“Identification of a unique pyridinic FeN4Cx electrocatalyst for N₂, reduction : tailoring the coordination and carbon topologies”. Nematollahi P, Neyts EC, Journal Of Physical Chemistry C 126, 14460 (2022). http://doi.org/10.1021/ACS.JPCC.2C03577
Abstract: Although the heterogeneity of pyrolyzed Fe???N???C materials is known and has been reported previously, the atomic structure of the active sites and their detailed reaction mechanisms are still unknown. Here, we identified two pyridinic Fe???N4-like centers with different local C coordinates, i.e., FeN4C8 and FeN4C10, and studied their electrocatalytic activity for the nitrogen reduction reaction (NRR) based on density functional theory (DFT) calculations. We also discovered the influence of the adsorption of NH2 as a functional ligand on catalyst performance on the NRR. We confirmed that the NRR selectivity of the studied catalysts is essentially governed either by the local C coordination or by the dynamic structure associated with the FeII/FeIII. Our investigations indicate that the proposed traditional pyridinic FeN4C10 has higher catalytic activity and selectivity for the NRR than the robust FeN4C8 catalyst, while it may have outstanding activity for promoting other (electro)catalytic reactions. <comment>Superscript/Subscript Available</comment
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.7
DOI: 10.1021/ACS.JPCC.2C03577
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“Simulating highly activated sticking of H₂, on Al(110) : quantum versus quasi-classical dynamics”. Tchakoua T, Powell AD, Gerrits N, Somers MF, Doblhoff-Dier K, Busnengo HF, Kroes G-J, The journal of physical chemistry: C : nanomaterials and interfaces 127, 5395 (2023). http://doi.org/10.1021/ACS.JPCC.3C00426
Abstract: We evaluate the importance of quantum effects on the sticking of H2 on Al(110) for conditions that are close to those of molecular beam experiments that have been done on this system. Calculations with the quasi-classical trajectory (QCT) method and with quantum dynamics (QD) are performed using a model in which only motion in the six molecular degrees of freedom is allowed. The potential energy surface used has a minimum barrier height close to the value recently obtained with the quantum Monte Carlo method. Monte Carlo averaging over the initial rovibrational states allowed the QD calculations to be done with an order of magnitude smaller computational expense. The sticking probability curve computed with QD is shifted to lower energies relative to the QCT curve by 0.21 to 0.05 kcal/mol, with the highest shift obtained for the lowest incidence energy. Quantum effects are therefore expected to play a small role in calculations that would evaluate the accuracy of electronic structure methods for determining the minimum barrier height to dissociative chemisorption for H2 + Al(110) on the basis of the standard procedure for comparing results of theory with molecular beam experiments.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.7
DOI: 10.1021/ACS.JPCC.3C00426
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“Quantitative 3D Investigation of Nanoparticle Assemblies by Volumetric Segmentation of Electron Tomography Data Sets”. Kavak S, Kadu AA, Claes N, Sánchez-Iglesias A, Liz-Marzán LM, Batenburg KJ, Bals S, The journal of physical chemistry: C : nanomaterials and interfaces 127, 9725 (2023). http://doi.org/10.1021/acs.jpcc.3c02017
Abstract: Morphological characterization of nanoparticle assemblies and hybrid nanomaterials is critical in determining their structure-property relationships as well as in the development of structures with desired properties. Electron tomography has become a widely utilized technique for the three-dimensional characterization of nanoparticle assemblies. However, the extraction of quantitative morphological parameters from the reconstructed volume can be a complex and labor-intensive task. In this study, we aim to overcome this challenge by automating the volumetric segmentation process applied to three-dimensional reconstructions of nanoparticle assemblies. The key to enabling automated characterization is to assess the performance of different volumetric segmentation methods in accurately extracting predefined quantitative descriptors for morphological characterization. In our methodology, we compare the quantitative descriptors obtained through manual segmentation with those obtained through automated segmentation methods, to evaluate their accuracy and effectiveness. To show generality, our study focuses on the characterization of assemblies of CdSe/CdS quantum dots, gold nanospheres and CdSe/CdS encapsulated in polymeric micelles, and silica-coated gold nanorods decorated with both CdSe/CdS or PbS quantum dots. We use two unsupervised segmentation algorithms: the watershed transform and the spherical Hough transform. Our results demonstrate that the choice of automated segmentation method is crucial for accurately extracting the predefined quantitative descriptors. Specifically, the spherical Hough transform exhibits superior performance in accurately extracting quantitative descriptors, such as particle size and interparticle distance, thereby allowing for an objective, efficient, and reliable volumetric segmentation of complex nanoparticle assemblies.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 3.7
Times cited: 2
DOI: 10.1021/acs.jpcc.3c02017
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“Conformation-Dependent Monolayer and Bilayer Structures of an Alkylated TTF Derivative Revealed using STM and Molecular Modeling”. Delfino CL, Hao Y, Martin C, Minoia A, Gopi E, Mali KS, Van der Auweraer M, Geerts YH, Van Aert S, Lazzaroni R, De Feyter S, The Journal of Physical Chemistry C 127, 23023 (2023). http://doi.org/10.1021/acs.jpcc.3c04913
Abstract: In this study, the multi-layer self-assembled molecular network formation of an alkylated tetrathiafulvalene compound is studied at the liquid-solid interface between 1-phenyloctane and graphite. A combined theoretical/experimental approach associating force-field and quantum-chemical calculations with scanning tunnelling microscopy is used to determine the two-dimensional self-assembly beyond the monolayer, but also to further the understanding of the molecular adsorption conformation and its impact on the molecular packing within the assemblies at the monolayer and bilayer level.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 3.7
DOI: 10.1021/acs.jpcc.3c04913
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“Additivity of Atomic Strain Fields as a Tool to Strain-Engineering Phase-Stabilized CsPbI3Perovskites”. Teunissen JL, Braeckevelt T, Skvortsova I, Guo J, Pradhan B, Debroye E, Roeffaers MBJ, Hofkens J, Van Aert S, Bals S, Rogge SMJ, Van Speybroeck V, The Journal of Physical Chemistry C 127, 23400 (2023). http://doi.org/10.1021/acs.jpcc.3c05770
