Cooperative surface multifunctional sites of Pd/Bi2MoO6 nanosheets for precise synthesis of Schiff bases via one-pot photocatalytic coupling of benzyl alcohol and nitrobenzene

Abstract

Here, Pd nanoparticles (NPs)-decorated Bi2MoO6 nanosheets are created successfully for the photocatalytic coupling of nitrobenzene (NB) and benzyl alcohol (BA) to produce N-Benzylideneaniline (NBA) in N2 atmosphere under visible light. The optimized catalyst (Pd0.75/BMNS) achieves a remarkable conversion of 98.1 % for NB with a high selectivity of 95.1 % towards NBA. Pd0.75/BMNS surface is endowed with a variety of active sites, including oxygen vacancies (Vo), Mo5+, and Pd NPs. In situ Fourier-transform infrared spectroscopy (FT-IR) result exhibits that both NB and BA can be activated via the coordination of –N–O···Mo5+ and -C-N···Mo5+, respectively. The presence of Vo and a Schottky junction significantly facilitates the transfer and separation of photogenerated carriers, thereby boosting the catalytic efficiency. The holes and electrons would be transferred to surface for the oxidization of BA to benzaldehyde and reduction of NB to aniline, respectively. Subsequently, a spontaneous reaction for the coupling of aniline and benzaldehyde are occurred to generate NBA. The surface multifunctional sites jointly achieve the high photocatalytic efficiency over Pd0.75/BMNS. This work presents a strategic approach to design photocatalysts with multifunctional active sites for organic synthesis.