Original Article in 2016

Selenium atoms were selectively introduced in particular locations such as the pseudo-edge sites of hole-cluster defects in the basal plane and edge defect sites of the fully amorphorized surface of reduced graphene oxide (rGO), inducing a dramatic change of electrical transport properties of rGO by electron doping.

We develop a new type of flexible nanohybrid microelectrode by decorating high dense PtAu alloy nanoflowers on 3D porous ionic liquid functionalized graphene wrapped activated carbon fiber. In virtue of the unique array of structural and chemical properties, the resultant hierarchical nanohybrid microelectrode exhibits a collection of good sensing performances, and can be used in near-cell sensitive detection of cancer biomarker secreted from different female cancer cells in normal state and treated by antitumor drug, which provides important information in distinguishing different cancer cells and normal cells and evaluating the therapeutic activity of antitumor drug towards the live cancer cells.

Novel fluorescent Ag nanoclusters are prepared based on an etching method with citrate and GSH as the stabilizer of Ag nanocrystals and the etchant. The as-prepared Ag nanoclusters show good pH-switchable agglomeration and dispersion accompanied with the reversible agglomeration induced signal quenching. The pH-regulated behavior mechanism has been discussed, and the Ag nanoclusters is introduced as a probe to establish regenerable biosensing platform for urea and glucose detection.

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.

Organic liquid separation is currently an important but troublesome issue, which closely related to resource recycling and environmental protection. Here we reported a wettability-tunable nanofibrous membrane that can be used for efficient separation of wide ranges of immiscible organic liquid mixtures.

To achieve the room-temperature Datta-Das spin transistor at the nanoscale, we propose a new mechanism to produce giant Rashba splittings in the quantum-well-state (QWS) of normal metal (NM) thin films by exploiting the asymmetric properties of spin states at the topological insulator (TI) interface based on the NM/TI heterostructure. In such a hybrid system, the TI spin–momentum-locking Dirac-surface states strongly modify the NM QWSs, leading to extremely large Rashba splittings in the NM QWSs. The giant Rashba splitting as well as the nearly 100% spin polarizations in the NM QWSs manifest great potential for manipulating spin without magnetic fields in spintronic devices.

Centimeter-sized, epitaxial hexagonal boron nitride (h-BN) few-layer films were heteroepitaxially grown on Ni(111) single-crystal substrates using atmospheric pressure chemical vapor deposition with ammonia-borane single precursor. The grown films were transferred to arbitrary substrates via an electrochemical delamination technique, and the remaining Ni(111) substrates were repeatedly re-used. Over repeated growth and transfer after the initial annealing, no significant degradation of Ni(111) substrates was observed and the crystallinity of h-BN layers was reproduced reliably. The grown h-BN films showed typical physical characteristics of h-BN, with a high uniformity over a wide area. The large-area synthesis and transfer of atomically thin uniform epitaxial h-BN layers can be applied in various fields where high quality two-dimensional insulating layers are required.

A highly conductive fibers and sensitive textile pressure sensors are developed by extremely low-temperature atomic layer deposition (ALD) of Pt. The low-temperature Pt ALD is achieved under 100 °C without any reactive reactant, enabling cotton fibers to have excellent electrical properties. The pressure sensors fabricated using the conductive fibers exhibit high performances, and can be applied to smart fabrics which can distinguish features of occupants.

Spherical, twiddle and hollow hemispherical reduced graphene oxide (rGO) structures could be fabricated by tuning the GO assembly in the diffusion-controlled micro-droplets, and their size and thickness could be adjusted by controlling the concentration of GO and pH of the droplets. Besides, the porous rGO architecture was produced via wet etching of rGO-SiO₂ composites, and their plasamon effect was characterized.

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.

ZrTe₅ has attracted intensive research interests because of the potential topological property. Here based on the transports and optic experiments, we observe unusual Landau quantization, non-trivial Berry phase and highly anisotropic carrier mass, which reveals quasi-two-dimensional Dirac fermions in bulk ZrTe₅. The system is understood as locating at the critical point between a three-dimensional (3D) Dirac semimetal and a topological insulator. New physics or device application can be possibly realized in this quasi-2D ultra-relativistic system beyond graphene.

