Synergy of palladium species and hydrogenation for enhanced photocatalytic activity of {001} facets dominant TiO2 nanosheets

{001} facets dominant TiO2 nanosheets have attracted intensive attention in the photocatalytic field, due to their undercoordinated Ti-5c centers, higher surface energy, and photocatalytic activity than those of any other low-energy facet. However, a fluorine-rich (001) surface is controversial to the photocatalytic activity of TiO2 nanocrystals. We have removed the surface F atoms bonding with Ti by hydrogenation method successfully, and found that {001} facets dominant TiO2 nanosheets without the terminated F atoms showed dramatic enhancement in the photocatalytic activity. Moreover, the clean (001) surface was more in favor of the deposition of PdO than the fluorine-rich surface, and the amorphous structure from the hydrogenation is beneficial to the reduction of PdCl42- to Pd nanoparticles. The PdO attached on {001} facets and the amorphous structure promoted the separation of charge carriers, and Pd nanoparticles transferred plasmonic-induced electrons to the conduction band of hydrogenated TiO2 under simulated solar irradiation. Thus, a significantly enhanced photocatalytic activity of Pd-H-TiO2 is achieved on degrading organic environmental pollution, due to the synergy of palladium species and hydrogenation on {001} facets exposed TiO2.