricated. AgPt NPs with an average size of approximately 26 nm were uniformly attached to the sidewalls of MWCNTs to form an effective and strongly mechanical conductive network. These composites were then exposed to microwave plasma irradiation, which can lower the contact resistance between the metallic NPs and CNTs and reinforce the network bridges. The resulting AgPt–MWCNT–PET thin films exhibit improved optoelectronic and mechanical properties, and they possess a sheet resistance of 154 Ω/sq with a transmittance of 80% at 550 nm. These values are competitive with those of most other CNT-based films. Most importantly, the corresponding sheet conductivity does not decrease even after 500 bending cycles. Therefore, the as-produced AgPt–MWCNT–PET films may be direct alternatives to indium tin oxide and other transparent conducting oxide films.

Gold nanoparticle (AuNP) films stacked with individual AuNPs have been shown to exhibit novel electric, plasmonic, and photoelectric properties for wide applications. Here, we developed an efficien...

With an aim to develop environment friendly and inexpensive materials for electrochemical capacitor electrodes, nanocrystalline γ-MnO2 with layered architecture of schist-like structure was successfully synthesized by reducing mixed MnSO4×H2O and CTAMnO4 precursors in stoichiometric amounts through a hydrothermal process. The as-prepared MnO2 was characterized by field emission scanning electron microscopy, X-ray diffraction, and thermal gravimetric analysis. Also, cyclic voltammetry was employed to investigate the electrochemical properties of the products in neutral KCl aqueous solution, showing a higher enhanced capacitive performance than that of the sample without a coating of schist-like γ-MnO2, indicating that our MnO2-based electrode provides a promising opportunity for high-performance energy storage devices.

Open rings of multi-walled carbon nanotubes were stacked to form porous networks on a poly(ethylene terephthalate) substrate to form a flexible conducting film (MWCNT-PET) with good electrical conductivity and transparency by a combination of ultrasonic atomization and spin-coating technique. To enhance the electric flexibility, we spin-coated a cast film of poly(vinyl alcohol) onto the MWCNT-PET substrate, which then underwent a thermo-compression process. Field-emission scanning electron microscopy of the cross-sectional morphology illustrates that the film has a robust network with a thickness of ~ 175 nm, and it remarkably exhibits a sheet resistance of approximately 370 Ω/sq with ~ 77% transmittance at 550 nm even after 500 bending cycles. This electrical conductivity is much superior to that of other MWCNT-based transparent flexible films.

Three types of counter electrode (CE) were fabricated: (i) the Pt-CE represents the platinum counter electrode, (ii) the CB-CE is carbon black counter electrode and (iii) the CBNT-CE is carbon black and carbon nanotube counter electrode. The low cost CBNT-CE with high catalytic activity was achieved by the introduced of carbon nanotubes. The photo to current conversion efficiency of the CBNT-CE device is 5.57 %, which has the potential to replace the Pt counter electrode in dye-sensitized solar cells. Furthermore, the measurements of electrochemical impedance and cyclic voltammetry were employed to interpret the effect of carbon nanotubes.

We have dramatically induced the photoluminescence intensity of CdSe quantum dots emitted from plasma antennas, an intuitive picture consisted of a dense shell of CdSe nanocrystals spontenously deposited onto Au metallic grating nanowires which result from the connection of Au nanocrystals through hydrogen bonding. The Au-CdSe nanowires exhibit a remarkable red-shift surface plasmons energy band (77 nm) from 529 to 606 nm with respect to the complex-like colloids in a methanol solution and induced a narrower solid-state band-edge photoluminescence at 625 nm with a peakwidth of 23 nm.

Electrodeposition method, a simple, cheap, and flexible approach, to fabricate gold nanoparticle (Au NPs) films with an area larger than 1 cm 2 on indium tin oxide (ITO) electrodes modified with (3-mercaptopropyl) trimethoxysilane (MPTMS) was presented. Size-controllable and high loading Au NPs were obtained, which were characterized by field-emission scanning electron microscopic (FESEM) and UV-vis spectroscopy. Our current method provides a versatile and facile pathway to fabricate large-scale metal nanoparticles thin film, enhancing alternatives for academic investigation and industrial application.

