| 1. |
- Langer, Judith, et al.
(författare)
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Present and Future of Surface-Enhanced Raman Scattering
- 2020
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-086X .- 1936-0851. ; 14:1, s. 28-117
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Forskningsöversikt (refereegranskat)abstract
- The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article. ©
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| 2. |
- Zhao, Bing, 1990, et al.
(författare)
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Electrically controlled spin-switch and evolution of Hanle spin precession in graphene
- 2019
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Ingår i: 2D Materials. - : IOP Publishing. - 2053-1583. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- Next generation of spintronic devices aims to utilize the spin-polarized current injection and transport to control the magnetization dynamics in the spin logic and memory technology. However, the detailed evolution process of the frequently observed bias current-induced sign change phenomenon of the spin polarization has not been examined in details and the underlying microscopic mechanism is not well understood. Here, we report the observation of a systematic evolution of the sign change process of Hanle spin precession signal in the graphene nonlocal spintronic devices at room temperature. By tuning the interface tunnel resistances of the ferromagnetic contacts to graphene, different transformation processes of Hanle spin precession signal are probed in a controlled manner by tuning the injection bias current/voltage. Detailed analysis and first-principles calculations indicate a possible magnetic proximity and the energy dependent electronic structure of the ferromagnet-graphene interface can be responsible for the sign change process of the spin signal and open a new perspective to realize a spin-switch at very low bias-current or voltage.
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| 3. |
- Zhang, Jinbao, et al.
(författare)
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Chemical Dopant Engineering in Hole Transport Layers for Efficient Perovskite Solar Cells : Insight into the Interfacial Recombination
- 2018
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Ingår i: ACS Nano. - : American Chemical Society (ACS). - 1936-0851 .- 1936-086X. ; 12:10, s. 10452-10462
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Tidskriftsartikel (refereegranskat)abstract
- Chemical doping of organic semiconductors has been recognized as an effective way to enhance the electrical conductivity. In perovskite solar cells (PSCs), various types of dopants have been developed for organic hole transport materials (HTMs); however, the knowledge of the basic requirements for being efficient dopants as well as the comprehensive roles of the dopants in PSCs has not been clearly revealed. Here, three copper-based complexes with controlled redox activities are applied as dopants in PSCs, and it is found that the oxidative reactivity of dopants presents substantial impacts on conductivity, charge dynamics, and solar cell performance. A significant improvement of open- circuit voltage (V-oc) by more than 100 mV and an increase of power conversion efficiency from 13.2 to 19.3% have been achieved by tuning the doping level of the HTM. The observed large variation of V-oc for three dopants reveals their different recombination kinetics at the perovskite/HTM interfaces and suggests a model of an interfacial recombination mechanism. We also suggest that the dopants in HTMs can also affect the charge recombination kinetics as well as the solar cell performance. Based on these findings, a strategy is proposed to physically passivate the electron- hole recombination by inserting an ultrathin Al2O3 insulating layer between the perovskite and the HTM. This strategy contributes a significant enhancement of the power conversion efficiency and environmental stability, indicating that dopant engineering is one crucial way to further improve the performance of PSCs.
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| 4. |
- Kang, Kai, et al.
(författare)
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Auction-based cloud service allocation and sharing for logistics product service system
- 2021
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 278
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Tidskriftsartikel (refereegranskat)abstract
- Sustainability is increasingly viewed as a desired goal of social development. The logistics industry without exception is aware of the importance of sustainable development. To achieve this goal, the logistics industry is leveraging cutting-edge technologies, such as product service systems (PSS) and cloud manufacturing (CMfg), to design logistics product service systems (LPSS). In LPSS, public logistics resources are allocated to customers and private logistics resources are shared between customers. However, logistics resource allocation and sharing services have been impeded by a lack of efficient methods. In this context, this paper proposes an auction-based cloud service allocation and sharing method for LPSS. Firstly, LPSS is defined and elaborated based on the adoption of PSS in the logistics industry. Secondly, multi-unit Vickery (MV) auctions and one-sided Vickrey-Clarke-Groves (O-VCG) combinatorial auctions are proposed to address logistics resource allocation and sharing problems respectively in LPSS. Two auctions are introduced specifically, and their relevant properties are investigated, including incentive compatibility, allocative efficiency, budget balance, and individual rationality. Thirdly, computational studies are conducted to examine the performance of two auctions. The results reveal that MV auctions can efficiently allocate public logistics resources through ensuring the utility of logistics service providers under dynamic supply and demand. Additionally, O-VCG auctions can effectively integrate and share idle private logistics resources, which promotes sustainability in the logistics industry. Through integrating MV auctions with O-VCG auctions, the utility of logistics service providers can be increased.
