A comparative study on photoelectrochemical performance of TiO2 photoanodes enhanced by different polyoxometalates

Based on the incorporation of polyoxometalates (POMs) into TiO₂ film, the photoelectrochemical performance of POMs/TiO₂ anode was elucidated by comparative investigation on the electron transport and electron–hole recombination in POMs/TiO₂ anode. The photoelectrochemical performance of the POMs/TiO₂ anode was clearly dependent on the type and content of POMs. Compared to the TiO₂ anode, the POMs/TiO₂ anode with low POMs loadings (0.75%) displayed the enhanced photoelectrochemical performance, while the excessive content (7.5%) of POMs could almost cause a negative effect. Thus, POMs could act as either “shallow electron trap” or “deep electron trap” depending on the different types and contents of POMs. This study reveals that the introduction of POMs into TiO₂ anode could facilitate photogenerated electron transfer and reduce electron–hole recombination, which is urgently desired to develop advanced composite materials of POMs/TiO₂ for application in photoelectrochemical catalysis and solar cells.