共查询到20条相似文献，搜索用时 15 毫秒
1.
Antonio Politano Gennaro Chiarello Zhilin Li Vito Fabio Lin Wang Liwei Guo Xiaolong Chen Danil W. Boukhvalov 《Advanced functional materials》2018,28(23)
By means of density functional theory and experiments, surface chemical reactivity of single crystals of NbAs and TaAs Weyl semimetals is studied. Weyl semimetals exhibit outstanding reactivity toward simple molecules (oxygen, carbon monoxide, and water), with several active sites available for surface chemical reactions (adsorption, decomposition, formation of reaction products, recombination of decomposition fragments). When different chemical species are adsorbed on Weyl semimetals, strong lateral interactions between coadsorbed species occur, evidenced by CO‐promoted water decomposition at room temperature. The resulting ? OH groups react with CO to form HCOO, which is an intermediate species in water–gas shift reaction. These findings unambiguously demonstrate that Weyl semimetals could be effectively used in catalysis, whereas their employment in nanoelectronics or plasmonics is complicated by the poor ambient stability, due to the rapid surface oxidation, inevitably occurring unless protective capping layers are used. 相似文献
2.
Danil W. Boukhvalov Silvia Nappini Mykhailo Vorokhta Tevfik Onur Menteş Lesia Piliai Mohammad Panahi Francesca Genuzio Jessica De Santis Chia-Nung Kuo Chin Shan Lue Valentina Paolucci Andrea Locatelli Federica Bondino Antonio Politano 《Advanced functional materials》2021,31(50):2106228
Recently, germanium selenide (GeSe) has emerged as a promising van der Waals semiconductor for photovoltaics, solar light harvesting, and water photoelectrolysis cells. Contrary to previous reports claiming perfect ambient stability based on experiments with techniques without surface sensitivity, here, by means of surface-science investigations and density functional theory, it is demonstrated that actually both: i) the surface of bulk crystals; and ii) atomically thin flakes of GeSe are prone to oxidation, with the formation of self-assembled germanium-oxide skin with sub-nanometric thickness. Surface oxidation leads to the decrease of the bandgap of stoichiometric GeSe and GeSe1−x, while bandgap energy increases upon surface oxidation of Ge1−xSe. Remarkably, the formation of a surface oxide skin on GeSe crystals plays a key role in the physicochemical mechanisms ruling photoelectrocatalysis: the underlying van der Waals semiconductor provides electron–hole pairs, while the germanium-oxide skin formed upon oxidation affords the active sites for catalytic reactions. The self-assembled germanium-oxide/germanium-selenide heterostructure with different bandgaps enables the activation of photocatalytic processes by absorption of light of different wavelengths, with inherently superior activity. Finally, it is discovered that, depending on the specific solvent-GeSe interaction, the liquid phase exfoliation of bulk crystals can induce the formation of Se nanowires. 相似文献
3.
Danil W. Boukhvalov Raju Edla Anna Cupolillo Vito Fabio Raman Sankar Yanglin Zhu Zhiqiang Mao Jin Hu Piero Torelli Gennaro Chiarello Luca Ottaviano Antonio Politano 《Advanced functional materials》2019,29(18)
Materials exhibiting nodal‐line fermions promise superb impact on technology for the prospect of dissipationless spintronic devices. Among nodal‐line semimetals, the ZrSiX (X = S, Se, Te) class is the most suitable candidate for such applications. However, the surface chemical reactivity of ZrSiS and ZrSiSe has not been explored yet. Here, by combining different surface‐science tools and density functional theory, it is demonstrated that the formation of ZrSiS and ZrSiSe surfaces by cleavage is accompanied by the washing up of the exotic topological bands, giving rise to the nodal line. Moreover, while the ZrSiS has a termination layer with both Zr and S atoms, in the ZrSiSe surface, reconstruction occurs with the appearance of Si surface atoms, which is particularly prone to oxidation. It is demonstrated that the chemical activity of ZrSiX compounds is mostly determined by the interaction of the Si layer with the ZrX sublayer. A suitable encapsulation for ZrSiX should not only preserve their surfaces from interaction with oxidative species, but also provide a saturation of dangling bonds with minimal distortion of the surface. 相似文献
4.
