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Ruting Huang, Shoushuang Huang, Dayong Chen, Qian Zhang, Thanh-Tung Le, Qing Wang, Zhangjun Hu, Zhiwen Chen
One-dimensional (1D) heterostructured photocatalysts with controllable texture properties and compositions have attracted increasing interest owing to their unique optical, structural, and electronic advantages. Herein, 1D Co3 O4 -SnO2 heteronanorods were rationally designed and synthesized through a facile solution-based approach. Benefiting from both of their heterostructural and compositional characteristics, the resulting Co3 O4 -SnO2 heteronanorods exhibit high photocatalytic performance for the degradation of Rhodamine B (RhB) under visible-light irridation...
January 22, 2019: Journal of Colloid and Interface Science
Mengmeng Lao, Kun Rui, Guoqiang Zhao, Peixin Cui, Xusheng Zheng, Shi Xue Dou, Wenping Sun
Heterostructured nanomaterials, generally possessing unique physicochemical properties different from the individual components, have great potential in a wide range of applications. New platinum (Pt)/nickel bicarbonate (Ni(HCO3)2) heterostructures herein are designed towards efficient alkaline hydrogen evolution reaction (HER). Notably, the specific and mass activity of Pt in Pt/Ni(HCO3)2 are substantially improved as compared with bare Pt NPs. The Ni(HCO3)2 provides abundant water adsorption/dissociation sites and modulate the electronic structure of Pt, both of which determine the elementary reaction kinetics of alkaline HER...
February 15, 2019: Angewandte Chemie
Cheng Gong, Xiang Zhang
Magnetism, originating from the moving charges and spin of elementary particles, has revolutionized important technologies such as data storage and biomedical imaging, and continues to bring forth new phenomena in emergent materials and reduced dimensions. The recently discovered two-dimensional (2D) magnetic van der Waals crystals provide ideal platforms for understanding 2D magnetism, the control of which has been fueling opportunities for atomically thin, flexible magneto-optic and magnetoelectric devices (such as magnetoresistive memories and spin field-effect transistors)...
February 15, 2019: Science
Suman Bera, Amlan Roy, Amit K Guria, Sagar Mitra, Narayan Pradhan
Insights of formation mechanism of a dual layered and doped heterostructure material SnIIS-SnIV:Sb2S3 is reported. In presence of mixed alkyl thiols, first nanotubes of Sb2S3 were formed and then introducing Sn(IV), SnIIS were deposited onto the surface of these tubular structures. Annealing further at a constant temperature, sluggish transformation resulted Sn(II)S-Sn(IV) doped Sb2S3 heterostructure which finally turned to flake like layered doped Sb2S3 nanostructures. SnS and Sb2S3, both being layered materials, were explored for the study of Na-ion storage, and these heterostructures were observed superior in comparison to the individual material as well as the final doped nanostructures...
February 15, 2019: Journal of Physical Chemistry Letters
Yuan-Chang Liang, Yen-Chen Liu
In this study, TiO₂⁻ZnFe₂O₄ (ZFO) core-shell nanorods with various ZFO crystallite thicknesses were synthesized through sputtering-deposited ZFO thin films onto the surfaces of TiO₂ nanorods. By coupling the ZFO narrow bandgap oxide with TiO₂, an enhanced photodegradation efficiency of methylene orange under irradiation was achieved. Structural analyses revealed that ZFO crystallites fully covered the surfaces of the TiO₂ nanorods. The sputtering-deposited ZFO crystallites on the head region of the composite nanorods were markedly thicker than those covering the lateral region of the composite nanorods...
February 5, 2019: Nanomaterials
Dana Toloman, Ovidiu Pana, Maria Stefan, Adriana Popa, Cristian Leostean, Sergiu Macavei, Dan Silipas, Ioana Perhaita, Mihaela Diana Lazar, Lucian Barbu-Tudoran
Interface modified SnO2 -TiO2 composite nanoparticles were produced in two stages: first SnO2 nanoparticles were prepared by chemical precipitation in the presence of polyvinylpyrrolidone (PVP) and thermally treated at 500 °C then TiO2 was deposited on top of modified SnO2 and followed by a final annealing. As a consequence SnO2 -TiO2 composite nanoparticles get crystallized while PVP is decomposed into monomer units and other attached smaller molecular fragments. TGA coupled with FT-IR spectroscopy confirmed the presence of monomers and other moieties as a result of PVP thermal fragmentation...
February 7, 2019: Journal of Colloid and Interface Science
Yannick Hermans, Sebastián Murcia-López, Andreas Klein, Roel van de Krol, Teresa Andreu, Joan Ramón Morante, Thierry Toupance, Wolfram Jaegermann
The formation of heterostructures has proven to be a viable way to achieve high photoelectrochemical water splitting efficiencies with BiVO4 based photoanodes. Especially, cobalt and nickel based oxides are suitable low cost contact materials. However, the exact role of these contact materials is not yet completely understood because of the difficulty to individually quantify the effects of surface passivation, charge carrier separation and catalysis on the efficiency of a heterostructure. In this study, we used photoelectron spectroscopy in combination with in situ thin film deposition to obtain direct information on the interface structure between polycrystalline BiVO4 and NiO, CoOx and Sn-doped In2O3 (ITO)...
