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“Structure determination of spherical MCM-41 particles”. Pauwels B, Van Tendeloo G, Thoelen C, van Rhijn W, Jacobs PA, Advanced materials 13, 1317 (2001). http://doi.org/10.1002/1521-4095(200109)13:17<1317::AID-ADMA1317>3.0.CO;2-5
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 91
DOI: 10.1002/1521-4095(200109)13:17<1317::AID-ADMA1317>3.0.CO;2-5
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“Three-dimensional characterization of helical silver nanochains mediated by protein assemblies”. Leroux F, Gysemans M, Bals S, Batenburg KJ, Snauwaert J, Verbiest T, van Haesendonck C, Van Tendeloo G, Advanced materials 22, 2193 (2010). http://doi.org/10.1002/adma.200903657
Abstract: Characterization methods for the structural investigation of biotemplates for nanodevices remain widely unexplored, despite the fact that biotemplating methods for nanodevice fabrication are becoming more widespread. In this study several techniques are used to characterize the morphology and 3D distribution of silver nanoparticles deposited on insulin fibrils.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 19.791
Times cited: 51
DOI: 10.1002/adma.200903657
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“Tiling silicalite-1 nanoslabs into 3D mosaics”. Kremer SPB, Kirschhock CEA, Aerts A, Villani K, Martens JA, Lebedev OI, Van Tendeloo G, Advanced materials 15, 1705 (2003). http://doi.org/10.1002/adma.200305266
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 82
DOI: 10.1002/adma.200305266
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“Homojunction of oxygen and titanium vacancies and its interfacial n-p effect”. Wu S-M, Liu X-L, Lian X-L, Tian G, Janiak C, Zhang Y-X, Lu Y, Yu H-Z, Hu J, Wei H, Zhao H, Chang G-G, Van Tendeloo G, Wang L-Y, Yang X-Y, Su B-L, Advanced materials 30, 1802173 (2018). http://doi.org/10.1002/ADMA.201802173
Abstract: The homojunction of oxygen/metal vacancies and its interfacial n-p effect on the physiochemical properties are rarely reported. Interfacial n-p homojunctions of TiO2 are fabricated by directly decorating interfacial p-type titanium-defected TiO2 around n-type oxygen-defected TiO2 nanocrystals in amorphous-anatase homogeneous nanostructures. Experimental measurements and theoretical calculations on the cell lattice parameters show that the homojunction of oxygen and titanium vacancies changes the charge density of TiO2; a strong EPR signal caused by oxygen vacancies and an unreported strong titanium vacancies signal of 2D H-1 TQ-SQ MAS NMR are present. Amorphous-anatase TiO2 shows significant performance regarding the photogeneration current, photocatalysis, and energy storage, owing to interfacial n-type to p-type conductivity with high charge mobility and less structural confinement of amorphous clusters. A new homojunction of oxygen and titanium vacancies concept, characteristics, and mechanism are proposed at an atomic-/nanoscale to clarify the generation of oxygen vacancies and titanium vacancies as well as the interface electron transfer.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 39
DOI: 10.1002/ADMA.201802173
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“Electrostatic force-driven oxide heteroepitaxy for interface control”. Ren Z, Wu M, Chen X, Li W, Li M, Wang F, Tian H, Chen J, Xie Y, Mai J, Li X, Lu X, Lu Y, Zhang H, Van Tendeloo G, Zhang Z, Han G, Advanced materials 30, 1707017 (2018). http://doi.org/10.1002/ADMA.201707017
Abstract: Oxide heterostructure interfaces create a platform to induce intriguing electric and magnetic functionalities for possible future devices. A general approach to control growth and interface structure of oxide heterostructures will offer a great opportunity for understanding and manipulating the functionalities. Here, it is reported that an electrostatic force, originating from a polar ferroelectric surface, can be used to drive oxide heteroepitaxy, giving rise to an atomically sharp and coherent interface by using a low-temperature solution method. These heterostructures adopt a fascinating selective growth, and show a saturation thickness and the reconstructed interface with concentrated charges accumulation. The ferroelectric polarization screening, developing from a solid-liquid interface to the heterostructure interface, is decisive for the specific growth. At the interface, a charge transfer and accumulation take place for electrical compensation. The facile approach presented here can be extremely useful for controlling oxide heteroepitaxy and producing intriguing interface functionality via electrostatic engineering.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 4
DOI: 10.1002/ADMA.201707017
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“Liquid-alloy-assisted growth of 2D ternaryGa2In4S9 toward high-performance UV photodetection”. Wang F, Gao T, Zhang Q, Hu Z-Y, Jin B, Li L, Zhou X, Li H, Van Tendeloo G, Zhai T, Advanced materials 31, 1806306 (2019). http://doi.org/10.1002/ADMA.201806306
