Techniques and instrumentation articles within NPG Asia Materials

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  • Article
    | Open Access

    The interplay of electron-electron and electron-lattice interactions plays an important role in determining exotic properties in strongly correlated electron systems. Here, we report the discovery of two distinct and simultaneous commensurate CDWs, Wigner crystal and Peierls-like instabilities, in Sr0.95NbO3.37 using resonant soft X-ray scattering. These CDWs arise from charge anisotropy and redistribution in Nb 4d – O 2p hybridization and influence transport and optical gaps. The strength of Wigner crystal is within the strong coupling limit. This study paves the way for utilizing RSXS to distinguish CDWs and calls for further investigation of electron‒electron and electron–lattice interactions in inorganic systems

    • Angga Dito Fauzi
    • , Caozheng Diao
    •  & Andrivo Rusydi

  • Article
    | Open Access

    Adhesive polydimethylsiloxane (PDMS) film is successfully fabricated by casting process using thermoplastic polyurethane (TPU). During the curing process, the PDMS lightly cross-linked at the interface with the TPU exhibited a remarkable increase in adhesion properties. The catalytic reaction used for polymerization was regulated by the TPU, which is known to adsorb metal ions. This adhesive PDMS film (APF) demonstrated outstanding adhesion on various substrates under dry and underwater conditions and maintained adhesion even after repeated use. Our findings suggest that the APF could be used an effective waterproof patch by adhering to the surfaces of objects submerged in water.

    • Sangyeun Park
    • , Minhyeok Kim
    •  & Hongyun So

  • Article
    | Open Access

    This study reports the direct observation of atomic density fluctuations in silica glass using angstrom-beam electron diffraction. The local atomic fluctuations are found to originate from quasi-periodic arrays of nanoscale columnar atomic configurations and interstitial tubular voids. The present study also reveals longer-range fluctuations associated with the shoulder of the first sharp diffraction peak. These findings may help to understand the properties and performance of materials.

    • Akihiko Hirata
    • , Shuya Sato
    •  & Shinji Kohara

  • Article
    | Open Access

    The structure of a commercially important glass-ceramic ZrO2-doped lithium aluminosilicate system during its initial nucleation stage was investigated by an X-ray multiscale analysis which enables us to observe the structure from the atomic to the nanometer scale by using diffraction, small-angle scattering, absorption, and anomalous scattering techniques. The combinatorial approach revealed that the formation of edge sharing between the ZrOx polyhedra and (Si/Al)O4 tetrahedra, and that the Zr-centric periodic structure in which the local structure of the Zr4+ ions resembled a cubic or tetragonal ZrO2 crystalline phase was potentially the initial crystal nucleus for the Zr-doped lithium aluminosilicate glass-ceramic.

    • Yohei Onodera
    • , Yasuyuki Takimoto
    •  & Shinji Kohara

  • Article
    | Open Access

    An interfacial co-assembly strategy for synthesizing gradient mesoporous hollow silica sheets is reported. The SO42− and NH4+ were aggregated by protonated amphiphilic polymer PVP and formed (NH4)2SO4 crystals at the n-pentanol-water interface. Negatively charged silica oligomers can be confined on the (NH4)2SO4 crystal surface by the Coulomb interaction of NH4+ and co-assembled with CTAB under the catalysis of ammonia molecules. After removing the (NH4)2SO4 cores and CTAB template by washing and extraction, the first layer of mesoporous hollow silica was formed. Modulating the n-pentanol-water interface to n-hexane-water interface, n-hexane swelled CTAB micelle co-assembled with silica oligomers and formed the second layer of mesoporous silica with larger pore size. The finally obtained gradient mesoporous silica sheet shows remarkable gradient rejection rates for molecules with different sizes.

    • Yangbo Dong
    • , Danyang Feng
    •  & Zhen-An Qiao

  • Article
    | Open Access

    A facile and scalable approach was developed using ultrafine bubble (UFB)-assisted heteroagglomeration to fabricate high-concentration, impurity-free nanoceramic/metal composite powders for additive manufacturin. Individual ZrO2 or Al2O3 nanoparticles up to ~10 wt% were homogeneously decorated on the surface of Ti-6Al-4V powders through the bridging effect of the negatively charged UFBs. The nanoceramics were completely decomposed and dissolved into the matrix upon laser irradiation; therefore, a unique Ti nanocomposite exhibiting both high strength and ductility was obtained.

