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“Insights into the Photoelectrocatalytic Behavior of gCN-Based Anode Materials Supported on Ni Foams”. Benedoue S, Benedet M, Gasparotto A, Gauquelin N, Orekhov A, Verbeeck J, Seraglia R, Pagot G, Rizzi GA, Balzano V, Gavioli L, Noto VD, Barreca D, Maccato C, Nanomaterials 13, 1035 (2023). http://doi.org/10.3390/nano13061035
Abstract: Graphitic carbon nitride (gCN) is a promising n-type semiconductor widely investigated for photo-assisted water splitting, but less studied for the (photo)electrochemical degradation of aqueous organic pollutants. In these fields, attractive perspectives for advancements are offered by a proper engineering of the material properties, e.g., by depositing gCN onto conductive and porous scaffolds, tailoring its nanoscale morphology, and functionalizing it with suitable cocatalysts. The present study reports on a simple and easily controllable synthesis of gCN flakes on Ni foam substrates by electrophoretic deposition (EPD), and on their eventual decoration with Co-based cocatalysts [CoO, CoFe2O4, cobalt phosphate (CoPi)] via radio frequency (RF)-sputtering or electrodeposition. After examining the influence of processing conditions on the material characteristics, the developed systems are comparatively investigated as (photo)anodes for water splitting and photoelectrocatalysts for the degradation of a recalcitrant water pollutant [potassium hydrogen phthalate (KHP)]. The obtained results highlight that while gCN decoration with Co-based cocatalysts boosts water splitting performances, bare gCN as such is more efficient in KHP abatement, due to the occurrence of a different reaction mechanism. The related insights, provided by a multi-technique characterization, may provide valuable guidelines for the implementation of active nanomaterials in environmental remediation and sustainable solar-to-chemical energy conversion.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 5.3
Times cited: 3
DOI: 10.3390/nano13061035
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“Realization of a tunable artificial atom at a supercritically charged vacancy in graphene”. Mao J, Jiang Y, Moldovan D, Li G, Watanabe K, Taniguchi T, Masir MR, Peeters FM, Andrei EY, Nature physics 12, 545 (2016). http://doi.org/10.1038/nphys3665
Abstract: Graphene’s remarkable electronic properties have fuelled the vision of a graphene-based platform for lighter, faster and smarter electronics and computing applications. One of the challenges is to devise ways to tailor graphene’s electronic properties and to control its charge carriers. Here we show that a single-atom vacancy in graphene can stably host a local charge and that this charge can be gradually built up by applying voltage pulses with the tip of a scanning tunnelling microscope. The response of the conduction electrons in graphene to the local charge is monitored with scanning tunnelling and Landau level spectroscopy, and compared to numerical simulations. As the charge is increased, its interaction with the conduction electrons undergoes a transition into a supercritical regime where itinerant electrons are trapped in a sequence of quasi-bound states which resemble an artificial atom. The quasi-bound electron states are detected by a strong enhancement of the density of states within a disc centred on the vacancy site which is surrounded by halo of hole states. We further show that the quasi-bound states at the vacancy site are gate tunable and that the trapping mechanism can be turned on and off, providing a mechanism to control and guide electrons in graphene.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 22.806
Times cited: 93
DOI: 10.1038/nphys3665
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“Asymmetric Modulation on Exchange Field in a Graphene/BiFeO3Heterostructure by External Magnetic Field”. Song H-D, Wu Y-F, Yang X, Ren Z, Ke X, Kurttepeli M, Tendeloo GV, Liu D, Wu H-C, Yan B, Wu X, Duan C-G, Han G, Liao Z-M, Yu D, Nano letters 18, 2435 (2018). http://doi.org/10.1021/acs.nanolett.7b05480
Abstract: Graphene, having all atoms on its surface, is favorable to extend the functions by introducing the spin–orbit coupling and magnetism through proximity effect. Here, we report the tunable interfacial exchange field produced by proximity coupling in graphene/BiFeO3 heterostructures. The exchange field has a notable dependence with external magnetic field, and it is much larger under negative magnetic field than that under positive magnetic field. For negative external magnetic field, interfacial exchange coupling gives rise to evident spin splitting for N ≠ 0 Landau levels and a quantum Hall metal state for N = 0 Landau level. Our findings suggest graphene/BiFeO3 heterostructures are promising for spintronics.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 12.712
Times cited: 9
DOI: 10.1021/acs.nanolett.7b05480
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“Monolayer graphene from graphite oxide”. Dideykin A, Aleksenskiy AE, Kirilenko D, Brunkov P, Goncharov V, Baidakova M, Sakseev D, Vul' AY, Diamond and related materials 20, 105 (2011). http://doi.org/10.1016/j.diamond.2010.10.007
