Heterogeneous photocatalysis for C–H bond activation

The present critical review reports the recent progress of the last 5 years in the activation of the C–H bond to produce value-added organic products through photocatalytic oxidation of aliphatic, alicyclic and aromatic hydrocarbons. This method has great potential to provide a green and sustainable synthesis route to produce several industrially important chemicals, such as methanol, formaldehyde, formic acid, cyclohexanone, cyclohexanol, phenol, benzaldehyde, etc. Currently, the most popular and abundant heterogeneous photocatalyst is titanium dioxide, which has already found applications for water splitting, degradation of organic contaminations in water and air as well as the creation of self-cleaning coatings. The main limitation of titanium dioxide is associated with its large band gap value (Eg = 3.0–3.4 eV), which requires the construction of novel photocatalytic materials with sensitivity to visible light and high activity. Thus, the main attention in this review has been paid to the development of highly active visible light-responsive photocatalysts for C–H bond activation in hydrocarbons with a special focus to create heterojunctions as the most promising approach.