Secured access to clean water resources is a fundamental need of human society and nanoparticulate TiO₂ is amongst the most important materials for the photocatalytic degradation of organic pollutants. While TiO₂-nanoparticles (NPs) thus offer photocatalytically effective routes to wastewater treatment, separation of NPs from reaction media is difficult and catalyst recycling often impossible. Immobilization of TiO₂-NPs is therefore indispensable to facilitate handling as well as to control potential health and environmental hazards. We present silicone nanofilaments as a new flexible carrier type for TiO₂-NPs, because they can be deposited as thin carpets on a variety of substrates and their silicone nature renders them chemically and environmentally stable. We deposited TiO₂-NPs on thin carpets of silicone nanofilaments on glass slides in a convenient one-step reaction in ethanol/water mixtures from TiF₄ as precursor under mild conditions. The resulting nanocomposite material is characterized with a wide range of electron microscopy and other analytical techniques. The photocatalytic activity in the decomposition of methylene blue (MB) is proved and superior to TiO₂-NPs immobilized on bare glass supports. Furthermore, the substrates are reusable for several cycles without significant loss in activity.

In recent years, the development of high speed devices and their integrated circuits has facing some obstacles owing to localized heat generation in terms of safety and efficiency of devices. Nanofluids which were defined fluids containing nanometer-size particles, have been researched for their high and efficient heat transfer. It was reported that heat transfer enhancement was due to the Brownian motion of the nanoparticles contained in the fluids. Therefore, the diameter of nanoparticles in nanofluids is a key-factor in order to develop new heat transfer systems with higher energy-efficiency.

Recently our research group has developed a new synthesis method for well-defined nanoparticles in an aqueous solution, by solution plasma process (SPP). This process allows us to fabricate solutions containing high quantity of small monodispersed nanoparticles in order to obtain a heat transfer system with improved efficiency.

In this research, we aimed to reveal the heat transfer of nanofluids. The solution containing monodispersed gold nanoparticles was synthesized by SPP using a DC bipolar pulsed power supply. Gold nanofluids were synthesized with various concentrations of 0.1, 0.3, 0.6, 0.9 mM HAuCl4 and 4 times KOH of each HAuCl4 concentration in distilled water. The reaction time is 15 minutes. The solution plasma optical and electrical conditions were measured by OES and oscilloscope. The evaluation of the synthesized nanoparticles was performed by TEM analysis and UV vis spectroscopy. The dispersion stability was evaluated using zeta potential. In addition, KD2 pro & viscometer were used for heat transfer analysis of the synthesized nanofluids.

The decrease of the nanoparticles diameter from 13.8 ± 4.3 nm to 5.6 ± 1.4 nm was measured in dependence with the precursor concentration. The viscosity of the nanofludis increased with precursor concentration from 1.95 mPa·s to 2.05 mPa·s at 283 K (Viscosity of Di Water is 1.51 mPa·s.). A precursor concentration of 0.9 mM produced the smallest nanoparticles diameter of 5.6 ± 1.4 nm, and the highest increase of the thermal conductivity of 29.4 %.

Graphene, a two-dimensional sheet of sp²-bonded carbon arranged in a honeycomb lattice has attracted significant attention due to its interesting characteristics such as high carrier mobility, optical transparency, mechanical strength, and possible applications in various fields. Among the techniques developed for producing graphene, epitaxial growth on silicon carbide (SiC) is a promising method for large-scale production. Ion implantation is also a mature technology in large-scale electronic industry, which can take the epitaxial graphene into the semiconductor foundries.

Here we studied post ion-implant growth of epitaxial graphene on 6H-SiC substrates according to ion fluences, acceleration voltages, and substrate temperatures. N⁺ ions at 40-145keV were implanted with fluences of 1×10¹⁷ N⁺/cm² and 3×10¹⁷ N⁺/cm² into 6H-SiC substrates under room temperature (RT) and 650°C. The ion distributions and structural variations in the implanted samples have been studied using secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM) both before and after the graphene growth. This study revealed that the implanted N⁺ ion distributions in 6H-SiC are robust up to ~1330°C at which the epitaxial graphene begins to grow on Si-face of 6H-SiC and the graphene is formed only when the substrates are maintained at 650°C during ion implantation. This is believed to be due to the prominent damage recovery of 6H-SiC in high temperature implantations. The high crystallinity of the epitaxial graphene grown on the damage-recovered 6H-SiC was confirmed by photoelectron spectroscopy and low-energy electron diffraction.

Solution plasma process (SPP) is a new plasma system which could be used to synthesis metal nanoparticles. SPP is superior to other conventional methods, in term of ease of handling, low temperature, and short time treatment. It is therefore of our interest to apply the solution plasma process to prepare metal nanoparticles within mesoporous silica. The voltage, frequency and pulse width of solution plasma conditions were fixed at 1.6 kV, 15 KHz, and 2 µs, respectively. 1 mM of AgNO3 solution with 0.2 g mesoporous silica was treated with solution plasma for 15 minutes. The plasma-treated sample was filtrated prior to air dry for overnight. The dried sample was characterized by transmission electron microscopy (TEM). The TEM results showed that the silver nanoparticles could be performed during solution plasma treatment and filled within nanoscale channels of mesoporous silica matrix. This suggested that the solution plasma process could be a potential method for prepare metal nanoparticles within mesoporous silica.

A new hydrogen sensing concept is demonstrated based on the field emission form multi-walled carbon nanotubes. The low emission currents rise in proportional to hydrogen partial pressures above from 10^-9 to 10^-5 Torr. Catalytic Ni participated C-H reactions in low emission regime are considered the key factor of the sensing behavior. Simple setup, tiny structure, high sensitivity, and fast recovery make this innovative technique attractive to build miniature low cost hydrogen sensors for low pressure applications.