Abstract: CsPbI3 is a promising perovskite material for photovoltaic applications in its photoactive perovskite or black phase. However, the material degrades to a photovoltaically inactive or yellow phase at room temperature. Various mitigation strategies are currently being developed to increase the lifetime of the black phase, many of which rely on inducing strains in the material that hinder the black-to-yellow phase transition. Physical insight into how these strategies exactly induce strain as well as knowledge of the spatial extent over which these strains impact the material is crucial to optimize these approaches but is still lacking. Herein, we combine machine learning potential-based molecular dynamics simulations with our in silico strain engineering approach to accurately quantify strained large-scale atomic structures on a nanosecond time scale. To this end, we first model the strain fields introduced by atomic substitutions as they form the most elementary strain sources. We demonstrate that the magnitude of the induced strain fields decays exponentially with the distance from the strain source, following a decay rate that is largely independent of the specific substitution. Second, we show that the total strain field induced by multiple strain sources can be predicted to an excellent approximation by summing the strain fields of each individual source. Finally, through a case study, we illustrate how this additive character allows us to explain how complex strain fields, induced by spatially extended strain sources, can be predicted by adequately combining the strain fields caused by local strain sources. Hence, the strain additivity proposed here can be adopted to further our insight into the complex strain behavior in perovskites and to design strain from the atomic level onward to enhance their sought-after phase stability.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 3.7
DOI: 10.1021/acs.jpcc.3c05770
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“Improving Molecule–Metal Surface Reaction Networks Using the Meta-Generalized Gradient Approximation: CO2Hydrogenation”. Cai Y, Michiels R, De Luca F, Neyts E, Tu X, Bogaerts A, Gerrits N, The Journal of Physical Chemistry C 128, 8611 (2024). http://doi.org/10.1021/acs.jpcc.4c01110
Abstract: Density functional theory is widely used to gain insights into molecule−metal surface reaction networks, which is important for a better understanding of catalysis. However, it is well-known that generalized gradient approximation (GGA)
density functionals (DFs), most often used for the study of reaction networks, struggle to correctly describe both gas-phase molecules and metal surfaces. Also, GGA DFs typically underestimate reaction barriers due to an underestimation of the selfinteraction energy. Screened hybrid GGA DFs have been shown to reduce this problem but are currently intractable for wide usage. In this work, we use a more affordable meta-GGA (mGGA) DF in combination with a nonlocal correlation DF for the first time to study and gain new insights into a catalytically important surface
reaction network, namely, CO2 hydrogenation on Cu. We show that the mGGA DF used, namely, rMS-RPBEl-rVV10, outperforms typical GGA DFs by providing similar or better predictions for metals and molecules, as well as molecule−metal surface adsorption
and activation energies. Hence, it is a better choice for constructing molecule−metal surface reaction networks.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 3.7
DOI: 10.1021/acs.jpcc.4c01110
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“Plasma Catalysis Modeling: How Ideal Is Atomic Hydrogen for Eley–Rideal?”.Michiels R, Gerrits N, Neyts E, Bogaerts A, The Journal of Physical Chemistry C 128, 11196 (2024). http://doi.org/10.1021/acs.jpcc.4c02193
Abstract: Plasma catalysis is an emerging technology, but a lot of questions about the underlying surface mechanisms remain unanswered. One of these questions is how important Eley−Rideal (ER) reactions are, next to Langmuir−Hinshelwood reactions. Most plasma catalysis kinetic models predict ER reactions to be important and sometimes even vital for the surface chemistry. In this work, we take a critical look at how ER reactions involving H radicals are incorporated in kinetic models describing CO2 hydrogenation and NH3 synthesis. To this end, we construct potential energy surface (PES) intersections, similar to elbow plots constructed for dissociative chemisorption. The results of the PES intersections are in agreement with ab initio molecular dynamics (AIMD) findings in literature while being computationally much cheaper. We find that, for the reactions studied here, adsorption is more probable than a reaction via the hot atom (HA) mechanism, which in turn is more probable than a reaction via the ER mechanism. We also conclude that kinetic models of plasma-catalytic systems tend to overestimate the importance if ER reactions. Furthermore, as opposed to what is often assumed in kinetic models, the choice of catalyst will influence the ER reaction probability. Overall, the description of ER reactions is too much “ideal” in models. Based on our indings, we make a number of recommendations on how to incorporate ER reactions in kinetic models to avoid overestimation of their importance.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 3.7
DOI: 10.1021/acs.jpcc.4c02193
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“Core–Shell Colloidal Nanocomposites for Local Temperature Monitoring during Photothermal Heating”. Zani V, Renero-Lecuna C, Jimenez de Aberasturi D, di Silvio D, Kavak S, Bals S, Signorini R, Liz-Marzán LM, The Journal of Physical Chemistry C (2024). http://doi.org/10.1021/acs.jpcc.4c05593
Abstract: Determining temperature changes at the heating site to accurately control thermal treatments has been a major goal in the field of nanothermometry. In this study, we address the need to effectively monitor local temperature during the application of photothermal therapies, which is essential to prevent uncontrolled heating induced by nanoparticle sensitizers used in such treatments. For this purpose, we developed a synthetic protocol to produce a nanocomposite probe that allows local photothermal heating and simultaneous in situ optical nanothermometry, within the biological transparency windows. The nanocomposite material comprises gold nanorods for light-to-heat conversion and neodymium (Nd3+)-based nanoparticles for local temperature monitoring. An inert spacer made of mesoporous silica provides a core-shell structure and ensures uniform separation between both functionalities to prevent photoluminescence quenching. By using an 808 nm laser as the source for both heating and photoluminescence excitation, we demonstrate a direct correlation between local temperature and near infrared Nd3+ emission intensities, thereby providing precise local temperature monitoring. Different levels of local heating were studied by varying the incident laser power, resulting in a maximum temperature increase of 47 °C detected with the nanothermometers. Albeit presented here as a proof of concept, this concept can be translated to the design of materials for photothermal therapy.
