Phase-junction design of MOF-derived TiO2 photoanodes sensitized with Quantum Dots for efficient hydrogen generation

摘要： Photoelectrochemical (PEC) water splitting is a promising and environmentally friendly pathway for exploiting renewable energy sources, to address the ever-growing demand for clean energy. Due to its excellent photostability and favorable band alignment, titanium dioxide (TiO2) is the one of the most common metal oxide for water splitting. However, the efficiency in TiO2-based PEC systems is limited by the high recombination of photo-generated electron/hole pairs and large intrinsic band gap (3.2 eV) which limit the absorption of the sunlight. Herein, we explore a simple metal organic framework (MOF)-derived synthesis to obtain a controlled mixed-phase (anatase and rutile) of TiO2 nanoparticles, which retain the MOF crystal morphology. Compared with commercial TiO2 films, the MOF-derived TiO2 film sensitized by core-shell CdSe@CdS QDs, showed an enhanced PEC device stability of +42.1% and PEC performance of +47.6%. The enhanced performance is due to the presence of the mixed rutile/anatase phases, that creates a favorable band energy alignment for the separation of the photogenerated charges. The proposed MOF-derived TiO2 is an efficient strategy to improve the efficiency of the TiO2-QDs heterojunction based PEC system for hydrogen generation.