    • Mingqi Dong
    • , Weiwei Zhou
    •  & Naoyuki Nomura

  • Article
    | Open Access

    A high-performance bacterial cellulose/carbon nanotubes conductive fiber is developed through the in-situ biosynthesis. Through mimicking the structure of muscle fascicles, the composite fiber integrates high strength, high stiffness, high fatigue resistance, and stable electrical performance into one material. Based on those excellent properties, the muscle-inspired fiber is competitive to play a key role in the fields of intelligent fiber-based composites and devices.

    • Zhang-Chi Ling
    • , Huai-Bin Yang
    •  & Shu-Hong Yu

  • Article
    | Open Access

    The first prototype of the portable protein analyzer made with liquid crystal polymer microtubes is constructed to perform the processes of suspending, depositing, and separating for protein extraction and detection by combined photo/magnetic control. Such an analyzer specifically purifies, enriches, and detects various proteins in complex samples in a short time (20 min) and with trace sample consumption (5 μL) and a low detection limit (1 μg mL-1).

    • Yao Lu
    • , Lang Qin
    •  & Yanlei Yu

  • Article
    | Open Access

    Solid-phase crystallized Ce and H codoped In2O3 (ICO:H) transparent conducting films achieve very high electron mobility values of over 100 cm2/Vs and suitable low-carrier concentration, leading to high electrical conductivity and broadband optical transparency. However, a high-temperature annealing process for solid-phase crystallization is necessary to obtain high mobility. Therefore, such a high processing temperature limits the formation and adoption of these films on heat-sensitive flexible substrates. Herein, we used excimer laser irradiation to achieve an ICO:H film on flexible polyethylene terephthalate that had ultrahigh mobility of 133 cm2/Vs, which is the highest among those reported for flexible transparent electrodes.

    • Junichi Nomoto
    • , Takashi Koida
    •  & Tetsuo Tsuchiya

  • Article
    | Open Access

    In this work, a high-Tc (~117 K) joined with a high-Jc (>104 A/cm2, 100 K) are reported in the CuBa2Ca3Cu4O10+δ (Cu-1234) superconductor. Studies have shown that the ordering vacancies and platelike 90° micro-domains serve as efficient microstructure pinning centers which suppress the vortex flux flow and enhance Jc. And plenty of holes with 2pz symmetry owing to unique compressed [CuO6] octahedrons decrease superconducting anisotropy and enhance the interlayer coupling that guarantee a high-Jc.

    • Xuefeng Zhang
    • , Jianfa Zhao
    •  & Jing Zhu

  • Review Article
    | Open Access

    This review highlights the recent advances in fluorescence microscopic visualization of synthetic hydrogels, bio-macromolecular hydrogels, organohydrogels, and supramolecular hydrogels. Topics related to the structural changes of hydrogels, hydrogel mechanics, and super-resolution imaging of hydrogels based on fluorescence microscopy are introduced. The design concepts, imaging mechanisms, and potential applications of the novel fluorescence visualization strategies are discussed in detail. Finally, our opinions on the major challenges of current research, possible solutions, and future directions are shared.

    • Jinpan Zhong
    • , Tianyi Zhao
    •  & Mingjie Liu

  • Article
    | Open Access

    Clay nanosheets (CNSs) of synthetic hectorite have been used for synthesizing advanced functional gels that exhibit high mechanical toughness and many unprecedented characteristics, such as cell harvesting, instant strong adhesion, and self-healing. Upon varying the pH and salt concentration, the aqueous CNS dispersions were found to exhibit a maximum viscosity accompanied by gelation, in addition to large and complex time-dependent viscosity changes in the static state. Such anomalous viscosity dynamics depended on the types of clay and acid (salt), temperature, number of repetitions, and agitation conditions; their mechanisms were also discussed in terms of variations in the CNS microstructures.

