Carbon nanomaterials have attracted wide research upsurge owing to their conspicuous properties and excellent potential applications,which make them outstanding as an alternative to organic dyes and inorganic quantum dots.[1-3]More recently,they have been universally used in drug delivery,bioimaging probes,optical detection probes,light emitting diode materials and efficient visible light-active photocatalysts.[4-6]Carbon dots(CDs)as one of the most promising carbon-based nanomaterials have recently attracted substantial attention in bioimaging,security,photocatalysis,sensors and optoelectronic devices owing to their stability,low toxicity,widely available precursors and eco-friendly preparation compared with conventional photoluminescent materials.