Surface modification of highly porous 3D networks via atmospheric plasma treatment

Abstract

Tetrapodal ZnO (T‐ZnO) and aerographite networks represent two highly open porous (94.6 and 99.96%, respectively) model materials on which the impact of an atmospheric‐pressure plasma was studied for the first time. The air plasma treatment by a surface barrier discharge caused remarkable surface modifications on the T‐ZnO template, leading to a large number of oxygen vacancies. These observations were made using scanning electron microscopy (SEM) and Raman spectroscopy. In the second proposed set‐up, pellets of aerographite material were processed to a plasma jet with pressurized air and nitrogen. Hexamethyldisiloxane (HMDSO) was introduced as a precursor into the effluent jet for nanoparticle deposition. Opposing trends in atomic concentrations versus distance to the plasma source were observed when the gas (nitrogen or pressurized air) was changed. More pronounced nanoparticle coverage occurred in the pressurized air plasma. Their distribution was studied using SEM, energy‐dispersive X‐ray (EDX), and Raman spectroscopy. Because of the higher oxidation in the pressurized air plasma treatment, the deposited nanostructures appeared to be a mixture of Si and SiOx nanoparticles.

On the plasma permeability of highly porous ceramic framework materials using polymers as marker materials

“…[ 41–43 ] This comes with the advantage of low mechanical impact on the studied material samples compared to strong gas flows using atmospheric pressure plasma jets. [ 44 ] The walls of the plasma chamber are used as the grounded electrode, which results in a large geometric asymmetry (Figure 2a). Hence, a negative self‐bias occurs, which has been described elsewhere.…”

“…The porosity of this framework material in % can be calculated by comparing the network's density with the bulk density of ZnO ($${{\rm{\rho }}}_{\mathrm{ZnO}}=5.61$$ g cm −3 ) using the formula $${\rm{\phi }}=\left(1-\frac{{{\rm{\rho }}}_{\mathrm{network}}}{{{\rm{\rho }}}_{\mathrm{ZnO}}}\right)* 100$$. [ 44 ]…”

Improved Long‐Term Stability and Reduced Humidity Effect in Gas Sensing: SiO2 Ultra‐Thin Layered ZnO Columnar Films

“…The SiO 2 ultra-thin layer (of 10-20 nm) was deposited on the top of samples using the commercial atmospheric pressure plasma jet PFW 10 (Plasmatreat GmbH, Steinhagen, Germany) and hexamethyldisiloxane www.advmattechnol.de (HMDSO) as precursor similar as in other works. [63][64][65][66] The jet parameters were 300 V primary voltage, 19 kHz discharge frequency, and a plasma cycle time of 100%, which corresponds to a duty cycle of 50%. As working gas, 30 slm pressured air was used, and 1 slm N 2 (Air Liquide, 99.995% purity) was bubbled through the liquid HMDSO (Merck KGaA, GC, area% ≥ 98.5 area%).…”

Fabrication of ZnO Nanobrushes by H2–C2H2 Plasma Etching for H2 Sensing Applications

“…In comparison with surface modification by plasma treatment where no chemically enhanced etching takes place, the resulting morphologies differ strongly. 56 This emphasizes the necessity of careful control plasma treatment parameters to achieve the desired results.…”