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| 5. |
- Xu, Chao, et al.
(författare)
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Interweaving metal-€“organic framework-templated Co-€“Ni layered double hydroxide nanocages with nanocellulose and carbon nanotubes to make flexible and foldable electrodes for energy storage devices
- 2018
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Ingår i: Journal of Materials Chemistry A. - 2050-7488. ; 6:47, s. 24050-24057
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Tidskriftsartikel (refereegranskat)abstract
- Metal–organic frameworks (MOFs) and nanocellulose represent emerging and traditional porous materials, respectively. The combination of these two materials in specific ways could generate novel nanomaterials with integrated advantages and versatile functionalities. This study outlines the development of hierarchical porous and conductive nanosheets based on zeolitic imidazolate framework-67 (ZIF-67, a Co-based MOF)-templated Co–Ni layered double hydroxide (LDH) nanocages, Cladophora cellulose (CC) nanofibers, and multi-walled carbon nanotubes (CNTs). The LDH–CC–CNT nanosheets can be used as flexible and foldable electrodes for energy storage devices (ESDs). The electrodes are associated with a high areal capacitance of up to 1979 mF cm−2 at a potential scan rate of 1 mV s−1. A flexible, foldable, and hybrid ESD is assembled from LDH–CC–CNT and CC–CNT electrodes with a PVA/KOH gel. The entire device has an areal capacitance of 168 mF cm−2 and an energy density of 0.6 mW h cm−3 (60 μW h cm−2), at a power density of 8.0 mW cm−3 (0.8 mW cm−2). These promising results demonstrate the potential of using MOFs and sustainable cellulose in flexible, foldable electronic energy storage devices.
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| 6. |
- Zhang, Xiaoli, et al.
(författare)
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Synergistic effects in biphasic nanostructured electrocatalyst : Crystalline core versus amorphous shell
- 2017
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Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 41, s. 788-797
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Tidskriftsartikel (refereegranskat)abstract
- The recent study on active amorphous catalytic materials provokes rethinking of the previous research on atomic and electronic structures in the crystalline catalyst. Is there any active catalyst with biphasic structure, in particular the integration of crystalline and amorphous components? Inspired by this question, a crystalline-amorphous biphasic quaternary oxide catalyst is novelly fabricated via one-step solvothermal method in this work. The as-prepared catalyst displays a well-designed coreshell architecture composed of crystalline Co(ZnxNi2-x)O-4 nanorod (core) and amorphous NiO nanosheet (shell). This heterogeneous coreshell catalyst exhibits high activity in the oxygen evolution reaction by demonstrating a low over-potential of 1.57 V vs RHE, a high half-wave potential (0.89 V vs RHE), and long-term electrochemical stability for 25 h. It is found that the synergistic effects from the amorphization of the shell on the one hand, and the atomic/electronic structure of the crystalline core on the other hand, could significantly facilitate the catalytic activity both at the surface and in the bulk volume of the solid oxides. Therefore, this new developed crystalline-amorphous biphasic catalyst could provide instructive roles in the future design of new catalysts for O-2 evolution and other catalytic reactions.
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| 7. |
- Zhou, Shengyang, et al.
(författare)
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Cellulose Nanofiber @ Conductive Metal–Organic Frameworks for High-Performance Flexible Supercapacitors
- 2019
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Ingår i: ACS Nano. - : American Chemical Society. - 1936-0851 .- 1936-086X. ; 13:8, s. 9578-9586
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Tidskriftsartikel (refereegranskat)abstract
- Conductive metal–organic frameworks (c-MOFs) show great potential in electrochemical energy storage thanks to their high electrical conductivity and highly accessible surface areas. However, there are significant challenges in processing c-MOFs for practical applications. Here, we report on the fabrication of c-MOF nanolayers on cellulose nanofibers (CNFs) with formation of nanofibrillar CNF@c-MOF by interfacial synthesis, in which CNFs serve as substrates for growth of c-MOF nanolayers. The obtained hybrid nanofibers of CNF@c-MOF can be easily assembled into freestanding nanopapers, demonstrating high electrical conductivity of up to 100 S cm–1, hierarchical micromesoporosity, and excellent mechanical properties. Given these advantages, the nanopapers are tested as electrodes in a flexible and foldable supercapacitor. The high conductivity and hierarchical porous structure of the electrodes endow fast charge transfer and efficient electrolyte transport, respectively. Furthermore, the assembled supercapacitor shows extremely high cycle stability with capacitance retentions of >99% after 10000 continuous charge–discharge cycles. This work provides a pathway to develop flexible energy storage devices based on sustainable cellulose and MOFs.