February 14, 2019: Physical Chemistry Chemical Physics: PCCP
Guangzhao Wang, Feng Zhou, Binfang Yuan, Shuyuan Xiao, Anlong Kuang, Mingmin Zhong, Suihu Dang, Xiaojiang Long, Wanli Zhang
By means of a hybrid density functional, we comprehensively investigate the energetic, electronic, optical properties, and band edge alignments of two-dimensional (2D) CdS/g-C 3 N 4 heterostructures by considering the effect of biaxial strain and pH value, so as to improve the photocatalytic activity. The results reveal that a CdS monolayer weakly contacts with g-C 3 N 4 , forming a type II van der Waals (vdW) heterostructure. The narrow bandgap makes CdS/g-C 3 N 4 suitable for absorbing visible light and the induced built-in electric field between the interface promotes the effective separation of photogenerated carriers...
February 12, 2019: Nanomaterials
Xiaotian Zhang, Fu Zhang, Yuanxi Wang, Daniel S Schulman, Tianyi Zhang, Anushka Bansal, Nasim Alem, Saptarshi Das, Vincent H Crespi, Mauricio Terrones, Joan M Redwing
A defect-controlled approach for the nucleation and epitaxial growth of WSe2 on hBN is demonstrated. The WSe2 domains exhibit a preferred orientation of over 95% leading to a reduced density of inversion domain boundaries (IDBs) upon coalescence. First-principles calculations and experimental studies as a function of growth conditions and substrate pre-treatment confirm that WSe2 nucleation density and orientation are controlled by the hBN surface defect density rather than thermodynamic factors. Detailed transmission electron microscopy (TEM) analysis provides support for the role of single-atom vacancies on the hBN surface which trap W atoms and break surface symmetry leading to a reduced formation energy for one orientation of WSe2 domains...
February 13, 2019: ACS Nano
Fangfang Zhang, Yajie Chen, Wei Zhou, Can Ren, Haijing Gao, Guohui Tian
Rational architectural design and catalyst components are beneficial to improve the photoelectrochemical performance. Herein, hierarchical SnS2/CuInS2 nanosheet heterostructure porous films were fabricated and decorated with C60 to form photocathodes for photoelectrochemical water reduction. Large-size CuInS2 nanosheet film was firstly grown on the transparent conducting glass to form substrate film. Then small-size SnS2 nanosheets were epitaxially grown on the double-side of CuInS2 nanosheets to form uniform hierarchical porous laminar film...
February 13, 2019: ACS Applied Materials & Interfaces
Linping Wang, Yue Meng, Chunxiu Zhang, Hongbo Xiao, Yunlong Li, Yueming Tan, Qingji Xie
The photoelectrochemistry (PEC) performance of TiO2 is somewhat limited by its wide band gap and low quantum efficiency, and the innovation of its composite materials provides a promising solution for an improved performance. Herein, a composite of an Au nanorod@TiO2 core-shell nanostructure (AuNR@TiO2) and a melanin-like L-DOPA polymer (PD) is designed and prepared, where the outer-layer PD tethered by the TiO2-hydroxyl complexation and the AuNR core can intensify the long-wavelength light harvesting, and the AuNR@TiO2 core-shell structure can strengthen the hot-electron transfer to TiO2...
February 13, 2019: ACS Applied Materials & Interfaces
S M Sadaf, Y-H Ra, S Zhao, T Szkopek, Z Mi
We have studied the epitaxy and structural characterization of monolithic n-GaN/Al/p-AlGaN nanowire heterostructures. It is found that high quality, nearly defect free, full shell epitaxial Al can be grown in situ on Al(Ga)N nanowires and vice versa. Detailed scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) suggest that the Al (111) plane maintains an epitaxial relationship with Al(Ga)N (0001) in the nanowire growth direction...
February 13, 2019: Nanoscale
Charlie Gréboval, Eva Izquierdo, Clément Livache, Bertille Martinez, Marion Dufour, Nicolas Goubet, Nicolas Moghaddam, Junling Qu, Audrey Chu, Julien Ramade, Hervé Aubin, Hervé Cruguel, Mathieu Silly, Emmanuel Lhuillier, Sandrine Ithurria
We demonstrate the growth of 2D nanoplatelets (NPLs) made of a HgTe/CdS heterostructure, with an optical absorption reaching the shortwave infrared range. The material is an interesting platform to investigate the effect of dimensionality (0D vs. 2D) and confinement on the electronic spectrum and carrier dynamics in colloidal materials. We bring consistent evidence for the p-type nature of this material from transport and photoemission measurements. The majority carrier dynamics probed using pump-probe photoemission is found to be mostly dependent on the presence of a confinement barrier at the surface rather than on the material dimensionality...
