Control of CdSxSe1-x colloidal quantum dots sensitized TiO2 photoanode with different dosage of Se source for hydrogen generation

The use of quantum dots (QDs) to sensitize titanium TiO 2 in photoelectrochemical cells (PECs) for solar-driven water splitting represents a highly promising method for converting solar energy into storable chemical energy in the form of hydrogen. The characteristics and interfaces of the QDs play a crucial role in determining the range of light absorption and the efficiency of charge transport and separation upon photoexcitation. Herein, we build CdS x Se 1-x QDs sensitized TiO 2 photoanodes with different amount of Se source by one-step hydrothermal process using thioglycolic acid (TGA) as bifunctional linker. Our results demonstrate that TGA can both anchor QDs to TiO 2 and decompose S for CdS x Se 1-x QDs preparation. The influence of Se source dosage on PEC performance of CdS x Se 1-x /TiO 2 photoanode has been investigated. UV–vis absorption data shows the increase of Se source can enlarge light response range. X-ray photoelectron spectroscopy, transient open-circuit voltage decay and electron lifetime tests indicate proper thickness of SeO 2 which formed on CdS x Se 1-x QDs has the effect to block charges recombination between CdS x Se 1-x /TiO 2 photoanode and electrolyte, improving the electron lifetime of photogenerated electrons. Consequently, the photoelectrochemical cell (PEC) constructed with a CdS x Se 1-x /TiO 2 photoanode, prepared using 0.8 mmol of selenium source, has achieved a photocurrent density of 14.31 mA cm −2 and a photoconversion efficiency of 15.74 %. These results indicate significant potential for the production of green hydrogen.