Visible-light-driven photooxidation of alcohols using surface-doped graphitic carbon nitride

In recent years, graphitic carbon nitride (g-C3N4) has received substantial interest as a photocatalyst for metal-free, visiblelight promoted reactions. It exhibits a graphite-like, layered structure wherein tris-triazine units are connected through C–N-bonds forming a two-dimensional layer. g-C3N4 can be synthesized via various methods such as pyrolysis of urea or other nitrogen-rich precursors or layer exfoliation of bulk materials. Pure g-C3N4, however, is a rather poor photocatalyst, mainly due to the fast recombination of photoexcited, charge-separated states. Therefore, one focus of research lies in the improvement of its photocatalytic properties by modulating the potential of g-C3N4’s conductingand valence bands. 1 Particularly doping of g-C3N4 with other elements such as Y, 3 Fe, Pt, Au/Pd K, Ag, C or carbon-nanodots and many more has proven to be an efficient handle to modulate its properties. Also, doping with carbon-nanodots appears promising to increase the quantum efficiency of photocatalytic processes. Interestingly, g-C3N4 is mostly considered as a photocatalyst for (sun)-light driven water splitting, remediation of organic pollutants and catalytic CO2 reduction. 1 Applications for preparative organic synthesis are comparably few. For example, Goettmann et al. reported g-C3N4 catalysed Friedel–Crafts acylation. More recently, photocatalytic acetalisation of aldehydes and ketones, and hydrazine-driven reductions of alkenes and alkynes were reported using g-C3N4. 14,15 Selective oxidations especially of benzylic C–H-bonds have been reported using mesoporous g-C3N4 together with N–OHcocatalysts, or using transition metal doped g-C3N4. 14,20–22