Abstract: 2D ternary systems provide another degree of freedom of tuning physical properties through stoichiometry variation. However, the controllable growth of 2D ternary materials remains a huge challenge that hinders their practical applications. Here, for the first time, by using a gallium/indium liquid alloy as the precursor, the synthesis of high-quality 2D ternary Ga2In4S9 flakes of only a few atomic layers thick (approximate to 2.4 nm for the thinnest samples) through chemical vapor deposition is realized. Their UV-light-sensing applications are explored systematically. Photodetectors based on the Ga2In4S9 flakes display outstanding UV detection ability (R-lambda = 111.9 A W-1, external quantum efficiency = 3.85 x 10(4)%, and D* = 2.25 x 10(11) Jones@360 nm) with a fast response speed (tau(ring) approximate to 40 ms and tau(decay) approximate to 50 ms). In addition, Ga2In4S9-based phototransistors exhibit a responsivity of approximate to 10(4) A W-1@360 nm above the critical back-gate bias of approximate to 0 V. The use of the liquid alloy for synthesizing ultrathin 2D Ga2In4S9 nanostructures may offer great opportunities for designing novel 2D optoelectronic materials to achieve optimal device performance.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19.791
Times cited: 29
DOI: 10.1002/ADMA.201806306
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“Nonlayered CdSe flakes homojunctions”. Jin B, Liang F, Hu Z-Y, Wei P, Liu K, Hu X, Van Tendeloo G, Lin Z, Li H, Zhou X, Xiong Q, Zhai T, Advanced Functional Materials 30, 1908902 (2020). http://doi.org/10.1002/ADFM.201908902
Abstract: 2D homojunctions have stimulated extensive attention because of their perfect thermal and lattice matches, as well as their tunable band structures in 2D morphology, which provide fascinating opportunities for novel electronics and optoelectronics. Recently, 2D nonlayered materials have attracted the attention of researchers owing to their superior functional applications and diverse portfolio of the 2D family. Therefore, 2D nonlayered homojunctions would open the door to a rich spectrum of exotic 2D materials. However, they are not investigated due to their extremely difficult synthesis methods. Herein, nonlayered CdSe flakes homojunctions are obtained via self-limited growth with InCl3 as a passivation agent. Interestingly, two pieces of vertical wurtzite-zinc blende (WZ-ZB) homojunctions epitaxially integrate into WZ/ZB lateral junctions. These homojunctions show a divergent second-harmonic generation intensity, strongly correlated to the multiple twinned ZB phase, as identified by aberration-corrected scanning transmission electron microscopy and theoretical calculations. Impressively, the photodetector based on this WZ/ZB CdSe homojunction shows excellent performances, integrating a high photoswitching ratio (3.4 x 10(5)) and photoresponsivity (3.7 x 10(3) A W-1), suggesting promising potential for applications in electronics and optoelectronics.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19
Times cited: 8
DOI: 10.1002/ADFM.201908902
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“Excellent excitonic photovoltaic effect in 2D CsPbBr₃/CdS heterostructures”. Jin B, Zuo N, Hu Z-Y, Cui W, Wang R, Van Tendeloo G, Zhou X, Zhai T, Advanced Functional Materials , 2006166 (2020). http://doi.org/10.1002/ADFM.202006166
Abstract: P-n photovoltaic junctions are essential building blocks for optoelectronic devices for energy conversion. However, this photovoltaic efficiency has almost reached its theoretical limit. Here, a brand-new excitonic photovoltaic effect in 2D CsPbBr3/CdS heterostructures is revealed. These heterostructures, synthesized by epitaxial growth, display a clean interface and a strong interlayer coupling. The excitonic photovoltaic effect is a function of both the built-in equilibrium electrical potential energy and the chemical potential energy, which is generated by the significant concentration gradient of electrons and holes at the heterojunction interface. Excitingly, this novel photovoltaic effect results in a large open-circuit voltage of 0.76 V and a high power conversion efficiency of 17.5%. In addition, high photodetection performance, including a high photoswitch ratio (I-light/I-dark) of 10(5)and a fast response rate of 23 mu s are obtained. These findings provide a new platform for photovoltaic applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19
Times cited: 1
DOI: 10.1002/ADFM.202006166
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“Atomically deciphering the phase segregation in mixed halide perovskite”. Yang C-Q, Yin Z-W, Li W, Cui W-J, Zhou X-G, Wang L-D, Zhi R, Xu Y-Y, Tao Z-W, Sang X, Cheng Y-B, Van Tendeloo G, Hu Z-Y, Su B-L, Advanced functional materials , 1 (2024). http://doi.org/10.1002/ADFM.202400569
