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| Author | Gogoi, A.; Neyts, E.C.; Milošević, M.V.; Peeters, F.M. | ||||
| Title | Arresting aqueous swelling of layered graphene-oxide membranes with H3O+ and OH- ions | Type | A1 Journal article | ||
| Year | 2022 | Publication  |
ACS applied materials and interfaces | Abbreviated Journal | Acs Appl Mater Inter |
| Volume | 14 | Issue | 30 | Pages | 34946-34954 |
| Keywords | A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) | ||||
| Abstract | Over the past decade, graphene oxide (GO) has emerged as a promising membrane material with superior separation performance and intriguing mechanical/chemical stability. However, its practical implementation remains very challenging primarily because of its undesirable swelling in an aqueous environment. Here, we demonstrated that dissociation of water molecules into H3O+ and OH- ions inside the interlayer gallery of a layered GO membrane can strongly affect its stability and performance. We reveal that H3O+ and OH- ions form clusters inside the GO laminates that impede the permeance of water and salt ions through the membrane. Dynamics of those clusters is sensitive to an external ac electric field, which can be used to tailor the membrane performance. The presence of H3O+ and OH- ions also leads to increased stability of the hydrogen bond (H-bond) network among the water molecules and the GO layers, which further reduces water permeance through the membrane, while crucially imparting stability to the layered GO membrane against undesirable swelling. KEYWORDS: layered graphene-oxide membrane, aqueous stability, H3O+ and OH- ions, external electric field, molecular dynamics | ||||
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| Publisher | Place of Publication | Editor | |||
| Language | Wos | 000835946500001 | Publication Date | 2022-07-25 | |
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 1944-8244 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
| Impact Factor | 9.5 | Times cited | 9 | Open Access | OpenAccess |
| Notes | Approved | Most recent IF: 9.5 | |||
| Call Number | UA @ admin @ c:irua:189467 | Serial | 7127 | ||
| Permanent link to this record | |||||
| Author | Khalilov, U.; Bogaerts, A.; Neyts, E.C. | ||||
| Title | Toward the Understanding of Selective Si Nano-Oxidation by Atomic Scale Simulations | Type | A1 Journal article | ||
| Year | 2017 | Publication |
Accounts of chemical research | Abbreviated Journal | Accounts Chem Res |
| Volume | 50 | Issue | 50 | Pages | 796-804 |
| Keywords | A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) | ||||
| Abstract | The continuous miniaturization of nanodevices, such as transistors, solar cells, and optical fibers, requires the controlled synthesis of (ultra)thin gate oxides (<10 nm), including Si gate-oxide (SiO2) with high quality at the atomic scale. Traditional thermal growth of SiO2 on planar Si surfaces, however, does not allow one to obtain such ultrathin oxide due to either the high oxygen diffusivity at high temperature or the very low sticking ability of incident oxygen at low temperature. Two recent techniques, both operative at low (room) temperature, have been put forward to overcome these obstacles: (i) hyperthermal oxidation of planar Si surfaces and (ii) thermal or plasma-assisted oxidation of nonplanar Si surfaces, including Si nanowires (SiNWs). These nanooxidation processes are, however, often difficult to study experimentally, due to the key intermediate processes taking place on the nanosecond time scale. In this Account, these Si nano-oxidation techniques are discussed from a computational point of view and compared to both hyperthermal and thermal oxidation experiments, as well as to well-known models of thermal oxidation, including the Deal−Grove, Cabrera−Mott, and Kao models and several alternative mechanisms. In our studies, we use reactive molecular dynamics (MD) and hybrid MD/Monte Carlo simulation techniques, applying the Reax force field. The incident energy of oxygen species is chosen in the range of 1−5 eV in hyperthermal oxidation of planar Si surfaces in order to prevent energy-induced damage. It turns out that hyperthermal growth allows for two growth modes, where the ultrathin oxide thickness depends on either (1) only the kinetic energy of the incident oxygen species at a growth temperature below Ttrans = 600 K, or (2) both the incident energy and the growth temperature at a growth temperature above Ttrans. These modes are specific to such ultrathin