    • Yuji Kimura
    • , Shoichi Shimizu
    •  & Kazutoshi Haraguchi

  • Article
    | Open Access

    (Left) Schematic diagrams describing a single in-situ chemical-vapor-deposition process for growing two-dimensional Janus MoSSe without initial or follow-up treatments and the growth mechanism consisting of three steps; 1) growth of a MoS2 layer, 2) formation of vacancies on the top MoS2 layer by an annealing effect, and filling of Se atoms in the vacancies. (Right) Optical-microscopy and photoluminescence-mapping images for a typical two-dimensional Janus sample showing that the central MoSSe region is distinguished from the peripheral MoSe2 region.

    • Chan Wook Jang
    • , Won Jun Lee
    •  & Suk-Ho Choi

  • Article
    | Open Access

    A classification of Fe-pnictide heterointerfaces based on electrostatic principles into initially compensated and uncompensated interfaces is proposed and used for tailoring the interfacial microstructure and superconducting properties. We show that the heterointerface between LnOFeAs (Ln = La, Sm) and BaFe2As2 is nonpolar and remains clean and coherent with Co2+ addition. Co-diffusion results in superconductivity across the whole bilayer. In contrast, IFL formation occurs after adding O2−, and superconductivity with a 2D signature develops with time.

    • Silvia Haindl
    • , Sergey Nikolaev
    •  & Ian MacLaren

  • Article
    | Open Access

    Tailored hardening behavior of monolithic bulk metallic glass (BMG) is demonstrated experimentally. A 2D gradient rejuvenation is introduced into ZrCuAl BMG by a novel heat treatment method. The gradual change of free volume realizes sustainable hardening until fracture. The local free volume related to the rejuvenation state controls the shear band angle and the maximum effective shear stress. Hence, shear band propagation is prohibited and the formation of a complete shear plane transecting the whole specimen is blocked. The current approach offers a new paradigm for utilizing hardening capability of BMG as practical engineering materials.

    • Wookha Ryu
    • , Rui Yamada
    •  & Junji Saida

  • Article
    | Open Access

    A data-driven approach, called materials informatics (MI) method, is developed to maximize the inference ability even using a small training dataset. The idea is to use a joint representation with the three descriptors to describe physical and chemical multifaceted perspectives of materials. This ensemble-based machine learning was trained with only 29 training data. Experiments confirmed that the virtual-screening process successfully discovered five oxygen-ion conductors, that have not been reported.

    • Seiji Kajita
    • , Nobuko Ohba
    •  & Ryoji Asahi

  • Article
    | Open Access

    To enhance supercurrent of iron-chalcogenide (FST) superconductor thin films, we induced nanostrain in FST thin films. The nanostrain was generated around nanoscale defects which were formed by the inserted a trace amount of oxide artificially inside FST matrix during the growth of FST thin film using sequential pulsed laser deposition. In particular, the critical current density (Jc) of the nanostrained FST thin films was significantly improved without dominant degradation of critical transition temperature.

    • Sehun Seo
    • , Heesung Noh
    •  & Sanghan Lee

  • Review Article
    | Open Access

    Since the first report in 1970s, W–Cu composites have attracted extensive attentions owing to their outstanding integrated properties of high hardness, wear resistance and electrical conductivity and low thermal expansion coefficient. This article reviewed recent important progress in the fields of preparation, microstructural characterization, and mechanical and physical properties of W–Cu composites. Particularly, new technologies for microstructure refinement and strategies to enhance the comprehensive performance were summarized and evaluated. The future promising research issues, which may break though the bottleneck of existing performance level of W–Cu composites and facilitate the development of other refractory/non-ferrous metals based nanocomposites, were proposed.

    • Chao Hou
    • , Xiaoyan Song
    •  & Zuoren Nie

  • Article
    | Open Access

    (a) Schematic illustration of volume (v) - Pressure (P) - Temperature (T) diagram of the metallic glass. The process of creating ultra-dense glassy state through the high-pressure heat treatment is described (A → B → C → D → E). (b) New type of ultra-dense anomalous metallic glass was confirmed to be created by density and electric resistivity measurements.