Abstract: Mixed-halide perovskites show promising applications in tandem solar cells owing to their adjustable bandgap. One major obstacle to their commercialization is halide phase segregation, which results in large open-circuit voltage deficiency and J-V hysteresis. However, the ambiguous interplay between structural origin and phase segregation often results in aimless and unspecific optimization strategies for the device's performance and stability. An atomic scale is directly figured out the abundant Ruddlesden-Popper anti-phase boundaries (RP-APBs) within a CsPbIBr2 polycrystalline film and revealed that phase segregation predominantly occurs at RP-APB-enriched interfaces due to the defect-mediated lattice strain. By compensating their structural lead halide, such RP-APBs are eliminated, and the decreasing of strain can be observed, resulting in the suppression of halide phase segregation. The present work provides the deciphering to precisely regulate the perovskite atomic structure for achieving photo-stable mixed halide wide-bandgap perovskites of high-efficiency tandem solar cell commercial applications. The phase segregation in mixed halide perovskite film predominantly occurs at Ruddlesden-Popper anti-phase boundaries (RP-APBs)-enriched interfaces due to the defect-mediated lattice strain. The RP-APBs defects can be eliminated by compensating for their structural lead halide deficiency, resulting in the suppression of halide phase segregation. image
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19
DOI: 10.1002/ADFM.202400569
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“Mitigated oxygen loss in lithium-rich manganese-based cathode enabled by strong Zr-O affinity”. Wang G, Xie C, Wang H, Li Q, Xia F, Zeng W, Peng H, Van Tendeloo G, Tan G, Tian J, Wu J, Advanced functional materials , 2313672 (2024). http://doi.org/10.1002/ADFM.202313672
Abstract: Oxygen loss is a serious problem of lithium-rich layered oxide (LLO) cathodes, as the high capacity of LLO relies on reversible oxygen redox. Oxygen release can occur at the surface leading to the formation of spinel or rock salt structures. Also, the lattice oxygen will usually become unstable after long cycling, which remains a major roadblock in the application of LLO. Here, it is shown that Zr doping is an effective strategy to retain lattice oxygen in LLO due to the high affinity between Zr and O. A simple sol-gel method is used to dope Zr4+ into the LLOs to adjust the local electronic structure and inhibit the diffusion of oxygen anions to the surface during cycling. Compared with untreated LLOs, LLO-Zr cathodes exhibit a higher cycling stability, with 94% capacity retention after 100 cycles at 0.4 C, up to 223 mAh g-1 at 1 C, and 88% capacity retention after 300 cycles. Theoretical calculations show that due to the strong Zr-O covalent bonding, the formation energy of oxygen vacancies has effectively increased and the loss of lattice oxygen under high voltage can be suppressed. This study provides a simple method for developing high-capacity and cyclability Li-rich cathode materials for lithium-ion batteries. Oxygen release can occur at the cathode surface leading to the formation of spinel or rock salt structures. Here, it is shown that Zr doping is an effective strategy to retain lattice oxygen in lithium-rich layered oxides (LLO) due to the high affinity between Zr and O. LLO-Zr exhibit higher cycling stability, with 88% capacity retention after 300 cycles at 1 C. image
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 19
DOI: 10.1002/ADFM.202313672
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“Structural studies on superconducting materials and fullerites by electron microscopy”. Van Tendeloo G, Amelinckx S, Advanced materials 5, 620 (1993). http://doi.org/10.1002/adma.19930050904
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 17.493
Times cited: 2
DOI: 10.1002/adma.19930050904
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“High-voltage cycling induced thermal vulnerability in LiCoO₂, cathode : cation loss and oxygen release driven by oxygen vacancy migration”. Sun C, Liao X, Xia F, Zhao Y, Zhang L, Mu S, Shi S, Li Y, Peng H, Van Tendeloo G, Zhao K, Wu J, Acs Nano 14, 6181 (2020). http://doi.org/10.1021/ACSNANO.0C02237
Abstract: The release of the lattice oxygen due to the thermal degradation of layered lithium transition metal oxides is one of the major safety concerns in Li-ion batteries. The oxygen release is generally attributed to the phase transitions from the layered structure to spinel and rocksalt structures that contain less lattice oxygen. Here, a different degradation pathway in LiCoO2 is found, through oxygen vacancy facilitated cation migration and reduction. This process leaves undercoordinated oxygen that gives rise to oxygen release while the structure integrity of the defect-free region is mostly preserved. This oxygen release mechanism can be called surface degradation due to the kinetic control of the cation migration but has a slow surface to bulk propagation with continuous loss of the surface cation ions. It is also strongly correlated with the high-voltage cycling defects that end up with a significant local oxygen release at low temperatures. This work unveils the thermal vulnerability of high-voltage Li-ion batteries and the critical role of the surface fraction as a general mitigating approach.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 17.1
Times cited: 8
DOI: 10.1021/ACSNANO.0C02237
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“Direct observation of cation diffusion driven surface reconstruction at van der Waals gaps”. Cui W, Lin W, Lu W, Liu C, Gao Z, Ma H, Zhao W, Van Tendeloo G, Zhao W, Zhang Q, Sang X, Nature communications 14, 554 (2023). http://doi.org/10.1038/S41467-023-35972-9
