The biosynthesis of cadmium selenide quantum dots by Rhodotorula mucilaginosa PA-1 for photocatalysis

CdSe quantum dots (QDs) are semiconductor materials and possess unique optical and electronic properties, therefore being increasingly used in many fields. Biosynthesis of CdSe QDs has several advantages over the chemical synthesis route. In this study, the CdSe QDs were biosynthesized using a yeast Rhodotorula mucilaginosa PA-1 under the aerobic condition. The regulation of QDs biosynthesis was achieved by changing the concentration of precursors and the pH of the medium. The concentration of cadmium ions but not selenium ions determined the synthesis of CdSe QDs. Synthesized CdSe QDs with a narrow size distribution (3.2 +/- 0.4 nm) exhibited great photocatalytic activity under ultraviolet and visible light using a dye malachite green (MG) as a model pollutant. The photocatalytic degradation efficiency of MG was 86.5 % and 94.28 % after 60 min irradiation under ultraviolet and visible light, respectively, which is comparable for those catalyzed by various nanomaterials through chemical synthesis.