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| 8. |
- Jiao, Xingxing, et al.
(författare)
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Crumpled Nitrogen-Doped Graphene-Wrapped Phosphorus Composite as a Promising Anode for Lithium-Ion Batteries
- 2019
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Ingår i: ACS Applied Materials & Interfaces. - : American Chemical Society (ACS). - 1944-8252 .- 1944-8244. ; 11:34, s. 30858-30864
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Tidskriftsartikel (refereegranskat)abstract
- Red phosphorus (P) has recently gained wide attention because of the high theoretical capacity of 2596 mA h/g, which has been regarded as promising anode material for lithium-ion batteries (LIBs). However, the actual application of red P in LIBs is hampered by the huge expansion of volume and low electronic conductivity. Herein, we design a kind of red phosphorus/crumpled nitrogen-doped graphene (P/CNG) nanocomposites with high capacity density and great rate performance as anode material for LIBs. This anode material was rationally fabricated through the scalable ball-milling method. The nanocomposite structure of P/CNG improves the electron conductivity and alleviates volume change of raw red P because of the three-dimension (3D) framework, massive defects and active sites of CNG sheets. As expected, the P/CNG composite shows excellent electrochemical performances, including high capacity (2522.6 mA h/g at 130 mA/g), remarkable rate capability (1340.5 mA h/g at 3900 mA/g), and great cyclability (1470.1 mA h/g at 1300 mA/g for 300 cycles). This work may provide a broad prospect for a great rate performance of P-based anode material for LIBs.
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| 9. |
- Li, Chexin, et al.
(författare)
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Room-Temperature Non-Local Spin Transport in Few-Layer Black Phosphorus Passivated with MgO
- 2022
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Ingår i: Advanced Electronic Materials. - : Wiley. - 2199-160X .- 2199-160X. ; 8:7
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Tidskriftsartikel (refereegranskat)abstract
- Black phosphorus (BP), a new member of 2D materials, is an ideal selection to construct spin-based devices due to its tunable direct bandgap and high carrier mobility. Assembling van der Waals heterostructures is the most popular method to create spintronic devices for 2D materials, especially for the easily oxidized BP. However, it is too complicated to be realized for fabricating large-scale integrated circuits in practical applications. To overcome this flaw, an oxide layer on BP simultaneously serving as the protection layer and barrier to fabricate a Co/MgO/BP-based non-local spin valve is employed. The non-local spin signals demonstrate the diffusion of pure spin current in the BP channel, which is the direct evidence of the spin injection from Co into BP. Combining the Hanle precession measurements with the Bloch equation fitting, the spin transport parameters of the few-layer BP can be extracted. The spin diffusion length λs and spin relaxation time τs are 6.15 µm and 241.7 ps, respectively. Therefore, the MgO layer in the non-local spin valve can simplify the fabrication of 2D material-based spintronic devices and accelerate their applications.
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| 10. |
- Shao, Wen-Ze, et al.
(författare)
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On potentials of regularized Wasserstein generative adversarial networks for realistic hallucination of tiny faces
- 2019
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Ingår i: Neurocomputing. - : ELSEVIER. - 0925-2312 .- 1872-8286. ; 364, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Super-resolution of facial images, a.k.a. face hallucination, has been intensively studied in the past decades due to the increasingly emerging analysis demands in video surveillance, e.g., face detection, verification, identification. However, the actual performance of most previous hallucination approaches will drop dramatically when a very low-res tiny face is provided, due to the challenging multimodality of the problem as well as lack of an informative prior as a strong semantic guidance. Inspired by the latest progress in deep unsupervised learning, this paper focuses on tiny faces of size 16 x 16 pixels, hallucinating them to their 8 x upsampling versions by exploring the potentials of Wasserstein generative adversarial networks (WGAN). Besides a pixel-wise L2 regularization term imposed to the generative model, it is found that our advocated autoencoding generator with both residual and skip connections is a critical component for WGAN representing the facial contour and semantic content to a reasonable precision. With the additional Lipschitz penalty and architectural considerations for the critic in WGAN, the proposed approach finally achieves state-of-the-art hallucination performance in terms of both visual perception and objective assessment. The cropped CelebA face dataset is primarily used to aid the tuning and analysis of the new method, termed as tfh-WGAN. Experimental results demonstrate that the proposed approach not only achieves realistic hallucination of tiny faces, but also adapts to pose, expression, illuminance and occluded variations to a great degree.
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