Abstract: Weak interlayer van der Waals (vdW) bonding has significant impact on the surface/interface structure, electronic properties, and transport properties of vdW layered materials. Unraveling the complex atomistic dynamics and structural evolution at vdW surfaces is therefore critical for the design and synthesis of the next-generation vdW layered materials. Here, we show that Ge/Bi cation diffusion along the vdW gap in layered GeBi2Te4 (GBT) can be directly observed using in situ heating scanning transmission electron microscopy (STEM). The cation concentration variation during diffusion was correlated with the local Te-6 octahedron distortion based on a quantitative analysis of the atomic column intensity and position in time-elapsed STEM images. The in-plane cation diffusion leads to out-of-plane surface etching through complex structural evolutions involving the formation and propagation of a non-centrosymmetric GeTe2 triple layer surface reconstruction on fresh vdW surfaces, and GBT subsurface reconstruction from a septuple layer to a quintuple layer. Our results provide atomistic insight into the cation diffusion and surface reconstruction in vdW layered materials. Weak interlayer van der Waals (vdW) bonding has significant impact on the structure and properties of vdW layered materials. Here authors use in-situ aberration-corrected ADF-STEM for an atomistic insight into the cation diffusion in the vdW gaps and the etching of vdW surfaces at high temperatures.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 16.6
DOI: 10.1038/S41467-023-35972-9
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“Structure and microstructure of colossal magnetoresistant materials”. Van Tendeloo G, Lebedev OI, Hervieu M, Raveau B, Reports on progress in physics 67, 1315 (2004). http://doi.org/10.1088/0034-4885/67/8/R01
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 14.311
Times cited: 79
DOI: 10.1088/0034-4885/67/8/R01
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“Air- and water-resistant noble metal coated ferromagnetic cobalt nanorods”. Lentijo-Mozo S, Tan RP, Garcia-Marcelot C, Altantzis T, Fazzini PF, Hungria T, Cormary B, Gallagher JR, Miller JT, Martinez H, Schrittwieser S, Schotter J, Respaud M, Bals S, Van Tendeloo G, Gatel C, Soulantica K, ACS nano 9, 2792 (2015). http://doi.org/10.1021/nn506709k
Abstract: Cobalt nanorods possess ideal magnetic properties for applications requiring magnetically hard nanoparticles. However, their exploitation is undermined by their sensitivity toward oxygen and water, which deteriorates their magnetic properties. The development of a continuous metal shell inert to oxidation could render them stable, opening perspectives not only for already identified applications but also for uses in which contact with air and/or aqueous media is inevitable. However, the direct growth of a conformal noble metal shell on magnetic metals is a challenge. Here, we show that prior treatment of Co nanorods with a tin coordination compound is the crucial step that enables the subsequent growth of a continuous noble metal shell on their surface, rendering them air- and water-resistant, while conserving the monocrystallity, metallicity and the magnetic properties of the Co core. Thus, the as-synthesized coreshell ferromagnetic nanorods combine high magnetization and strong uniaxial magnetic anisotropy, even after exposure to air and water, and hold promise for successful implementation in in vitro biodiagnostics requiring probes of high magnetization and anisotropic shape.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 25
DOI: 10.1021/nn506709k
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“Atomic structure of quantum gold nanowires : quantification of the lattice strain”. Kundu P, Turner S, Van Aert S, Ravishankar N, Van Tendeloo G, ACS nano 8, 599 (2014). http://doi.org/10.1021/nn4052315
Abstract: Theoretical studies exist to compute the atomic arrangement in gold nanowires and the influence on their electronic behavior with decreasing diameter. Experimental studies, e.g., by transmission electron microscopy, on chemically synthesized ultrafine wires are however lacking owing to the unavailability of suitable protocols for sample preparation and the stability of the wires under electron beam irradiation. In this work, we present an atomic scale structural investigation on quantum single crystalline gold nanowires of 2 nm diameter, chemically prepared on a carbon film grid. Using low dose aberration-corrected high resolution (S)TEM, we observe an inhomogeneous strain distribution in the crystal, largely concentrated at the twin boundaries and the surface along with the presence of facets and surface steps leading to a noncircular cross section of the wires. These structural aspects are critical inputs needed to determine their unique electronic character and their potential as a suitable catalyst material. Furthermore, electron-beam-induced structural changes at the atomic scale, having implications on their mechanical behavior and their suitability as interconnects, are discussed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 20
DOI: 10.1021/nn4052315
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“Competing forces in the self-assembly of coupled ZnO nanopyramids”. Javon E, Gaceur M, Dachraoui W, Margeat O, Ackermann J, Ilenia Saba M, Delugas P, Mattoni A, Bals S, Van Tendeloo G, ACS nano 9, 3685 (2015). http://doi.org/10.1021/acsnano.5b00809
