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Yalei Zhao, Wenlong Zhang, Bin Yang, Jingquan Liu, Xiang Chen, Xiaolin Wang, Chunsheng Yang
The gas sensing enhancement methods for hydrothermal synthesized SnO2-based gas sensors could be performed from three areas: structural improvement, composition optimization and processing improvement, which were aimed to improve the performance of the gas sensors. There was 0-D, 1-D and 3-D structures reported in literatures. Controllable synthesis of different structures was deployed to increase specific surface area. Change of composition would intensively tailor the SnO2 structure, which affected the gas sensing performance...
August 16, 2017: Nanotechnology
Jindřich Mach, Pavel Procházka, Miroslav Bartošík, David Nezval, Jakub Piastek, Jan Hulva, Vojtěch Švarc, Martin Konečný, Lukáš Kormoš, Tomas Sikola
In this work we present the effect of low dose gallium (Ga) deposition (< 4 ML) performed in UHV (10-7 Pa) on the electronic doping and charge carrier scattering in graphene grown by chemical vapor deposition (CVD). In-situ graphene transport measurements performed with a graphene field-effect transistor (FET) structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 electrons per one Ga atom, while the further deposition and Ga cluster formation results in removing electrons from graphene (less n-doping)...
August 16, 2017: Nanotechnology
Yuzhu Zhang, Jianping Xu, Shaobo Shi, Yanyan Gao, Xiangguo Zhao, Chengtai Wei, Xiaosong Zhang, Lan Li
MoS2 with layered structure and distinct physical properties has attracted attention for electronic or optoelectronic devices. The photoelectric response properties of MoS2/ZnO heterojunctions based devices fabricated by spin-coating MoS2 nanosheets solutions on ZnO nanorod arrays (NRs) were investigated. The results revealed that MoS2 nanosheets were vertically aligned on the surface of ZnO NRs and the devices exhibit good photoresponse stability and reproducibility under UV and red light illuminations. The vertically aligned MoS2 nanosheets facilitate the fast photogenerated carrier separation and transport...
August 16, 2017: Nanotechnology
G M Hasan Ul Banna, Ii-Kyu Park
We report on the fabrication of ZnO nanorod (NR)-based flexible piezoelectric nanogenerators (PENGs) on carbon paper (CP). Structural investigations indicate that the ZnO NRs grew well along the porous CP surface. Optical investigation shows that the crystal quality of the ZnO NRs on the CP was comparable to that of NRs grown on Si substrate. As the molar concentration increased from 10 to 70 mM, and the output voltage and current increased consistently from 3.6 to 6.8 V and 0.79 to 1.45 μA, respectively. The enhancements of the voltage and current were attributed to the enhanced accumulation of the potentials generated by the increased number of series-connected ZnO NRs in the PENG devices...
August 15, 2017: Nanotechnology
Mingming Zou, Lu Feng, Zhang Bingxue, Xinxin Zhou, Minghui Yang
A kind of surface complex (Triethylamine and mesoporous W-N-TiO2 microspheres with large surface area: 117.5 m2g-1) catalysis were achieved via visible-light photoredox catalysis. Triethylamine behaves as a true redox mediator due to donating ability seems to be highly favorable. With lower bandgap (2.43 eV) and more positive level of VBM (2.905 V), W-N-TiO2 sample has ability to play active catalytic role yielding excellent conversion of the selective oxidation of thioanisole (75.16 %) within 12 h visible light irradiation...
August 15, 2017: Nanotechnology
Shuai Jiang, Ingo Lieberwirth, Katharina Landfester, Rafael Munoz-Espi, Daniel Crespy
We present the design of multicompartment metal oxide/silica nanofibrous photocatalysts by colloid-electrospinning and subsequent calcination. During the calcination process, silica nanomaterials are cemented to form the fibrous framework and metal oxide precursors are crystallized inside and onto the fibers. This multicompartment nanofibrous structure, constructed with nanoparticles and core-shell nanocapsules, is therefore beneficial for the separation of the materials and the light utilization due to the multiple reflections and scattering of incident light in the cavities...
August 14, 2017: Nanotechnology
Changhai Liu, Yangyang Qiu, Yujian Xia, Fang Wang, Xiaocun Liu, Xuhui Jeff Sun, Qian Liang, Zhidong Chen
Developing active, stable, and low-cost electrocatalysts to generate hydrogen is a great challenge in the fields of chemistry and energy. The nonprecious metal catalysts comprised of inexpensive and earth-abundant transition metals, regarded as promising substitute for noble metal catalysts used in hydrogen evolution reaction (HER), are still practically unfeasible mainly due to unsatisfactory activity and durability. Here we report the facile two-step preparation method for WOx nanowires with high concentration of oxygen vacancies (OVs) via calcination of W-polydopamine compound precursors...
