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Xiaoyin Li, Shunhong Zhang, Yaguang Guo, Fancy Qian Wang, Qian Wang
Palladium selenides have attracted considerable attention because of their intriguing properties and wide applications. Motivated by the successful synthesis of Pd₂Se₃ monolayer (Lin et al., Phys. Rev. Lett., 2017, 119, 016101), here we systematically study its physical properties and device applications using state-of-the-art first principles calculations. We demonstrate that the Pd₂Se₃ monolayer has a desirable quasi-direct band gap (1.39 eV) for light absorption, a high electron mobility (140.4 cm²V-1 s-1 ) and strong optical absorption (~10⁵ cm-1 ) in the visible solar spectrum, showing a great potential for absorber material in ultrathin photovoltaic devices...
October 14, 2018: Nanomaterials
Muhammad Ikram, Lujia Liu, He Lv, Yang Liu, Afrasiab Ur Rehman, Kan Kan, WeiJun Zhang, Lang He, Yang Wang, Ruihong Wang, Keying Shi
Synthesizing a gas sensor based on heterostructured nanomaterials (NMs) via a controllable morphology by a facile hydrothermal method is an area of frontier research. In the present work, we designed a facile strategy to synthesize a controllable morphology and composition for three component heterojunctions (MoS2 -Bi2 O3 -Bi2 S3 ) NMs using different hydrothermal reaction times. The Bi2 S3 easily form as an intermediate phase due to the strong interaction of the Bi2 O3 with MoS2 nanosheets (NSs). The as fabricated heterojunctions MB-5 NMs exhibited a sensitive response to NOx gas (Ra /Rg  = 10...
October 6, 2018: Journal of Hazardous Materials
Beata Bajorowicz, Ewa Kowalska, Joanna Nadolna, Zhishun Wei, Maya Endo, Bunsho Ohtani, Adriana Zaleska-Medynska
CdS quantum dot-decorated KNbO3 composite photocatalysts co-modified with Bi2S3 QDs were designed and synthesized by a combination of the hydrothermal method with a linker-assisted adsorption route, using starch and thioglycolic acid as capping agents, which facilitated the attachment of modifiers to the surface of potassium niobate. The quantum dots were successfully deposited onto the surface of the perovskite-type KNbO3 with a good dispersion and a stable heterostructure was formed. The as-prepared photocatalysts were subsequently characterized by UV-Vis diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) specific surface area, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) emission spectroscopy...
October 15, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Hong-En Wang, Kaili Yin, Xu Zhao, Ning Qin, Yu Li, Zhao Deng, Liuchun Zheng, Bao-Lian Su, Zhouguang Lu
A porous TiO2/BaTiO3 heterostructure composite has been developed as a polysulfide mediator for lithium-sulfur batteries. Superior electrochemical performance has been achieved, mainly attributed to the synergy of TiO2 and BaTiO3 with dual affinity to polysulfides from chemical and ferroelectric-induced polarization effects, and enhanced redox kinetics propelled by the TiO2/BaTiO3 heterojunctions.
October 15, 2018: Chemical Communications: Chem Comm
Agata Sabik, Piotr Mazur, Franciszek Gołek, Artur Trembulowicz, Grażyna Antczak
We have utilized scanning tunneling microscopy (STM) and low energy electron diffraction to determine the structural properties of two types of metal-phthalocyanines (MPcs), i.e., cobalt-phthalocyanine (CoPc) and hexadecafluorinated copper-phthalocyanine (F16 CuPc) on the Ag(100) surface. For coverage close to one monolayer, both systems form long-range ordered structures with square unit cells. The size and rotation of the unit cell with respect to the silver lattice depend on the chemical composition of MPc...
October 14, 2018: Journal of Chemical Physics
W Yang, H Graef, X Lu, G Zhang, T Taniguchi, K Watanabe, A Bachtold, E H T Teo, E Baudin, E Bocquillon, G Fève, J-M Berroir, D Carpentier, M O Goerbig, B Plaçais
Breakdown of the quantum Hall effect (QHE) is commonly associated with an electric field approaching the inter-Landau-level (LL) Zener field, the ratio of the Landau gap and the cyclotron radius. Eluded in semiconducting heterostructures, in spite of extensive investigation, the intrinsic Zener limit is reported here using high-mobility bilayer graphene and high-frequency current noise. We show that collective excitations arising from electron-electron interactions are essential. Beyond a noiseless ballistic QHE regime a large super-Poissonian shot noise signals the breakdown via inter-LL scattering...
September 28, 2018: Physical Review Letters
N Johnson, C Emary, S Ryu, H-S Sim, P See, J D Fletcher, J P Griffiths, G A C Jones, I Farrer, D A Ritchie, M Pepper, T J B M Janssen, M Kataoka
Using a recent time-of-flight measurement technique with 1 ps time resolution and electron-energy spectroscopy, we develop a method to measure the longitudinal-optical-phonon emission rate of hot electrons traveling along a depleted edge of a quantum Hall bar. Comparison to a single-particle model implies the scattering mechanism involves a two-step process via an intra-Landau-level transition. We show that this can be suppressed by control of the edge potential profile, and a scattering length >1  mm can be achieved, allowing the use of this system for scalable single-electron device applications...
