Functions For Practical Applications Research Articles

Prospective on doping engineering of conductive polymers for enhanced interfacial properties

Conductive polymers that combine the advantages of traditional polymers and organic conductors have recently received more and more attention in applications such as sensors, smart electronics, display, and energy conversion/storage. Interface properties including conductivity, mechanical properties, and mass transport/immobilization are key factors affecting the performance of these devices. Doping engineering provides an effective method to enhance interface properties of conducting polymers and bring new functions for practical applications. In this Perspective, we review some application examples of doping-tunable interfacial properties of conducting polymers with advanced features, i.e., enhancing conductivity by doping; tunable self-assembly of conductive polymers; structure-derived elasticity and its application in flexible pressure sensors; and enhanced interfacial transport and its applications in biosensors and lithium ion battery. Furthermore, this Perspective also discusses the challenges of this field and some possible solutions.

Motor and Rotor in One: Light-Active ZnO/Au Twinned Rods of Tunable Motion Modes.

Precise control of the motion of micromachines is the key to achieving their functions for practical applications. The main challenge is that a given micromachine can typically exhibit only one motion mode, i.e., translation or rotation, while having multiple modes of motion resulting from a simple actuation is still rare. Here we designed and synthesized photochemically powered zinc oxide/gold (ZnO/Au) rods that exhibit multiple motion modes. Under homogeneous UV irradiation, these ZnO/Au rods undergo a transition from ballistic motion to persistent rotational motion upon increasing the fuel concentration or the light intensity. In addition, the rods can switch modes from a circular motion to a helical motion and then a straight-line motion by tuning the angle of incident light. We envision that such attractive colloidal micromachines with controllable motions hold considerable promise for diverse practical applications.

Highly efficient thermal rectification in carbon/boron nitride heteronanotubes

Carbon/boron nitride heteronanotubes (CBNNTs) have attracted considerable attention owing to their unique properties and functions for practical applications in many fields. However, interfacial thermal transport in such heterostructures, which plays a pivotal role in determining their functional properties, is still unknown. In this work, we use non-equilibrium molecular dynamics (NEMD) simulations to study the thermal transport across CBNNTs interface. It is found that the heat flows preferentially from the BNNTs to the CNTs region, demonstrating pronounced thermal rectification (TR) effect. In addition, the TR ratio of zigzag CBNNTs is much more than that of armchair ones, especially under lager temperature bias. With the help of wave packet dynamics simulation and power spectrum calculation, the underlying mechanism of TR in CBNNTs is identified. Furthermore, the influence of system size, ambient temperature and defect density is studied to obtain the optimum conditions for TR. More importantly, we also found that the TR ratio of CBNNTs apparently decreases when taking account of the substrate interaction or tensile strain in practical design for thermal rectifier. Our results provide a certain guidance for designing high-efficiency thermal rectifier based CBNNTs.

Provably secure verifiable multi‐stage secret sharing scheme based on monotone span program

In multi-secret sharing (MSS) scheme, a dealer distributes multiple secrets among a set of participants, each of them according to an access structure. In this study, the authors propose a novel linear MSS with computational verifiability that provide many functions for practical applications in comparison with the previous works focusing on MSS schemes in the general scenario. This scheme has the same advantages as previous schemes; moreover, it is verifiable and multi-use secret sharing. Furthermore, in this scheme the secret reconstruction is according to the dealer's preassigned order. Also, they prove the security of the authors’ scheme in the standard model.

Interfacial thermal resistance of 2D and 1D carbon/hexagonal boron nitride van der Waals heterostructures

The newly emerging graphene/hexagonal boron nitride (h-BN) van der Waals heterostructures has attracted much research interest due to its new properties and functions for practical applications in nanodevices. In this work, molecular dynamics simulations are performed to study the interfacial thermal resistance (ITR) of a graphene/h-BN bilayer system as well as its one-dimensional counterpart, a concentric CNT/BNNT double-walled nanotube, based on the lumped capacity model. The calculated ITR is in an order of magnitude of 10−7–10−6 Km2/W and it monotonically decreases with temperature and interlayer/intertube coupling strength. It is believed that the ITR between graphene and h-BN is reduced through the enhancement of the coupling strength instead of the geometrical overlap of the phonon modes. Heat flux direction has no effect on the ITR of the graphene/h-BN bilayer, however, radial thermal rectification is found in the CNT/BNNT composite, with a largest thermal rectification factor of ∼90%. Thermal energy always prefers to transport from the outer nanotube towards the inner nanotube in the CNT/BNNT system over the opposite direction no matter the outer nanotube is CNT or BNNT because the outer nanotube has more high-frequency phonons than that of the inner nanotube in the CNT/BNNT system.

Bioinspired Graphene Nanopores with Voltage-Tunable Ion Selectivity for Na+ and K+

Biological protein channels have many remarkable properties such as gating, high permeability, and selectivity, which have motivated researchers to mimic their functions for practical applications. Herein, using molecular dynamics simulations, we design bioinspired nanopores in graphene sheets that can discriminate between Na(+) and K(+), two ions with very similar properties. The simulation results show that, under transmembrane voltage bias, a nanopore containing four carbonyl groups to mimic the selectivity filter of the KcsA K(+) channel preferentially conducts K(+) over Na(+). A nanopore functionalized by four negatively charged carboxylate groups to mimic the selectivity filter of the NavAb Na(+) channel selectively binds Na(+) but transports K(+) over Na(+). Surprisingly, the ion selectivity of the smaller diameter pore containing three carboxylate groups can be tuned by changing the magnitude of the applied voltage bias. Under lower voltage bias, it transports ions in a single-file manner and exhibits Na(+) selectivity, dictated by the knock-on ion conduction and selective blockage by Na(+). Under higher voltage bias, the nanopore is K(+)-selective, as the blockage by Na(+) is destabilized and the stronger affinity for carboxylate groups slows the passage of Na(+) compared with K(+). The computational design of biomimetic ion-selective nanopores helps to understand the mechanisms of selectivity in biological ion channels and may also lead to a wide range of potential applications such as sensitive ion sensors, nanofiltration membranes for Na(+)/K(+) separation, and voltage-tunable nanofluidic devices.