Carbon-nanodot-coverage-dependent photocatalytic performance of carbon nanodot/TiO2 nanocomposites under visible light*

Carbon nanodots (CDs) with visible absorption band and TiO2 are integrated to enhance the photosensitivity of TiO2. The CD/TiO2 nanocomposites show obvious CD-coverage-dependent photocatalytic performance. The CD/TiO2 nanocomposites with moderate CD coverge exhibit the highest photocatalytic activity after being irradiated with visible light, which is more excellent than that of TiO2. Too little CD coverage could result in poor visible light absorption, which limits the photocatalytic performance of CD/TiO2 nanocomposites. While, too much CD coverage weakens the photocatalytic activity of CD/TiO2 nanocomposites by restraining the extraction of conduction band electrons within TiO2 to generate active oxygen radicals and the electron transfer (ET) process from CDs to TiO2. These results indicate that rational regulation of CD coverage and the realization of efficient ET process are important means to optimize the photocatalytic performance of CD/TiO2 nanocomposites.