September 28, 2018: Physical Review Letters
Muhammad Ismail, Ijaz Talib, Anwar Manzoor Rana, Tahira Akbar, Shazia Jabeen, Jinju Lee, Sungjun Kim
Memory devices with bilayer CeO2-x /ZnO and ZnO/CeO2-x heterostructures sandwiched between Ti top and Pt bottom electrodes were fabricated by RF-magnetron sputtering at room temperature. N-type semiconductor materials were used in both device heterostructures, but interestingly, change in heterostructure and electroforming polarity caused significant variations in resistive switching (RS) properties. Results have revealed that the electroforming polarity has great influence on both CeO2-x /ZnO and ZnO/CeO2-x heterostructure performance such as electroforming voltage, good switching cycle-to-cycle endurance (~ 102 ), and ON/OFF ratio...
October 11, 2018: Nanoscale Research Letters
Shubhankar Das, Liran Avraham, Yevgeniy Telepinsky, Vladislav Mor, Moty Schultz, Lior Klein
Spintronic devices often require the ability to locally change the magnetic configuration of ferromagnetic structures on a sub-micron scale. A promising route for achieving this goal is the use of heavy metal/ferromagnetic heterostructures where current flowing through the heavy metal layer generates field-like and anti-damping like torques on the magnetic layer. Commonly, such torques are used to switch magnets with a uniaxial anisotropy between two uniformly magnetized states. Here, we use such torques to switch magnetization in Ta/Ni0...
October 11, 2018: Scientific Reports
G Walters, M Wei, O Voznyy, R Quintero-Bermudez, A Kiani, D-M Smilgies, R Munir, A Amassian, S Hoogland, E Sargent
The quantum-confined Stark effect (QCSE) is an established optical modulation mechanism, yet top-performing modulators harnessing it rely on costly fabrication processes. Here, we present large modulation amplitudes for solution-processed layered hybrid perovskites and a modulation mechanism related to the orientational polarizability of dipolar cations confined within these self-assembled quantum wells. We report an anomalous (blue-shifting) QCSE for layers that contain methylammonium cations, in contrast with cesium-containing layers that show normal (red-shifting) behavior...
October 11, 2018: Nature Communications
Jaewoo Shim, Sang-Hoon Bae, Wei Kong, Doyoon Lee, Kuan Qiao, Daniel Nezich, Yong Ju Park, Ruike Zhao, Suresh Sundaram, Xin Li, Hanwool Yeon, Chanyeol Choi, Hyun Kum, Ruoyu Yue, Guanyu Zhou, Yunbo Ou, Kyusang Lee, Jagadeesh Moodera, Xuanhe Zhao, Jong-Hyun Ahn, Christopher Hinkle, Abdallah Ougazzaden, Jeehwan Kim
Although flakes of two-dimensional (2D) heterostructures at micrometer scale can be formed with adhesive-tape methods, isolation of 2D flakes into monolayers is extremely time-consuming as it is a trial-and-error process. Controlling the number of 2D layers through direct growth also presents difficulty because of the high nucleation barrier on 2D materials. We demonstrate a layer-resolved 2D material splitting technique that permits the high-throughput production of multiple monolayers of wafer-scale (5 centimeter diameter) 2D materials by splitting single stacks of thick 2D materials grown on a single wafer...
October 11, 2018: Science
Xuerong Zheng, Yiqi Zhang, Hui Liu, Dongju Fu, Jianjun Chen, Jihui Wang, Cheng Zhong, Yida Deng, Xiaopeng Han, Wenbin Hu
Exploiting economical and high-performance bifunctional electrocatalysts toward hydrogen and oxygen evolution reactions (HER/OER) is at the heart of overall water splitting in large-scale application. Herein, an in situ and stepwise strategy for synthesizing core-shell Ni3 (S1- x Sex )2 @NiOOH (0 ≤ x ≤ 1) nanoarray heterostructures on nickel foam with tailored compositions for enhancing water-splitting performance is reported. A series of Ni3 (S1- x Sex )2 nanostructures is firstly grown on nickel foam via an in situ reaction in a heated polyol solution system...
October 11, 2018: Small
Yongbiao Zhai, Xueqing Yang, Feng Wang, Zongxiao Li, Guanglong Ding, Zhifan Qiu, Yan Wang, Ye Zhou, Su-Ting Han
Photonic memories as an emerging optoelectronic technology have attracted tremendous attention in the past few years due to their great potential to overcome the von Neumann bottleneck and to improve the performance of serial computers. Nowadays, the decryption technology for visible light is mature in photonic memories. Nevertheless, near-infrared (NIR) photonic memristors are less progressed. Herein, an NIR photonic memristor based on MoS2 -NaYF4 :Yb3+ , Er3+ upconversion nanoparticles (UCNPs) nanocomposites is designed...