Keywords: A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ;
Impact Factor: 3.7
DOI: 10.1021/acs.jpcc.4c05593
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“Kinetics of energy selective Cs encapsulation in single-walled carbon nanotubes for damage-free and position-selective doping”. Kato T, Neyts EC, Abiko Y, Akama T, Hatakeyama R, Kaneko T, The journal of physical chemistry: C : nanomaterials and interfaces 119, 11903 (2015). http://doi.org/10.1021/acs.jpcc.5b00300
Abstract: A method has been developed for damage-free cesium (Cs) encapsulation within single-walled carbon nanotubes (SWNTs) with fine position selectivity. Precise energy tuning of Cs-ion irradiation revealed that there is a clear energy window (2060 eV) for the efficient encapsulation of Cs through the hexagonal network of SWNT sidewalls without causing significant damage. This minimum energy threshold of Cs-ion encapsulation (∼20 eV) matches well with the value obtained by ab initio simulation (∼22 eV). Furthermore, position-selective Cs encapsulation was carried out, resulting in the successful formation of pn-junction SWNT thin films with excellent environmental stability.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 3
DOI: 10.1021/acs.jpcc.5b00300
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“CO2 conversion in a microwave plasma reactor in the presence of N2 : elucidating the role of vibrational levels”. Heijkers S, Snoeckx R, Kozák T, Silva T, Godfroid T, Britun N, Snyders R, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 119, 12815 (2015). http://doi.org/10.1021/acs.jpcc.5b01466
Abstract: A chemical kinetics model is developed for a CO2/N2 microwave plasma, focusing especially on the vibrational levels of both CO2 and N2. The model is used to calculate the CO2 and N2 conversion as well as the energy efficiency of CO2 conversion for different power densities and for N2 fractions in the CO2/N2 gas mixture ranging from 0 to 90%. The calculation results are compared with measurements, and agreements within 23% and 33% are generally found for the CO2 conversion and N2 conversion, respectively. To explain the observed trends, the destruction and formation processes of both CO2 and N2 are analyzed, as well as the vibrational distribution functions of both CO2 and N2. The results indicate that N2 contributes in populating the lower asymmetric levels of CO2, leading to a higher absolute CO2 conversion upon increasing N2 fraction. However, the effective CO2 conversion drops because there is less CO2 initially present in the gas mixture; thus, the energy efficiency also drops with rising N2 fraction.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 56
DOI: 10.1021/acs.jpcc.5b01466
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“Promising Piezoelectric Performance of Single Layer Transition-Metal Dichalcogenides and Dioxides”. Alyörük MM, Aierken Y, Çakır D, Peeters FM, Sevik C, The journal of physical chemistry: C : nanomaterials and interfaces 119, 23231 (2015). http://doi.org/10.1021/acs.jpcc.5b06428
Abstract: Piezoelectricity is a unique material property that allows one to convert mechanical energy into electrical one or vice versa. Transition metal dichalcogenides (TMDC) and transition metal dioxides (TMDO) are expected to have great potential for piezoelectric device applications due to their noncentrosymmetric and two-dimensional crystal structure. A detailed theoretical investigation of the piezoelectric stress (e 11 ) and piezoelectric strain (d 11 ) coefficients of single layer TMDCs and TMDOs with chemical formula MX 2 (where M= Cr, Mo, W, Ti, Zr, Hf, Sn and X = O, S, Se, Te) is presented by using first-principles calculations based on density func- tional theory. We predict that not only the Mo- and W-based members of this family but also the other materials with M= Cr, Ti, Zr and Sn exhibit highly promising piezoelectric properties. CrTe 2 has the largest e 11 and d 11 coefficients among the group VI elements (i.e., Cr, Mo, and W). In addition, the relaxed-ion e 11 and d 11 coefficients of SnS 2 are almost the same as those of CrTe 2 . Furthermore, TiO 2 and ZrO 2 pose comparable or even larger e 11 coefficients as compared to Mo- and W-based TMDCs and TMDOs. Our calculations reveal that TMDC and TMDO structures are strong candidates for future atomically thin piezoelectric applications such as transducers, sensors, and energy harvesting devices due to their piezoelectric coefficients that are comparable (even larger) to currently used bulk piezoelectric materials.
