Interfacial Charge Carrier Dynamics of the Three-Component In2O3-TiO2-Pt Heterojunction System

Abstract

The interfacial charge carrier dynamics of the three-component semiconductor semiconductor-metal heterojunction system were investigated and presented for the first time. The samples were prepared by selectively depositing Pt nanoparticles on the TiO2 surface of In2O3-decorated TiO2 nanobelts (In2O3-TiO2 nanobelts (NBs)) using the typical photodeposition method. For In2O3-TiO2 NBs, because of the difference in band structures between In2O3 and TiO2, the photoexcited electrons of In2O3 nanocrystals would preferentially transfer to TiO2 NBs to cause charge carrier separation. With the introduction of Pt on TiO2 surface, a fluent electron transfer from In2O3, through TiO2, and eventually to Pt was achieved, giving rise to the increasingly pronounced charge separation property for the as-prepared In2O3-TiO2-Pt NBs. The remarkable charge separation of the samples was revealed with the corresponding photocurrent measurements. Time-resolved photoluminescence spectra were measured to quantitatively analyze the electron transfer event between In2O3 and TiO2 for In2O3-TiO2 NBs and its dependence on Pt deposition. Upon the deposition of Pt, In2O3-TiO2 NBs showed an increased apparent electron-scavenging rate constant, fundamentally consistent with the result of their performance evaluation in photocatalysis. The current study provides a new paradigm for designing highly efficient three-component nanoheterojunction photocatalysts which can effectively produce chemical energy from absorbing light.