To improve the efficiency of the photocurrent conversion process, we have utilized copper phthalocyanine (CuPc) rods, which are capable of enhancing the interfacial area of electron transport and plasmonic gold nanoparticles (Au NPs), which can increase the separation and photogeneration of excitons, to produce a more effective system. In-plane horizontal CuPc rods, with diameters ranging from 0.2 to 1.5 microm, were electrodeposited onto the surface of plasmonic (Au NP) monolayers predeposited onto ITO substrates through electrolytic micelle disruption (EMD) methods.

The exact knowledge of helical carbon nanotube (HCNT) growth mechanism has not yet been completely clarified, and effective synthesis of high-purity helical carbon nanotubes in high yield still remains a tremendous challenge. In this study, HCNTs were synthesized via a catalytic chemical vapor deposition method using Fe nanoparticles as catalysts. We performed systematic experiments to investigate the specific effect of catalytic particle size (CPS) on the selective growth of HCNTs, such as on the morphology, yield, mobility of carbon atoms, and HCNT purity of carbon products. Our study showed that the CPS plays a key role in the selectivity to HCNTs, yield, and morphology of the carbon products, and a small catalytic particle is favorable to HCNT formation. We hope that this result may give a beneficial suggestion to obtain highly pure HCNTs. A CPS-dependent growth mechanism for HCNTs was finally proposed. Magnetic measurements demonstrated that the HCNTs are ferromagnetic properties and show high magnetization at room temperature.

We report the sonophysically-exfoliated methods access to the preparation of homogeneous-free multi-walled carbon nanotubes (MWCNTs) in water solution. Highly stable, uniform, individual MWCNTs are entirely performed through sodium dodecylsulfate surfactants by means of a tip sinicator. HRTEM images show that the crystalline finger walls of individual CNTs are apparently observed. Raman spectrum of MWCNTs shows that the so-called G'-band, associated with metallic electronic structure, was significantly observed at 2644 cm -1 with full-width at half-maximum of 262 cm -1 , indicating that the sonication physical methods do not alter their electric properties. Owing to its easy-to-use procedure and low cost of implementation, this approach could lead to the commercial viability of the large-scale MWCNTs processing.

High dense Cu nanoparticles thin films, with the average size of 25.1 nm, were prepared by electrodeposition Cu nanoparticles on Au electrodes pre-coated 1-decanethiol layers (Cu NPs/thiol/Au). It shows high electrocatalytic capability for the reduction of nitrite ion (NO2−) and exhibits a good reproducibility, which can be utilized as efficient electrochemical sensors. The detection limit of NO2− approaches ∼10−7 mM and the response time is fast with the average time of 2 s.

Twin carbon nanocoils (T-CNCs) were synthesized by means of acetylene decomposition over nickel nanoparticles. From the TEM image, one can see the growth of carbon nanocoils from the opposite sides of a nickel nanodisc, making an interangle of 180°. We examined the microwave electromagnetic (EM) and microwave-absorbing properties of the as-prepared and annealed (1400 °C in Ar) T-CNCs systematically. A composite containing the as-prepared T-CNCs (15 wt %) and paraffin exhibited strong microwave absorption in a frequency range of 2 to 18 GHz. Over an absorber of double-layered composite (2.5 and 3.5 mm thickness), an absorption bandwidth of ca. 10 GHz corresponding to reflection loss below −10 dB can be obtained. We found that the magnetic parameters of the composite are low and suggest that the good absorption properties of T-CNCs should be attributed to dielectric rather than magnetic loss. It was observed that the as-prepared T-CNCs are superior to the annealed T-CNCs in microwave absorption ability, and...