Abstract: Self-assembly (SA) of nanostructures has recently gained increasing interest. A clear understanding of the process is not straightforward since SA of nanoparticles is a complex multiscale phenomenon including different driving forces. Here, we study the SA between aluminum doped ZnO nanopyramids into couples by combining inorganic chemistry and advanced electron microscopy techniques with atomistic simulations. Our results show that the SA of the coupled nanopyramids is controlled first by morphology, as coupling only occurs in the case of pyramids with well-developed facets of the basal planes. The combination of electron microscopy and atomistic modeling reveals that the coupling is further driven by strong ligandligand interaction between the bases of the pyramids as dominant force, while screening effects due to Al doping or solvent as well as corecore interaction are only minor contributions. Our combined approach provides a deeper understanding of the complex interplay between the interactions at work in the coupled SA of ZnO nanopyramids.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 21
DOI: 10.1021/acsnano.5b00809
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“Hydrophobic interactions modulate self-assembly of nanoparticles”. Sánchez-Iglesias A, Grzelczak M, Altantzis T, Goris B, Pérez-Juste J, Bals S, Van Tendeloo G, Donaldson SH, Chmelka BF, Israelachvili JN, Liz-Marzán LM;, ACS nano 6, 11059 (2012). http://doi.org/10.1021/nn3047605
Abstract: Hydrophobic interactions constitute one of the most important types of nonspecific interactions in biological systems, which emerge when water molecules rearrange as two hydrophobic species come close to each other. The prediction of hydrophobic interactions at the level of nanoparticles (Brownian objects) remains challenging because of uncontrolled diffusive motion of the particles. We describe here a general methodology for solvent-induced, reversible self-assembly of gold nanoparticles into 3D clusters with well-controlled sizes. A theoretical description of the process confirmed that hydrophobic interactions are the main driving force behind nanoparticle aggregation.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 311
DOI: 10.1021/nn3047605
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“Knitting the catalytic pattern of artificial photosynthesis to a hybrid graphene nanotexture”. Quintana M, López AM, Rapino S, Toma FM, Iurlo M, Carraro M, Sartorel A, Maccato C, Ke X, Bittencourt C, Da Ros T, Van Tendeloo G, Marcaccio M, Paolucci F, Prato M, Bonchio M;, ACS nano 7, 811 (2013). http://doi.org/10.1021/nn305313q
Abstract: The artificial leaf project calls for new materials enabling multielectron catalysis with minimal overpotential, high turnover frequency, and long-term stability. Is graphene a better material than carbon nanotubes to enhance water oxidation catalysis for energy applications? Here we show that functionalized graphene with a tailored distribution of polycationic, quaternized, ammonium pendants provides an sp(2) carbon nanoplatform to anchor a totally inorganic tetraruthenate catalyst, mimicking the oxygen evolving center of natural PSII. The resulting hybrid material displays oxygen evolution at overpotential as low as 300 mV at neutral pH with negligible loss of performance after 4 h testing. This multilayer electroactive asset enhances the turnover frequency by 1 order of magnitude with respect to the isolated catalyst, and provides a definite up-grade of the carbon nanotube material, with a similar surface functionalization. Our innovation is based on a noninvasive, synthetic protocol for graphene functionalization that goes beyond the ill-defined oxidation-reduction methods, allowing a definite control of the surface properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 69
DOI: 10.1021/nn305313q
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“Light-induced selective deposition of Au nanoparticles on single-wall carbon nanotubes”. Quintana M, Ke X, Van Tendeloo G, Meneghetti M, Bittencourt C, Prato M, ACS nano 4, 6105 (2010). http://doi.org/10.1021/nn101183y
Abstract: Novel applications of single-walled carbon nanotubes (SWNT) rely on the development of new strategies to make them easier to handle without affecting their structural properties. In this work, we have selectively deposited Au nanoparticles (Au NP) on SWNT assisted by UV light irradiation. XPS analysis and UV-vis spectroscopy indicate that the deposition occurs at the defects generated after oxidation of the SWNT. By addition of n-dodecylthiol, the separation of oxidized tubes with Au NP (Au-ox-SWNT) from tubes devoid of Au NP (bare tubes, b-SWNT) was achieved. Raman and UV-vis-NIR spectra indicate that UV irradiation induces a faster nucleation of Au NP on metallic SWNT. This new technique can be useful for the preparation of nanohybrid composites with enhanced properties, as increased thermal stability, and to obtain purified SWNT.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 26
DOI: 10.1021/nn101183y
