Black TiO2-supported copper nanoparticles for efficient photocatalytic N-formylation of N-methylaniline with CO2

Photocatalytic N-formylation of amines with CO 2 is a promising strategy to convert CO 2 into value-added chemicals sustainably. In this work, a black TiO 2 -supported Cu photocatalyst is prepared through a solvothermal method for the N-formylation of N-methylaniline with NaBH 4 as the reducing agent. Cu nanoparticles and oxygen vacancies are formed on the surface of the photocatalyst after reduction with H 2 , which decreases the band-gap energy and promotes the separation of photogenerated electrons and holes, thereby improving the photocatalytic activity remarkably. A 100 % conversion is achieved after 9 h radiation, and the yield of N -methylformanilide reaches 81 %. Both the amount of NaBH 4 and the pressure of CO 2 show important influences on the activity and selectivity of the photocatalytic process, and the carbon and hydrogen in the aldehyde group are from CO 2 and NaBH 4 , respectively. The photocatalyst also shows promising cycling durability.