Yangyang Wang Zeyuan Ni Qihang Liu Ruge Quhe Jiaxin Zheng Meng Ye Dapeng Yu Junjie Shi Jinbo Yang Ju Li Jing Lu 《Advanced functional materials》2015,25(1):68-77
It is an ongoing pursuit to use metal as a channel material in a field effect transistor. All metallic transistor can be fabricated from pristine semimetallic Dirac materials (such as graphene, silicene, and germanene), but the on/off current ratio is very low. In a vertical heterostructure composed by two Dirac materials, the Dirac cones of the two materials survive the weak interlayer van der Waals interaction based on density functional theory method, and electron transport from the Dirac cone of one material to the one of the other material is therefore forbidden without assistance of phonon because of momentum mismatch. First‐principles quantum transport simulations of the all‐metallic vertical Dirac material heterostructure devices confirm the existence of a transport gap of over 0.4 eV, accompanied by a switching ratio of over 104. Such a striking behavior is robust against the relative rotation between the two Dirac materials and can be extended to twisted bilayer graphene. Therefore, all‐metallic junction can be a semiconductor and novel avenue is opened up for Dirac material vertical structures in high‐performance devices without opening their band gaps. 相似文献
5.
Junfeng Gao Anna Cupolillo Silvia Nappini Federica Bondino Raju Edla Vito Fabio Raman Sankar Yong‐Wei Zhang Gennaro Chiarello Antonio Politano 《Advanced functional materials》2019,29(26)
Cadmium arsenide (Cd3As2) has recently attracted considerable interest for the presence of 3D massless Dirac fermions with ultrahigh mobility and magnetoresistance. However, its surface properties are currently largely unexplored both theoretically and experimentally, due to the very large unit cell and the challenging growth of single‐crystal samples, respectively. Here, by combining ab initio calculations with surface‐science spectroscopic experiments, the presence of a surface reconstruction is unveiled in centimeter‐scale (112)‐oriented Cd3As2 single‐crystal foils produced by the self‐selecting vapor growth. Outermost Cd atoms descend into the As‐sublayer with a subsequent self‐passivation of the dangling bonds with As atoms, forming the triangle lattice previously imaged by scanning tunneling microscopy. Moreover, the oxidation mechanism of this reconstructed surface, dominated by the formation of As? O? Cd bonds, is revealed. Interestingly, it is found that the band structure of the reconstructed surface of Cd3As2 is quite robust against surface oxidation. Both computational and experimental findings point to a successful exploitation in technology of Cd3As2 single crystals. 相似文献
6.
Jinjun Ding Chuanpu Liu Yuejie Zhang Vijaysankar Kalappattil Rui Yu Uppalaiah Erugu Jinke Tang Haifeng Ding Hua Chen Mingzhong Wu 《Advanced functional materials》2021,31(11):2008411
This article reports damping enhancement in a ferromagnetic NiFe thin film due to an adjacent α-Sn thin film. Ferromagnetic resonance studies show that an α-Sn film separated from a NiFe film by an ultrathin Ag spacer can cause an extra damping in the NiFe film that is three times bigger than the intrinsic damping of the NiFe film. Such an extra damping is absent in structures where the α-Sn film interfaces directly with a NiFe film, or is replaced by a β-Sn film. The data suggest that the extra damping is associated with topologically nontrivial surface states in the topological Dirac semimetal phase of the α-Sn film. This work suggests that, like topological insulators, topological Dirac semimetal α-Sn may have promising applications in spintronics. 相似文献
7.
太赫兹波具有安全性好、透射性强、指纹特性等特点,在无损探测、雷达成像、空间通信等领域展现出巨大的应用前景,在现阶段的科学研究中热度不减。狄拉克半金属具有量子反常霍尔效应、零带隙受拓扑保护和超高迁移率等特性,在太赫兹探测领域展现出非凡特性,为探索实现室温太赫兹探测提供了新思路。本文介绍了基于狄拉克半金属材料太赫兹光电探测器的研究现状,讨论了器件性能与探测机理,并对其在太赫兹光电探测领域的发展前景进行了展望。 相似文献
8.