October 10, 2018: Advanced Materials
Se-Yang Kim, Jung Hwa Kim, Sungwoo Lee, Jinsung Kwak, Yongsu Jo, Euijoon Yoon, Gun-Do Lee, Zonghoon Lee, Soon-Yong Kwon
The recent emergence of vertically stacked van der Waals (vdW) heterostructures provides new opportunities for these materials to be employed in a wide range of novel applications. Understanding the interlayer coupling in the stacking geometries of the heterostructures and its effect on the resultant material properties is particularly important for obtaining materials with desirable properties. Here, we report that the atomic bonding between stacked layers and thereby the interlayer properties of the vdW heterostructures can be well tuned by the substrate surface defects using WS2 flakes directly grown on graphene...
October 10, 2018: Nanoscale
Liying Zhang, Wei Qin, Leiqiang Li, Shunfang Li, Ping Cui, Yu Jia, Zhenyu Zhang
As a highly appealing new member of the two-dimensional (2D) materials family, stanene was first epitaxially grown on a three-dimensional topological insulator of Bi2Te3; yet, to date, a standing challenge is to drastically improve the overall quality of such stanene overlayers for a wide range of potential applications in next-generation quantum devices. Here we use state-of-the-art first-principles approaches to explore the atomistic growth mechanisms of stanene on different Bi2Te3(111)-based substrates, with intriguing discoveries...
October 10, 2018: Nanoscale
Martin Sheehan, Quentin M Ramasse, Hugh Geaney, Kevin M Ryan
Herein, we report a novel approach to form axial heterostructure nanowires composed of linearly distinct Ni silicide (Ni2Si) and Si segments via a one-pot solution synthesis method. Initially, Si nanowires are grown using Au seeds deposited on a Ni substrate with the Si delivery in the solution phase using a liquid phenylsilane precursor. Ni silicide then forms axially along the wires through progressive Ni diffusion from the growth substrate, with a distinct transition between the silicide and pure Si segments...
October 10, 2018: Nanoscale
Xiao Hu, Hang Wei, Jia Liu, Jian Zhang, Xiannian Chi, Peng Jiang, Lianfeng Sun
Engineering the morphology and structure of low-dimensional carbon nanomaterials is important to study their mechanical and electrical properties and even superconductivity. Herein, first the techniques that are used to engineer carbon nanotubes, including manipulation, morphology modification, and fabrication of complex nanostructures, are reviewed. This is followed by a summary of the methods applied to fabricate graphene nanostructures, such as heterostructures and nanoenvelopes of graphene. Lastly, an insight into the applications of low-dimensional-carbon-based electronics is given, such as carbon nanotube (CNT) transistors, graphene-based nanoenvelopes, and graphene-contacted CNT field-effect transistors (FETs), which are promising components in future electronics...
October 9, 2018: Advanced Materials
Muhammad Asif, Ayesha Aziz, Ghazala Ashraf, Zhengyun Wang, Junlei Wang, Muhammad Azeem, Xuedong Chen, Fei Xiao, Hongfang Liu
The development of structurally modified metal oxide heteroarchitectures with higher energy facets exposed has been of extensive research interests because of their unique construction and synergy effect of multi-functioning characteristics. In this study, we reported for the first time the development of a distinct type of gold nanoislands (AuNIs) on metal oxides (i.e., Cu2O-CuO) octadecahedral (ODH) heterostructures through galvanic exchange reaction, where Cu2O not only acts as stabilizer but also functions as reductant...
October 9, 2018: ACS Applied Materials & Interfaces
Yuan Li, Marek B Majewski, Saiful M Islam, Shiqiang Hao, Akshay A Murthy, Jennifer G DiStefano, Eve D Hanson, Yaobin Xu, C Wolverton, Mercouri G Kanatzidis, Michael R Wasielewski, Xinqi Chen, Vinayak P Dravid
Molybdenum disulfide (MoS2) has been recognized as a promising cost-effective catalyst for water-splitting hydrogen production. However, the desired performance of MoS2 is often limited by insufficient edge-terminated active sites, poor electrical conductivity, and inefficient contact to the supporting substrate. To address these limitations, we developed a unique nanoarchitecture, namely winged Au@MoS2 heterostructures enabled by our discovery of the "seeding effect" of Au nanoparticles for the chemical vapor deposition synthesis of vertically-aligned few-layer MoS2 wings...
October 8, 2018: Nano Letters
Johannes Christian Leutenantsmeyer, Josep Ingla-Aynés, Jaroslav Fabian, Bart J van Wees
We report the first observation of a large spin-lifetime anisotropy in bilayer graphene (BLG) fully encapsulated between hexagonal boron nitride. We characterize the out-of-plane (τ_{⊥}) and in-plane (τ_{∥}) spin lifetimes by oblique Hanle spin precession. At 75 K and the charge neutrality point (CNP), we observe a strong anisotropy of τ_{⊥}/τ_{∥}=8±2. This value is comparable to graphene-transition-metal-dichalcogenide heterostructures, whereas our high-quality BLG provides with τ_{⊥} up to 9 ns, a spin lifetime more than 2 orders of magnitude larger...
September 21, 2018: Physical Review Letters
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