oxides, and are not observed in traditional thermal oxidation, nor theoretically considered by already existing models. In the case of thermal or plasma-assisted oxidation of small Si nanowires, on the other hand, the thickness of the ultrathin oxide is a function of the growth temperature and the nanowire diameter. Below Ttrans, which varies with the nanowire diameter, partially oxidized SiNW are formed, whereas complete oxidation to a SiO2 nanowire occurs only above Ttrans. In both nano-oxidation processes at lower temperature (T < Ttrans), final sandwich c-Si|SiOx|a-SiO2 structures are obtained due to a competition between overcoming the energy barrier to penetrate into Si subsurface layers and the compressive stress (∼2−3 GPa) at the Si crystal/oxide interface. The overall atomic-simulation results strongly indicate that the thickness of the intermediate SiOx (x < 2) region is very limited (∼0.5 nm) and constant irrespective of oxidation parameters. Thus, control over the ultrathin SiO2 thickness with good quality is indeed possible by accurately tuning the oxidant energy, oxidation temperature and surface curvature. In general, we discuss and put in perspective these two oxidation mechanisms for obtaining controllable ultrathin gate-oxide films, offering a new route toward the fabrication of nanodevices via selective nano-oxidation. |
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| Publisher | Place of Publication | Editor | |||
| Language | Wos | 000399859800016 | Publication Date | 2017-04-18 | |
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 0001-4842 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
| Impact Factor | 20.268 | Times cited | 5 | Open Access | OpenAccess |
| Notes | Fonds Wetenschappelijk Onderzoek, 12M1315N ; | Approved | Most recent IF: 20.268 | ||
| Call Number | PLASMANT @ plasmant @ c:irua:142638 | Serial | 4561 | ||
| Permanent link to this record | |||||
| Author | Heyne, M.H.; Marinov, D.; Braithwaite, N.; Goodyear, A.; de Marneffe, J.-F.; Cooke, M.; Radu, I.; Neyts, E.C.; De Gendt, S. | ||||
| Title | A route towards the fabrication of 2D heterostructures using atomic layer etching combined with selective conversion | Type | A1 Journal article | ||
| Year | 2019 | Publication |
2D materials | Abbreviated Journal | 2D Mater |
| Volume | 6 | Issue | 3 | Pages | 035030 |
| Keywords | A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) | ||||
| Abstract | Heterostructures of low-dimensional semiconducting materials, such as transition metal dichalcogenides (MX2), are promising building blocks for future electronic and optoelectronic devices. The patterning of one MX2 material on top of another one is challenging due to their structural similarity. This prevents an intrinsic etch stop when conventional anisotropic dry etching processes are used. An alternative approach consist in a two-step process, where a sacrificial silicon layer is pre-patterned with a low damage plasma process, stopping on the underlying MoS2 film. The pre-patterned layer is used as sacrificial template for the formation of the top WS2 film. This study describes the optimization of a cyclic Ar/Cl-2 atomic layer etch process applied to etch silicon on top of MoS2, with minimal damage, followed by a selective conversion of the patterned Si into WS2. The impact of the Si atomic layer etch towards the MoS2 is evaluated: in the ion energy range used for this study, MoS2 removal occurs in the over-etch step over 1-2 layers, leading to the appearance of MoOx but without significant lattice distortions to the remaining layers. The combination of Si atomic layer etch, on top of MoS2, and subsequent Si-to-WS2 selective conversion, allows to create a WS2/MoS2 heterostructure, with clear Raman signals and horizontal lattice alignment. These results demonstrate a scalable, transfer free method to achieve horizontally individually patterned heterostacks and open the route towards wafer-level processing of 2D materials. | ||||
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| Publisher | Place of Publication | Editor | |||
| Language | Wos | 000468335500004 | Publication Date | 2019-04-23 | |
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 2053-1583 | ISBN | Additional Links | UA library record; WoS full record; WoS citing articles | |
| Impact Factor | 6.937 | Times cited | Open Access | Not_Open_Access | |
| Notes | Approved | Most recent IF: 6.937 | |||
| Call Number | UA @ admin @ c:irua:160229 | Serial | 5266 | ||
| Permanent link to this record | |||||