NanoEnergy 2018



Nature utilizes hydrophilic-hydrophobic biomolecular entities to perform self-organized structural and functional tasks, including the formation of cellular compartments and motion, separation of chemicals or self-healing properties in a highly energy efficient manner. So far, no inorganic artificial micro/nanostructure units are known that self-organize and mimic such functions just by adding liquid. Here we develop the first nanomaterial exhibiting hydrophilic wetting and hydrophobic dewetting. Consisting of gallium nitride nanoscopically thin membranes shaped as hollow microtetrapods, which we term aerogalnite (AGaN), the nanomaterial is extremely porous, mechanically flexible, stretchable, and exhibits hydrophilicity under tension and hydrophobicity when compressed against water. Self-assembling the AGaN tetrapods on water enabled us to develop self-healing waterproof rafts carrying liquid droplets 500-times as heavy as rafts, and to demonstrate self-propelled liquid marbles exhibiting velocity of rotation as high as 750 rot/min. The specific force of the detachment of AGaN from the water surface was experimentally determined to equal 35 mN/cm2. The new developed material aerogalnite and its peculiar characteristics are promising for applications in sensorics, microfluidic devices and microrobotics.


plesco 2018 2

Abstract: In this paper, we report on functionalization of graphene aerogelwith a CdS thin film deposited by magnetron sputtering and on the development of flexible pressure sensors based on ultra-lightweight CdS-aerogel nanocomposite. Analysis by scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis disclose the uniform deposition of nanocrystalline CdS films with quasi-stoichiometric composition. The piezoresistive response of the aforementioned nanocomposite in the pressure range from 1 to 5 atm is found to be more than one order of magnitude higher than that inherent to suspended graphene membranes, leading to an average sensitivity as high as 3.2 × 10−4 kPa−1.

Gaponenko 2018

Abstract: We report on anomalous light retroreflection from strongly absorbing nanoporous semiconductor materials, GaAs and InP, with strongly polarized retroreflected light with linear polarization coinciding with that of incident beams. The high polarization of retroreflected waves suggests coherent backscattering as the underlying physical mechanism. This phenomenon resulting from multiple scattering is supposed to be possible in an absorbing medium owing to longitudinal electromagnetic waves generated at interfaces. Strong absorption for transverse waves has negligible effect on longitudinal ones and therefore does not prevent their multiple scattering but ensures a high refraction index promoting strong scattering. This hypothesis is supported by a theoretical model and calculations.

memristor 2018

Abstract: We demonstrate experimentally that single crystalline GaN nanomembranes arranged in simple networks exhibit learning mechanisms such as habituation and dishabituation followed by storage of the response to a certain electrical stimulus. These artificial learning mechanisms are analogous to non-associative learning processes which are identical in simple animals and human beings. We found that the learning time depends on the number of GaN membranes in parallel, and this parameter decreases by 30% when three memristors are connected in parallel compared to the learning time of a single memristor. Moreover, an increased number of parallel memristors reduces the eventual asymmetry in the temporal response of the circuit at positive and negative step voltages.

Plesco 2018 sci rep

Abstract: In the present work, we report on development of three-dimensional flexible architectures consisting of an extremely porous three-dimensional Aerographite (AG) backbone decorated by InP micro/nanocrystallites grown by a single step hydride vapor phase epitaxy process. The systematic investigation of the hybrid materials by scanning electron microscopy demonstrates a rather uniform spatial distribution of InP crystallites without agglomeration on the surface of Aerographite microtubular structures. X-ray diffraction, transmission electron microscopy and Raman scattering analysis demonstrate that InP crystallites grown on bare Aerographite are of zincblende structure, while a preliminary functionalization of the Aerographite backbone with Au nanodots promotes the formation of crystalline In2O3 nanowires as well as gold-indium oxide core-shell nanostructures. The electromechanical properties of the hybrid AG-InP composite material are shown to be better than those of previously reported bare AG and AG-GaN networks. Robustness, elastic behavior and excellent translation of the mechanical deformation to variations in electrical conductivity highlight the prospects of AG-InP applications in tactile/strain sensors and other device structures related to flexible electronics.

electr. chem 2017

Abstract: Electroplating is shown to represent a simple and effective tool for assessing the conductivity of InP nanostructures fabricated by electrochemical etching of InP wafers. A mixture of nanowalls, nanowires and nanobelts was fabricated by anodic etching of crystalline bulk n-InP with free electron concentration of 1.3 × 1018 cm−3 under applied voltage of 13 V. We found that electroplating of Au occurs differently on these three nanostructures under identical electroplating conditions. A monolayer of densely packed Au nanodots with the diameter of around 20 nm is deposited on nanowires, while the density of Au nanodots deposited on nanowalls proves to be much smaller. At the same time no electroplating occurs on nanobelts. The evidenced distinctive features of electroplating processing are determined by different electrical conductivities of InP nanostructures. The produced materials are characterized by scanning electron microscopy (SEM), high-resolution scanning transmission electron microscopy (HR-STEM), electron nano-diffraction, selected area electron diffraction (SAED), and energy dispersive X-ray analysis (EDAX).

doi: 10.1149/2.1071704jes