Raul Santiago Isaac Alcón Jordi Ribas-Arino Mercè Deumal Ibério de P. R. Moreira Stefan T. Bromley 《Advanced functional materials》2021,31(6):2004584
Quantum materials hold huge technological promise but challenge the fundamental understanding of complex electronic interactions in solids. The Mott metal–insulator transition on half-filled lattices is an archetypal demonstration of how quantum states can be driven by electronic correlation. Twisted bilayers of 2D materials provide an experimentally accessible means to probe such transitions, but these seemingly simple systems belie high complexity due to the myriad of possible interactions. Herein, it is shown that electron correlation can be simply tuned in experimentally viable 2D hexagonally ordered covalent organic radical frameworks (2D hex-CORFs) based on single layers of half-filled stable radical nodes. The presented carefully procured theoretical analysis predicts that 2D hex-CORFs can be varied between a correlated antiferromagnetic Mott insulator state and a semimetallic state by modest out-of-plane compressive pressure. This work establishes 2D hex-CORFs as a class of versatile single-layer quantum materials to advance the understanding of low dimensional correlated electronic systems. 相似文献
9.
Philip Schulz Leah L. Kelly Paul Winget Hong Li Hyungchul Kim Paul F. Ndione Ajaya K. Sigdel Joseph J. Berry Samuel Graham Jean‐Luc Brédas Antoine Kahn Oliver L. A. Monti 《Advanced functional materials》2014,24(46):7381-7389
The interfacial electronic structure between oxide thin films and organic semiconductors remains a key parameter for optimum functionality and performance of next‐generation organic/hybrid electronics. By tailoring defect concentrations in transparent conductive ZnO films, we demonstrate the importance of controlling the electron transfer barrier at the interface with organic acceptor molecules such as C60. A combination of electron spectroscopy, density functional theory computations, and device characterization is used to determine band alignment and electron injection barriers. Extensive experimental and first principles calculations reveal the controllable formation of hybridized interface states and charge transfer between shallow donor defects in the oxide layer and the molecular adsorbate. Importantly, it is shown that removal of shallow donor intragap states causes a larger barrier for electron injection. Thus, hybrid interface states constitute an important gateway for nearly barrier‐free charge carrier injection. These findings open new avenues to understand and tailor interfaces between organic semiconductors and transparent oxides, of critical importance for novel optoelectronic devices and applications in energy‐conversion and sensor technologies. 相似文献
10.
11.
Zhibin Liu Hatem M. A. Amin Yuman Peng Manuel Corva Rossitza Pentcheva Kristina Tschulik 《Advanced functional materials》2023,33(1):2210945
Deciphering the influence of nanocatalyst morphology on their catalytic activity in the oxygen evolution reaction (OER), the limiting reaction in water splitting process, is essential to develop highly active precious metal-free catalysts, yet poorly understood. The intrinsic OER activity of Co3O4 nanocubes and spheroids is probed at the single particle level to unravel the correlation between exposed facets, (001) vs. (111), and activity. Single cubes with predominant (001) facets show higher activity than multi-faceted spheroids. Density functional theory calculations of different terminations and reaction sites at (001) and (111) surfaces confirm the higher activity of the former, expressed in lower overpotentials. This is rationalized by a change in the active site from octahedral to tetrahedral Co and the potential-determining step from *OH to *O for the cases with lowest overpotentials at the (001) and (111) surfaces, respectively. This approach enables the identification of highly active facets to guide shape-selective syntheses of improved metal oxide nanocatalysts for water oxidation. 相似文献
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13.
Stable oxide topological insulators (TIs) have been sought for years, but none have been found; whereas heavier (selenides, tellurides) chalcogenides can be TIs. The basic contradiction between topological insulation and thermodynamic stability is pointed out, offering a narrow window of opportunity. The electronic motif is first identified and can achieve topological band inversion in ABO3 as a lone‐pair, electron‐rich B atom (e.g., Te, I, Bi) at the octahedral site. Then, twelve ABO3 compounds are designed in the assumed cubic perovskite structure, which satisfy this electronic motif and are indeed found by density function theory calculations to be TIs. Next, it is illustrated that poorly screened ionic oxides with large inversion energies undergo energy‐lowering atomic distortions that destabilize the cubic TI phase and remove band inversion. The coexistence windows of topological band inversion and structure stability can nevertheless be expanded under moderate pressures (15 and 35 GPa, respectively, for BaTeO3 and RbIO3). This study traces the principles needed to design stable oxide topological insulators at ambient pressures as a) a search for oxides with small inversion energies; b) design of large inversion‐energy oxide TIs that can be stabilized by pressure; and c) a search for covalent oxides where TI‐removing atomic displacements can be effectively screened out. 相似文献
14.