    • Rui Yamada
    • , Yuki Shibazaki
    •  & Junji Saida

  • Article
    | Open Access

    Synchrotron-based Bragg coherent x-ray diffraction (CXD) measurements proposed to study giant magnetorestriction in nickel NW: (a) Monochromatic X-ray beam is focused by Kirkpatrick-Baez mirrors, which creates a localized illumination on the sample (S). By rotating the sample through the Bragg condition in increments of about 0.005 degrees, CXD patterns in the vicinity of the (111) and (002) reciprocal lattice points are recorded with a two-dimensional pixelated detector. A series of diffraction patterns (collected as a function of external magnetic field H) are shown here. The interference fringes are due to the finite extent of the nanowire. The color scale is calibrated in units of X-ray photons per pixel; the center of the pattern reaches a value of 9,000, but is saturated here. (b) SQUID-hysteresis loops of a 200 nm wide and 2 micron long nickel nanowire measured with an applied field at room temperature. (c) Relative change in the lattice spacing (corresponding to the asymmetry and shift of the center of mass of the measured Bragg peaks) along the < 100 > direction and the < 110 > directions. Measurements are taken during a cyclic loading (increasing magnetic field strength) and unloading procedure.

    • Anastasios Pateras
    • , Ross Harder
    •  & Edwin Fohtung

  • Perspective
    | Open Access

    This perspective highlights various representative manufacturing methods of 3D microelectronic devices and their specific features/limitations. It offers an outlook on future developments in the manufacturing of 3D multifunctional microelectronics devices, and provides some perspectives on the remaining challenges as well as possible solutions. Mechanically guided 3D assembly based on compressive buckling is proposed as a versatile platform that can be merged with micromanufacturing technologies and/or other assembly methods to provide access to microelectronic devices with more types of integrated functions and highly increased densities of functional components.

    • Xiaogang Guo
    • , Zhaoguo Xue
    •  & Yihui Zhang

  • Article
    | Open Access

    We propose an innovative skin-over-liquid system made of a periodic array of highly compliant microbumps actuated through an electrode-free electrohydrodynamic (EHD) pressure. We demonstrate that these structures are highly repeatable and are capable to swell and deflate easily under a simple thermal stimulation driven by pyroelectric effect, thus providing a challenging platform that can be actively controlled at microscale. We show the proof of principle by swelling these microbumps for stimulating mechanically live cells in vitro, thus opening the route to more reliable and easy to accomplish assays in the field of mechanobiology.

    • O. Gennari
    • , R. Rega
    •  & S. Grilli

  • Article
    | Open Access

    In textile electronics, micro to millimeter-scaled misalignment is commonly occurred during the high-throughput and bulk-scaled textile manufacturing process, thus the exact performance control of the fiber-based active devices is very difficult in low-cost wearable electronics. In this research, we developed novel single-strand organic electrochemical transistors and proposed dimension-independent characterization method (i.e., the current variation ratio in variation of logarithmic concentration of electrolyte) for ion concentration sensing. Furthermore, we demonstrated the pseudo two-terminal transistor operation by incorporating electrochemical gate electrode onto the surface of the source electrode, leading to single-strand fiber device platform.

    • Youngseok Kim
    • , Taekyung Lim
    •  & Myung-Han Yoon

  • Review Article
    | Open Access

    In this article, we review the prototypical phase-transition material-VO2, which undergoes structure and conductivity changes simultaneously. The recent progresses in the transition mechanism are also discussed. Besides, this work gives a comprehensive understanding of the phase-transition modulations, such as element doping, electric field (current and gating) and tensile/compression strain, as well as employing laser.

    • Zewei Shao
    • , Xun Cao
    •  & Ping Jin

  • Review Article
    | Open Access

    Advanced in situ/operando synchrotron based X-ray characterization techniques are powerful tools in providing valuable information about the complicate reaction mechanisms in lithium-ion batteries. In this review, the state-of-the-art of in situ/operando synchrotron-based X-ray techniques and their combination for battery research are introduced. Various types of in situ cell designs and practical operation tips for experimental set ups are also discussed.

    • Seong-Min Bak
    • , Zulipiya Shadike
    •  & Xiao-Qing Yang

  • Article
    | Open Access

    Cryothermal cycling can induce rejuvenation as well as relaxation of metallic glasses. The surface apparent Young’s modulus and its spatial distribution width increase after the treatment, while in bulk effect depends on the glass composition. This increase is temporary and disappears after some time of room temperature aging. Effect is connected with a large distribution of relaxation times in metallic glasses due to their heterogeneous structure and the formation of complex native oxide on the glass surface. Cryothermal cycling can improve or degrade the plasticity of metallic glasses and the atomic bond structure determines the outcome of the treatment.