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.536
Times cited: 134
DOI: 10.1021/acs.jpcc.5b06428
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“The Dominant Pathways for the Conversion of Methane into Oxygenates and Syngas in an Atmospheric Pressure Dielectric Barrier Discharge”. De Bie C, van Dijk J, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 119, 22331 (2015). http://doi.org/10.1021/acs.jpcc.5b06515
Abstract: A one-dimensional fluid model for a dielectric barrier discharge in CH4/O2 and CH4/CO2 gas mixtures is developed. The model describes the gas-phase chemistry for partial oxidation and for dry reforming of methane. The spatially averaged densities of the various plasma species are presented as a function of time and initial gas mixing ratio. Besides, the conversion of the inlet gases and the selectivities of the reaction products are calculated. Syngas, higher hydrocarbons, and higher oxygenates are typically found to be important reaction products. Furthermore, the main underlying reaction pathways for the formation of syngas, methanol, formaldehyde, and other higher oxygenates are determined.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 46
DOI: 10.1021/acs.jpcc.5b06515
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“Selective Plasma Oxidation of Ultrasmall Si Nanowires”. Khalilov U, Yusupov M, Bogaerts A, Neyts EC, The journal of physical chemistry: C : nanomaterials and interfaces 120, 472 (2016). http://doi.org/10.1021/acs.jpcc.5b11027
Abstract: Device performance of Si|SiOx core-shell based nanowires critically depends on the exact control over the oxide thickness. Low-temperature plasma oxidation is a highly promising alternative to thermal oxidation allowing for improved control over the oxidation process, in particular for ultrasmall Si nanowires. We here elucidate the room temperature plasma oxidation mechanisms of ultrasmall Si nanowires using hybrid molecular dynamics / force-bias Monte Carlo simulations. We demonstrate how the oxidation and concurrent water formation mechanisms are a function of the oxidizing plasma species and we demonstrate how the resulting core-shell oxide thickness can be controlled through these species. A new mechanism of water formation is discussed in detail. The results provide a detailed atomic level explanation of the oxidation process of highly curved Si surfaces. These results point out a route toward plasma-based formation of ultrathin core-shell Si|SiOx nanowires at room temperature.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 3
DOI: 10.1021/acs.jpcc.5b11027
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“Gold Nanostar-Coated Polystyrene Beads as Multifunctional Nanoprobes for SERS Bioimaging”. Serrano-Montes AB, Langer J, Henriksen-Lacey M, Jimenez de Aberasturi D, Solís DM, Taboada JM, Obelleiro F, Sentosun K, Bals S, Bekdemir A, Stellacci F, Liz-Marzán LM, The journal of physical chemistry: C : nanomaterials and interfaces 120, 20860 (2016). http://doi.org/10.1021/acs.jpcc.6b02282
Abstract: Hybrid colloidal nanocomposites comprising polystyrene beads and plasmonic gold nanostars are reported as multifunctional optical nanoprobes. Such self-assembled structures are excellent Raman enhancers for bio-applications as they feature plasmon modes in the near infrared “first biological transparency window”. In this proof of concept study, we used 4- mercaptobenzoic acid as a Raman-active molecule to optimize the density of gold nanostars on polystyrene beads, improving SERS performance and thereby allowing in vitro cell culture imaging. Interestingly, intermediate gold nanostar loadings were found to yield higher SERS response, which was confirmed by electromagnetic modeling. These engineered hybrid nanostructures notably improve the possibilities of using gold nanostars as SERS tags. Additionally, when fluorescently labeled polystyrene bead are used as colloidal carriers, the composite particles can be applied as promising tools for multimodal bioimaging.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 64
DOI: 10.1021/acs.jpcc.6b02282
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“Peculiar piezoelectric properties of soft two-dimensional materials”. Sevik C, Çakir D, Gulseren O, Peeters FM, The journal of physical chemistry: C : nanomaterials and interfaces 120, 13948 (2016). http://doi.org/10.1021/acs.jpcc.6b03543
Abstract: Group II-VI semiconductor honeycomb monolayers have a noncentrosymmetric crystal structure and therefore are expected to be important for nano piezoelectric device applications. This motivated us to perform first principles calculations based on density functional theory to unveil the piezoelectric properties (i.e., piezoelectric stress (e(11)) and piezoelectric strain (d(11)) coefficients) of these monolayer materials with chemical formula MX (where M = Be, Mg, Ca, Sr, Ba, Zr, Cd and X = S, Se, Te). We found that these two-dimensional materials have peculiar piezoelectric properties with d(11) coefficients 1 order of magnitude larger than those of commercially utilized bulk materials. A clear trend in their piezoelectric properties emerges, which
Keywords: A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Impact Factor: 4.536
Times cited: 39
DOI: 10.1021/acs.jpcc.6b03543
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“How Oxygen Vacancies Activate CO2 Dissociation on TiO2 Anatase (001)”. Huygh S, Bogaerts A, Neyts EC, The journal of physical chemistry: C : nanomaterials and interfaces 120, 21659 (2016). http://doi.org/10.1021/acs.jpcc.6b07459
Abstract: The adsorption, dissociation, and diffusion of CO2 on the anatase (001) surface was studied using DFT by means of the generalized gradient approximation using the Perdew−Burcke−Ernzerhof (PBE)-functional and applying corrections for long-range dispersion interactions. Different stable adsorption configurations were identified for the fully oxidized surface. The most stable adsorption configuration is the monodentated carbonate-like structure. Small energy barriers were identified for the conversion of a physisorbed to a chemisorbed configuration.
