Original Article

We have developed a simple, effective, one-step, catalyst-free chemical vapor deposition method for the synthesis of high-quality LaB₆ nanostructure nanowire arrays. Field-emission (FE) measurements at room temperature (RT) show that LaB₆ nanowire arrays possess the best FE characteristics among all one-dimensional LaB₆ nanostructures, exhibiting with a low turn-on electric field, a low threshold electric field, a high current and a good stability. Temperature-dependent FE on the nanowire arrays shows that the turn-on and threshold electric fields decreased rapidly whereas the emission current density increases significantly in the ambient temperature from RT to 723 K.

Natural systems employ energy converters in the form of chlorophores or chemical entities to transform light into a mechanical response, which allows them to open and close pores. Inspired by nature, in this work, we used metallic nanoparticles as opto-thermal energy converters to switch thermally responsive polymers incorporated into nanporous membranes to open and close fluid flow.

A novel marine silk fiber (named aneroin) from sea anemone has been discovered, and wet-spun and electrospun silk fibers from purified recombinant aneroins have been successfully fabricated. Aneroin fibers have promising mechanical properties, suggesting that this protein has potential for use as a novel fibrous biomaterial. Its use would expand the applications of silk in the development of multifunctional and bio-inspired materials.

The gas-sensing performances of the Au NP-embedded silica nanowire can be enhanced by visible light (532 nm) illumination at room temperature, which improves not only sensing response but also recover time.

We report on the promising thermoelectric performance of p-type polycrystalline BiCuSeO, which is a layered oxyselenide composed of conductive (Cu₂Se₂)²⁻ layers that alternate with insulating (Bi₂O₂)²⁺ layers. Electrical transport properties can be optimized by substituting Bi³⁺ with Ca²⁺. Moreover, BiCuSeO shows very low thermal conductivity in the temperature ranges of 300 (∼0.9 W m⁻¹K⁻¹) to 923 K (∼0.45 W m⁻¹ K⁻¹). These intrinsically low thermal conductivity values may result from the weak chemical bonds of the material as well as the strong anharmonicity of the bonding arrangement. The combination of the optimized power factor and the intrinsically low thermal conductivity results in a high ZT of ∼0.9 at 923 K for Bi_0.925Ca_0.075CuSeO.

Modulating the drug release from polyester matrices independently from the material properties would be beneficial to those designing biodegradable medical implants, such as drug delivery devices, stents and screws. We propose that modulated drug release can be obtained via an additive-free mechanism in polyesters by simply controlling polymer erosion through acidic terminal functional groups. The formulations can be tuned to produce large ranges in drug release with relatively small changes in terminal acidic functional groups. For example, poly(lactic-co-glycolic acid) (PLGA) 53/47 thin films could be tuned to have 10–90% drug release at 20 days, depending on the concentration of acidic terminal groups.

We propose the simple and novel ‘aqueous route’ for realizing oxide thin-film transistors (TFTs) at low annealing temperatures <200 °C with low cost. These results provide substantial progress toward solution-processed metal-oxide TFT through naturally born unique indium complex and post annealing. They exhibit acceptable electrical performance with good large-area uniformity at low temperature. The additional vacuum annealing facilitates the condensation reaction by effective removal of byproduct water molecule and activates the In₂O₃ TFT at low temperature, even with 100 °C annealing. Also, we have demonstrated the flexible and transparent oxide TFTs on a plastic substrate with good stability to the external gate bias stress.

Nanoscale graphene oxide (NGO) has emerged as extremely attractive nanomaterials for diagnostics and therapeutics. In this work, we present a systematic study on the in vivo distribution and pulmonary toxicity of NGO for up to 3 months after exposure. Radioisotope tracing and morphological observation demonstrated that intratracheally instilled NGO was mainly retained in the lung. NGO could result in acute lung injury (ALI) and chronic pulmonary fibrosis, which raises environmental concerns about the large-scale production of graphene oxide. Nevertheless, we also noted that the NGO-induced ALI was related to oxidative stress and could effectively be relieved with dexamethasone treatment.

Biological sensing with silicon nanowires has drawn much attention due to the enhanced sensitivity of these devices. However, both bottom-up and top-down fabrication techniques are thus far resistant to commercialization, mainly due to the incompatibility of the bottom-up methodology with mass production and the non-standard, top-down process complexity. We report on a specific, label-free, and real-time detection of femtomolar protein concentrations with a novel type of nanowire-based biosensor. The biosensor is based on an electrostatically formed nanowire that requires standard integrated circuit processes with relaxed fabrication requirements.

We demonstrate a single-domain photovoltaic switch based on lateral BiFeO₃ channels, in which such photovoltaic switching is achieved by a coherent single-domain reversal with a short electrical pulse. We then provide visual evidence for such operations with a series of spatially and spectrally resolved short circuit photocurrent images. Specifically, it reveals that the sequential photovoltaic current images directly reflect the remanent polarization states of a single-domain channel. We also verify that, in multidomain channels, the diffusive switching characteristics is determined not only by the internal polarization vector within the domain but also by oxygen vacancy migration at the domain walls.

