The surface functionalization of radio frequency magnetron-sputtered zinc oxide (ZnO) thin films tailored by low-pressure Ar/NH mixture surface-wave plasmas (SWPs) is discussed based on the results of photoluminescence (PL), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectrophotometric measurements. At an Ar/NH gas mixture ratio of 70%/30%, both the PL intensity of the near-band-edge emission and the XRD intensity of the ZnO(002) reflection peak were enhanced by about 5.5 and 8 times, respectively, compared to the values for the as-grown sample. Furthermore, the XPS and spectrophotometric analyses using the fluorescent dye showed that the amine group functionalization over the surface of the ZnO films reached their maximum values at the same gas ratio. From the results of optical emission spectroscopic and ion mass spectrometric measurements in the Ar/NH mixture SWPs, it is inferred that the nitrogen-containing reactive species, such as NH ( x = 1-4) ions and NH ( y = 1, 2) molecules in addition to H radicals might crucially interact with the defective ZnO surface lattices to repair the ZnO thin films from compressive to strain-free crystallized structures, enhance the PL intensity, and produce the amine group surface functionalization.

Owing to its low toxicity toward living organisms and specific optical properties, we promote the use of zinc oxide (ZnO) as an alternative to existing semiconductor-based materials for developing new bioimaging techniques. ZnO nanoparticles (NPs) were prepared using the laser ablation technique in oxygen reactive atmosphere at room temperature by ablating a commercial high-purity ZnO target. The surface functionalization of ZnO NPs was successfully achieved using a dry chemical reactor with ammonia/argon mixture plasma. The roles of various plasma ions in the surface interaction with ZnO NPs were investigated to understand the mechanism of functionalization by quadrupole mass spectrometry.

Flower-like ZnO architectures assembled with many nanorods were successfully synthesized through Thermionic Vacuum Arc, operated both in direct current (DC-TVA) and a pulsed mode (PTVA), and coupled with annealing in an oxygen atmosphere. The prepared coatings were analysed by scanning-electron microscopy with energy-dispersive X-ray-spectroscopy (SEM-EDX), X-ray-diffraction (XRD), and photoluminescence (PL) measurements. By simply modifying the TVA operation mode, the morphology and uniformity of ZnO nanorods can be tuned. The photocatalytic performance of synthesized nanostructured ZnO coatings was measured by the degradation of methylene-blue (MB) dye and ciprofloxacin (Cipro) antibiotic. The ZnO (PTVA) showed enhancing results regarding the photodegradation of target contaminants. About 96% of MB molecules were removed within 60 min of UV irradiation, with a rate constant of 0.058 min−1, which is almost nine times higher than the value of ZnO (DC-TVA). As well, ZnO (PTVA) presented superior photocatalytic activity towards the decomposition of Cipro, after 240 min of irradiation, yielding 96% degradation efficiency. Moreover, the agar-well diffusion assay performance against both Gram-positive and Gram-negative bacteria confirms the degradation of antibiotic molecules by the UV/ZnO (PTVA) approach, without the formation of secondary hazardous products during the photocatalysis process. Repeated cyclic usage of coatings revealed excellent reusability and operational stability.

Hollow carbon nanospheres with controlled morphologies were synthesized via the copper-carbon direct current arc discharge method by alternating the concentrations of methane in the reactant gas mixture. A self-healing process to keep the structural integrity of encapsulated graphitic shells was evolved gradually by adding methane gas from 0% to 20%. The outer part of the coated layers expanded and hollow nanospheres grew to be large fluffy ones with high methane concentrations from 30% to 50%. A self-repairing function by the reattachment of broken graphitic layers initiated from near-electrode space to distance was also distinctly exhibited. By comparing several comparable metals (e.g. copper, silver, gold, zinc, iron and nickel)-carbon arc discharge products, a catalytic carbon-encapsulation mechanism combined with a core-escaping process has been proposed. Specifically, on the basis of the experimental results, copper could be applied as a unique model for both the catalysis of graphitic encapsulation and as an adequate template for the formation of hollow nanostructures.

