Enhanced photocatalytic benzyl alcohol oxidation over Bi4Ti3O12 ultrathin nanosheets

Ultrathin Bi4Ti3O12 nanosheets (NS) with the thickness about 3.9 nm were successfully synthesized by a hydrothermal method and were used as a photocatalyst for the oxidation of benzyl alcohol (BA) to benzaldehyde (BAD). The photocatalytic performance of NS is about 8 times higher than that of bulk Bi4Ti3O12. In-situ FTIR of pyridine adsorption and NH3-TPD reveal that NS has more surface Lewis acid sites (Ti4+) for the adsorption and activation of BA. The photogenerated electrons (e-) and holes (h+) of NS can be fully used to produce the superoxide radicals and carbon-centered radicals, respectively. The monolayer nanosheet structure of NS not only greatly promotes the separation of photogenerated carriers, but also achieves the efficient activation of BA molecules via the CO⋯Ti coordination. This work successfully reveals the surface/interface interactions between the surface active sites of a photocatalyst and the reactive molecules via using ultrathin nanosheet as a molecular platform.