Abstract: Graphene, a new carbon material, is attracting presently an increasing research interest. It stems from the unique electrical and mechanical properties of graphene predicted by theory. Experimental studies of graphene are, however, severely curtailed by a lack of an appropriate technique for its preparation. Mechanical cleavage of graphite proved to be ineffective, since it yields only very small (a few microns in size) particles of monolayer graphene. The rapidly developing approach based on chemical exfoliation of graphite produces large-area coatings composed primarily of arbitrarily oriented multilayer graphene particles. We have developed a technique for preparation of monolayer graphene sheets involving liquid exfoliation of crystalline graphite, which includes synthesis of graphite oxide by deep oxidation as an intermediate stage. Electron diffraction traces, as well as the variation of diffracted intensities with local orientation of graphene sheets, AFM, and HRTEM images testify to a remarkably good monolayer structure of the graphite oxide particles obtained by our technique. These results open a way to setting up high-efficiency production of monolayer graphene sheets appropriate for electrical and optical measurements and fabrication of structures for use in the field of applications.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 2.561
Times cited: 48
DOI: 10.1016/j.diamond.2010.10.007
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“Selective organic functionalization of graphene bulk or graphene edges”. Quintana M, Montellano A, Esau del Rio Castillo A, Van Tendeloo G, Bittencourt C, Prato M, Chemical communications 47, 9330 (2011). http://doi.org/10.1039/c1cc13254g
Abstract: Graphene sheets have been functionalized with a PAMAM dendron, finding that graphene can be efficiently functionalized all over the surface, or only at the edges, depending on the reactions used in the functionalization process.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 6.319
Times cited: 84
DOI: 10.1039/c1cc13254g
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“A graphene oxide amplification platform tagged with tyrosinase-zinc oxide quantum dot hybrids for the electrochemical sensing of hydroxylated polychlorobiphenyls”. Rather JA, Pilehvar S, De Wael K, Sensors and actuators : B : chemical 190, 612 (2014). http://doi.org/10.1016/J.SNB.2013.09.018
Abstract: Graphene oxide can act as an amplification platform for the immobilization of a hybrid structure composed of tyrosinase (Tyr) and zinc oxide quantum dots (ZnO QDs). This article describes how this platform increases the sensitivity for the detection of hydroxylated polychlorobiphenyls (OH-PCBs). The adsorption of Tyr (with low isoelectric point) on the positively charged surface of ZnO QDs is based on electrostatic interactions. The scanning electron microscopic images and UVvis spectroscopic analysis demonstrated the adsorption of Tyr on ZnO QDs. The stepwise assembly process of the fabricated biosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The synthesized ZnO QDs and graphene oxide were characterized by Raman spectroscopy, infrared spectroscopy, X-ray diffraction and scanning electron microscopic techniques. The determination of OH-PCBs was carried out by using square wave voltammetry over the concentration range of 2.827.65 μM with a detection limit of 0.15 μM with good reproducibility, selectivity and acceptable stability. The high value of surface coverage of ZnO QDs and small value of MichaelisMenten constant (View the MathML source) confirmed an excellent loading of the Tyr and a high affinity of the biosensor toward the detection of OH-PCBs. This biosensor and the described sensing platform offer a great potential for rapid, cost-effective and on-field analysis of OH-PCBs.
Keywords: A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 5.401
Times cited: 26
DOI: 10.1016/J.SNB.2013.09.018
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“Reduction-enhanced water flux through layered graphene oxide (GO) membranes stabilized with H3O+ and OH- ions”. Gogoi A, Neyts EC, Peeters FM, Physical chemistry, chemical physics 26, 10265 (2024). http://doi.org/10.1039/D3CP04097F
Abstract: Graphene oxide (GO) is one of the most promising candidates for next generation of atomically thin membranes. Nevertheless, one of the major issues for real world application of GO membranes is their undesirable swelling in an aqueous environment. Recently, we demonstrated that generation of H3O+ and OH- ions (e.g., with an external electric field) in the interlayer gallery could impart aqueous stability to the layered GO membranes (A. Gogoi, ACS Appl. Mater. Interfaces, 2022, 14, 34946). This, however, compromises the water flux through the membrane. In this study, we report on reducing the GO nanosheets as a solution to this issue. With the reduction of the GO nanosheets, the water flux through the layered GO membrane initially increases and then decreases again beyond a certain degree of reduction. Here, two key factors are at play. Firstly, the instability of the H-bond network between water molecules and the GO nanosheets, which increases the water flux. Secondly, the pore size reduction in the interlayer gallery of the membranes, which decreases the water flux. We also observe a significant improvement in the salt rejection of the membranes, due to the dissociation of water molecules in the interlayer gallery. In particular, for the case of 10% water dissociation, the water flux through the membranes can be enhanced without altering its selectivity. This is an encouraging observation as it breaks the traditional tradeoff between water flux and salt rejection of a membrane.