CO2 dissociation is found to be unfeasible on the stoichiometric surface. The introduction of oxygen vacancy defects gives rise to new highly stable adsorption configurations with a stronger activation of the C−O bonds. This leads to the possibility of exothermic dissociation of CO2 with barriers up to 22.2 kcal/mol,
corresponding to chemical lifetimes of less than 4 s at 300 K. These reactions cause a CO molecule to be formed, which will easily desorb, and the reduced surface to become oxidized. It is clear that oxygen vacancy defects play a key role in the catalytic activity of an anatase (001) surface. Oxygen vacancies play an important role in the dissociation of CO2 on the anatase (001) surface, and will play a significant role in complex problems, such as the catalytic conversion of CO2 to value-added chemicals.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 49
DOI: 10.1021/acs.jpcc.6b07459
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“CO2Hydrogenation in a Dielectric Barrier Discharge Plasma Revealed”. De Bie C, van Dijk J, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 120, 25210 (2016). http://doi.org/10.1021/acs.jpcc.6b07639
Abstract: The hydrogenation of carbon dioxide in a dielectric barrier discharge plasma is studied with a one-dimensional fluid model. The spatially averaged densities of the most important end products formed in the CO2/H2 mixture are determined as a function of the initial gas mixing ratio. CO and H2O are found to be present at the highest densities and to a lower content also CH4, C2H6, CH2O, CH3OH, O2, and some other higher hydrocarbons and oxygenates. The main underlying reaction
pathways for the conversion of the inlet gases and the formation of CO, CH4, CH2O, and CH3OH are pointed out for various gas mixing ratios. The CO2 conversion and the production of value added products is found to be quite low, also in comparison to a CO2/CH4 mixture, and this can be explained by the model.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 16
DOI: 10.1021/acs.jpcc.6b07639
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“Influence of the Material Dielectric Constant on Plasma Generation inside Catalyst Pores”. Zhang Y-R, Neyts EC, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 120, 25923 (2016). http://doi.org/10.1021/acs.jpcc.6b09038
Abstract: Plasma catalysis is gaining increasing interest for various environmental applications, but the crucial question is whether plasma can be created inside catalyst pores and under which conditions. In practice, various catalytic support materials are used, with various dielectric constants. We investigate here the influence of the dielectric constant on the plasma properties inside catalyst pores and in the sheath in front of the pores, for various pore sizes. The calculations are performed by a two-dimensional fluid model for an atmospheric pressure dielectric barrier discharge in helium. The electron impact ionization rate, electron temperature, electron and ion density, as well as the potential distribution and surface charge density, are analyzed for a better understanding of the discharge behavior inside catalyst pores. The results indicate that, in a 100 μm pore, the electron impact ionization in the pore, which is characteristic for the plasma generation inside the pore, is greatly enhanced for dielectric constants below 300. Smaller pore sizes only yield enhanced ionization for smaller dielectric constants, i.e., up to εr = 200, 150, and 50 for pore sizes of 50, 30, and 10 μm. Thus, the most common catalyst supports, i.e., Al2O3 and SiO2, which have dielectric constants around εr = 8−11 and 4.2, respectively, should allow more easily that microdischarges can be formed inside catalyst pores, even for smaller pore sizes. On the other hand, ferroelectric materials with dielectric constants above 300 never seem to yield plasma enhancement inside catalyst pores, not even for 100 μm pore sizes. Furthermore, it is clear that the dielectric constant of the material has a large effect on the extent of plasma enhancement inside the catalyst pores, especially in the range between εr = 4 and εr = 200. The obtained results are explained in detail based on the surface charge density at the pore walls,
and the potential distribution and electron temperature inside and above the pores. The results obtained with this model are
important for plasma catalysis, as the production plasma species in catalyst pores might affect the catalyst properties, and thus
improve the applications of plasma catalysis.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 34
DOI: 10.1021/acs.jpcc.6b09038
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“Mechanisms of Peptide Oxidation by Hydroxyl Radicals: Insight at the Molecular Scale”. Verlackt CCW, Van Boxem W, Dewaele D, Lemière F, Sobott F, Benedikt J, Neyts EC, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 121, 5787 (2017). http://doi.org/10.1021/acs.jpcc.6b12278
Abstract: Molecular dynamics (MD) simulations were performed to provide atomic scale insight in the initial interaction between hydroxyl radicals (OH) and peptide systems in solution. These OH radicals are representative reactive oxygen species produced by cold atmospheric plasmas. The use of plasma for biomedical applications is gaining increasing interest, but the fundamental mechanisms behind the plasma modifications still remain largely elusive. This study helps to gain more insight in the underlying mechanisms of plasma medicine but is also more generally applicable to peptide oxidation, of interest for other applications. Combining both reactive and nonreactive MD simulations, we are able to elucidate the reactivity of the amino acids inside the peptide systems and their effect on their structure up to 1 μs. Additionally, experiments were performed, treating the simulated peptides with a plasma jet. The computational results presented here correlate well with the obtained experimental data and highlight the importance of the chemical environment for the reactivity of the individual amino acids, so that specific amino acids are attacked in higher numbers than expected. Furthermore, the long time scale simulations suggest that a single oxidation has an effect on the 3D conformation due to an increase in hydrophilicity and intra- and intermolecular interactions.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 5
DOI: 10.1021/acs.jpcc.6b12278
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“Modeling of CO2Splitting in a Microwave Plasma: How to Improve the Conversion and Energy Efficiency”. Berthelot A, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 121, 8236 (2017). http://doi.org/10.1021/acs.jpcc.6b12840
