Highly dispersed CdS on C3N4 for selective cleavage of Cβ-O-4 bonds in lignin model compound under blue light

Photocatalytic cleavage of lignin Cβ-O-4 bonds is a very effective method to promote the high-value utilization of lignin because lignin can provide a large number of aromatics. However, the higher carrier recombination rate severely inhibits the efficiency of photocatalytic cleavage of Cβ-O-4 bonds in lignin model compound. Here, heterojunction photocatalysts CdS-C3N4 were successfully synthesized through the photodeposition of different masses of CdS on the surface of C3N4. The obtained photocatalyst CdS-C3N4 can effectively break the lignin Cβ-O-4 bonds in 2-Phenoxy-1-phenylethanol (lignin model compound) and the products formed are mainly phenol (Phol) and acetophenone (Ap). More importantly, the yields of Phol and Ap were up to 86.5% and 74.3%, after only irradiation for 1.5 h, respectively, under optimum conditions. A mechanistic study showed that photocatalytic reaction follows a photogenerated electron-hole coupled mechanism. The high photocatalytic performance of CdS-C3N4 is mainly ascribed to the fast photogenerated electron-hole separation capability and good dispersion of CdS on C3N4. This work offers an idea for selective cleavage of lignin Cβ-O-4 bonds by constructing a heterojunction photocatalyst.