In this study, we developed an elongated parallel plate type dielectric barrier discharge(DBD) device with pre-ionization electrodes for large-area surface modification of fluorine contained resin films, such as polytetrafluoroethylene (PTFE) and ethylene tetrafluoroethylene (ETFE). By optimizing a phase difference between pre-ionization and main discharge voltages, we confirmed that an intensified DBD plasma was generated between main electrodes having an electrode area of 50 × 200 mm 2 and a gap of 5 mm. Uniformity of surface modification of fluorine contained resin films treated by DBD plasmas were examined under air and helium circumstances using carboxyl-reactive fluorescence dye for different polymer materials (PTFE, ETFE and polyethylene) and treatment times.

Despite its great potential for thin films deposition and technological applications, the HiPIMS technology has its own limitations including the control of ion energy and flux towards the substrate when coping with the deposition of electrical insulating films and/or the deposition onto insulating/electrically grounded substrates. The bipolar-HiPIMS has been recently developed as a strategy to accelerate the plasma ions towards a growing film maintained at ground potential. In this work, the benefits of bipolar-HiPIMS deposition onto floating or nonconductive substrates are explored. The effect of bipolar-HIPIMS pulsing configuration, magnetic balance-unbalance degree, and substrate’s condition on plasma characteristics, microstructure evolution, and mechanical properties of CrN coatings was investigated. During the deposition with a balanced magnetron configuration, a significant ion bombardment effect was detected when short negative pulses and relative long positive pulses were used. XRD analysis and AFM observations revealed significant microstructural changes by increasing the positive pulse duration, which results in an increase in hardness from 7.3 to 16.2 GPa, during deposition on grounded substrates, and from 4.9 to 9.4 GPa during the deposition on floating substrates. The discrepancies between the hardness values of the films deposited on floating substrates and those of the films deposited on grounded substrates become smaller/larger when a type I/type II unbalanced magnetron configuration is used. Their hardness ratio was found to be 0.887, in the first case, and 0.393, in the second one. Advanced application-tailored coatings can be deposited onto floating substrates by using the bipolar-HiPIMS technology if short negative pulses, relative long positive pulses together with type I unbalanced magnetron are concomitantly used.

Eco-friendly and facile zinc oxide (ZnO) synthesis of zinc-oxide-based nanomaterials with specific properties is a great challenge due to its excellent industrial applications in the field of semiconductors and solar cells. In this paper, we report the production of zinc oxide thin films at relatively low deposition temperature employing a simple and non-toxic method at low substrate temperature: pulsed laser ablation, as a first step for developing a n-ZnO/p-Si heterojunction. Single-phase n-type zinc oxide thin films are confirmed by an X-ray diffraction (XRD) pattern revealed by the maximum diffraction intensity from the (002) plane. Absorbance measurements indicate an increase in the band gap energy close to the bulk ZnO. A 350 °C substrate temperature led to obtaining a highly porous film with high crystallinity and high bandgap, showing good premises for further applications.

Scaling up atmospheric pressure dielectric barrier discharges is a challenging prerequisite to expanding their industrial applications. In this study, we present the results of large-volume dielectric barrier discharges (DBDs) with a parallel plate electrode configuration having an electrode surface of 50×200 mm 2 and an interelectrode gap of 5 mm. Highly dense filamentary DBD plasma was stably generated over a large area using pre-ionization electrodes embedded in the one of electrodes. We show that the role of the pre-triggering system is crucial in producing a densely distributed filamentary discharge over the electrode surface, especially at the main discharge voltage values of 14.0-18.0 kVp-p and pre-ionization voltage of 7.0-10.0 kVp-p at the same frequency, ranging from 1 to 4 kHz. By tuning the phase difference between the preionization and main discharge voltages to around 180 degrees, both discharge current amplitude and duration time per period of main DBDs are maximized. The present results indicate that such a large-volume DBD is extremely versatile and suited for a wide range of industrial applications.