    • Sergey V. Ketov
    • , Artem S. Trifonov
    •  & Alan Lindsay Greer

  • Original Article
    | Open Access

    Smart surface with tunable properties is vital for modern intelligent applications. Here we demonstrate a novel surface that enables fast surface changing based on a bioinspired micro-air-sacs network. The pneumatic smart surface allows for rapid and large-amplitude topography deformation through pneumatic control, and permits dynamic wettability switching between dominant and latent states. A smart surface with contrastive rose-petal-like and lotus-leaf-like wetting characters is presented and utilized as a droplet manipulator for in situ capture and release of water droplets on demand.

    • Jian-Nan Wang
    • , Yu-Qing Liu
    •  & Hong-Bo Sun

  • Original Article
    | Open Access

    Nature-inspired from the stimuli-responsive soft material in plants, multifunctional hybrid membrane with thermo-responsiveness and conductivity is synthesized by in situ formation of conductive PPy on a PNIPAm matrix. The hybrid membrane exhibits thermo-responsive electrical properties, thermo-responsive deformability, and a thermo-responsive charge effect. This simple yet efficient platform may open a new era of stimuli-responsive hydrogels to fabricate a variety of high performance electrical, electrochemical and biomedical devices

    • Hyejeong Kim
    • , Kiwoong Kim
    •  & Sang Joon Lee

  • Original Article
    | Open Access

    A flash-evaporation printing technology is developed that employs freestanding carbon nanotubes as a flash evaporator. The target materials precoated on the flash evaporator are printed onto substrates by gas-phase transportation. This methodology offers a printable solution for hybrid perovskite thin films, and can also be used to print patterns and a wide variety of materials on large panels.

    • Haoming Wei
    • , Xingyue Zhao
    •  & Kaili Jiang

  • Original Article
    | Open Access

    We designed various bending hydrogels with symmetric structure that responds to temperature gradient, with inspiration from pine cone. We verified the motion changes based on the amount of content, alignment angle and shape of the layer. The developed system can be applied to various fields, because the direction and curvature can be controlled easily.

    • Kahye Song
    •  & Sang Joon Lee

  • Review
    | Open Access

    The microstructure dynamics of electrode materials during battery cycling is dictated by the coupling between their lattice, charge and orbital characteristics, as shown in the schematic. TEM monitoring enables tracking lattice and chemical bonding at high spatial resolution, and thereby establishes the relationship between structure and performances.

    • Yuren Wen
    • , Dongdong Xiao
    •  & Lin Gu

  • Original Article
    | Open Access

    A novel approach to produce stretchable and deformable printed circuit boards is reported and applied to enable the realization of metamorphic electronic products, which conform to take on new three-dimensional shapes. The test structures morph from planar, to spherical, to cone-like topologies.

    • Shantonu Biswas
    • , Andreas Schöberl
    •  & Heiko O Jacobs

  • Original Article
    | Open Access

    Morphology and nanomechanical properties by atomic force microscopy (AFM) in 1:1 correspondence for the poly(N-isopropylacrylamide) (PNIPAM) hydrogel in a water environment. Measurements were performed in force volume mode at medium resolution (64 × 64) using a 2550 nm spherical tip: morphology (A) and Young’s modulus mechanical map (B). Force (nN) vs indentation (nm) graph (C) that highlights the raw data and Hertz fit. Histogram of Young’s modulus values in log-normal scale with Gaussian distribution fits (D) for the quantitative analysis and error calculation.

    • Massimiliano Galluzzi
    • , Chandra S Biswas
    •  & Florian J Stadler

  • Original Article
    | Open Access

    Planar arrays of optofluidic vortices are generated with photothermal gradients from an array of graphene oxide heaters to achieve multiform manipulations. As a tweezer, each vortex can rapidly capture and confine particles without any restriction on shapes or materials. As a motor, it can actuate any trapped particle to persistently rotate/spin in clockwise or anti-clockwise mode. Such a high-performance ‘workshop’ can be used for various self-assembly ranging from colloid-based clusters, chains, capsules, shells, and ultra-thin films, through particles’ surface modification and fusion, to nanowires-based architectures.