February 13, 2019: Nanoscale
Dae-Kyoung Kim, Seok-Bo Hong, Kwangsik Jeong, Changmin Lee, Hyoungsub Kim, Mann-Ho Cho
This study used a spatially controlled boron doping technique that enables a p-n junction diode to be realized within a single two-dimensional (2D) black phosphorus (BP) nanosheet for high performance photovoltaic application. The reliability of the BP surface and state-of-the-art 2D p-n heterostructure's gated junctions was obtained using the controllable pulsed plasma process technique. Chemical and structural analyses of the boron-doped BP were performed using X-ray photoelectron spectroscopy, transmission electron microscopy, and first-principles density functional theory (DFT) calculations, and the electrical characteristics of a field-effect transistor based on the p-n heterostructure were determined...
February 12, 2019: ACS Nano
Ailton J Garcia, Leonarde N Rodrigues, Saimon Filipe Covre da Silva, Sergio L Morelhão, Odilon D D Couto, Fernando Iikawa, Christoph Deneke
Overcoming the critical thickness limit in pseudomorphic growth of lattice mismatched heterostructures is a fundamental challenge in heteroepitaxy. On-demand transfer of light-emitting structures to arbitrary host substrates is an important technological method for optoelectronic and photonic device implementation. The use of freestanding membranes as compliant substrates is a promising approach to address both issues. In this work, the feasibility of using released GaAs/InGaAs/GaAs membranes as virtual substrates to thin films of InGaAs alloys is investigated as a function of the indium content in the films...
February 12, 2019: Nanoscale
Yan Shen, Huanjun Chen, Ningsheng Xu, Yang Xing, Hao Wang, Runze Zhan, Li Gong, Jinxiu Wen, Chao Zhuang, Xuexian Chen, Ximiao Wang, Yu Zhang, Fei Liu, Jun Chen, Juncong She, Shaozhi Deng
Light-driven electron emission plays an important role in modern optoelectronic devices. However, such a process usually requires a light field either with a high intensity or a high frequency, which is not favor for its implementations and difficult for its integrations. To solve these issues, we propose to combine plasmonic nanostructures with nano-electron-emitters of low work function. In such a heterostructure, hot-electrons generated by plasmon resonances upon light excitation can be directly injected into the adjacent emitter, which can subsequently be emitted into the vacuum...
February 12, 2019: ACS Nano
Qizhong Zhu, Matisse Wei-Yuan Tu, Qingjun Tong, Wang Yao
Van der Waals heterostructures of two-dimensional (2D) materials provide a powerful approach toward engineering various quantum phases of matter. Examples include topological matter such as quantum spin Hall (QSH) insulator and correlated matter such as exciton superfluid. It can be of great interest to realize these vastly different quantum phases matter on a common platform; however, their distinct origins tend to restrict them to material systems of incompatible characters. Here, we show that heterobilayers of 2D valley semiconductors can be tuned through interlayer bias between an exciton superfluid, a quantum anomalous Hall insulator, and a QSH insulator...
January 2019: Science Advances
N Peimyoo, M D Barnes, J D Mehew, A De Sanctis, I Amit, J Escolar, K Anastasiou, A P Rooney, S J Haigh, S Russo, M F Craciun, F Withers
Similar to silicon-based semiconductor devices, van der Waals heterostructures require integration with high- k oxides. Here, we demonstrate a method to embed and pattern a multifunctional few-nanometer-thick high- k oxide within various van der Waals devices without degrading the properties of the neighboring two-dimensional materials. This transformation allows for the creation of several fundamental nanoelectronic and optoelectronic devices, including flexible Schottky barrier field-effect transistors, dual-gated graphene transistors, and vertical light-emitting/detecting tunneling transistors...
January 2019: Science Advances
Chuang Han, Shao-Hai Li, Zi-Rong Tang, Yi-Jun Xu
Considerable effort has been devoted to manipulating the optical absorption of metal nanostructures for diverse applications. However, it still remains a challenge to develop a general and flexible method to promote broadband absorption of metal nanostructures without changing their size and shape. Here, we report a new strategy of hybridizing two conceptually different optical models to realize broadband absorption enhancement of metal nanoparticles (NPs), which is enabled by constructing a core-shell heterostructure, consisting of a spherical dielectric core covered by a metal NPs interlayer and tunable semiconductor shell...
December 28, 2018: Chemical Science
Wei Teng, Youmei Wang, Qin Lin, Hui Zhu, Yubin Tang, Xinyong Li
Molybdenum disulfide (MoS₂), as a typical layered transition metal sulfide, has been widely used in photocatalysis. Here, we report layered MoS₂ nanosheet-coated TiO₂ heterostructures that were prepared using a simple photo-assisted deposition method. The as-prepared samples were investigated in detail by using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Results demonstrated that the MoS₂ nanosheets uniformly covered the outer surface of TiO₂...
June 1, 2019: Journal of Nanoscience and Nanotechnology
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