The Future of Plasma Nanoscience
Editor: Erik C. Neyts

Over the past 20 years, plasma nanoscience has become a mature and vibrant field. It deals with both the fundamental science and applications of low-temperature plasmas, ion beams, lasers, and related approaches and how this relates to the fabrication, synthesis, modification, and integration in and of nanoscale materials, structures and functional devices. The complexity often encountered in research in this field intrinsically calls for both fundamental and applied research, both experimental and theoretical. Plasma nanoscience, therefore, is a highly multidisciplinary field, bringing together researchers from physics, chemistry, medicine, engineering, biochemistry, informatics and more.

This Special Issue in Frontiers of Chemical Science and Engineering themed “The Future of Plasma Nanoscience” is the direct result of the iPlasmaNano-VIII conference held in 2017 in Antwerp, Belgium. This edition focused on modeling and simulation of fundamental processes, plasma nanocatalysis, plasma medicine, nanomaterials and plasmas for micro-electronics.
Publication years
Loading ...
Article types
Loading ...
  • Select all
    Mahmoud Trad, Alexandre Nominé, Natalie Tarasenka, Jaafar Ghanbaja, Cédric Noël, Malek Tabbal, Thierry Belmonte
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 360-368.

    The synthesis of CdO, Ag2O (5 nm) and Ag (~20‒30 nm) nano-objects is achieved simultaneously by nanosecond-pulsed discharges in liquid nitrogen between one cadmium electrode and one silver electrode. Oxidation occurs when liquid nitrogen is fully evaporated and nanoparticles are in contact with the air. No alloy is formed, whatever the conditions, even though both elements are present simultaneously, as showed by time-resolved optical emission spectroscopy. This lack of reactivity between elements is attributed to the high pressure within the discharge that keeps each metallic vapor around the electrode it comes from. Each element exhibits a specific behavior. Cubic Cd particles, formed at 4 kV, get elongated with filamentary tips when the applied voltage reaches 7 and 10 kV. Cd wires are formed by assembly in liquid nitrogen of Cd nanoparticles driven by dipole assembly, and not by dielectrophoresis. On the contrary, silver spherical particles get assembled into 2D dendritic structures. The anisotropic growth of these structures is assumed to be due to the existence of pressure gradients.

    Xiuqi Fang, Carles Corbella, Denis B. Zolotukhin, Michael Keidar
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 350-359.

    Graphene platelet networks (GPNs) were deposited onto silicon substrates by means of anodic arc discharge ignited between two graphite electrodes. Substrate temperature and pressure of helium atmosphere were optimized for the production of the carbon nanomaterials. The samples were modified or destroyed with different methods to mimic typical environments responsible of severe surface degradation. The emulated conditions were performed by four surface treatments, namely thermal oxidation, substrate overheating, exposition to glow discharge, and metal coating due to arc plasma. In the next step, the samples were regenerated on the same substrates with identical deposition technique. Damaging and re-growth of GPN samples were systematically characterized by scanning electron microscopy and Raman spectroscopy. The full regeneration of the structural and morphological properties of the samples has proven that this healing method by arc plasma is adequate for restoring the functionality of 2D nanostructures exposed to harsh environments.

    Rusen Zhou, Renwu Zhou, Xianhui Zhang, Kateryna Bazaka, Kostya (Ken) Ostrikov
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 340-349.

    Continuous processes which allow for large amount of wastewater to be treated to meet drainage standards while reducing treatment time and energy consumption are urgently needed. In this study, a dielectric barrier discharge plasma water bed system was designed and then coupled with granular activated carbon (GAC) adsorption to rapidly remove acid fuchsine (AF) with high efficiency. Effects of feeding gases, treatment time and initial concentration of AF on removal efficiency were investigated. Results showed that compared to the N2 and air plasmas treatments, O2 plasma processing was most effective for AF degradation due to the strong oxidation ability of generated activated species, especially the OH radicals. The addition of GAC significantly enhanced the removal efficiency of AF in aqueous solution and shorten the required time by 50%. The effect was attributed to the ability of porous carbon to trap and concentrate the dye, increasing the time dye molecules were exposed to the plasma discharge zone, and to enhance the production of OH radicals on/in GAC to boost the degradation of dyes by plasma as well as in situ regenerate the exhausted GAC. The study offers a new opportunity for continuous effective remediation of wastewater contaminated with organic dyes using plasma technologies.

    Ana Mora-Boza, Francisco J. Aparicio, María Alcaire, Carmen López-Santos, Juan P. Espinós, Daniel Torres-Lagares, Ana Borrás, Angel Barranco
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 330-339.

    Novel antibacterial materials for implants and medical instruments are essential to develop practical strategies to stop the spread of healthcare associated infections. This study presents the synthesis of multifunctional antibacterial nanocoatings on polydimethylsiloxane (PDMS) by remote plasma assisted deposition of sublimated chlorhexidine powders at low pressure and room temperature. The obtained materials present effective antibacterial activity against Escherichia coli K12, either by contact killing and antibacterial adhesion or by biocide agents release depending on the synthetic parameters. In addition, these multifunctional coatings allow the endure hydrophilization of the hydrophobic PDMS surface, thereby improving their biocompatibility. Importantly, cell-viability tests conducted on these materials also prove their non-cytotoxicity, opening a way for the integration of this type of functional plasma films in biomedical devices.

    Pascal Brault, William Chamorro-Coral, Sotheara Chuon, Amaël Caillard, Jean-Marc Bauchire, Stève Baranton, Christophe Coutanceau, Erik Neyts
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 324-329.