    • Jiapeng Zheng
    • , Xiaobo Xing
    •  & Sailing He

  • Original Article
    | Open Access

    We report the catalyst-free growth of InAs/InxGa1−xAs coaxial nanorod heterostructures on large-area graphene layers using molecular beam epitaxy and our investigation of the chemical composition and crystal structure of these heterostructures using electron microscopy. Cross-sectional electron microscopy images showed that InxGa1−xAs layers, having uniform composition, coated heteroepitaxially the entire surface of the InAs nanorods, without interfacial layers or structural defects. The catalyst-free growth mechanism of InAs nanorods on graphene was investigated using in situ reflection high-energy electron diffraction.

    • Youngbin Tchoe
    • , Janghyun Jo
    •  & Gyu-Chul Yi

  • Original Article
    | Open Access

    Applying in situ TEM techniques to GST-based vertical PCRAM cells, we directly observed the DC set switching process of real devices for the first time. The results show that the microstructure of crystalline GST matrix is an important structural parameter determining the local temperature distribution. In the case of highly crystallized GST matrix, the device failure occurred via two-step void formation due to the polarity-dependent electromigration.

    • Kyungjoon Baek
    • , Kyung Song
    •  & Sang Ho Oh

  • Original Article
    | Open Access

    A highly stretchable CuNW electrode was fabricated on PDMS substrate by the vacuum filtration method. The fundamental stretchability of CuNW films was demonstrated with a newly structured PDMS matrix. Our novel helix-structured CuNW/PDMS electrode showed excellent stretchability at an extremely high strain of 700%, showing a resistance variation of 3.9.

    • Yulim Won
    • , Areum Kim
    •  & Jooho Moon

  • Original Article
    | Open Access

    Graphene-supported polymer brushes were developed as a new type of functional quasi-2D polymers that are transparent, lightweight, freestanding, flexible, transferable and patternable. These 2D objects are demonstrated to be functional sheets for the responsive control of surface wettability and DNA biosensors.

    • Tingting Gao
    • , Sze-Wing Ng
    •  & Zijian Zheng

  • Original Article
    | Open Access

    Combining a stimulus-responsive material and the Marangoni effect, a smart microactuator consisting of UV-responsive photoresist and surfactant was fabricated. The locomotion of a device loaded with the microactuator was initiated upon irradiation with 365-nm UV light, stopped when the light was turned off, and restarted when the light was turned back on. This work is the first example using the chemical Marangoni effect to produce photoresponsive motion on a water surface.

    • Meng Xiao
    • , Chao Jiang
    •  & Feng Shi

  • Original Article
    | Open Access

    A novel and cost-effective activation process has been developed to macroscopically produce three-dimensional (3D) porous Ni@NiO core-shell electrode by activated Ni foam (ANF) in HCl aqueous solution. The ANF electrode yielded a remarkable areal capacitance of 2.0 F cm−2 at a high current density of 8 mA cm−2 and exhibited ultrahigh long-term cycling stability without any decay of capacitance after 100 000 cycles.

    • Minghao Yu
    • , Wang Wang
    •  & Yexiang Tong

  • Original Article
    | Open Access

    Irradiated vertically aligned supported 2.5 dimensional nanowires (NWs) show strong optical absorption due to the leaky mode resonance (LMR), and optical standing waves (SWs) created by waveguiding effects. Silver nanoparticles (AgNPs) have their plasmonic electric (E) field strengths modulated under the effect of the LMR and SW as a function of the optical indices (n, k) of the NWs. At (n=3.88, k=0), a theoretical maxima of the E-field was obtained, which matches closely with the Si (3.84, 0.02) system. The optimized hybrid system, AgNPs on silicon NW, demonstrates pico-femto molar detection of marine toxins by surface plasmon-aided SERS.

    • Yi-Fan Huang
    • , Chiung-Yi Chen
    •  & Surojit Chattopadhyay

  • Original Article
    | Open Access

    Au/Ni12P5 core/shell nanocrystals with single crystalline shells are synthesized via an in situ phosphorization of dumbbell-like Au–Ni nanoparticles (NPs) as precursors. The obtained core/shell Au/Ni12P5 NPs are served as supercapacitor electrode materials with distinct enhanced super-capacitance characteristics compared with pure Ni12P5 and oligomer-like Au–Ni12P5 NPs. This synthesis method provides a new strategy to fabricate metal–semiconductor nanomaterials for enhanced properties.