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“Measuring point defect density in individual carbon nanotubes using polarization-dependent X-ray microscopy”. Felten A, Gillon X, Gulas M, Pireaux J-J, Ke X, Van Tendeloo G, Bittencourt C, Najafi E, Hitchcock AP, ACS nano 4, 4431 (2010). http://doi.org/10.1021/nn1002248
Abstract: The presence of defects in carbon nanotubes strongly modifies their electrical, mechanical, and chemical properties. It was long thought undesirable, but recent experiments have shown that introduction of structural defects using ion or electron irradiation can lead to novel nanodevices. We demonstrate a method for detecting and quantifying point defect density in individual carbon nanotubes (CNTs) based on measuring the polarization dependence (linear dichroism) of the C 1s → π* transition at specific locations along individual CNTs with a scanning transmission X-ray microscope (STXM). We show that STXM can be used to probe defect density in individual CNTs with high spatial resolution. The quantitative relationship between ion dose, nanotube diameter, and defect density was explored by purposely irradiating selected sections of nanotubes with kiloelectronvolt (keV) Ga+ ions. Our results establish polarization-dependent X-ray microscopy as a new and very powerful characterization technique for carbon nanotubes and other anisotropic nanostructures.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 26
DOI: 10.1021/nn1002248
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“Surface-Facet-Dependent Phonon Deformation Potential in Individual Strained Topological Insulator Bi2Se3 Nanoribbons”. Yan Y, Zhou X, Jin H, Li C-Z, Ke X, Van Tendeloo G, Liu K, Yu D, Dressel M, Liao Z-M, ACS nano 9, 10244 (2015). http://doi.org/10.1021/acsnano.5b04057
Abstract: Strain is an important method to tune the properties of topological insulators. For example, compressive strain can induce superconductivity in Bi2Se3 bulk material. Topological insulator nanostructures are the superior candidates to utilize the unique surface states due to the large surface to volume ratio. Therefore, it is highly desirable to monitor the local strain effects in individual topological insulator nanostructures. Here, we report the systematical micro-Raman spectra of single strained Bi2Se3 nanoribbons with different thicknesses and different surface facets, where four optical modes are resolved in both Stokes and anti-Stokes Raman spectral lines. A striking anisotropy of the strain dependence is observed in the phonon frequency of strained Bi2Se3 nanoribbons grown along the ⟨112̅0⟩ direction. The frequencies of the in-plane Eg2 and out-of-plane A1g1 modes exhibit a nearly linear blue-shift against bending strain when the nanoribbon is bent along the ⟨112̅0⟩ direction with the curved {0001} surface. In this case, the phonon deformation potential of the Eg2 phonon for 100 nm-thick Bi2Se3 nanoribbon is up to 0.94 cm–1/%, which is twice of that in Bi2Se3 bulk material (0.52 cm–1/%). Our results may be valuable for the strain modulation of individual topological insulator nanostructures.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 14
DOI: 10.1021/acsnano.5b04057
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“Photovoltaic effect and evidence of carrier multiplication in graphene vertical homojunctions with asymmetrical metal contacts”. Chen JJ, Wang Q, Meng J, Ke X, Van Tendeloo G, Bie YQ, Liu J, Liu K, Liao ZM, Sun D, Yu D;, ACS nano 9, 8851 (2015). http://doi.org/10.1021/acsnano.5b02356
Abstract: Graphene exhibits exciting potentials for high-speed wideband photodetection and high quantum efficiency solar energy harvest because of its broad spectral absorption, fast photoelectric response, and potential carrier multiplication. Although photocurrent can be generated near a metalgraphene interface in lateral devices, the photoactive area is usually limited to a tiny one-dimensional line-like interface region. Here, we report photoelectric devices based on vertical graphene two-dimensional homojunction, which is fabricated via vertically stacking four graphene monolayers with asymmetric metal contacts. The devices show excellent photovoltaic output with excitation wavelength ranging from visible light to mid-infrared. The wavelength dependence of the internal quantum efficiency gives direct evidence of the carrier multiplication effect in graphene. The simple fabrication process, easy scale-up, large photoresponsive active area, and broadband response of the vertical graphene device are very promising for practical applications in optoelectronics and photovoltaics.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 11
DOI: 10.1021/acsnano.5b02356
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“Polyethylene glycol conjugated polymeric nanocapsules for targeted delivery of quercetin to folate-expressing cancer cells in vitro and in vivo”. El-Gogary RI, Rubio N, Wang JTW, Al-Jamal WT, Bourgognon M, Kafa H, Naeem M, Klippstein R, Abbate V, Leroux F, Bals S, Van Tendeloo G, Kamel AO, Awad GAS, Mortada ND, Al-Jamal KT;, ACS nano 8, 1384 (2014). http://doi.org/10.1021/nn405155b