Keywords: A1 Journal article; Condensed Matter Theory (CMT); Modelling and Simulation in Chemistry (MOSAIC)
Impact Factor: 3.3
DOI: 10.1039/D3CP04097F
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“Effect of straining graphene on nanopore creation using Si cluster bombardment: A reactive atomistic investigation”. Berdiyorov GR, Mortazavi B, Ahzi S, Peeters FM, Khraisheh MK, Journal of applied physics 120, 225108 (2016). http://doi.org/10.1063/1.4971767
Abstract: Graphene nanosheets have recently received a revival of interest as a new class of ultrathin, high-flux, and energy-efficient sieving membranes because of their unique two-dimensional and atomically thin structure, good flexibility, and outstanding mechanical properties. However, for practical applications of graphene for advanced water purification and desalination technologies, the creation of well controlled, high-density, and subnanometer diameter pores becomes a key factor. Here, we conduct reactive force-field molecular dynamics simulations to study the effect of external strain on nanopore creation in the suspended graphene by bombardment with Si clusters. Depending on the size and energy of the clusters, different kinds of topography were observed in the graphene sheet. In all the considered conditions, tensile strain results in the creation of nanopores with regular shape and smooth edges. On the contrary, compressive strain increases the elastic response of graphene to irradiation that leads to the formation of net-like defective structures with predominantly carbon atom chains. Our findings show the possibility of creating controlled nanopores in strained graphene by bombardment with Si clusters. Published by AIP Publishing.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 2.068
Times cited: 10
DOI: 10.1063/1.4971767
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“Electronic Mach-Zehnder interference in a bipolar hybrid monolayer-bilayer graphene junction”. Mirzakhani M, Myoung N, Peeters FM, Park HC, Carbon 201, 734 (2023). http://doi.org/10.1016/J.CARBON.2022.09.058
Abstract: Graphene matter in a strong magnetic field, realizing one-dimensional quantum Hall channels, provides a unique platform for studying electron interference. Here, using the Landauer-Buttiker formalism along with the tightbinding model, we investigate the quantum Hall (QH) effects in unipolar and bipolar monolayer-bilayer graphene (MLG-BLG) junctions. We find that a Hall bar made of an armchair MLG-BLG junction in the bipolar regime results in valley-polarized edgechannel interferences and can operate a fully tunable Mach-Zehnder (MZ) interferometer device. Investigation of the bar-width and magnetic-field dependence of the conductance oscillations shows that the MZ interference in such structures can be drastically affected by the type of (zigzag) edge termination of the second layer in the BLG region [composed of vertical dimer or non-dimer atoms]. Our findings reveal that both interfaces exhibit a double set of Aharonov-Bohm interferences, with the one between two oppositely valley-polarized edge channels dominating and causing a large amplitude conductance oscillation ranging from 0 to 2e2/h. We explain and analyze our findings by analytically solving the Dirac-Weyl equation for a gated semi-infinite MLG-BLG junction.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 10.9
Times cited: 3
DOI: 10.1016/J.CARBON.2022.09.058
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“Modeling of edge scattering in graphene interconnects”. Contino A, Ciofi I, Wu X, Asselberghs I, Celano U, Wilson CJ, Tokei Z, Groeseneken G, Sorée B, IEEE electron device letters 39, 1085 (2018). http://doi.org/10.1109/LED.2018.2833633
Abstract: Graphene interconnects are being considered as a promising candidate for beyond CMOS applications, thanks to the intrinsic higher carrier mobility, lower aspect ratio and better reliability with respect to conventional Cu damascene interconnects. However, similarly to Cu, line edge roughness can seriously affect graphene resistance, something which must be taken into account when evaluating the related performance benefits. In this letter, we present a model for assessing the impact of edge scattering on the resistance of graphene interconnects. Our model allows the evaluation of the total mean free path in graphene lines as a function of graphene width, diffusive scattering probability and edge roughness standard deviation and autocorrelation length. We compare our model with other models from literature by benchmarking them using the same set of experimental data. We show that, as opposed to the considered models from literature, our model is capable to describe the mobility drop with scaling caused by significantly rough edges.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.048
Times cited: 1
DOI: 10.1109/LED.2018.2833633
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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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“Electric field activated hydrogen dissociative adsorption to nitrogen-doped graphene”. Ao ZM, Peeters FM, The journal of physical chemistry: C : nanomaterials and interfaces 114, 14503 (2010). http://doi.org/10.1021/jp103835k
Abstract: Graphane, hydrogenated graphene, was very recently synthesized and predicted to have great potential applications. In this work, we propose a new promising approach for hydrogenation of graphene based on density functional theory (DFT) calculations through the application of a perpendicular electric field after substitutionally doping by nitrogen atoms. These DFT calculations show that the doping by nitrogen atoms into the graphene layer and applying an electrical field normal to the graphene surface induce dissociative adsorption of hydrogen. The dissociative adsorption energy barrier of an H2 molecule on a pristine graphene layer changes from 2.7 to 2.5 eV on N-doped graphene, and to 0.88 eV on N-doped graphene under an electric field of 0.005 au. When increasing the electric field above 0.01 au, the reaction barrier disappears. Therefore, N doping and applying an electric field have catalytic effects on the hydrogenation of graphene, which can be used for hydrogen storage purposes and nanoelectronic applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 4.536
Times cited: 110
DOI: 10.1021/jp103835k
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“The evolution of twin patterns in perthitic K-feldspar from garnitic pegmatites”. Sánchez-Muñoz L, García-Guinea J, Zagorsky VY, Juwono T, Modreski PJ, Cremades A, Van Tendeloo G, de Moura OJM, Canadian mineralogist 50, 989 (2012). http://doi.org/10.3749/canmin.50.4.989