Abstract: Microwave plasmas are one of the most promising techniques for CO2 conversion into value-added chemicals and fuels since they are very energy efficient. Nevertheless, experiments show that this high energy efficiency is only reached at low pressures and significantly drops toward atmospheric pressure, which is a clear limitation for industrial applications. In this paper, we use a zerodimensional reaction kinetics model to simulate a CO2 microwave plasma in a pressure range from 50 mbar to 1 bar, in order to evaluate the reasons for this decrease in energy efficiency at atmospheric pressure. The code includes a detailed description of the vibrational kinetics of CO2, CO, and O2 as well as the energy exchanges between them because the vibrational kinetics is known to be crucial for energy efficient CO2 splitting. First, we use a self-consistent gas temperature calculation in order to assess the key performance indicators for CO2 splitting, i.e., the CO2 conversion and corresponding energy efficiency. Our results indicate that lower pressures and higher power densities lead to more vibrational excitation, which is beneficial for the conversion. We also demonstrate the key role of the gas temperature. The model predicts the highest conversion and energy efficiencies at pressures around 300 mbar, which is in agreement with experiments from the literature. We also show the beneficial aspect of fast gas cooling in the afterglow at high pressure. In a second step, we study in more detail the effects of pressure, gas temperature, and power density on the vibrational distribution function and on the dissociation and recombination mechanisms of CO2, which define the CO2 splitting efficiency. This study allows us to identify the limiting factors of CO2 conversion and to propose potential solutions to improve the process.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 47
DOI: 10.1021/acs.jpcc.6b12840
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“One-Step Microheterogeneous Formation of Rutile@Anatase Core–Shell Nanostructured Microspheres Discovered by Precise Phase Mapping”. Tarasov A, Hu Z-Y, Meledina M, Trusov G, Goodilin E, Van Tendeloo G, Dobrovolsky Y, The journal of physical chemistry: C : nanomaterials and interfaces 121, 4443 (2017). http://doi.org/10.1021/acs.jpcc.6b12991
Abstract: Nanostructured core−shell microspheres with a rough rutile core and a thin anatase shell are synthesized via a one-step heterogeneous templated hydrolysis process of TiCl4 vapor on the aerosol water−air interface. The rutile-in-anatase core−shell structure has been evidenced by different electron microscopy techniques, including electron energy-loss spectroscopy and 3D electron tomography. A new mechanism for the formation of a crystalline rutile core inside the anatase shell is proposed based on a statistical evaluation of a large number of electron microscopy data. We found that the control over the TiCl4 vapor pressure, the ratio between TiCl4 and H2O aerosol, and the reaction conditions plays a crucial role in the formation of the core−shell morphology and increases the yield of nanostructured microspheres.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 4
DOI: 10.1021/acs.jpcc.6b12991
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“A Comprehensive Study of the Electrodeposition of Nickel Nanostructures from Deep Eutectic Solvents: Self-Limiting Growth by Electrolysis of Residual Water”. Mernissi Cherigui EA, Sentosun K, Bouckenooge P, Vanrompay H, Bals S, Terryn H, Ustarroz J, The journal of physical chemistry: C : nanomaterials and interfaces 121, 9337 (2017). http://doi.org/10.1021/acs.jpcc.7b01104
Abstract: The electrodeposition of nickel nanostructures on glassy carbon was investigated in 1:2 choline chloride – urea (1:2 ChCl-U) deep eutectic solvent (DES). By combining electrochemical techniques with ex-situ FE-SEM, XPS, HAADF-STEM and EDX, the electrochemical processes occurring during nickel deposition were better understood. Special attention was given to the interaction between the solvent and the growing nickel nanoparticles. The application of a suffciently negative potential results into the electrocatlytic hydrolisis of residual water in the DES, which leads to the formation of a mixed layer of Ni/Ni(OH)2(ads). In addition, hydrogen bonds between hydroxide species and the DES components could be formed, quenching the growth of the nickel clusters favouring their aggregation. Due to these processes, a highly dense distribution of nickel nanostructures can be obtained within a wide potential range. Understanding the role of residual water and the interactions at the interface during metal electrodeposition from DESs is essential to produce supported nanostructures in a controllable way for a broad range of applications and technologies.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 66
DOI: 10.1021/acs.jpcc.7b01104
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“Mechanistic Insight into the Photocatalytic Working of Fluorinated Anatase {001} Nanosheets”. Kus M, Altantzis T, Vercauteren S, Caretti I, Leenaerts O, Batenburg KJ, Mertens M, Meynen V, Partoens B, Van Doorslaer S, Bals S, Cool P, The journal of physical chemistry: C : nanomaterials and interfaces 121, 26275 (2017). http://doi.org/10.1021/acs.jpcc.7b05586
Abstract: Anatase nanosheets with exposed {001} facets
have gained increasing interest for photocatalytic applications. To
fully understand the structure-to-activity relation, combined
experimental and computational methods have been exploited.
Anatase nanosheets were prepared under hydrothermal conditions
in the presence of fluorine ions. High resolution scanning
transmission electron microscopy was used to fully characterize
the synthesized material, confirming the TiO2 nanosheet
morphology. Moreover, the surface structure and composition
of a single nanosheet could be determined by annular bright-field
scanning transmission electron microscopy (ABF-STEM) and
STEM electron energy loss spectroscopy (STEM-EELS). The photocatalytic activity was tested for the decomposition of organic
dyes rhodamine 6G and methyl orange and compared to a reference TiO2 anatase sample. The anatase nanosheets with exposed
{001} facets revealed a significantly lower photocatalytic activity compared to the reference. In order to understand the
mechanism for the catalytic performance, and to investigate the role of the presence of F−, light-induced electron paramagnetic
resonance (EPR) experiments were performed. The EPR results are in agreement with TEM, proving the presence of Ti3+
species close to the surface of the sample and allowing the analysis of the photoinduced formation of paramagnetic species.
