1. Catalytic conversion of nonequilibrium hydrogen and nitrogen species from low-pressure inductively coupled plasma to ammoniaRok Zaplotnik, Alenka Vesel, Ganji Parameswaram, Gregor Primc, Miha Čekada, Gregor Dolanc, Miran Mozetič, 2026, izvirni znanstveni članek Povzetek: Gas conversion between hydrogen (H2), nitrogen (N2), and ammonia (NH3) is a scientific topic of interest in both methods for low-temperature synthesis of ammonia and energy-efficient production of hydrogen for powering fuel cells. The efficiency of catalysts for ammonia synthesis at room temperature was evaluated. A mixture of hydrogen and nitrogen with a ratio in a broad range between 1.5:1 and 80:1 was passed through a plasma sustained by inductively coupled radio frequency discharge in the H mode at a power of 700 W and pressures between 40 and 100 Pa. Several catalysts were placed in the flowing afterglow where the H and N densities were of the order of 1021 m−3, and the conversion efficiency (η) was evaluated. The efficiency increased almost linearly with increasing enthalpy of nitride formation. The best results were observed for copper, for which the conversion was almost twice the value in the same system without the catalyst. The efficiency of NH3 production by the conversion of N atoms into NH3 molecules versus the gas mixture exhibited a broad maximum and was as large as η ≈ 29% in the mixture of hydrogen and nitrogen between 3:1 and 10:1.
Ključne besede: hydrogen production
Objavljeno v DiRROS: 14.05.2026; Ogledov: 54; Prenosov: 27
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2. Utilization of waste plastic for plasma-assisted deposition of carbon nanowalls on electrodes for sustainable high-performance energy-storage devicesAlenka Vesel, Gregor Primc, Miran Mozetič, Melita Tramšek, Evelin Gruden, Haojie Fei, Petr Sáha, Marián Lehocký, Rok Zaplotnik, 2026, izvirni znanstveni članek Povzetek: Current global policies, such as circular economy, electrification, and low carbon footprint dictate the replacement of fossil fuels for synthesizing electrodes of graphene supercapacitors with renewable sources. The traditional method for depositing graphene and similar structures is based on gaseous hydrocarbons. The possibility of replacing them with waste plastic is presented. We used propane and waste plastics (mostly polypropylene) for the deposition of a few µm-thick deposit of carbon nanowalls composed of vertically oriented multilayer graphene-like sheets on electrodes by plasma-enhanced chemical vapor deposition (PECVD). We studied their morphology and structure, as well as the performance of coin-shaped supercapacitors. The graphene-like coatings were deposited in plasma sustained at the pressure of 16 Pa by inductively coupled RF discharge in the H mode at the forward power of 500 W and power density approximately 8x106 W/m3. Such a powerful plasma caused thermal decomposition of the waste plastic. Optical emission spectroscopy showed significant differences only within the first few seconds of plasma treatment, which was enough to supply precursors for graphene growth. Both scanning and transmission electron microscopies showed similar structures for deposits prepared from propane or waste plastic, and the deposition rates of roughly 100 nm/s were observed. Waste plastic enabled the deposition of 2–3 times densely packed multilayer graphene-like sheets of a typical thickness of 5 nm at deposition times over 1 min. Raman spectroscopy indicated a somewhat lower concentration of defects for samples deposited from polypropylene, but the ID/IG versus the average distance between the neighboring multilayer graphene-like sheets followed the same line. The specific capacitance increased steeply with deposition time for deposits prepared from waste plastic and it was found to be linearly dependent on the ratio between the effective and projected areas of both precursors. The capacitance versus the ID/IG followed the same curve for both precursors. The results demonstrate the feasibility of replacing gaseous hydrocarbons with waste plastics for PECVD deposition of graphene electrodes.
