Combining carbon dots with WO_3-x nanodots for utilizing the full spectrum of solar radiation in photocatalysis

Artificial photocatalytic systems represent a promising and available technology to directly convert sunlight into usable energy resources. Unfortunately, the current photocatalysts often absorb an only small range of sunlight spectra, hence greatly limiting the utilization efficiency of solar energy. Herein, we firstly developed a hybrid system that combines carbon dots (CDs) and oxygen-deficient WO3-x nanodots through a mild solvothermal method. This hybrid system features the heterojunction structure with dimensions smaller than 15 nm and can effectively utilize the full spectrum of solar radiation in photocatalytic oxidative reactions. In hybrid system, the CDs can enhance visible light harvesting ability of WO3-x nanodots and deliver their photoinduced carriers to the intermediate energy bands induced by oxygen-deficient of WO3-x. After further excitation with low energy photons, then more chemically useful carriers can be generated to participate fully in catalytic activation and reaction processes, resulting in 3.2 times higher photocatalytic activities of CDs@WO3-x than WO3-x nanodots.