    Molecular dynamics simulations are carried out for describing growth of Pd and PdO nanoclusters using the ReaxFF force field. The resulting nanocluster structures are successfully compared to those of nanoclusters experimentally grown in a gas aggregation source. The PdO structure is quasi-crystalline as revealed by high resolution transmission microscope analysis for experimental PdO nanoclusters. The role of the nanocluster temperature in the molecular dynamics simulated growth is highlighted.

    J. Christopher Whitehead
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 264-273.

    The issues of describing and understanding the changes in performance that result when a catalyst is placed into plasma are discussed. The different chemical and physical interactions that result and how their combination might produce beneficial results for the plasma-catalytic processing of different gas streams are outlined with particular emphasis being placed on the different range of spatial and temporal scales that must be considered both in experiment and modelling. The focus is on non-thermal plasma where the lack of thermal equilibrium creates a range of temperature scales that must be considered. This contributes in part to a wide range of inhomogeneity in different properties such as species concentrations and electric fields that must be determined experimentally by in situ methods and be incorporated into modelling. It is concluded that plasma-catalysis is best regarded as conventional catalysis perturbed by the presence of a discharge, which modifies its operating conditions, properties and outcomes often in a very localised way. The sometimes used description “plasma-activated catalysis” is an apt one.

    Annemie Bogaerts, Maksudbek Yusupov, Jamoliddin Razzokov, Jonas Van der Paal
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 253-263.

    Plasma is gaining increasing interest for cancer treatment, but the underlying mechanisms are not yet fully understood. Using computer simulations at the molecular level, we try to gain better insight in how plasma-generated reactive oxygen and nitrogen species (RONS) can penetrate through the cell membrane. Specifically, we compare the permeability of various (hydrophilic and hydrophobic) RONS across both oxidized and non-oxidized cell membranes. We also study pore formation, and how it is hampered by higher concentrations of cholesterol in the cell membrane, and we illustrate the much higher permeability of H2O2 through aquaporin channels. Both mechanisms may explain the selective cytotoxic effect of plasma towards cancer cells. Finally, we also discuss the synergistic effect of plasma-induced oxidation and electric fields towards pore formation.

    Anna Khlyustova, Cédric Labay, Zdenko Machala, Maria-Pau Ginebra, Cristina Canal
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 238-252.

    Reactive oxygen and nitrogen species (RONS) are among the key factors in plasma medicine. They are generated by atmospheric plasmas in biological fluids, living tissues and in a variety of liquids. This ability of plasmas to create a delicate mix of RONS in liquids has been used to design remote or indirect treatments for oncological therapy by treating biological fluids by plasmas and putting them in contact with the tumour. Documented effects include selective cancer cell toxicity, even though the exact mechanisms involved are still under investigation. However, the “right” dose for suitable therapeutical activity is crucial and still under debate. The wide variety of plasma sources hampers comparisons. This review focuses on atmospheric pressure plasma jets as the most studied plasma devices in plasma medicine and compiles the conditions employed to generate RONS in relevant liquids and the concentration ranges obtained. The concentrations of H2O2, NO2, NO3 and short-lived oxygen species are compared critically to provide a useful overview for the reader.

    Michael Bonitz, Alexey Filinov, Jan-Willem Abraham, Karsten Balzer, Hanno Kählert, Eckhard Pehlke, Franz X. Bronold, Matthias Pamperin, Markus Becker, Dettlef Loffhagen, Holger Fehske
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 201-237.

    Solids facing a plasma are a common situation in many astrophysical systems and laboratory setups. Moreover, many plasma technology applications rely on the control of the plasma-surface interaction, i.e., of the particle, momentum and energy fluxes across the plasma-solid interface. However, presently often a fundamental understanding of them is missing, so most technological applications are being developed via trial and error. The reason is that the physical processes at the interface of a low-temperature plasma and a solid are extremely complex, involving a large number of elementary processes in the plasma, in the solid as well as fluxes across the interface. An accurate theoretical treatment of these processes is very difficult due to the vastly different system properties on both sides of the interface: Quantum versus classical behavior of electrons in the solid and plasma, respectively; as well as the dramatically differing electron densities, length and time scales. Moreover, often the system is far from equilibrium. In the majority of plasma simulations surface processes are either neglected or treated via phenomenological parameters such as sticking coefficients, sputter rates or secondary electron emission coefficients. However, those parameters are known only in some cases and with very limited accuracy. Similarly, while surface physics simulations have often studied the impact of single ions or neutrals, so far, the influence of a plasma medium and correlations between successive impacts have not been taken into account. Such an approach, necessarily neglects the mutual influences between plasma and solid surface and cannot have predictive power.

    In this paper we discuss in some detail the physical processes of the plasma-solid interface which brings us to the necessity of coupled plasma-solid simulations. We briefly summarize relevant theoretical methods from solid state and surface physics that are suitable to contribute to such an approach and identify four methods. The first are mesoscopic simulations such as kinetic Monte Carlo and molecular dynamics that are able to treat complex processes on large scales but neglect electronic effects. The second are quantum kinetic methods based on the quantum Boltzmann equation that give access to a more accurate treatment of surface processes using simplifying models for the solid. The third approach are ab initio simulations of surface process that are based on density functional theory (DFT) and time-dependent DFT. The fourths are nonequilibrium Green functions that able to treat correlation effects in the material and at the interface. The price for the increased quality is a dramatic increase of computational effort and a restriction to short time and length scales. We conclude that, presently, none of the four methods is capable of providing a complete picture of the processes at the interface. Instead, each of them provides complementary information, and we discuss possible combinations.

    Erik C. Neyts
    Frontiers of Chemical Science and Engineering, 2019, 13(2): 199-200.