We have synthesized a monolayer 1T-NbSe₂ on bilayer graphene by molecular-beam-epitaxy method and investigated its electronic states by angle-resolved photoemission spectroscopy. In contrast to metallic 2H-NbSe₂, monolayer 1T-NbSe₂ was found to show insulating characteristics with a finite energy gap and strong modulation of density of states with periodicity. This suggests the Mott-insulating ground state of monolayer 1T-NbSe₂ with the formation of ‘star of David’ clusters. We also found that 1T and 2H phases are selectively fabricated by simply controlling the substrate temperature during epitaxy. The present result opens a pathway toward the crystal-phase engineering based with transition-metal dichalcogenides.

Hybrid calcium titanyl oxalate (HCTO) composite containing anisotropic spindly microparticles and irregular nanoparticles have been synthesized via a facile precipitation route under mild conditions for the first time. The hybrid particles act synergistically to enhance electrorheological (ER) activity and reduce field-off viscosity, thereby resulting in ER fluids with ultrahigh ER efficiency. The results presented thus provide a new strategy for improving the performance of ER fluids.

New design of the p-MTJ spin-valve using W bridging and capping layer demonstrated no significant crystallinity degradation and no considerable Fe atoms diffusion, thus achieving the TMR ratio of ~143% at an ex-situ annealing temperature of 400 ^oC. A better crystallinity of the MgO layer for W case than Ta case would be related to less diffusion amount of metal atoms and lattice strain in MgO layer. In addition, higher Fe and Co atom concentrations of Co₂Fe₆B₂ free and pinned layers for W case than Ta case would be associated with less solubilities in W layers than Ta layers.

A new stress-driven structural collapse and etching mechanism for the synthesis of Au nanorings via a direct one-pot solution-based chemical reaction is presented. The nanoparticle-mediated recrystallization process contributes to the formation of Au nanoframes that contain unusual stress, which promotes the breakup of the nanoframes and conversion into Au nanorings. The Au nanorings have tunable hole sizes and exhibit interesting localized surface plasmon features owing to the coupling of bonding and antibonding modes on the inner and outer surfaces of the nanorings.

Microstructure evolutions upon cooling in three ferroelastic systems having different defect concentrations, c=0.02, 0.14 and 0.40, respectively. Green color in the figures represents the parent phase; blue and red colors represent the two different martensitic variants. As the defect concentration increases, the behavior of the ferroelastic system shifts from ‘the cooler the faster’ (c=0.02 and 0.14) to ‘the cooler the slower’ (c=0.40).

We develop a robust full-Brillouin zone soft-phonon-searching algorithm, with outstanding accuracy and efficiency in pinpointing general phonon instability within the joint material-reciprocal spaces in crystals. By combining finite-element modeling with embedded phonon algorithm and atomistic simulation, we show how a zone-boundary soft phonon is first triggered in a perfect aluminum crystal under nanoindentation, which subsequently leads to a transient new crystal phase and ensuing nucleation of a deformation twin. We propose a two-stage mechanism governing the transformation of unstable short-wave phonons into lattice defects, fundamentally different from that initially triggered by soft long-wavelength phonons.

A new principle for management of dopant–dopant and dopant–host interactions by manipulation of mesoscale heterogeneity in a single active material is presented. The proposed mesoscale engineering approach results in dramatically inhomogeneous broadening of dopant, and for the first time show success in simultaneously extending emission bandwidth and flattening spectral shape in a doped glass and fiber.

A modified polybenzimidazole (mPBI) was synthesized to tame the polysulfides (PS) shuttling in Li–S batteries via dual actions. As a binder, the mPBI mechanically and chemically offers strong electrode integrity and high sulfur loading, inhibits sulfur loss and prolongs lifespan for sulfur electrode. As a functional agent, the mPBI builds a shield onto the separator to block PS migration so as to further suppress the PS shuttling. This strategy confers an excellent performance of 750 mAh g⁻¹ (or 5.2 mAh cm⁻²) after 500 cycles at C/5 for the resultant Li–S battery with an ultralow capacity fading rate of 0.08% per cycle.

(a–c) Reciprocal space maps about (022) reflections of PZN-PT (011) under various poling states, exhibiting various ferroelastic strain states. (d) Electric impulse-induced non-volatile tuning of magnetic anisotropy between the distinct strain states A and B due to the ferroelectric partially coupled ferroelastic domain switching. (e) Hysteresis loops of magnetic resonance fields of FeGaB as a function of the electric field applied on PZN-PT (011), arising from the electric field-induced ferroelectric phase transition from rhombohedral to orthogonal (R–O).