Abstract: Grains of K-feldspar are commonly seen as heterogeneous mixtures of mineral species and varieties with random microstructures. Most consider that observable features arise from incomplete re-equilibrations owing to slow kinetic and localized effects of aqueous fluids (catalyst), with geological environment and chemical impurities playing only a secondary role. Here, an alternative approach is explored by studying well-preserved regularities in the twin patterns of K-feldspars formed in the subsolidus stage from a historical perspective. Selected samples from granitic pegmatites were studied by polarized light optical microscopy (PLOM), electron-probe micro-analysis (EPMA), scanning (SEM) and transmission electron microscopy (TEM), cathodoluminescence imaging (CL), micro-Raman spectroscopy (MRS) and 31P nuclear magnetic resonance (NMR). We have found that the essential feature of this crystalline medium is the astounding capability to recrystallize in self-organized twin patterns. The mechanism involves coupling between short-range atomic motion, and long-range displacive correlations propagated as ideal and non-ideal Albite and Pericline orientations. We suggest a general evolutionary process to explain the development of macroscopic twin patterns in microcline, based on three twin generations as microtwins, macrotwins and cryptotwins. Evolutionary variants also were identified; they depend on both internal crystallochemical features and an external geological stimulus. We suggest a continuous monoclinictriclinic transformation for impure K-feldspar, whereas a discontinuous inversion occurs where the starting composition is close to the ideal chemical formula. Twin patterns can evolve by twin coarsening to single-orientation microcline if the system releases energy, or by twin fragmentation to finely twinned microcline if the system stores energy. Hence, K-feldspar is seen here as a very sensitive medium in which precious geological information is recorded in the form of twin patterns, and thus useful for general geological challenges.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 0.817
Times cited: 11
DOI: 10.3749/canmin.50.4.989
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“Grain-boundary-induced strain and distortion in epitaxial bilayer MoS₂, lattice”. Mehta AN, Mo J, Pourtois G, Dabral A, Groven B, Bender H, Favia P, Caymax M, Vandervorst W, Journal Of Physical Chemistry C 124, 6472 (2020). http://doi.org/10.1021/ACS.JPCC.0C01468
Abstract: Grain boundaries between 60 degrees rotated and twinned crystals constitute the dominant type of extended line defects in two-dimensional transition metal dichalcogenides (2D MX2) when grown on a single crystalline template through van der Waals epitaxy. The two most common 60 degrees grain boundaries in MX2 layers, i.e., beta- and gamma-boundaries, introduce distinct distortion and strain into the 2D lattice. They impart a localized tensile or compressive strain on the subsequent layer, respectively, due to van der Waals coupling in bilayer MX2 as determined by combining atomic resolution electron microscopy, geometric phase analysis, and density functional theory. Based on these observations, an alternate route to strain engineering through controlling intrinsic van der Waals forces in homobilayer MX2 is proposed. In contrast to the commonly used external means, this approach enables the localized application of strain to tune the electronic properties of the 2D semiconducting channel in ultra-scaled nanoelectronic applications.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.7
Times cited: 2
DOI: 10.1021/ACS.JPCC.0C01468
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Zhang K (2023) Revealing the correlation between titania support properties and propylphosphonic acid modification by in-depth characterization. XVI, 262 p
Abstract: Grafting organophosphonic acids modification (PAs) on metal oxides has shown to be a flexible technology to tune the surface properties of metal oxides for various applications. Nevertheless, there are still puzzles that need to be addressed, such as the correlations between metal oxides properties (types of surface reactive sites) and the modification (modification degree), the correlations between metal oxides properties and the properties of modified surfaces. Moreover, the currently used liquid-phase method for the grafting has associated impeding effects of solvent on tailoring the modification degrees, and also causes the formation of metal phosphonate side products. The solid-phase method can induce the unwanted changes in crystal phase of supports. Based on these questions, the three titania supports with divergent surface properties were selected as the metal oxides supports investigated, propylphosphonic acid (3PA) modification was carried out under the same synthesis conditions: four different concentrations, two solvents (water or toluene), and one reaction time (4 h) and temperature (90 ). MeOH chemisorption was introduced to probe the surface (un)reactive sites for 3PA modification. On the other hand, MeOH chemisorption and inverse gas chromatography (IGC) were combined to characterize the changes in surface polarity and acidic properties induced by the modification. Next, a solid-phase method, manual grinding, was proposed to graft 3PA on titania, avoiding the impeding effects of solvent on improving modification degree and the formation of the titania phosphonate side products, as well as preserving the crystal phase. The results indicate that methanol chemisorption can qualitatively analyze the surface active sites that are consumed by 3PA modification, its chemisorption capacity shows the consistent trend with the maximum modification degree, hereby revealing the kinds of interactions that are important in controlling surface coverage. Titania supports is found to play an important role in changes in surface polarity and acidic properties by charactering the three modified titania samples at a similar modification degree using the methanol chemisorption coupled with in-situ infrared and thermogravimetric-mass spectrometer, and the IGC. Moreover, IGC provides additional information about the changes in binding modes. Furthermore, grafting 3PA modification on titania was achieved by manual grinding. Compared to the liquid-phase method, the maximum modification degree obtained by the manual grinding is 25 % higher while using 83.3 % or 75.0% lower amounts of expensive 3PA and limiting the formation of titania phosphonate side products. Compared to the reactive milling method, the proposed manual grinding method preserves the crystal phase(s) of titania.
Keywords: Doctoral thesis; Laboratory of adsorption and catalysis (LADCA)
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Finizola e Silva M, Van Schoubroeck S, Cools J, Aboge DO, Ouma M, Olweny C, Van Passel S (2024) Local actors' perspectives on sustainable food value chains : evidence from a Q-methodology study in Kenya. 36–51
Abstract: Governments and international organizations are increasingly determined to create more sustainable food value chains (SFVCs). However, only little empirical evidence is available on how SFVCs are understood. Enquiring African food value chain actors allows gathering valuable insights into their perception of sustainability, which characteristics of sustainable food value chains they prioritize, and which obstacles to a sustainable transformation they identify. By means of a Q-methodology involving interviews with 33 Kenyan respondents, four perspectives were distinguished. The first perspective, “economic productivity and growth,” prioritizes economic growth and has only limited attention to the social dimension of sustainability. The second perspective, “food security and food availability,” believes that ensuring food security should be the key goal of SFVCs. The third perspective, “environment first,” is dedicated to the environmental dimension of sustainability; the perspective implies that protecting natural resources is the primary way to sustain this level of production. The fourth perspective, “transformative knowledge,” entails that by innovating and sharing knowledge, food value chains can become more sustainable in different areas. Overall, this study provides reliable insights into how Kenyan food value chain actors perceive sustainability in their sector and which elements they believe should be prioritized when rethinking food systems. The study results are valuable for policy-making to further define an SFVC in Kenya and to pave the way for a sustainable transformation of the food sector in developing countries.
