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Jin H.,Shenzhen University | Li J.,Shenzhen University | Dai Y.,State Key Laboratory of Crystal Materials | Wei Y.,Shenzhen University
Physical Chemistry Chemical Physics | Year: 2017

In this paper, we present a comprehensive study on the electronic and optoelectronic properties of indium monochalcogenide (InX with X = S, Se, Te) monolayers with and without strains. Our results show that InX monolayers are indirect semiconductors. Upon the application of strain, the band structures can be modulated and an indirect-to-direct bandgap transition is observed in an InSe monolayer. The electron mobility of up to 2.0 × 103 cm2 (V s)-1 is quantitatively determined in the framework of deformation potential theory. Though the mobility of holes is relatively small, it can be greatly improved by introducing compressive strain, with a value up to 2.8 × 103 cm2 (V s)-1. In addition, the performance of the photoresponse of InX monolayers is evaluated based on first-principles calculations. Under illumination, the InX based systems exhibit high photoresponsivity (Rph = 0.18 A W-1) and external quantum efficiency (EQE = 62.5%), which can be further enhanced via strain. Owing to such excellent electronic and optoelectronic merits, InX monolayers will become promising candidates for next-generation ultrathin and flexible electronic and optoelectronic devices. © the Owner Societies 2017.


News Article | September 12, 2016
Site: www.materialstoday.com

A new aerogel nanomaterial that reduces the amount of noble metals, such as platinum or palladium, needed to make fuel cells should reduce the cost of such devices making them more commercially viable according to researchers in the USA and China. The aerogel could also improve efficiency. Chengzhou Zhu, Qiurong Shi, Shaofang Fu, Junhua Song, Dan Du, and Yuehe Lin of the Department of Mechanical and Materials Engineering, at Washington State University, Pullman and Haibing Xia of the State Key Laboratory of Crystal Materials, Shandong University, Jinan, have developed a rapid synthesis of aerogels that avoids the need for noble metals. The materials could find use in hydrogen-powered fuel cells as a novel component of this promising environmentally friendly energy solution for the generation of electricity. Aerogels are solids that are certainly worthy of their colloquial name of solid smoke in that they are 92 percent air by volume. They are powerful insulators and have found applications in diving wet suits, firefighting equipment and protective clothing, windows, in paints and as fuel cell catalysts. In this latter application it is the vast surface area per unit volume and high porosity that make the materials useful as catalytic components. The Washington State team has now created a series of bimetallic aerogels, that combine the relatively inexpensive transition metal copper with the precious noble metal which is needed in a smaller quantity in their aerogels. The team made the bimetallic aerogel system using their one-step, high-temperature reduction method to first create a hydrogel exploiting enhanced gelation kinetics. The hydrogel is, to all intents and purposes, the liquid-filled form of the aerogel. The liquid component can subsequently be removed by careful drying to leave behind the seemingly delicate three-dimensional network of the aerogel. The novel synthesis has reduced the standard manufacturing time of a hydrogel from three days to just six hours. "This will be a great advantage for large scale production," explains WSU's Zhu. The research was undertaken as part of WSU's Grand Challenges, a suite of research initiatives aimed at large societal issues. It is particularly relevant to the challenge of sustainable resources and its theme of energy. "The resultant PdCu aerogel with ultrathin nanowire networks exhibits excellent electrocatalytic performance toward ethanol oxidation, holding promise in fuel-cell applications," the team reports in the journal Advanced Materials [Zhu, et al., Adv. Mater. (2016) DOI: 10.1002/adma.201602546] David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase, he is author of the popular science book "Deceived Wisdom".


Jin H.,State Key Laboratory of Crystal Materials | Jin H.,University of British Columbia | Dai Y.,State Key Laboratory of Crystal Materials | Ma Y.-D.,State Key Laboratory of Crystal Materials | And 4 more authors.
Journal of Materials Chemistry C | Year: 2015

A three-dimensional (3D) topological Dirac semimetal (TDSM) Cd3As2 has very recently been discovered, which can be turned into a variety of quantum phases by breaking either time reversal symmetry or inversion symmetry. Here, we present a density functional theory (DFT) study to systematically investigate the doping effects of 3d transition-metal (TM) atoms (Ti:Cu) in Cd3As2. The results reveal that the introduced 3d TMs lower the symmetries of the system, resulting in massive Dirac fermions with gap opening at the Dirac point. The substitution of Cr atoms could tailor Cd3As2 to a ferromagnetic half-metal due to the effective p-d exchange. The Monte Carlo simulations predict that the Curie temperature (Tc) of Cr-Cd3As2 is up to room temperature, suggesting powerful potential for further spintronic applications. © 2015 The Royal Society of Chemistry.


Jin H.,State Key Laboratory of Crystal Materials | Jin H.,University of British Columbia | Dai Y.,State Key Laboratory of Crystal Materials | Ma X.-C.,State Key Laboratory of Crystal Materials | And 3 more authors.
RSC Advances | Year: 2015

Searching for novel photocatalysts is one of the most important topics in photocatalytic fields. For this purpose, in the present work, the structural, electronic, and optical properties of GeH as well as a GeH/graphene heterointerface are studied based on hybrid density functional calculations including the nonlocal van der Waals correction. Our results show that the strain-engineered GeH monolayer captures a broad range of the solar spectrum. Moreover, photogenerated electron-hole pairs can be efficiently separated in the GeH/graphene heterojunction by formation of a Schottky barrier. Comparing to a pure GeH monolayer, the hybrid GeH/graphene complex displays an enhanced optical absorption in the visible region, suggesting powerful potential in energy and environmental applications. This journal is © The Royal Society of Chemistry.


