Earth-Abundant CaCO3-Based Photocatalyst for Enhanced ROS Production, Toxic By-Product Suppression, and Efficient NO Removal

Photoinduced reactive oxygen species (ROS)-based pollutant removal is one of the ideal solutions to achieve the conversion of solar energy into chemical energy and thus to address environmental pollution. Here, earth-abundant CaCO3-decorated g-C3N4 (g-C3N4 labeled as CN, CaCO3-decorated g-C3N4 sample labeled as CN-CCO) has been constructed by a facile thermal polymerization method for safe and efficient photocatalytic NO removal. The decorated CaCO3 as "transit hub" extends the pi bonds of CN to deviate from the planes and steers the random charge carriers, which thus provides extra active sites and expedites spatial charge separation to facilitate adsorption/activation of reactants and promote formation of ROS participating in the removal of pollutant. Furthermore, boosted generation of ROS regulates the photocatalytic NO oxidation pathway and thus increases the selectivity of products. NO prefers to be directly oxidized into final product (nitrate) rather than toxic intermediates (NO2), which is well demonstrated by theoretically simulated ROS-based reaction pathways and experimental characterization. The present work promotes the degradation of pollutant and simultaneously suppresses the formation of toxic by-product, which paves the way for ROS-based pollutant removal.