August 14, 2017: Nanotechnology
Qian Zhang, Jieqiong Hu, Diyuan Zheng, Anhua Dong, Hui Wang
We report a large magnetically tuned lateral photovoltaic effect (LPE) observed in nanoscale Co-SiO2-Si structures. This tunable effect strongly depends on the location of two electrodes. The change ratio of lateral photovoltage (LPV) can reach up to a considerable value of 94.15% under external magnetic field of 1.77 Teslas. This phenomenon is mainly ascribed to the asymmetric Lorentz force acting on the photo-current in the region of edge area of the nanostructure. It adds a new functionality to the traditional LPE-based devices, and provides a potential prospect for the development of multifunctional high-sensitive photoelectric devices or sensors...
August 14, 2017: Nanotechnology
Federica Rigoni, Rishi Maiti, Camilla Baratto, Maurizio Donarelli, Jennifer MacLeod, Bahrati Gupta, Mei Lyu, Andrea Ponzoni, Giorgio Sberveglieri, Nunzio Motta, Guido Faglia
An easy transfer procedure to obtain graphene-based gas sensing devices operating at room temperature is presented. Starting from chemical vapor deposition (CVD)-grown graphene on copper foil, we obtained single layer graphene which could be transferred onto arbitrary substrates. In particular, we placed single layer graphene on top of a SiO<sub>2</sub>/Si substrate with pre-patterned Pt electrodes to realize a chemiresistor gas sensor able to operate at room temperature. The responses to ammonia (10, 20, 30 ppm) and nitrogen dioxide (1, 2, 3 ppm) are shown at different values of relative humidity, in dark and under 254 nm UV light...
August 14, 2017: Nanotechnology
Fabrizio Porrati, Roland Sachser, Gian Carlo Gazzadi, Stefano Frabboni, Andreas Terfort, Michael Huth
The fabrication of nanopatterned multilayers, as used in optical and magnetic applications, is usually achieved by two independent steps, which consist in the preparation of multilayer films and in the successive patterning by means of lithography and etching processes. Here we show that multilayer nanostructures can be fabricated by using focused electron beam induced deposition (FEBID), which allows the direct writing of nanostructures of any desired shape with nanoscale resolution. In particular, [Co2Fe=Si]n multilayers are prepared by the alternating deposition from the metal carbonyl precursors, HFeCo3(CO)12 and Fe(CO)5, and neopentasilane, Si5H12...
August 14, 2017: Nanotechnology
Jue Wang, Shanlin Pan
We report fabricating vertically standing Ag nanoplates and nanowires on top of a transparent conductive substrate of indium tin oxides (ITO) with the assistance of porous anodic aluminum oxide (AAO) membrane. Two-dimensional Ag nanoplates are electrodeposited onto ITO surface which is covered with an AAO membrane without using an adhesion layer. Ag nanoplates obtained using AAO membranes majorly present 3×{222} superlattice fringes, different from the 3×{422} superlattice fringes reported in the previous study...
August 14, 2017: Nanotechnology
Dongju Lee, Jin-Ju Park, Min-Ku Lee, Gyoung-Ja Lee
Developing a thermally stable nanofluid that can maintain good thermo-conductive and flow performance at moderate or elevated temperatures for prolonged periods of time is a great challenge in heat transfer applications. Here, the thermal conductivity and rheological properties as well as their thermal stability characteristics of a nanofluid containing two-dimensional (2D) hexagonal boron nitride nanosheets (h-BNNSs) in ethylene glycol (EG) are presented, in comparison with those for a graphene oxide (GO) nanofluid as a counterpart...
August 14, 2017: Nanotechnology
Cheolsang Yoon, Hyo-Jun Kim, Myung-Hoon Kim, Kyusoon Shin, Young-Joo Kim, Kangtaek Lee
We present matrix-free methods for fabricating highly luminescent and transparent CdSe/ZnS quantum dot (QD)/polymer nanocomposites utilizing poly(methyl methacrylate) (PMMA)-grafted QDs with various molecular weights. We found that the QD-PMMA nanocomposites prepared by these matrix-free methods were superior to those prepared by a simple blending method in relation to their optical property, QD dispersion, and quantum efficiency. In particular, a matrix-free nanocomposite containing PMMA with a molecular weight of 2,000 had the highest quantum efficiency (52...