    • Sibin Duan
    •  & Rongming Wang

  • Original Article
    | Open Access

    A novel two-step approach is presented for the fabrication of self-assembled monolayers of platinum nanocrystals (SAM-Pt) uniformly deposited on a transparent conducting oxide (TCO) surface to serve as a counter electrode (CE) for dye-sensitized solar cells (DSSCs). A true self-assembled Pt nanocrystalline monolayer with a mean particle size of ∼3 nm at facet {111} was unambiguously observed in the high-resolution TEM images. We emphasize that the SAM-Pt films feature a clean surface, uniform morphology, narrow size distribution, small Pt loading and great catalytic activity; the present approach is hence not only suitable for DSSCs but is also promising for many other energy-related applications that require platinum as an efficient catalyst to expedite the oxygen reduction reaction (ORR).

    • Lu-Lin Li
    • , Hsin-Hui Wu
    •  & Eric Wei-Guang Diau

  • Original Article
    | Open Access

    By fabricating a pH-responsive smart device with tunable surface-wetting properties, we have realized continuous in situ separations of oil/water/oil ternary mixtures without ex situ treatments of cleaning or drying. In air, the superhydrophobic/superoleophilic surface of the smart device allowed heavy oil to permeate through while preventing water from passing. When exposed to alkaline water, the superhydrophilicity/underwater superoleophobicity of the smart device surface prevented the passage of hexane while allowing water to penetrate. In this way, efficient separation and collection of the individual components of a complex oil/water/oil mixture was realized in a continuous process with no ex situ treatments. This method could provide a strategy for continuous separations of oil/water/oil ternary mixtures, which are common in practical oil spill cases.

    • Guannan Ju
    • , Mengjiao Cheng
    •  & Feng Shi

  • Review
    | Open Access

    Surfaces that display contact angles >150° along with a low contact angle hysteresis for both low and high surface tension liquids are known as superomniphobic surfaces. Such surfaces have several applications, including self-cleaning, non-fouling, stain-free clothing, drag reduction, corrosion prevention and separation of liquids. In this review, we discuss the design criteria, recent studies, applications, challenges and potential of superomniphobic surfaces.

    • Arun K Kota
    • , Gibum Kwon
    •  & Anish Tuteja

  • Original Article
    | Open Access

    A highly thermal and oxidation-resistive AZO/Cu nanowire/AZO composite electrode for thin-film solar cells was fabricated at room temperature without any atmospheric control. Our novel transparent composite electrode showed good thermal oxidation stability as well as high conductivity (∼35.9 Ω/sq), transparency (83.9% at 550 nm) and flexibility.

    • Yulim Won
    • , Areum Kim
    •  & Jooho Moon

  • Original Article
    | Open Access

    Nanoscale functionalized graphenes are fabricated by atomic force microscopy lithography with the desired coverage of a selective functional group using the simple method of the electrical control, and their recovery through moderate thermal treatments. Surprisingly, our controlled coverage of functional groups can reach 94.9% for oxygen and 49.0% for hydrogen, well beyond the coverage achieved by conventional methods.

    • Ik-Su Byun
    • , Wondong Kim
    •  & Bae Ho Park

  • Review
    | Open Access

    Mesocrystals are superstructures with a crystallographically ordered alignment of nanoparticles and posses unique characteristics such as a high surface area, pore accessibility, and good electronic conductivity and thermal stability. This review summarizes the recent developments of metal oxide mesocrystals in the fields of energy conversion and storage.

    • Takashi Tachikawa
    •  & Tetsuro Majima

  • Original Article
    | Open Access

    Flexible and transparent electronics, such as interactive digital products and human-friendly health-care monitors, are expected to fundamentally change the way of our daily life. Inorganic semiconductors, as a class of important functional materials, are key components of electronic devices. However, their applications in soft electronics are severely confined due to the brittleness. We demonstrate that by structural design of a nanobelt network, extraordinary mechanical flexibility and high optical transparency can be achieved in conventionally fragile ceramics. High-performance photodetectors based on this inorganic nanobelt network are demonstrated on multiple flexible substrates, which strongly indicates its great potential in soft electronics.

    • Siya Huang
    • , Hui Wu
    •  & Wei Pan

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