Gold photosensitized SrTiO3 for visible-light water oxidation induced by Au interband transitions

Abstract

Gold nanoparticle (NP) photosensitization over semiconductors with a large band gap has emerged as a promising strategy for developing visible-light responsive photocatalytic materials. However, its application in harsh photocatalytic oxidation still remains a significant challenge. Furthermore, energetic charge carriers created in Au interband transitions under visible light are frequently ignored in this field. In the current work, for the first time, a remarkable visible-light photocatalytic water oxidation activity (14.9 μmol h⁻¹: 0.2 g catalyst, 5 mmol AgNO₃), even slightly higher than that of commercial WO₃, was achieved over Au photosensitized SrTiO₃ (1.1 wt%). In an elaborate study, electron transfer from gold to SrTiO₃ was confirmed by STEM-EDS characterization on selective Ag deposition over SrTiO₃. A combined investigation of apparent quantum efficiency results, theoretical simulation study on Au NPs optical excitation and relative band position analysis in Au/SrTiO₃ reveals that these hot electrons transferred from gold to SrTiO₃ mainly come from Au interband transitions other than plasmon resonance, while leaving holes on Au with enough oxidative potentials are responsible for water oxidation. The capability of involving Au interband transition in photosensitization for visible light water oxidation opens up new opportunities in designing and preparing visible-light responsive photocatalysts.