Designing Multilayered Photoanodes for Broad-Scope Thiol Trifluoromethylation

Broad substrate generality in radical organic synthesis is often limited by the kinetic mismatch between substrate-dependent radical generation and the rapid, nonselective reactivity of highly active radical species. In this study, we report the development of Co₂P-loaded carbon nitride (CN) dots as a cocatalyst for WO₃ films, creating a multilayered photoanode designated as Co₂P@CN-WO₃. Under 450 nm irradiation, the model reaction of p-methylthiophenol with trifluoromethanesulfonyl chloride resulted in 4-(trifluoromethylthio)toluene, achieving a conversion of 95%, a selectivity of 91%, and an overall yield of 86.5%. The photoanode retained ca. 80% activity after 84 h of continuous operation. The protocol was remarkably applicable to 84 thiol substrates, and the yields of 16 challenging substrates can be further optimized by adjusting the parameters of the photoelectrocatalysis (PEC) system. Mechanistic studies reveal that the CN layer improves substrate-interface contact, whereas Co₂P serves as a catalytically active site for sulfur-centered radical generation and S─CF₃ bond formation, promoting this thiol trifluoromethylation. This work provides a photoelectrode design strategy for achieving broad-scope radical transformations by PEC.