Keywords: Administrative Services; A1 Journal article; Engineering sciences. Technology; Engineering Management (ENM)
DOI: 10.1007/S13412-023-00854-5
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“Investigating Reaction Intermediates during the Seedless Growth of Gold Nanostars Using Electron Tomography”. Choo P, Arenas-Esteban D, Jung I, Chang WJ, Weiss EA, Bals S, Odom TW, ACS nano 16, 4408 (2022). http://doi.org/10.1021/acsnano.1c10669
Abstract: Good’s buffers can act both as nucleating and shape- directing agents during the synthesis of anisotropic gold nanostars (AuNS). Although different Good’s buffers can produce AuNS shapes with branches that are oriented along specific crystallographic directions, the mechanism is not fully understood. This paper reports how an analysis of the intermediate structures during AuNS synthesis from HEPES, EPPS, and MOPS Good’s buffers can provide insight into the formation of seedless AuNS. Electron tomography of AuNS structures quenched at early times (minutes) was used to characterize the morphology of the incipient seeds, and later times were used to construct the growth maps. Through this approach, we identified how the crystallinity and shape of the first structures synthesized with different Good’s buffers determine the final AuNS morphologies.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 17.1
Times cited: 12
DOI: 10.1021/acsnano.1c10669
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“Gold-sputtered microelectrodes with built-in gold reference and counter electrodes for electrochemical DNA detection”. Thiruvottriyur Shanmugam S, Trashin S, De Wael K, Analyst (2020). http://doi.org/10.1039/D0AN01387K
Abstract: Gold-sputtered microelectrodes with built-in gold reference and counter electrodes represent a promising platform for the development of disposable DNA sensors. Pretreating gold electrode surfaces and immobilization of DNA thereon is commonly employed in biosensing applications. However, with no scientific or practical guidelines to prepare a DNA sensor using these miniature gold-sputtered microelectrodes, cleaning and immobilization steps need to be systematically optimized and updated. In this work, we present efficient cleaning and modification of miniaturized gold-sputtered microelectrodes with thiolated DNA probes for DNA detection. Additional discussions on subtleties and nuances involved at each stage of pretreating and modifying gold-sputtered microelectrodes are included to present a robust, well-founded protocol. It was evident that the insights on cleaning polycrystalline gold disk electrodes with a benchmark electrode surface for DNA sensors, cannot be transferred to clean these miniature gold-sputtered microelectrodes. Therefore, a comparison between five different cleaning protocols was made to find the optimal one for gold-sputtered microelectrodes. Additionally, two principally different immobilization techniques for gold-sputtered microelectrode modification with thiolated ssDNA were compared i.e., immobilization through passive chemisorption and potential perturbation were compared in terms of thiol-specific attachment and thiol-unspecific adsorption through nitrogenous bases. The hybridization performance of these prepared electrodes was characterized by their sensitive complementary DNA capturing ability, detected by a standard alkaline phosphatase assay. Immobilization through passive chemisorption proved to be efficient in capturing the complementary target DNA with a detection limit of 0.14 nM and sensitivity of 9.38 A M−1 cm2. In general, this work presents a comprehensive understanding of cleaning, modification and performance of gold-sputtered microelectrodes with built-in gold reference and counter electrodes for both fundamental investigations and practical DNA sensing applications.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 4.2
DOI: 10.1039/D0AN01387K
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“Predicting the surface plasmon resonance wavelength of gold-silver alloy nanoparticles”. Verbruggen SW, Keulemans M, Martens JA, Lenaerts S, The journal of physical chemistry: C : nanomaterials and interfaces 117, 19142 (2013). http://doi.org/10.1021/JP4070856
Abstract: Gold-silver alloy nanoparticles display surface plasmon resonance (SPR) over a broad range of the UV-vis spectrum. We propose a model to predict the SPR wavelength of gold-silver alloy colloids based on the combined effect of alloy composition and particle size. The SPR wavelength is derived from extinction spectra simulated using available experimental dielectric constant data and accounts for particle size by applying Mie theory. Comparison of calculated values with experimental data evidences the accuracy of the model. The new SPR wavelength estimation tool will be of particular interest for developing dedicated bimetallic plasmonic nanostructures.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
Impact Factor: 4.536
Times cited: 51
DOI: 10.1021/JP4070856
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“Formation and thermal stability of gold-silica nanohybrids : insight into the mechanism and morphology by electron tomography”. Kundu P, Heidari H, Bals S, Ravishankar N, Van Tendeloo G, Angewandte Chemie: international edition in English 53, 3970 (2014). http://doi.org/10.1002/anie.201309288
Abstract: Gold-silica hybrids are appealing in different fields of applications like catalysis, sensorics, drug delivery, and biotechnology. In most cases, the morphology and distribution of the heterounits play significant roles in their functional behavior. Methods of synthesizing these hybrids, with variable ordering of the heterounits, are replete; however, a complete characterization in three dimensions could not be achieved yet. A simple route to the synthesis of Au-decorated SiO2 spheres is demonstrated and a study on the 3D ordering of the heterounits by scanning transmission electron microscopy (STEM) tomography is presentedat the final stage, intermediate stages of formation, and after heating the hybrid. The final hybrid evolves from a soft self-assembled structure of Au nanoparticles. The hybrid shows good thermal stability up to 400 degrees C, beyond which the Au particles start migrating inside the SiO2 matrix. This study provides an insight in the formation mechanism and thermal stability of the structures which are crucial factors for designing and applying such hybrids in fields of catalysis and biotechnology. As the method is general, it can be applied to make similar hybrids based on SiO2 by tuning the reaction chemistry as needed.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 11.994
