Improvement of Visible-Light H 2 Evolution Activity of Pb 2 Ti 2 O 5.4 F 1.2 Photocatalyst by Coloading of Rh and Pd Cocatalysts.

Pb 2 Ti 2 O 5.4 F 1.2 modified with various metal cocatalysts was studied as a photocatalyst for visible-light H 2 evolution. Although unmodified Pb 2 Ti 2 O 5.4 F 1.2 showed negligible activity, modification of its surface with Rh led to the best observed promotional effect among the Pb 2 Ti 2 O 5.4 F 1.2 samples modified with a single metal cocatalyst. The H 2 evolution activity was further enhanced by coloading with Pd; the Rh-Pd/Pb 2 Ti 2 O 5.4 F 1.2 photocatalyst showed 3.2 times greater activity than the previously reported Pt/Pb 2 Ti 2 O 5.4 F 1.2 . X-ray absorption fine-structure spectroscopy, photoelectrochemical, and transient absorption spectroscopy measurements indicated that the coloaded Rh and Pd species, which were partially alloyed on the Pb 2 Ti 2 O 5.4 F 1.2 surface, improved the electron-capturing ability, thereby explaining the high activity of the coloaded Rh-Pd/Pb 2 Ti 2 O 5.4 F 1.2 catalyst toward H 2 evolution.