Silvia Nappini Danil W. Boukhvalov Gianluca D'Olimpio Libo Zhang Barun Ghosh Chia‐Nung Kuo Haoshan Zhu Jia Cheng Michele Nardone Luca Ottaviano Debashis Mondal Raju Edla Jun Fuji Chin Shan Lue Ivana Vobornik Jory A. Yarmoff Amit Agarwal Lin Wang Lixue Zhang Federica Bondino Antonio Politano 《Advanced functional materials》2020,30(22)
By means of theory and experiments, the application capability of nickel ditelluride (NiTe2) transition‐metal dichalcogenide in catalysis and nanoelectronics is assessed. The Te surface termination forms a TeO2 skin in an oxygen environment. In ambient atmosphere, passivation is achieved in less than 30 min with the TeO2 skin having a thickness of about 7 Å. NiTe2 shows outstanding tolerance to CO exposure and stability in water environment, with subsequent good performance in both hydrogen and oxygen evolution reactions. NiTe2‐based devices consistently demonstrate superb ambient stability over a timescale as long as one month. Specifically, NiTe2 has been implemented in a device that exhibits both superior performance and environmental stability at frequencies above 40 GHz, with possible applications as a receiver beyond the cutoff frequency of a nanotransistor. 相似文献
15.
Mao-Hua Du Jiaqiang Yan Valentino R. Cooper Markus Eisenbach 《Advanced functional materials》2021,31(3):2006516
MnBi2Te4 and MnBi4Te7 are intrinsic antiferromagnetic topological insulators, offering a promising materials platform for realizing exotic topological quantum states. However, high densities of intrinsic defects in these materials not only cause bulk metallic conductivity, preventing the measurement of quantum transport in surface states, but may also affect magnetism and topological properties. In this paper, systematic density functional theory calculations reveal specific material chemistry and growth conditions that determine the defect formation and dopant incorporation in MnBi2Te4 and MnBi4Te7. The large strain induced by the internal heterostructure promotes the formation of large-size-mismatched antisite defects and substitutional dopants. The results here show that the abundance of antisite defects is responsible for the observed n-type metallic conductivity. A Te-rich growth condition is predicted to reduce the bulk free electron density, which is confirmed by experimental synthesis and transport measurements in MnBi2Te4. Furthermore, Na doping is proposed to be an effective acceptor dopant to pin the Fermi level within the bulk band gap to enable the observation of surface quantum transport. The defect engineering and doping strategies proposed here should stimulate further studies for improving synthesis and for manipulating magnetic and topological properties in MnBi2Te4, MnBi4Te7, and related magnetic topological insulators. 相似文献
16.
Youness Kaddar Wei Zhang Hanna Enriquez Yannick J. Dappe Azzedine Bendounan Gérald Dujardin Omar Mounkachi Abdallah El kenz Abdelilah Benyoussef Abdelkader Kara Hamid Oughaddou 《Advanced functional materials》2023,33(21):2213664
2D materials beyond graphene and in particular 2D semiconductors have raised interest due to their unprecedented electronic properties, such as high carrier mobility or tunable bandgap. Blue phosphorene is an allotrope of black phosphorene that resembles graphene as it presents a honeycomb structure. However, it is known to have semiconductor character and the crucial point is to determine whether this hexagonal phase of phosphorene presents Dirac fermions as in graphene. Here, the first compelling experimental evidence of Dirac fermions in blue phosphorene layer grown on Cu(111) surface is presented. The results highlight the formation of a highly ordered blue phosphorene sheet with a clear Dirac cone at the high symmetry points of the Brillouin Zone. The charge carriers behave as massless relativistic particles. Therefore, all the expectations held for graphene, such as high-speed electronic devices based on ballistic transport at room temperature, may also be applied to blue phosphorene. 相似文献
17.