Over Ni nanoparticles generated by means of a combined sol−gel/reduction method, crystalline plait-like carbon nanocoils (CNCs) were synthesized in acetylene pyrolysis at 415 °C. The field-emission scanning electron microscope (FE-SEM) and high-resolution transmission electron microscope (HR-TEM) images reveal that there are often two CNCs in opposite handedness fused in one nanoplait. By optimization of reaction parameters, maximum purities and yields of plait-like CNCs and single CNCs were 99.35 wt % and 99.53 wt %, and ca. 18759.8% and 21269.6%, respectively. The pyrolysis of acetylene was carried out at 415 °C, and no dilute gas such as argon and nitrogen was needed. Thus, we have provided a simple, low-cost, and environmentally friendly approach for the mass production of CNCs with ultrahigh purity. The microwave absorption properties of the as-prepared plait-like CNCs and single CNCs were examined systematically. The results demonstrated that the as-prepared plait-like CNCs exhibit good microwave ab...

An oxotungsten–silica mesoporous structure (WSBA-15) has a hierarchical crystalline architecture in which the W dopants possess tetrahedral coordination geometries for the mixed-valence states W6+, W5+, and W4+. The WSBA-15 catalyst can be recycled—without any loss of activity—for the direct oxidation (30% H2O2) of cyclohexene to colorless, crystalline adipic acid (55% yield) under organic solvent-free conditions.

An aquo-accessible chromatic change in a crystal was induced by means of a reversible coordination geometry shift from octahedra in [Co(C 12 H 8 N 2 )(HO 3 P-C2H4-PO 3 H)(OH2)2] (1) to trigonal-bipyramid in [Co(C 12 H 8 N 2 )(HO 3 P-C2H4-P03H)] (2) at the cobalt(II) center; the crystal-to-crystal phase transition was confirmed by powder X-ray diffraction and solid-state UV-vis diffuse reflectance spectra.

The compound cesium niobate, Cs 2 Nb 4 O 11 , is an antiferroelectric, as demonstrated by double hysteresis loops in the electric field versus polarization plot. The crystal structure refinement by X-ray diffraction at both 100 and 297 K shows it to have a centrosymmetric structure in point group mmm and orthorhombic space group Pnna , which is consistent with its antiferroelectric behavior. The 100-K structure data is reported herein. The lattice is comprised of niobium-centered tetrahedra and octahedra connected through shared vertices and edges; cesium atoms occupy channels afforded by the three-dimensional polyhedral network. Antiferroelectricity is produced by antiparallel displacements of niobium atoms along the c -axis at the phase transition temperature of 165 °C. The critical field for onset of ferroelectric behavior in a single-crystal sample is 9.5 kV/cm at room temperature.

Al x Ga1-x N films and Al x Ga1-x N/GaN heterostructures were prepared on the ( $$11\bar{2} 0$$ ) sapphire substrates at elevated temperatures by alternate supply of trimethylgallium (TMG)/trimethylaluminum (TMA) and ammonia (NH3) in an inductively heated quartz reactor. X-ray studies reveal the monocrystalline nature of these Al-containing structures. The results of absorption measurements of the Al x Ga1-x N films exhibit clear cut-off energies of the films. Based on the investigations of transmission electron microscopy (TEM), Al x Ga1-x N films and Al x Ga1-x N/GaN structures were found to deposit on the ( $$11\bar{2}0$$ ) sapphire substrates with AlGaN and $$ _{{\rm AlGaN}}$$ being parallel to $$ _{{\rm sapphire}}$$ and $$ _{{\rm sapphire}}$$ , respectively.

