Ba-vacancy induces semiconductor-like photocatalysis on insulator BaSO₄

Semiconductor-based photocatalysis has attracted considerable interdisciplinary attention for its diverse applications in environmental remediation and solar energy conversion. However, pure earth-abundant insulators have been seldom considered as photocatalysts because of the unfeasible electronic excitation. In this work, we make the earth-abundant insulator BaSO₄ as conceptually new photocatalyst via Ba-vacancy engineering for the first time. The BaSO₄ with Ba-vacancy is synthesized by a facile precipitation method and applied for photocatalytic NO removal in air. XAFS spectroscopy and DFT calculations demonstrate the formation of Ba-vacancy. Also, defect level induced by Ba-vacancy between the wide band gap is demonstrated, which endows insulator BaSO₄ with semiconductor-like photocatalytic performance. Besides, according to the TPD analysis and theoretical simulation, Ba species is functioned as the NOx storage center for the primary accumulation of NO molecule on substrate, and simultaneously Ba-vacancy is equipped with the capability to redistribute charge carriers and thus accelerate the activation of NO molecule by the donation of electrons to electron-deficient areas, facilitating the conversion of NO into a higher valance state for further favorable photocatalytic oxidation. In situ DRIFTS spectra are applied to dynamically monitor intermediates and products on photocatalyst surface, revealing the reaction process and the enhancement role of Ba-vacancy. This work opens a new research doorway on earth-abundant insulators for the development of a new family of photocatalyst.