Ultrathin ZnTi-LDH nanosheet: A bifunctional Lewis and Brönsted acid photocatalyst for synthesis of N-benzylideneanilline via a tandem reaction

Two ultrathin ZnTi-LDH nanosheets with different thickness (1.4 and 4.0 nm) were prepared to study the interplay between the active site and catalytic performance in photocatalytic synthesis of N-benzylideneanilline via a tandem reaction. ZnTi-LDH nanosheet possesses dual isolated active sites including the coordinatively unsaturated Ti atoms (Lewis acid sites) and the H atoms of OH groups (Brönsted acid sites), achieving the activation of benzyl alcohol and nitrobenzene via C–O···Ti species and N–O···H–O species, respectively. Photogenerated holes and electrons facilitate the oxidation of benzyl alcohol to benzaldehyde and the reduction of nitrobenzene to aniline, respectively. The thinner sample possesses more active sites, facilitating not only the activation of reactants but also the separation of photogenerated carriers. Therefore, a thinner ZnTi-LDH nanosheet shows the high conversion (100%) and the high selectivity (96%). Finally, a synergetic photocatalytic mechanism connected to the molecular activation is illustrated at the molecule level.