Abstract: In this work we describe the formulation and characterization of chemically modified polymeric nanocapsules incorporating the anticancer drug, quercetin, for the passive and active targeting to tumors. Folic acid was conjugated to poly(lactide-co-glycolide) (PLGA) polymer to facilitate active targeting to cancer cells. Two different methods for the conjugation of PLGA to folic acid were employed utilizing polyethylene glycol (PEG) as a spacer. Characterization of the conjugates was performed using FTIR and H-1 NMR studies. The PEG and folk acid content was independent of the conjugation methodology employed. PEGylation has shown to reduce the size of the nanocapsule; moreover, zeta-potential was shown to be polymer-type dependent. Comparative studies on the cytotoxicity and cellular uptake of the different formulations by He La cells, in the presence and absence of excess folic acid, were carried out using MTT assay and Confocal Laser Scanning Microscopy, respectively. Both results confirmed the selective uptake and cytotoxicity of the folic acid targeted nanocapsules to the folate enriched cancer cells in a folate-dependent manner. Finally, the passive tumor accumulation and the active targeting of the nanocapsules to folate-expressing cells were confirmed upon intravenous administration in He La or IGROV-1 tumor-bearing mice. The developed nanocapsules provide a system for targeted delivery of a range of hydrophobic anticancer drugs in vivo.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 144
DOI: 10.1021/nn405155b
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“Self-organization of highly symmetric nanoassemblies : a matter of competition”. Galván-Moya JE, Altantzis T, Nelissen K, Peeters FM, Grzelczak M, Liz-Marán LM, Bals S, Van Tendeloo G, ACS nano 8, 3869 (2014). http://doi.org/10.1021/nn500715d
Abstract: The properties and applications of metallic nanoparticles are inseparably connected not only to their detailed morphology and composition but also to their structural configuration and mutual interactions. As a result, the assemblies often have superior properties as compared to individual nanoparticles. Although it has been reported that nanoparticles can form highly symmetric clusters, if the configuration can be predicted as a function of the synthesis parameters, more targeted and accurate synthesis will be possible. We present here a theoretical model that accurately predicts the structure and configuration of self-assembled gold nanoclusters. The validity of the model is verified using quantitative experimental data extracted from electron tomography 3D reconstructions of different assemblies. The present theoretical model is generic and can in principle be used for different types of nanoparticles, providing a very wide window of potential applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
Impact Factor: 13.942
Times cited: 34
DOI: 10.1021/nn500715d
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“Study of the interface between rhodium and carbon nanotubes”. Suarez-Martinez I, Ewels CP, Ke X, Van Tendeloo G, Thiess S, Drube W, Felten A, Pireaux J-J, Ghijsen J, Bittencourt C, ACS nano 4, 1680 (2010). http://doi.org/10.1021/nn9015955
Abstract: X-ray photoelectron spectroscopy at 3.5 keV photon energy, in combination with high-resolution transmission electron microscopy, is used to follow the formation of the interface between rhodium and carbon nanotubes. Rh nucleates at defect sites, whether initially present or induced by oxygen-plasma treatment. More uniform Rh cluster dispersion is observed on plasma-treated CNTs. Experimental results are compared to DFT calculations of small Rh clusters on pristine and defective graphene. While Rh interacts as strongly with the carbon as Ti, it is less sensitive to the presence of oxygen, suggesting it as a good candidate for nanotube contacts.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 26
DOI: 10.1021/nn9015955
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“Tailoring ZnSe-CdSe colloidal quantum dots via cation exchange : from core/shell to alloy nanocrystals”. Groeneveld E, Witteman L, Lefferts M, Ke X, Bals S, Van Tendeloo G, de Mello Donega C, ACS nano 7, 7913 (2013). http://doi.org/10.1021/nn402931y
Abstract: We report a study of Zn2+ by Cd2+ cation exchange (CE) in colloidal ZnSe nanocrystals (NCs). Our results reveal that CE in ZnSe NCs is a thermally activated isotropic process. The CE efficiency (i.e., fraction of Cd2+ ions originally in solution, Cdsol, that is incorporated in the ZnSe NC) increases with temperature and depends also on the Cdsol/ZnSe ratio. Interestingly, the reaction temperature can be used as a sensitive parameter to tailor both the composition and the elemental distribution profile of the product (Zn,Cd)Se NCs. At 150 °C ZnSe/CdSe core/shell hetero-NCs (HNCs) are obtained, while higher temperatures (200 and 220 °C) produce (Zn1xCdx)Se gradient alloy NCs, with increasingly smoother gradients as the temperature increases, until homogeneous alloy NCs are obtained at T ≥ 240 °C. Remarkably, sequential heating (150 °C followed by 220 °C) leads to ZnSe/CdSe core/shell HNCs with thicker shells, rather than (Zn1xCdx)Se gradient alloy NCs. Thermal treatment at 250 °C converts the ZnSe/CdSe core/shell HNCs into (Zn1xCdx)Se homogeneous alloy NCs, while preserving the NC shape. A mechanism for the cation exchange in ZnSe NCs is proposed, in which fast CE takes place at the NC surface, and is followed by relatively slower thermally activated solid-state cation diffusion, which is mediated by Frenkel defects. The findings presented here demonstrate that cation exchange in colloidal ZnSe NCs provides a very sensitive tool to tailor the nature and localization regime of the electron and hole wave functions and the optoelectronic properties of colloidal ZnSeCdSe NCs.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 153
