Formation of Stainless Steel Nanoballs via Submerged Glow-discharge Plasma and their Microstructural Analysis with Evaluation of Photocatalytic Activity

Abstract

Stainless steel has shown potential as a catalytic material in bulk form. However, it only becomes active in an aqueous acidic environment and elevated temperatures. This study aims to produce stainless steel nanoparticles that have high photocatalytic activity in a neutral medium and at room temperature and to elucidate the photocatalytic activity mechanism of the nanoparticles. Spherical, photocatalytic nanoparticles called "nanoballs" were synthesized by the submerged glow-discharge method. Stainless steel SUS316L grade wire was used as the cathode, platinum mesh was used as the anode while the electrolyte was potassium carbonate. The nanoballs were obtained after centrifuging and washing with water. The physical characteristics of the photocatalytic nanoballs were analysed by scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. The nanoballs were mixed with methylene blue and irradiated with ultraviolet light for the evaluation of photocatalytic reaction. The photodecomposition samples were determined using UV-vis spectrometry. The by-products of the photodecomposition were evaluated using mass spectrometry. The results show that stainless steel nanoballs have photocatalytic activity when irridiated with ultraviolet light at room temperature. Submerged glow-discharge plasma method can synthesize nanoparticles rapidly using only metal wires as the electrode.

Characterization of metal oxide micro/nanoparticles elaborated by plasma electrolytic oxidation of aluminium and zirconium alloys

“…Surprisingly, they did not evidence the simultaneous formation of Al2O3 particles. In addition, the synthesis of particles via cathodic plasma electrolysis processes is widely documented in the literature [19][20][21][22][23][24][25][26][27][28][29]. During cathodic plasma electrolysis, a thin gaseous envelope (mainly containing hydrogen) forms around the cathode; the latter is therefore separated from the surrounding electrolyte.…”

“…When particles enter into the surrounding cold electrolyte, they usually solidify into spherical nanoballs with diameter ranging from 10 nm to 10 µm, depending on the operating material and the electrolyte chemistry [22][23]. When subsequently exposed to air, the surface of some particles gets oxidized, thus forming core-shell structures with attractive new properties like photocatalytic effects for instance [24][25][26][27]. Various metal or metal oxide nanoparticles have been successfully produced by cathodic plasma electrolysis including steel, copper titanium, zinc, silver, nickel, gold and platinum [21,28,29].…”

Fabrication of Iron Oxide Nanoparticles via Submerged Photosynthesis and the Morphologies under Different Light Sources

“…Recently, the wide range of nanoscale forms of these materials has gained much attention owing to their anticipated properties and application in different areas, such as photoelectron devices, sensors, catalysts, etc. [1][2][3][4][5][6][7] Among these metal oxides, studies have especially focused on iron oxide nanocrystals (NCs) in biomedical application, such as diagnostic magnetic resonance imaging (MRI), [8][9][10] thermal therapy, 11,12) and drug delivery 8,13,14) because of their superparamagnetic properties, 9,15) biocompatibility, 16,17) and nontoxicity. Additionally, because most of the iron oxides have a bandgap in visible light spectral region (~ 2 eV), [18][19][20] they are promising materials for optoelectronics and photonics applications with solar energy.…”