Zhang J.,CAS Technical Institute of Physics and Chemistry | Yu H.,State Key Laboratory of Crystal Materials | Li Y.,CAS Technical Institute of Physics and Chemistry | Li Y.,University of Chinese Academy of Sciences | And 3 more authors.
Optics Letters | Year: 2012

We report efficient, diode-pumped, self-frequency doubling (SFD) in the newly developed laser crystal Nd3+:Na3La 9O3(BO3)8 (Nd:NLBO). More than 730 mW of fundamental output power at 1072 nm was achieved with a slope efficiency of 16.2. With incident pump power of 8 W, 29 mW of green cw laser emission at 536 nm was observed with proper phase matching. This initial performance and the good optical properties of the crystalline host are encouraging for the development of a high power diode-pumped SFD visible light laser source. © 2012 Optical Society of America.


Wang Y.,Shandong Jiaotong University | Liu H.,State Key Laboratory of Crystal Materials
Advanced Materials Research | Year: 2011

In this paper, the Ti-O-Compound nanobelts from commercial TiO2 (annatase phase) were synthesized via the alkali-hydrothermal process. The as-synthesized nanobelts are sodium titanate, hydrogen titanate and anatase with general formula Na2Ti3O7, H2Ti 3O7 and TiO2, respectively. The nanobelts are characterized by Thermogravimetric/Differential Thermal Analysis (TG/DTA), X-ray Diffraction (XRD), Infrared Spectra (IR) and Scanning Electron Microscope (SEM) apparatuses. The characterization indicates that the nanobelts with typical widths of 50 to 200 nm, thicknesses of 20 to 50 nm, and up to a few millimeters in length. The conversion mechanisms between the layer titanate and anatase of nanobelts have been discussed in this study. © (2011) Trans Tech Publications, Switzerland.


Wang Z.,State Key Laboratory of Crystal Materials | Huang B.,State Key Laboratory of Crystal Materials | Dai Y.,Shandong University | Zhang X.,State Key Laboratory of Crystal Materials | And 5 more authors.
CrystEngComm | Year: 2012

3D hierarchical TiO 2 nanoboxes, enclosed by six ordered arranged TiO 2 nanorod arrays, were prepared via a template-engaged topotactic transformation process from TiOF 2 nanocubes. The lattice matching between TiOF 2 and anatase TiO 2 was regarded as the key for the preferential growth and ordered arrangement of the TiO 2 nanorods. © The Royal Society of Chemistry 2012.


PubMed | State Key Laboratory of Crystal Materials and Shandong University
Type: | Journal: Chemistry (Weinheim an der Bergstrasse, Germany) | Year: 2017

Two-dimensional atomically thick materials, reduced graphene oxide (RGO) and layered molybdenum disulphide (MoS2) have been potentially investigated as novel energy storage materials because of their distinct physicochemical properties. However, these materials suffer from rapid capacity decay and low rate capability. This study describes a facile binder-free approach to fabricate large-scale 3D network structure MoS2@carbon nanotube (CNT)/RGO composites for application in flexible supercapacitor devices. The as-obtained composites possess a hierarchical porosity and an interconnected framework. The electrochemical supercapacitive measurements of the MoS2@CNT/RGO electrode show a high specific capacitance of 129 mF cm-2 at 0.1 mA cm-2. Moreover, the symmetric supercapacitor devices based on the as-obtained composites exhibit a long lifetime (94.7% capacitance retention after 10,000 cycles) and a high electrochemical performance (29.7 mF cm-2). The present experimental findings will evoke scalable binder-free synthesis of MoS2@CNT/RGO hybrid electrodes with enhanced flexible supercapacitive performance in portable and wearable energy storage devices.


PubMed | State Key Laboratory of Crystal Materials and Shenzhen University
Type: | Journal: Physical chemistry chemical physics : PCCP | Year: 2017

In this paper, we present a comprehensive study on the electronic and optoelectronic properties of indium monochalcogenide (InX with X = S, Se, Te) monolayers with and without strains. Our results show that InX monolayers are indirect semiconductors. Upon the application of strain, the band structures can be modulated and an indirect-to-direct bandgap transition is observed in an InSe monolayer. The electron mobility of up to 2.0 10


PubMed | State Key Laboratory of Crystal Materials and Shenzhen University
Type: | Journal: Scientific reports | Year: 2016

Searching for novel photocatalysts is one of the most important topic in photocatalytic fields. In the present work, we propose a feasible approach to improve the photocatalytic activities of 2D bilayers through surface decoration, i.e. hydrogenation, halogenation, and hydroxylation. Our investigations demonstrate that after surface modification, the optical adsorption expands into the visible region, while a built-in electric field is induced due to the interlayer coupling, which can promote the charge separation for photogenerated electron-hole pairs. Our results show that the indirect-direct band gap transition of SiC, SnC, BN and GaN can be realised through adatom decoration. Furthermore, the surface-modified 2D bilayers have suitable VBM and CBM alignments with the oxidation and reduction potentials for water splitting, suggesting powerful potentials in energy and environmental applications.

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