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, cyclo-hexanol, 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 contamina-tions 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 photo -catalytic 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.