August 14, 2017: Nanotechnology
Yuefan Wei, Hejun Du, Junhua Kong, Van Thai Tran, Jia Kai Koh, Chenyang Zhao, Chaobin He
Zinc oxide (ZnO) has gained much attention nowadays due to its excellent physical and chemical properties, and been extensively studied in energy harvesting applications, such as photovoltaic and piezoelectric devices. In recent years, its reversible wettability has also been attracting increasing interests. The wettability of ZnO nanostructures with various morphologies was studied. However, to our best knowledge, there is still a lack of investigations on further modifications on ZnO to provide more benefits outweighed to pristine ZnO...
August 11, 2017: Nanotechnology
Lili Li, Jie Yang
Molecular dynamics simulation with the Stillinger-Weber potential is employed to study the mechanical behaviors of single-layer black phosphorus (SLBP) at different temperatures. The SLBP is initially loaded by a uniaxial tensile/compressive prestrain in either armchair or zigzag direction then stretched or compressed in the direction that is orthogonal to the direction of the prestrain. It is found that overall, mechanical properties such as tensile/compressive Young's modulus, tensile/compressive strength and yield strength are enhanced by a compressive prestrain but are reduced by a tensile prestrain, and that an armchair-oriented prestrain can improve mechanical properties more significantly than a zigzag-oriented prestrain...
August 10, 2017: Nanotechnology
Parikshit Sahatiya, Sushmee Badhulika
Electronic structure and carrier behavior in semiconductor junctions can be effectively modulated on application of strain. This work represents the first demonstration of large area, flexible, paper based Gr/MoS2 broadband photodetector using low-cost solution processed hydrothermal method and enhancement in photodetection through strain modulation by assembling the device on PDMS. Optimization in terms of process parameters were done to obtain trilayer MoS2 over Gr-cellulose paper. Under strain, potential barrier variation and piezopotential induced in MoS2 leads to 79...
August 10, 2017: Nanotechnology
Himanshu Sekhar Panda, Niraj Kumar, Viresh Kumar
We demonstrated a green, facile and rapid microwave-mediated process for fabricating carbon black (CB) incorporated Ni/Co hydroxide porous nanocomposite and studied the effect of various mass loading of CB on supercapacitor performance. Structure and interactions between CB and Ni/Co hydroxide are characterized by using X-Ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, which suggested the miniaturization of single phase Ni/Co hydroxide formation time. Morphology study revealed that the addition of CB in Ni/Co hydroxide develops loose network structure with well-defined architectural pores...
August 9, 2017: Nanotechnology
Sang Woo Seo, Ha Seung Lee, Dong Hee Shin, Ju Hwan Kim, Chan Wook Jang, Jong Min Kim, Sung Kim, Suk-Ho Choi
We first employ highly-stable and -flexible (CF<sub>3</sub>SO<sub>2</sub>)<sub>2</sub>NH-doped graphene (TFSA/GR) and GR-encapsulated TFSA/GR (GR/TFSA/GR) transparent conductive electrodes (TCEs) prepared on polyethylene terephthalate substrates for flexible organic solar cells (OSCs). Compared to conventional indium tin oxide (ITO) TCEs, the TFSA-doped-GR TCEs show higher optical transmittance and larger sheet resistance. The TFSA/GR and GR/TFSA/GR TCEs show work functions of 4...
August 9, 2017: Nanotechnology
Dongke Li, Yicheng Jiang, Jingjing Liu, Pei Zhang, Jun Xu, Wei Li, Kunji Chen
Here, we report the enhanced luminescence and optical gain by appropriate P doping in Si nanocrystals/SiO2 multilayers with ultra-small size of ~1.9nm. The luminescence intensity is enhanced by 19.4% comparing with that of un-doped one and the optical gain is as high as 171.8 cm-1, which can be attributed to the reduction of surface defect states by the passivation of P impurities as reveled by electron spin resonance spectra. Further increasing the P doping ratios results in the increase of conduction electrons due to the substitutionally doping of phosphorus into the Si NCs, which favors the Auger recombination process...
August 9, 2017: Nanotechnology
Akhil Ajay, Caroline Botum Lim, David Allan Browne, Jakub Polaczynski, Edith Bellet-Amalric, Joel Bleuse, Martien den Hertog, Eva Monroy
In this paper, we study band-to-band and intersubband characteristics of GaN/AlN heterostructures (planar and nanowires) structurally designed to absorb in the short-wavelength infrared region, particularly at 1.55 µm. We compare the effect of doping the GaN sections with Si and Ge, and we discuss the variation of free-carrier screening with the doping density and well/nanodisk size. We observe that nanowire heterostructures consistently present longer photoluminescence decay times than their planar counterparts, which supports the existence of an in-plane piezoelectric field associated to the sheer component of the strain tensor, leading to lateral electron-hole separation...
August 8, 2017: Nanotechnology
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