Cobalt-doped carbon nanodots as an interfacial modifier for efficient solar-driven water splitting

Photoelectrochemical water splitting with bismuth vanadate (BiVO4) photoanodes is a promising strategy for solar-driven hydrogen production. However, the unfavorable interfacial charge behavior causes severe charge recombination and photocorrosion issue of BiVO4. Herein, cobalt-doped carbon nanodots (CoCDs) are employed for efficient charge extraction due to Co impurity level, which form band alignment with BiVO4, as well as accelerate surface reaction. As a result, the obtained CoCDs/BVO photoanode demonstrates an outstanding photocurrent density of 5.26 mA/cm2 at 1.23 V vs. reversible hydrogen electrode under AM 1.5 G illumination, superior to most BiVO4 photoanodes with cocatalysts. Carbon nanodots turn out to be an excellent matrix to activate and stabilize Co atoms and tightly anchor onto BiVO4, which makes them good interfacial modifier. This work paves an avenue for the optimization of semiconductor/liquid interface and the application of carbon nanomaterials in photoelectrodes.