Controllable Generation of Reactive Oxygen Species on Cyano-Group-Modified Carbon Nitride for Selective Epoxidation of Styrene

Summary: The controlled generation of reactive oxygen species (ROS) to selectively epoxidize styrene is a grand challenge. Herein, cyano-group-modified carbon nitrides (CNCYx and CN-Ty) are prepared, and the catalysts show better performance in regulating ROS and producing styrene oxide than the cyano-free sample. The in situ diffuse reflectance infrared and density functional theory calculation results reveal that the cyano group acts as the adsorption and activation site of oxygen. X-ray photoelectron spectroscopy and NMR spectrum results confirm that the cyano group bonds with the intact heptazine ring. This unique structure could inhibit H2O2 and ⋅OH formation, resulting in high selectivity of styrene oxide. Furthermore, high catalytic activity is still achieved when the system scales up to 2.7 L with 100 g styrene under solar light irradiation. The strategy of cyano group modification gives a new insight into regulating spatial configuration for tuning the utilization of oxygen-active species and shows potential applications in industry.