Significant enhancement of the photoelectrochemical activity of WO3 nanoflakes by carbon quantum dots decoration

This work reports on single-crystal WO3 nanoflakes decorated with carbon quantum dots (CQDs) for efficient photoelectrochemical energy conversion system. The promising photoanodes can be fabricated via seed-mediated solvothermal method in combination with subsequent impregnation-assembling. A photocurrent density of 1.46 mA cm−2 at 1.0 V vs. Ag/AgCl can be achieved for the CQDs/WO3 electrode when performing linear sweep voltammetry measurements in 1 M H2SO4 solution under AM 1.5G illumination, which is about two times higher than that of the bare WO3 electrode. The enhancement of photoelectrochemical performance is ascribed to the enhanced light harvesting ability of CQDs and its accelerating charge transfer across the interface between CQDs/WO3 electrode and electrolyte. The improved activity indicates the potential of CQDs/WO3 as an efficient electrode for photoelectrochemical solar energy conversion.