Facile one-pot synthesis of gold/tin oxide quantum dots for visible light catalytic degradation of methylene blue: Optimization of plasmonic effect

Abstract

Discovery and development of novel photocatalysts with superior performance in visible light is a fundamental step toward tackling several environment and energy related issues. In this study, a simple one-pot solvothermal approach was adopted to fabricate a series of novel SnO2 quantum dot/gold (SQD/Au) nanocomposites. The structure, morphology, chemical composition, and the optical and photocatalytic performance of the as-prepared SQD/Au nanocomposites were described. The dispersion of Au nanoparticles (NPs) over SQDs can significantly improve the synergistic charge transfer mechanism, which retards the reunion of photoinduced electron-hole pairs and results in decreased emission intensity. In particular, the SQD/Au nanocomposites with 1.00 mL in 100 mM gold chloride loading achieve a methylene blue (MB) degradation of 99% under visible light illumination within 150 min. This can be ascribed to the plasmonic effect of Au NPs in the visible region and the SQDs acting as an electron tank to receive the photoinduced electrons. Furthermore, the formation of a Schottky barrier between SQDs and Au NPs improved the charge separation efficiency, and enhanced the photocatalytic activity. A possible photocatalytic mechanism for the improved degradation efficiency of MB by SQD/Au nanocomposites is also proposed.