Sarah Salah | Searcharxiv

arXiv2026

Atmospheric-Pressure Ar/Air Plasma Jet-Induced Degradation of Azo Dyes in Aqueous Solutions: Kinetic and Mechanistic Insights

Atmospheric-pressure non-thermal plasmas are promising platforms for advanced oxidation in water treatment, yet quantitative coupling between reactive species delivery, solution chemistry, and molecular fragmentation remains unclear. We investigate degradation of two structurally related azo dyes using an Ar plasma jet in a plasma-liquid discharge configuration with an immersed counter-electrode to enhance interfacial coupling. Plasma exposure generated a reactive oxygen and nitrogen species environment and strong acidification, increasing proton concentration up to 49-fold. UV-Vis analysis showed rapid chromophore decay, achieving 0.88 and 0.94 removal within 40 min. Biphasic kinetics indicated a transition from radical-flux-controlled to transport-influenced regimes. Fluorescence and Raman spectroscopy confirmed transient oxidized intermediates and progressive pi-conjugation breakdown, elucidating plasma-driven oxidative fragmentation mechanisms.

physics.plasm-ph↗

arXiv2026

Tuning Optical Properties of FTO via Carbonaceous Al2O3 Microdot Deposition by DC plasma sputtering

Fluorine-doped tin oxide (FTO) is a key transparent conductive oxide for photovoltaic and optoelectronic devices, yet its high reflectance limits light-trapping efficiency. This work demonstrates a simple DC plasma sputtering approach to deposit carbonaceous Al2O3 microdots on FTO under controlled Ar, O2, and Ar-O2 atmospheres. For plasma discharge in the normal mode, with plasma density 10^9 cm^-3 and temperature of 2 eV, Volmer-Weber growth produced discrete microdots whose size and distribution were tuned by gas composition: dense, uniform dots in Ar (approximately 0.89 um radius), agglomerated structures in O2, and intermediate morphologies in mixed atmospheres. Structural analysis confirmed Al2O3 formation with carbon incorporation, while SEM revealed morphology-driven optical behavior. UV-Vis measurements showed that Ar-O2 coatings achieved the lowest reflectance across the visible range, outperforming bare FTO and other conditions. These findings establish a clear link between sputtering parameters, surface morphology, and optical performance, offering a scalable route to anti-reflective, light-trapping coatings for next-generation solar cells and optoelectronic devices.

physics.plasm-ph↗