Oxygen vacancies confined in SnO ₂ nanoparticles for desirable electronic structure and enhanced visible light photocatalytic activity

Electronic structure in principle determines the light absorbance, charge transfer and separation, and consequently, photocatalytic property of a photocatalyst. Herein, we report rutile SnO ₂ with a desirable electronic structure that exhibits a narrowed bandgap and an increased valence band width resulted from the introduction of homogeneous oxygen vacancies. XPS, Raman, ESR and PL spectra demonstrate the homogeneous oxygen vacancies confined in SnO ₂ nanoparticles. Moreover, the first principle calculations theoretically reveal the desirable electronic structure. The narrowed bandgap further contributes to extended light absorption range and the increased valence band width leads to efficient charge transfer and separation, hence facilitating the visible light photoreactivity. As a result, the defected SnO ₂ exhibits a superior visible light photocatalytic activity. More strikingly, the photodegration of methyl orange (MO) is completely accomplished within only 20 min under λ ≥ 420 nm. Briefly, this work both experimentally and theoretically indicates that homogeneous oxygen vacancies confined in SnO ₂ nanoparticles lead to the optimized electronic structure and, consequently, the remarkable visible light photocatalytic activity. This could open up an innovative strategy for designing potentially efficient photocatalysts.