Further, ab initio calculations of the anisotropic effective mass of electrons and electron holes in anatase show a very high effective
mass of electrons in the [001] direction, having a negative impact on the mobility of electrons toward the {001} surface and thus
the photocatalysis. Finally, motivated by the experimental results that indicate the presence of fluorine atoms at the surface, we
performed ab initio calculations to determine the position of the band edges in anatase slabs with different terminations of the
{001} surface. The presence of fluorine atoms near the surface is shown to strongly shift down the band edges, which indicates
another reason why it can be expected that the prepared samples with a large amount of {001} surface, but with fluorine atoms
near the surface, show only a low photocatalytic activity.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 4.536
Times cited: 20
DOI: 10.1021/acs.jpcc.7b05586
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“Bottom-Up Mechanical Nanometrology of Granular Ag Nanoparticles Thin Films”. Benetti G, Caddeo C, Melis C, Ferrini G, Giannetti C, Winckelmans N, Bals S, J Van Bael M, Cavaliere E, Gavioli L, Banfi F, The journal of physical chemistry: C : nanomaterials and interfaces 121, 22434 (2017). http://doi.org/10.1021/acs.jpcc.7b05795
Abstract: Ultrathin metal nanoparticles coatings, synthesized by gas-phase deposition, are emerging as go-to materials in a variety of fields ranging from pathogens control, sensing to energy storage. Predicting their morphology and mechanical properties beyond a trial-and-error approach is a crucial issue limiting their exploitation in real-life applications. The morphology and mechanical properties of Ag nanoparticles ultrathin films, synthesized by supersonic cluster beam deposition, are here assessed adopting a bottom-up, multi-technique approach. A virtual film model is proposed merging high resolution scanning transmission electron microscopy, supersonic cluster beam dynamics and molecular dynamics simulations. The model is validated against mechanical nanometrology measurements and is readily extendable to metals other than Ag. The virtual film is shown to be a flexible and reliable predictive tool to access morphology-dependent properties such as mesoscale gas-dynamics and elasticity of ultrathin films synthesized by gas-phase deposition.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 30
DOI: 10.1021/acs.jpcc.7b05795
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“CO2Conversion in a Gliding Arc Plasmatron: Elucidating the Chemistry through Kinetic Modeling”. Heijkers S, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 121, 22644 (2017). http://doi.org/10.1021/acs.jpcc.7b06524
Abstract: By means of chemical kinetics modeling, it is possible to elucidate the main dissociation mechanisms of CO2 in a gliding arc plasmatron (GAP). We obtain good agreement between the calculated and experimental conversions and energy efficiencies, indicating that the model can indeed be used to study the underlying mechanisms. The calculations predict that vibration-induced dissociation is the main dissociation mechanism of CO2, but it occurs mainly from the lowest vibrational levels because of fast thermalization of the vibrational distribution. Based on these findings, we propose ideas for improving the performance of the GAP, but testing of these ideas in the simulations reveals that they do not always lead to significant enhancement, because of other side effects, thus illustrating the complexity of the process. Nevertheless, the model allows more insight into the underlying mechanisms to be obtained and limitations to be identified.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 6
DOI: 10.1021/acs.jpcc.7b06524
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“CO2Conversion in a Gliding Arc Plasmatron: Multidimensional Modeling for Improved Efficiency”. Trenchev G, Kolev S, Wang W, Ramakers M, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 121, 24470 (2017). http://doi.org/10.1021/acs.jpcc.7b08511
Abstract: The gliding arc plasmatron (GAP) is a highly efficient atmospheric plasma source, which is very promising for CO2 conversion applications. To understand its operation principles and to improve its application, we present here comprehensive modeling results, obtained by means of computational fluid dynamics simulations and plasma modeling. Because of the complexity of the CO2 plasma, a full 3D plasma model would be computationally impractical. Therefore, we combine a 3D turbulent gas flow model with a 2D plasma and gas heating model in order to calculate the plasma parameters and CO2 conversion characteristics. In addition, a complete 3D gas flow and plasma model with simplified argon chemistry is used to evaluate the gliding arc evolution in space and time. The calculated values are compared with experimental data from literature as much as possible in order to validate the model. The insights obtained in this study are very helpful for improving the application of CO2 conversion, as they allow us to identify the limiting factors in the performance, based on which solutions can be provided on how to further improve the capabilities of CO2 conversion in the GAP.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
DOI: 10.1021/acs.jpcc.7b08511
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“Modeling Plasma-based CO2and CH4Conversion in Mixtures with N2, O2, and H2O: The Bigger Plasma Chemistry Picture”. Wang W, Snoeckx R, Zhang X, Cha MS, Bogaerts A, The journal of physical chemistry: C : nanomaterials and interfaces 122, 8704 (2018). http://doi.org/10.1021/acs.jpcc.7b10619
Abstract: Because of the unique properties of plasma technology, its use in gas conversion applications is gaining significant interest around the globe. Plasma-based CO2 and CH4 conversion has become a major research area. Many investigations have already been performed regarding the single-component gases, that is, CO2 splitting and CH4 reforming, as well as for two-component mixtures, that is, dry reforming of methane