Times cited: 10
DOI: 10.1002/anie.201309288
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“Surfactant layers on gold nanorods”. Mosquera J, Wang D, Bals S, Liz-Marzan LM, Accounts of chemical research 56, 1204 (2023). http://doi.org/10.1021/ACS.ACCOUNTS.3C00101
Abstract: Gold nanorods (Au NRs) are an exceptionally promising tool in nanotechnology due to three key factors: (i) their strong interaction with electromagnetic radiation, stemming from their plasmonic nature, (ii) the ease with which the resonance frequency of their longitudinal plasmon mode can be tuned from the visible to the near-infrared region of the electromagnetic spect r u m based on their aspect ratio, and (iii) their simple and cost-effective preparation through seed-mediated chemical growth. In this synthetic method, surfactants play a critical role in controlling the size, shape, and colloidal stabi l i t y of Au NRs. For example, surfactants can stabilize specific crystallographic facets during the formation of Au NRs, leading to t h e formation of NRs with specific morphologies. The process of surfactant adsorption onto the NR surface may result in various assemblies of surfactant molecules, such as spherical micelles, elongated micelles, or bilayers. Again, the assembly mode is critical toward determining the further availabi l i t y of the Au NR surface to the surrounding medium. Despite its importance and a great deal of research effort, the interaction between Au NPs and surfactants remains insufficiently understood, because the assembly process is influenced by numerous factors, including the chemical nature of the surfactant, the surface morphology of Au NPs, and solution parameters. Therefore, gaining a more comprehensive understanding of these interactions is essential to unlock the full potential of the seed-mediated growth method and the applications of plasmonic NPs. A plethora of characterization techniques have been applied to reach such an understanding , but many open questions remain. In this Account, we review the current knowledge on the interactions between surfactants and Au NRs. We briefly introduce the state-of-the-art methods for synthesizing Au NRs and highlight the crucial role of cationic surfactants during this process. The self-assembly and organization of surfactants on the Au NR surface is then discussed to better understand their role in seed-mediated growth. Subsequently, we provide examples and elucidate how chemical additives can be used to modulate micellar assemblies, in turn allowing for a finer control over the growth of Au NRs, including chiral NRs. Next, we review the main experimental characterization and computational modeling techniques that have been applied to shed light on the arrangement of surfactants on Au NRs and summarize the advantages and disadvantages for each technique. The Account ends with a “Conclusions and Outlook” section, outlining promising future research directions and developments that we consider are sti l l required, mostly related to the application of electron microscopy in liquid and in 3D. Finally, we remark on the potential of exploiting machine learning techniques to predict synthetic routes for NPs with predefined structures and properties.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 18.3
Times cited: 8
DOI: 10.1021/ACS.ACCOUNTS.3C00101
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“Collective Plasmonic Properties in Few-Layer Gold Nanorod Supercrystals”. Hamon C, Novikov SM, Scarabelli L, Solís DM, Altantzis T, Bals S, Taboada JM, Obelleiro F, Liz-Marzán LM, ACS Photonics 2, 1482 (2015). http://doi.org/10.1021/acsphotonics.5b00369
Abstract: Gold nanorod supercrystals have been widely employed for the detection of relevant bioanalytes with detection limits ranging from nano- to picomolar levels,
confirming the promising nature of these structures for biosensing. Even though a relationship between the height of the supercrystal (i.e., the number of stacked nanorod layers)and the enhancement factor has been proposed, no systematic
study has been reported. In order to tackle this problem, we prepared gold nanorod supercrystals with varying numbers of stacked layers and analyzed them extensively by atomic force microscopy, electron microscopy and surface enhanced Raman scattering. The experimental results were compared to numerical
simulations performed on real-size supercrystals composed of thousands of nanorod building blocks. Analysis of the hot spot distribution in the simulated supercrystals showed the presence of standing waves that were distributed at different depths, depending on the number of layers in each supercrystal. On the basis of these theoretical results, we interpreted the experimental
data in terms of analyte penetration into the topmost layer only, which indicates that diffusion to the interior of the supercrystals would be crucial if the complete field enhancement produced by the stacked nanorods is to be exploited. We propose that our conclusions will be of high relevance in the design of next generation plasmonic devices.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 6.756
Times cited: 70
DOI: 10.1021/acsphotonics.5b00369
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“Evidence for metalsupport interactions in Au modified TiOx/SBA-15 materials prepared by photodeposition”. Mei B, Wiktor C, Turner S, Pougin A, Van Tendeloo G, Fischer RA, Muhler M, Strunk J, ACS catalysis 3, 3041 (2013). http://doi.org/10.1021/cs400964k
Abstract: Gold nanoparticles have been efficiently photodeposited onto titanate-loaded SBA-15 (Ti(x)/SBA-15) with different titania coordination. Transmission electron microscopy shows that relatively large Au nanoparticles are photodeposited on the outer surface of the Ti(x)/SBA-15 materials and that TiOx tends to form agglomerates in close proximity to the Au nanoparticles, often forming coreshell Au/TiOx structures. This behavior resembles typical processes observed due to strong-metal support interactions. In the presence of gold, the formation of hydrogen on Ti(x)/SBA-15 during the photodeposition process and the performance in the hydroxylation of terephthalic acid is greatly enhanced. The activity of the Au/Ti(x)/SBA-15 materials is found to depend on the TiOx loading, increasing with a larger amount of initially isolated TiO4 tetrahedra. Samples with initially clustered TiOx species show lower photocatalytic activities. When isolated zinc oxide (ZnOx) species are present on Ti(x)/SBA-15, gold nanoparticles are smaller and well dispersed within the pores. Agglomeration of TiOx species and the formation of Au/TiOx structures is negligible. The dispersion of gold and the formation of Au/TiOx in the SBA-15 matrix seem to depend on the mobility of the TiOx species. The mobility is determined by the initial degree of agglomeration of TiOx. Effective hydrogen evolution requires Au/TiOx coreshell composites as in Au/Ti(x)/SBA-15, whereas hydroxylation of terephthalic acid can also be performed with Au/ZnOx/TiOx/SBA-15 materials. However, isolated TiOx species have to be grafted onto the support prior to the zinc oxide species, providing strong evidence for the necessity of TiOSi bridges for high photocatalytic activity in terephthalic acid hydroxylation.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 10.614