This paper reports a facile cyclic reduction–decomposition method for the aqueous-based synthesis of highly luminescent Ag nanoclusters (NCs) with tunable emissions. A reduction–decomposition–reduction cycle was used to modify the non-luminescent Ag NC intermediates with improved stability against subsequent etching by thiol ligands, which created a mild size-/structure-focusing (or etching) environment and produced highly luminescent Ag NCs with intense red (Ag₁₆(SG)₉) and green (Ag₉(SG)₆) emission. The highly luminescent Ag NCs also possessed superior antimicrobial properties against the multidrug-resistant bacteria Pseudomonas aeruginosa via generating a high concentration of intracellular reactive oxygen species.

Springtails, wingless arthropods, are adapted to cutaneous respiration in temporarily rain-flooded habitats by a hierarchically structured skin surface. A tunable polymer replication process was applied to dissect the contributions of different structural elements and surface chemistry to the omniphobic performance of the skin.

We report that single-layered and single-crystalline graphene flakes (GFs) with highly regular and hexagonal symmetric patterns can be grown on a liquid copper surface using a CH₄ chemical vapor deposition (CVD) method. Different morphologies of these GFs can be precisely tailored by varying the composition of inert gas/H₂ carrier gas mixture, and the GF edges can be continuously tuned over the full spectrum from negative to zero to positive curvature in a controllable way. This study provides a well-behaved two-dimensional crystal growth system mimicking snowflakes, opening rich opportunities for engineering graphene patterns and studying graphene structure/property relationships.

Multilevel nonvolatile transistor memories were fabricated with inserted electret dielectric of star-shaped poly((4-diphenylamino)benzyl methacrylate). The devices could be controllably charged and retain the digital states even when the supply voltage was removed. The multilevel data storage characteristics by applying different gate voltages suggested novel ‘write-many-read-many memory’ behaviors.

Organic field-effect transistors with a self-doped (SD) polyaniline charge-trapping energy well structure exhibit outstanding nonvolatile memory characteristics. The charges generated by the field-effect operation are effectively stored in the SD poly(o-anthranilic acid) charge-trapping energy well layer so that the present memory transistor performs excellent data writing–reading–erasing functions with highly stable data retention characteristics.

The key factor and mechanism for reported toxicity of CNTs are unclear. Here we firstly quantify the contribution of metal residues and fiber structure to the toxicity of CNTs. Significant quantities of metal can be mobilized from CNTs into surrounding fluids, depending on the properties and constituent of biological microenvironment and metal particles. Hydroxyl radicals were generated by CNT containing metal impurities and leachable metal, while several inherent biomolecules facilitate the generation of free radical. Cell viability is highly dependent on the amount of metal residues and iron in particular but not tube structure, while the negative effect of CNT was limited in a certain concentration range below 80 μg ml⁻¹.

Graphene, owing to its remarkable electronic and structural properties, has attracted considerable attention in both science and technology communities. However, a major roadblock to the realization of graphene-based field-effect transistors is the fact that large-area graphene behaves like a semimetal with zero bandgap, making it unsuitable for real applications in sensing, detecting and switching systems. Surface functionalization could result in the construction of periodic micro/nanostructures by breaking sp² bonds and forming sp³ bonds. Therefore, direct chemical grafting might provide a useful way to covalently modify graphene for tailoring its properties. Owing to the inert reactivity of its surface, however, up to date only few chemical reactions were used to modify its atomic structure. Here, we demonstrate a controllable and efficient means of mild plasma methylation to manipulate the reversible interconversion of two distinct species of graphene (one crystalline and the other methylated). The strategy of incorporating diverse functional substituents (methyl group and hydrogen atoms here) into graphene instead of a single type of chemical groups could provide a useful route for the development of different applications, such as chemical/biosensors and multifunctional electrical circuits. Moreover, the methylated graphene with fine tunability is stable at room temperature, which suggests the intrinsic potential of novel applications in graphene-based optoelectronic devices that invites further studies.

It is commonly believed that bulk SnO2 is not a suitable ultraviolet (UV) light emitter due to the dipole-forbidden nature of its band-edge states, which has hindered its potential use in optical applications. Here, we demonstrate both theoretically and experimentally an effective method to break the dipole-forbidden rule in SnO2 via nano-engineering its crystalline structure. Furthermore, we designed and fabricated a prototypical UV-light-emitting diode (LED) based on SnO2 thin films. Our methodology is transferable to other semiconductors with ‘forbidden’ energy gaps, offering a promising route toward adding new members to the family of light-emitting materials.

Peptide-mimic poly(n-hexyl isocyanate) (PHIC) with stiff chain characteristics demonstrated to selectively form a well-ordered hexagonal close packing structure with 8₃ helical conformation in the nansocale thin films annealed with carbon disulfide. Moreover, this polymer showed to selectively form a well-ordered multi-bilayer structure with β-sheet conformation in the thin films annealed with toluene. These two self-assembled structures were reversibly transformed by consecutive annealing with carbon disulfide and toluene. These chain conformations and self-assembled structures were confirmed by synchrotron grazing incidence X-ray scattering analysis.

Increasing the Seebeck coefficient has long been pursued for increasing thermoelectric efficiency, but other changes in transport properties may compensate this effect and ultimately lead to no improvement in figure of merit. The Seebeck coefficient can be enhanced by either the addition of resonant states or the involvement of multiple band conduction. This work demonstrates the beneficial effect of multiple band conduction for highefficiency thermoelectrics.