Oxygen Vacancies-Induced Dendritic SrTiO3/CdS p–n Heterostructures Photocatalyst for Ultrahigh Hydrogen Evolution

Abstract

Owing to great efficient routes for charge carrier separation and transfer, heterostructure photocatalysts play significant roles in many photocatalytic reactions. Based on the bionic structure, an interesting composite photocatalyst of cadmium sulfide dewdrops on ultrathin strontium titanate branches with oxygen vacancies is successfully constructed by a simple chemical bath deposition method. The oxygen vacancies act as electron traps in the dendritic perovskite SrTiO3 nanostructure. Meanwhile, the CdS can provide abundant active sites for the hydrogen evolution reaction. The results demonstrate that SrTiO3/CdS-5% nanocomposite with oxygen vacancies achieves the highest hydrogen production rate of 4537.9 μmol g−1 h−1 under visible light, which is over 50 times more than that of the single SrTiO3 with oxygen vacancies (79.36 μmol g−1 h−1), pure CdS (81.79 μmol g−1 h−1), and more than 750 times that of pure SrTiO3 (6.132 μmol g−1 h−1). Density generalized function theory calculations show that the bandgap values of SrTiO3/CdS nanocomposite with oxygen vacancies are narrower than that of the original SrTiO3 and CdS, in which the electrons flow from CdS to SrTiO3, and form an internal electric field at the interface, prolonging the carrier lifetime. Importantly, this work provides a reasonable reference for the preparation of efficient structure-based biomimetic composite photocatalysts.