Times cited: 22
DOI: 10.1021/cs400964k
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“Electron tomography based on highly limited data using a neural network reconstruction technique”. Bladt E, Pelt DM, Bals S, Batenburg KJ, Ultramicroscopy 158, 81 (2015). http://doi.org/10.1016/j.ultramic.2015.07.001
Abstract: Gold nanoparticles are studied extensively due to their unique optical and catalytical properties. Their exact shape determines the properties and thereby the possible applications. Electron tomography is therefore often used to examine the three-dimensional (3D) shape of nanoparticles. However, since the acquisition of the experimental tilt series and the 3D reconstructions are very time consuming, it is difficult to obtain statistical results concerning the 3D shape of nanoparticles. Here, we propose a new approach for electron tomography that is based on artificial neural networks. The use of a new reconstruction approach enables us to reduce the number of projection images with a factor of 5 or more. The decrease in acquisition time of the tilt series and use of an efficient reconstruction algorithm allows us to examine a large amount of nanoparticles in order to retrieve statistical results concerning the 3D shape.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 25
DOI: 10.1016/j.ultramic.2015.07.001
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“Size effect of bifunctional gold in hierarchical titanium oxide-gold-cadmium sulfide with slow photon effect for unprecedented visible-light hydrogen production”. Zhao H, Li C-F, Hu Z-Y, Liu J, Li Y, Hu J, Van Tendeloo G, Chen L-H, Su B-L, Journal Of Colloid And Interface Science 604, 131 (2021). http://doi.org/10.1016/J.JCIS.2021.06.167
Abstract: Gold nanoparticles (Au NPs) with surface plasmonic resonance (SPR) effect and excellent internal electron transfer ability have widely been combined with semiconductors for photocatalysis. However, the in-depth effects of Au NPs in multicomponent photocatalysts have not been completely understood. Herein, ternary titanium oxide-gold-cadmium sulfide (TiO2-Au-CdS, TAC) photocatalysts, based on hierarchical TiO2 inverse opal photonic crystal structure with different Au NPs sizes have been designed to reveal the SPR effect and internal electron transfer of Au NPs in the presence of slow photon effect. It appears that the SPR effect and internal electron transfer ability of Au NPs, depending on their sizes, play a synergistic effect on the photocatalytic enhancement. The ternary TAC-10 photocatalyst with – 10 nm Au NPs demonstrates an unprecedented hydrogen evolution rate of 47.6 mmolh-1g 1 under visible-light, demonstrating- 48% enhancement comparing to the sample without slow photon effect. In particular, a 9.83% apparent quantum yield under 450 nm monochromatic light is achieved for TAC-10. A model is proposed and finite-difference time-domain (FDTD) simulations reveal the size influence of Au NPs in ternary TAC photocatalysts. This work suggests that the rational design of bifunctional Au NPs coupling with slow photon effect could largely promote hydrogen production from visible-light driven water splitting. (c) 2021 Elsevier Inc. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 4.233
DOI: 10.1016/J.JCIS.2021.06.167
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“Size-dependent strain and surface energies of gold nanoclusters”. Ali S, Myasnichenko VS, Neyts EC, Physical chemistry, chemical physics 18, 792 (2016). http://doi.org/10.1039/c5cp06153a
Abstract: Gold nanocluster properties exhibit unique size-dependence. In this contribution, we employ reactive molecular dynamics simulations to calculate the size- and temperature-dependent surface energies, strain energies and atomic displacements for icosahedral, cuboctahedral, truncated octahedral and decahedral Au-nanoclusters. The calculations demonstrate that the surface energy decreases with increasing cluster size at 0 K but increases with size at higher temperatures. The calculated melting curves as a function of cluster size demonstrate the Gibbs-Thomson effect. Atomic displacements and strain are found to strongly depend on the cluster size and both are found to increase with increasing cluster size. These results are of importance for understanding the size-and temperature-dependent surface processes on gold nanoclusters.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.123
Times cited: 37
DOI: 10.1039/c5cp06153a
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“An N-myristoylated globin with a redox-sensing function that regulates the defecation cycle in Caenorhabditis elegans”. Tilleman L, De Henau S, Pauwels M, Nagy N, Pintelon I, Braeckman BP, De Wael K, Van Doorslaer S, Adriaensen D, Timmermans J-P, Moens L, Dewilde S, PLoS ONE 7, e48768 (2012). http://doi.org/10.1371/JOURNAL.PONE.0048768
Abstract: Globins occur in all kingdoms of life where they fulfill a wide variety of functions. In the past they used to be primarily characterized as oxygen transport/storage proteins, but since the discovery of new members of the globin family like neuroglobin and cytoglobin, more diverse and complex functions have been assigned to this heterogeneous family. Here we propose a function for a membrane-bound globin of C. elegans, GLB-26. This globin was predicted to be myristoylated at its N-terminus, a post-translational modification only recently described in the globin family. In vivo, this globin is found in the membrane of the head mesodermal cell and in the tail stomato-intestinal and anal depressor muscle cells. Since GLB-26 is almost directly oxidized when exposed to oxygen, we postulate a possible function as electron transfer protein. Phenotypical studies show that GLB-26 takes part in regulating the length of the defecation cycle in C. elegans under oxidative stress conditions.
