Achievement of High Photocatalytic Performance to BaTi 4 O 9 Toward Overall H 2 O Splitting

The improvement of photocatalytic activity of BaTi 4 O 9 to overall H 2 O splitting was investigated. From the evaluation of co‐catalysts, Rh 0.7 Cr 1.3 O 3 was preferable. However, this co‐catalyst was degrading with the progress of the photocatalytic reaction. When CoO x was co‐loaded as the co‐catalyst for O 2 evolution reaction over the surface, the steady progress of the photocatalytic reaction can be confirmed. Here, effective way and condition for loading CoO x co‐catalyst as well as effective preparation method of BaTi 4 O 9 were demonstrated in order to improve the photocatalytic activity of BaTi 4 O 9 with Rh 0.7 Cr 1.3 O 3 and CoO x co‐catalysts to the overall H 2 O splitting. As the results, the photocatalyst prepared by preferable method and condition showed high photocatalytic activity to the overall H 2 O splitting, where the apparent quantum yield (AQY) at 313 nm reached to 41 %.