Ključne besede: carbon nanomaterials, carbonnanowalls, electrode material, supercapacitators
Objavljeno v DiRROS: 28.04.2026; Ogledov: 158; Prenosov: 108
Celotno besedilo (19,51 MB)
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3. Surface functionalization of medical-grade polyvinyl chloride treated with ammonia plasmaRok Zaplotnik, Nina Recek, Gregor Primc, Andrej Gyergyek, Marián Lehocký, Alenka Vesel, Miran Mozetič, 2026, izvirni znanstveni članek Ključne besede: PVC polymer, ammonia plasma
Objavljeno v DiRROS: 20.02.2026; Ogledov: 436; Prenosov: 224
Celotno besedilo (7,28 MB)
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5. Hydrophilization of rice seeds by plasma treatments – super-hydrophilic surface finish and hydrophobic recoveryAlenka Vesel, Anca Macovei, Alma Balestrazzi, Dane Lojen, Gregor Primc, Rok Zaplotnik, Nives Ogrinc, Marián Lehocký, Miran Mozetič, 2025, izvirni znanstveni članek Povzetek: The hydrophobic character of rice seeds protects them from quick water adsorption and, thus, premature germination. This property is, however, a drawback in modern agriculture, where rapid and uniform germination represents a high-quality trait. A method for rapid hydrophilization of the Lomello variety of rice is presented. The rice seeds were treated with low-pressure gaseous plasma to tailor the wettability. The treatment of seeds with hulls with oxygen plasma afterglow enabled the super-hydrophilic surface finish within 10 ms. Such extremely fast hydrophilization was attributed to irreversible surface oxidation by neutral oxygen atoms whose flux onto the seeds was approximately 3 × 1023 m−2s−1. Dehulled seeds were made super-hydrophilic by subsequent treatments with hydrogen and oxygen plasma, and the required dose of O atoms was between 2 × 1023 and 6 × 1024 m−2. Larger doses caused a loss of the super-hydrophilicity. Hydrophilization kinetics is proposed and supported by measuring surface wettability, morphology, and composition using various techniques. The hydrophobic recovery of seeds with hulls is marginal within the first few days after plasma treatments, but dehulled seeds lose the super-hydrophilic surface finish within a few minutes after the plasma treatment when stored at ambient conditions.
Ključne besede: rice seed, water adsorption, surface treatment, wettability, super-hydrophilicity
Objavljeno v DiRROS: 10.11.2025; Ogledov: 461; Prenosov: 300
Celotno besedilo (13,19 MB)
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6. Defluorination of polytetrafluoroethylene surface by hydrogen plasmaAlenka Vesel, Dane Lojen, Rok Zaplotnik, Gregor Primc, Miran Mozetič, Jernej Ekar, Janez Kovač, Marija Gorjanc, Manja Kurečič, Karin Stana-Kleinschek, 2022, samostojni znanstveni sestavek ali poglavje v monografski publikaciji Ključne besede: polytetrafluoroethylene, fluorine depletion, hydrogen plasma, VUV radiation, surface modification, hydrophilic
Objavljeno v DiRROS: 10.11.2025; Ogledov: 438; Prenosov: 249
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10. Plasma treatment-promising tool for preparation of disposable monolithic columnsIta Junkar, Gregor Primc, Tanja Lukan, Matic Resnik, Janez Kovač, Andrijana Sever Škapin, Aleš Podgornik, Miran Mozetič, 2015, izvirni znanstveni članek Povzetek: Atmospheric pressure plasma jet was employed to improve adhesion between polypropylene (PP) column wall and monolith used in chromatography. Different treatment conditions for modification of PP tube were used and the effects of treatment were analysed with X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Modified surfaces had higher oxygen content and surface was covered with small grain like structures. To explore effects of modification on adhesion between PP tube and monolith tensile strength measurements were conducted. It was shown that appropriate treatment conditions significantly increased bonding strength. The improvement of adhesion was attributed to increased oxygen functional groups obtained from plasma.
Objavljeno v DiRROS: 05.09.2025; Ogledov: 551; Prenosov: 303
Celotno besedilo (1,00 MB)
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