(CO2/CH4), partial oxidation of methane (CH4/O2), artificial photosynthesis (CO2/H2O), CO2 hydrogenation (CO2/H2), and even first steps toward the influence of N2 impurities have been taken, that is, CO2/N2 and CH4/N2. In this Feature Article we briefly discuss the advances made in literature for these different steps from a plasma chemistry modeling point of view. Subsequently, we present a comprehensive plasma chemistry set, combining the knowledge gathered in this field so far and supported with extensive experimental data. This set can be used for chemical kinetics plasma modeling for all possible combinations of CO2, CH4, N2, O2, and H2O to investigate the bigger picture of the underlying plasmachemical pathways for these mixtures in a dielectric barrier discharge plasma. This is extremely valuable
for the optimization of existing plasma-based CO2 conversion and CH4 reforming processes as well as for investigating the influence of N2, O2, and H2O on these processes and even to support plasma-based multireforming processes.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.536
Times cited: 28
DOI: 10.1021/acs.jpcc.7b10619
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“High Coke Resistance of a TiO2Anatase (001) Catalyst Surface during Dry Reforming of Methane”. Huygh S, Bogaerts A, Bal KM, Neyts EC, Journal Of Physical Chemistry C 122, 9389 (2018). http://doi.org/10.1021/acs.jpcc.7b10963
Abstract: The resistance of a TiO2 anatase (001) surface to coke formation was studied in the context of dry reforming of methane using density functional theory (DFT) calculations. As carbon atoms act as precursors for coke formation, the resistance to coke formation can be measured by the carbon coverage of the surface. This is related to the stability of different CHx (x = 0−3) species and their rate of hydrogenation and dehydrogenation on the TiO2 surface. Therefore, we studied the reaction mechanisms and their corresponding rates as a function of the temperature for the dehydrogenation of the species on the surface. We found that the stabilities of C and CH are significantly lower than those of CH3 and CH2. The hydrogenation rates of the different species are significantly higher than the dehydrogenation rates in a temperature range of 300−1000 K. Furthermore, we found that dehydrogenation of CH3, CH2, and CH will only occur at appreciable rates starting from 600, 900, and 900 K, respectively. On the basis of these results, it is clear that the anatase (001) surface has a high coke resistance, and it is thus not likely that the surface will become poisoned by coke during dry reforming of methane. As the rate limiting step in dry reforming is the dissociative adsorption of CH4, we studied an alternative approach to thermal catalysis. We found that the temperature threshold for dry reforming is at least 700 K. This threshold temperature may be lowered by the use of plasma-catalysis, where the appreciable rates of adsorption of plasma-generated CHx radicals result in bypassing the rate limiting step of the reaction.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 4.536
Times cited: 1
DOI: 10.1021/acs.jpcc.7b10963
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“Do Binary Supracrystals Enhance the Crystal Stability?”.Yang Z, Altantzis T, Bals S, Tendeloo GV, Pileni M-P, The journal of physical chemistry: C : nanomaterials and interfaces 122, 13515 (2018). http://doi.org/10.1021/acs.jpcc.7b12373
Abstract: We study the oxygen thermal stability of two binary
systems. The larger particles are magnetic amorphous Co (7.2 nm) or
Fe3O4 (7.5 nm) nanocrystals, whereas the smaller ones (3.7 nm) are
Au nanocrystals. The nanocrystal ordering as well as the choice of the
magnetic nanoparticles very much influence the stability of the binary
system. A perfect crystalline structure is obtained with the Fe3O4/Au
binary supracrystals. For the Co/Au binary system, oxidation of Co
results in the chemical transformation from Co to CoO, where the size
of the amorphous Co nanoparticles increases from 7.2 to 9.8 nm in
diameter. During the volume expansion of the Co nanoparticles, Au
nanoparticles within the binary assemblies coalesce and are at the
origin of the instability of the binary nanoparticle supracrystals. On the
other hand, for the Fe3O4/Au binary system, the oxidation of Fe3O4 to
γ-Fe2O3 does not lead to a size change of the nanoparticles, which
maintains the stability of the binary nanoparticle supracrystals. A similar behavior is observed for an AlB2-type Co−Ag binary
system: The crystalline structure is maintained, whereas in disordered assemblies, coalescence of Ag nanocrystals is observed.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 5
DOI: 10.1021/acs.jpcc.7b12373
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“Multimode Electron Tomography as a Tool to Characterize the Internal Structure and Morphology of Gold Nanoparticles”. Winckelmans N, Altantzis T, Grzelczak M, Sánchez-Iglesias A, Liz-Marzán LM, Bals S, The journal of physical chemistry: C : nanomaterials and interfaces 122, 13522 (2018). http://doi.org/10.1021/acs.jpcc.7b12379
Abstract: Three dimensional (3D) characterization of structural defects in nanoparticles by transmission electron microscopy is far from straightforward. We propose the use of a dose-efficient approach, so-called multimode tomography, during which tilt series of low and high angle annular dark field scanning transmission electron microscopy projection images are acquired simultaneously. In this manner, not only reliable information can be obtained concerning the shape of the nanoparticles, but also the twin planes can be clearly visualized in 3D. As an example, we demonstrate the application of this approach to identify the position of the seeds with respect to the twinning planes in anisotropic gold nanoparticles synthesized using a seed mediated growth approach.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT)
Impact Factor: 4.536
Times cited: 23
DOI: 10.1021/acs.jpcc.7b12379
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