Metal and semiconductor nanoparticles display fascinating size-dependent structural, electronic, optical, magnetic, and chemical properties, which make them promising materials to be tailored and functionalized as fundamental building blocks for emerging nanotechnology applications. Because of the strong dependence of nanoparticle properties on their quantum-scale dimensions, the synthesis of nanoparticles with a small size and shape variation is of key importance. At present, size-, shape-, composition-, and surface-chemistry-controlled nanoparticles can be synthesized by colloidal-solution methods for a wide range of materials. Furthermore, strategies have been developed in which monodispersed nanoparticles can form self-assembled, long-range nanoparticle lattices (2D and 3D) under appropriate conditions. The next important challenge for emerging nanotechnological applications (chemical and biological sensing, electronics, optoelectronics) is to perform controlled and hierarchical self-assembly of monodispersed nanoparticles from the solution phase into ordered and specifically designed nanoparticle structures immobilized on solid-surface templates. In this paper, we report an approach for controlled assembly of metal (Au) and semiconducting (CdSe/ZnS core/shell) thiol-terminated nanoparticles onto electrically patterned Si3N4/SiO2/Si (NOS) electret films with an unprecedented resolution. In the past few years, several important breakthroughs in scanning-probe-based lithographic techniques using tip-induced local electrochemical reactions of self-assembled monolayers (SAMs) or tip-induced local-transport processes, such as dip-pen nanolithography, were developed for fabricating surface templates, which can be used to assemble nanoparticles on solid supports. In these techniques, the patterning process is realized by molecular reaction or transport through a water meniscus that naturally occurs between the tip and sample under ambient conditions. Therefore, the typical resolution and writing speed of such techniques is controlled by parameters such as probe scan speed, temperature, humidity, and molecule type. Furthermore, the reaction or transport rate is limited by the reaction or ink-transport process. As a result, these types of lithographic mechanism limit the line-writing speed to the range 0.1–10 lm s and the dotwriting time to the range of a few milliseconds to tens of seconds per dot (size-dependent) under ambient conditions. Recently, electrostatic-force-based assembly of nanoparticles has been proposed as a general, precise, and reliable methodology for such purposes. In the most direct type of electrostatic-force-based assembly, charge patterns are created by scanning-probe or microcontact charging techniques onto electret materials via electronor hole-tunneling processes. As the electret materials can retain electric charge or polarization for a long time, these charge patterns can be used as templates for assembling charged or polarizable nanoparticles. The major advantage of electrostatic lithography is that, in contrast to diffusion processes, the patterning speed can be enhanced over three orders of magnitude. However, because electrostatic forces scale with surface area and particle size, nanoscale electrostatic assembly of nanoparticles is a formidable task. Xerography (a form of electrophotography) is currently one of the prevailing methods for pattern generation or replication, with ∼ 100 lm resolution. In this process, charged toner particles (with diameters in the range of several micrometers) are attracted by electrostatic-charge patterns (latent electrostatic images) created on a photosensitive electret, and the images are developed with these toner particles. Very recently, nanoscale xerography (nanoxerography) using an electrical microcontact printing process or a scanningprobe-based process was proposed as a means for nanoscale pattern generation or replication. In this work, by using an optimized electret structure (NOS dielectric stack), improved local-charging conditions under high vacuum, and chemically modified nanoparticles (5 nm thiol-terminated gold colloids, see the literature and the Experimental section for the synthesis procedure), we are able to perform selective attachment of gold colloidal nanoparticles onto the patterned electret in a toluene solution at a resolution of ∼ 30 nm. Furthermore, in our process, only a C O M M U N IC A IO N S

A family of well-defined prophyrin wires, 5,10,15,20-tetrakis(4-N-ethylpyridyl)porphyrin salts [H 2 TEPyP 4+ .A] (A = 2CdI 4 2- 1; 6I - 2; 4I - 3), has been synthesized by hydrothermal methods and was structurally characterized by X-ray single-crystal diffraction. Controlling the packing of π-π stacking backbones was achieved by means of adjusting the counterbalanced anions: tetragonal packing for 1 and 2; hexagonal-like for 3. The optical properties related to the packing structures were studied by solid-state diffuse reflectance spectra. The blue-shift of Soret band demonstrated the H-aggregate form in the porphyrin wires.