Keywords: A1 Journal article; Engineering sciences. Technology; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation)
Impact Factor: 2.806
Times cited: 6
DOI: 10.1371/JOURNAL.PONE.0048768
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Admasu WF (2021) Socioeconomic and environmental impact of expropriation of agricultural land for urbanisation in Ethiopia. 162 p
Abstract: Globally, incorporation of agricultural lands into the urban boundary has been a common phenomenon. Governments use various alternatives to access the required land, including land expropriation procedures, which refers to the compulsorily taking of land from the landholders without their consent by paying compensation. In Ethiopia, the urban population is growing rapidly which resulted into an increase in the demand for urban land for housing construction, public services provision, and infrastructure developments. As the Ethiopian constitution prohibits sale of landholders, governments, at various levels, have been expropriating land from the surrounding farmers to meet the demand for urban land. The general objective of this thesis is to improve the understanding of the impacts of local land deals for urbanization on socioeconomics of farmers and the environment. The findings of this thesis revealed that there are gaps in the current practices of land expropriation for urban expansion that should be improved. The results showed that the compensation paid to the affected farmers is found to be economically inappropriate, i.e., not enough to restore the affected farmers’ livelihoods, in contrast with the land laws that allows a compensation amount that would put previous land users in a better or the same wellbeing as before the land expropriation. In addition, it is indicated that the land expropriation process does not take into account the value of ecosystem services, which are benefits obtain from the land, and important for the wellbeing of the society. We conclude that while land expropriation is an important tool to obtain land from the landholders when it is needed for public purposes, the practices in the study area show it is adversely affecting the socioeconomics of farmers and the environment.
Keywords: Doctoral thesis; Engineering Management (ENM)
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“Bridging global, basin and local-scale water quality modeling towards enhancing water quality management worldwide”. Tang T, Strokal M, van Vliet MTH, Seuntjens P, Burek P, Kroeze C, Langan S, Wada Y, Current Opinion in Environmental Sustainability 36, 39 (2019). http://doi.org/10.1016/J.COSUST.2018.10.004
Abstract: Global water quality (WQ) modeling is an emerging field. In this article, we identify the missing linkages between global and basin/local-scale WQ models, and discuss the possibilities to fill these gaps. We argue that WQ models need stronger linkages across spatial scales. This would help to identify effective scale-specific WQ management options and contribute to future development of global WQ models. Two directions are proposed to improve the linkages: nested multiscale WQ modeling towards enhanced water management, and development of next-generation global WQ models based-on basin/local-scale mechanistic understanding. We highlight the need for better collaboration among WQ modelers and policy-makers in order to deliver responsive water policies and management strategies across scales.
Keywords: A1 Journal article; Engineering sciences. Technology; Sustainable Energy, Air and Water Technology (DuEL)
DOI: 10.1016/J.COSUST.2018.10.004
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“Basalt addition improves the performance of young grassland monocultures under more persistent weather featuring longer dry and wet spells”. Reynaert S, Vienne A, de Boeck HJ, D'Hose T, Janssens I, Nijs I, Portillo-Estrada M, Verbruggen E, Vicca S, Agricultural and forest meteorology 340, 109610 (2023). http://doi.org/10.1016/J.AGRFORMET.2023.109610
Abstract: Global warming is altering the intra-annual variability of precipitation patterns in the mid-latitudes, including a shift towards longer dry and wet spells compared to historic averages. Such fluctuations will likely alter soil water and nutrient dynamics of managed ecosystems which could negatively influence their functioning (e.g., productivity and fodder quality). Here, we investigated whether basalt addition could attenuate effects of increasingly persistent precipitation regimes (PR) on two agricultural grassland monocultures differing in drought resistance (low: Lolium perenne (LP) vs high: Festulolium (FL)) and digestibility (high: LP, low: FL), while improving soil C sequestration. In total, 32 experimental mesocosms were subjected to either a low (1-day wet/ dry alternation) or a highly (30-day wet/dry alternation) persistent PR over 120 days, keeping total precipitation equal. In half of these mesocosms, we mixed basalt with the top 20 cm soil layer at a rate of 50 t ha-1. Overall, 30-day PR increased average water availability resulting in improved aboveground biomass and shoot digestibility for both species, in spite of elevated physiological stress. These PR also increased shoot Si, K, N and C but reduced Ca accumulation. Basalt addition generally increased soil Al, Ni, Mg, Ca, P, K and Si availability without altering root biomass or total soil carbon. Moreover, differences in root N content and C:N ratio between species were reduced. Interestingly, basalt modified the PR effects on productivity. Within 30-day PR, basalt stimulated aboveground biomass (& PLUSMN;14%) and root Si and K contents without altering plant digestibility, palatability, crude protein content or Ni/Al content. These results indicate that basalt can stimulate grassland productivity and soil nutrient availability under more persistent PR without negatively affecting fodder quality. Hence, basalt application may improve the performance of young temperate grassland monocultures under climate change, though dry soil conditions may limit effects on soil C sequestration during summer.
Keywords: A1 Journal article; Plant and Ecosystems (PLECO) – Ecology in a time of change
Impact Factor: 6.2
DOI: 10.1016/J.AGRFORMET.2023.109610
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