Photogenerated Electron Transfer Process in Heterojunctions: In Situ Irradiation XPS

Abstract Photoelectron transfer between heterojuctions is an important process for photocatalysis, and identification of the electron transfer process provides valuable information for catalyst design. Herein, Ti 3 C 2 , one of the widely used two‐dimensional materials, is used to produce a heterojunction of TiO 2 and Ti 3 C 2 by an in situ growth method and the photogenerated electrons transfer between the two components for photocatalytic water splitting to hydrogen is investigated. Theoretical simulation and experimental tests proclaim that electrons transfer from Ti 3 C 2 to TiO 2 forms an internal electric field, which implies that there exists the driving force of electronic movement from TiO 2 to Ti 3 C 2 . In situ irradiation X‐ray photoelectron spectroscopy shows the binding energies of TiC (in Ti 3 C 2 ) and TiO (in TiO 2 ) move toward negative and positive positions, respectively, verifying the photogenerated electrons produced from TiO 2 and transferring to Ti 3 C 2 driven by the internal electric field. In addition, the amount of TiO 2 nanoparticles also affects the hydrogen evolution rate. Several parallel experiments are designed to uncover the fact that less or excess amount of TiO 2 nanoparticles leads to a tinier shift of binding energy, which hints the quantity of heterojunction is a considerable factor in photocatalytic performance. This work develops a new method to directly monitor the photoelectron transfer process between heterojuctions.