Photocatalysis is a promising technology for addressing environmental and energy issues. Most photo catalysts are semiconductors, while a minority are metals. Unlike these two types of materials, insulators display a large band gap separating occupied and unoccupied levels. However, it is still possible to excite charge carriers in insulators via specific defects. Herein, we report an insulating carbonate (BaCO3) that displayed photocatalytic activity towards the removal of NO in air. The oxygen defects produced during the preparation process endow the as-prepared carbonate with the ability to generate charge carriers for oxidation of NO under UV light irradiation. Furthermore, other salts, such as sulphate and phosphate insulators, have also been observed to possess photocatalytic activity. These findings suggest that this new family of earth-abundant insulator photocatalysts can provide promising opportunities for photo-energy conversion and environmental remediation, opening up a new direction in catalysis science. (C) 2017 Elsevier B.V. All rights reserved.