Synthesis of stainless steel nanoballs via submerged glow-discharge plasma and its photocatalytic performance in methylene blue decomposition

Stainless steel nanoparticles or ‘nanoballs’ have been synthesised using submerged glow-discharge plasma. Transmission electron microscopy showed that the nanoballs are uniformly spherical and size distribution estimation showed that their diameters are below 200 nm. The decomposition of methylene blue solution under ultraviolet light with the wavelength of 354 nm was observed in the presence of stainless steel nanoballs. A mixture of stainless steel nanoballs and 0.1% methylene blue dye was irradiated with ultraviolet light. The concentration of methylene blue was reduced to baseline level in 72 hours. This shows that the stainless steel nanoballs have photocatalytic ability. In stainless steel nanoballs, methylene blue showed two different decomposition pathways; showing fast and slow reactions. Also, methylene blue was oxidised into sulphoxide before reducing into lighter by-products. X-ray diffraction analysis has shown that the nanoballs consist of Fe2O3 and Cr2O3, which are photocatalytically active species.