Enhanced visible light photocatalysis over Pt-loaded Bi2O3: an insight into its photogenerated charge separation, transfer and capture

In this study, we have fabricated crystalline metallic Pt nanoparticles-loaded alpha-Bi2O3 microrods (Pt/Bi2O3) using a precipitation method, followed by an impregnation-reduction deposition route. The Pt/Bi2O3 catalysts have much higher photocatalytic activities than that of the pure Bi2O3 for the degradation of RhB and 2,4-DCP under visible light irradiation. The photogenerated charge separation, transfer, and capture in the photocatalysis of Pt/Bi2O3 were investigated in detail according to the various characterizations and analyses of the photogenerated active species and H2O2. It was revealed that the loaded Pt plays an important mediating role in the efficient separation of photogenerated electron-hole pairs by rapidly transferring electrons from the excited Bi2O3 to the surface oxygen. As a result, the reduction of O-2 to form H2O2 by the photogenerated electrons was promoted, leaving more holes on the deep valence band to drive the degradation of organic compounds and the production of (OH)-O-center dot radicals, which were responsible for the enhanced photocatalysis of Pt/Bi2O3.