DOI: 10.1021/nn402931y
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“Three-dimensional valency mapping in ceria nanocrystals”. Goris B, Turner S, Bals S, Van Tendeloo G, ACS nano 8, 10878 (2014). http://doi.org/10.1021/nn5047053
Abstract: Using electron tomography combined with electron energy loss spectroscopy (EELS), we are able to map the valency of the Ce ions in CeO2-x nanocrystals in three dimensions. Our results show a clear facet-dependent reduction shell at the surface of ceria nanoparticles; {111} surface facets show a low surface reduction, whereas at {001} surface facets, the cerium ions are more likely to be reduced over a larger surface shell. Our generic tomographic technique allows a full 3D data cube to be reconstructed, containing an EELS spectrum in each voxel. This possibility enables a three-dimensional investigation of a plethora of material-specific physical properties such as valency, chemical composition, oxygen coordination, or bond lengths, triggering the synthesis of nanomaterials with improved properties.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 85
DOI: 10.1021/nn5047053
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“Direct Observation of Luminescent Silver Clusters Confined in Faujasite Zeolites”. Altantzis T, Coutino-Gonzalez E, Baekelant W, Martinez GT, Abakumov AM, Van Tendeloo G, Roeffaers MBJ, Bals S, Hofkens J, ACS nano 10, 7604 (2016). http://doi.org/10.1021/acsnano.6b02834
Abstract: One of the ultimate goals in the study of metal clusters is the correlation between the atomic-scale organization and their physicochemical properties. However, direct observation of the atomic organization of such minuscule metal clusters is heavily hindered by radiation damage imposed by the different characterization techniques. We present direct evidence of the structural arrangement, at an atomic level, of luminescent silver species stabilized in faujasite (FAU) zeolites using aberration-corrected scanning transmission electron microscopy. Two different silver clusters were identified in Ag-FAU zeolites, a trinuclear silver species associated with green emission and a tetranuclear silver species related to yellow emission. By combining direct imaging with complementary information obtained from X-ray powder diffraction and Rietveld analysis, we were able to elucidate the main differences at an atomic scale between luminescent (heat-treated) and nonluminescent (cation-exchanged) Ag-FAU zeolites. It is expected that such insights will trigger the directed synthesis of functional metal nanocluster-zeolite composites with tailored luminescent properties.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 57
DOI: 10.1021/acsnano.6b02834
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“Selective laser-assisted synthesis of tubular van der Waals heterostructures of single-layered PbI2 within carbon nanotubes exhibiting carrier photogeneration”. Sandoval S, Kepic D, Perez del Pino A, Gyorgy E, Gomez A, Pfannmöller M, Van Tendeloo G, Ballesteros B, Tobias G, ACS nano 12, 6648 (2018). http://doi.org/10.1021/ACSNANO.8B01638
Abstract: The electronic and optical properties of two-dimensional layered materials allow the miniaturization of nanoelectronic and optoelectronic devices in a competitive manner. Even larger opportunities arise when two or more layers of different materials are combined. Here, we report on an ultrafast energy efficient strategy, using laser irradiation, which allows bulk synthesis of crystalline single-layered lead iodide in the cavities of carbon nanotubes by forming cylindrical van der Waals heterostructures. In contrast to the filling of van der Waals solids into carbon nanotubes by conventional thermal annealing, which favors the formation of inorganic nanowires, the present strategy is highly selective toward the growth of monolayers forming lead iodide nanotubes. The irradiated bulk material bearing the nanotubes reveals a decrease of the resistivity as well as a significant increase in the current flow upon illumination. Both effects are attributed to the presence of single-walled lead iodide nanotubes in the cavities of carbon nanotubes, which dominate the properties of the whole matrix. The present study brings in a simple, ultrafast and energy efficient strategy for the tailored synthesis of rolled-up single-layers of lead iodide (i.e., single-walled PbI2 nanotubes), which we believe could be expanded to other two-dimensional (2D) van der Waals solids. In fact, initial tests with ZnI2 already reveal the formation of single-walled ZnI2 nanotubes, thus proving the versatility of the approach.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 13.942
Times cited: 8
DOI: 10.1021/ACSNANO.8B01638
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