Fabrication of Excellent Heterojunction Assisting by Interfaced Oxygen Vacancy to Improve the Separation Capacity of Photogenerated Carriers

Heterojunction connecting by interface chemical bonds is a promising method as it can provide more efficient route for photogenerated charge separation. In this work, the oxygen vacancies are introduced into the surface of SrTiO3 by a one-step hydrogenation method. SrTiO3 with oxygen vacancy (STO) is compounded with Cd0.5Zn0.5S (CZS) by hydrothermal method, resulting in the successful formation of a good heterojunction structure. By comparing with the pristine SrTiO3/CZS composites, it is found that the oxygen vacancies play an important role in the formation of excellent heterojunctions, in addition to the traditional reports as charge traps and adsorption sites or the ability to cause band changes. X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscope results disclose that S2- enters the oxygen vacancy on the (110) plane of STO and interacts with the adjacent Ti in the van der Waals force to form the Ti-O-S group, which results in the formation of excellent heterojunctions and makes the CZS nanoparticles growth evenly on the STO nanoplates. Furthermore, the formation of excellent heterojunction and the introduction of interfaced oxygen vacancy significantly improve the separation efficiency of photogenerated charge carriers, which dramatically increases the photoelectrochemical performance.