Mingyan Liu Yibin Zhao Fang Wu Licheng Wang Jiamin Yao Yunwei Yang Cong Liu Yi Wan Erjun Kan 《Advanced Electronic Materials》2023,9(2):2201023
2D materials are regarded as ideal candidates for fabricating flexible devices in electronics, due to their intrinsic clean surface and malleability. However, due to the weak interaction between 2D materials and the substrates underneath, bending or stretching will inevitably cause severe slippage, which degrades the device's performance or even leads to failure. The realization of no slippage between 2D materials and substrates under ultrahigh strain has become a key topic in the field of flexible electronics. Here, a strategy to overcome this limitation, by which strain can be effectively transferred to 2D materials is demonstrated. By applying this improved method to few-layer β-InSe, it is found that the loaded strain reaches as high as 7.2% without any slippage, along with an apparent redshift of ≈4.18 cm−1 in Raman scattering signals. The evolution trend of bandgap observed in the luminous properties of β-InSe is consistent with the author's density functional theory (DFT) calculations. This convenient method can be intensively expanded to other van der Waals (vdW) layered materials and sheds light on flexible electronic applications. 相似文献
18.
Lei Zhang Tong Yang Muhammad Fauzi Sahdan Arramel Wenshuo Xu Kaijian Xing Yuan Ping Feng Wenjing Zhang Zhuo Wang Andrew T. S. Wee 《Advanced Electronic Materials》2021,7(11):2100559
2D platinum diselenide (PtSe2) has received significant attention for 2D transistor applications due to its high carrier mobility. Here, using molecular beam epitaxy, the growth of 2D PtSe2 is investigated on highly oriented pyrolytic graphite (HOPG) and their electronic properties are unveiled via X-ray photoelectron spectroscopy, Raman spectra, and scanning tunnelling microscopy/spectroscopy as well as density functional theory (DFT) calculations. PtSe2 adopts a layer-by-layer growth mode on HOPG and shows a decreasing bandgap with increasing layer number. For the layer numbers from one to four, PtSe2 has bandgaps of 2.0 ± 0.1, 1.1 ± 0.1, 0.6 ± 0.1, and 0.20 ± 0.1 eV, respectively, and becomes semimetal from the fifth layer. DFT calculations reproduce the layer-dependent evolution of both the bandgap and band edges, suggest an indirect bandgap structure, and elucidate the underlying physics at the atomic level. 相似文献
19.
光子晶体由于具有可设计、可调谐以及对光的超 常调控等优异性能,近年已成为重 要的光学拓扑态研究平台。狄拉克(Dirac)锥型线性色散的奇异特性可实现丰富的物理现 象,诸如Dirac振荡、拓扑边缘态、零折射率等,更是凝聚态拓扑现象的物理根源。本文重 点对近年Dirac光子晶体在面发射激光器中的应用进行了详细介绍,指出将Dirac光子晶 体引入到半导体激光器中,可 实现大面积超低阈值、高亮度、单纵模和单横模的拓扑腔面发射激光器(topological cavity surface emitting lasers,TCSELs),同时对基于Dirac光子晶体原理发展出的TCSELs进行了总结与展望。 相似文献
20.
Dozens of layered V2IV2VI6 (V=P, As, Sb, Bi; IV=Si, Ge, Sn, Pb; VI=S, Se, Te) materials are investigated, several of which have been successfully synthesized in experiment. Among them, nine strong topological insulators (TIs), two strong Z2 topological metals (TMs), and nearly twenty trivial insulators are predicted at their equilibrium structures. The TIs are in the (1;111) topological class, with energy gaps ranging from 0.04 to 0.2 eV. The strong Z2 TMs and the trivial insulators belong to the (1;111) and (0;000) topological classes, respectively. Small compressive strains easily turn some of the trivial insulators into strong TIs. This study enriches not only the family of topological materials but also the family of van der Waals layered materials, providing promising candidates for the future spintronic devices. 相似文献