Low-content Pt or Au loaded TiO2-CeO2 catalysts for efficient selective hydrogenation of cinnamaldehyde under UV and visible light

The selective hydrogenation of cinnamaldehyde (CAL) is a key reaction for producing valuable intermediates in pharmaceuticals, fragrances, and fine chemicals. However, achieving high selectivity toward the C=O bond reduction of CAL under mild conditions remains challenging. In this study, an efficient and sustainable photocatalytic strategy for the selective transfer hydrogenation of cinnamaldehyde to cinnamyl alcohol under mild conditions was reported. The low-loading 0.5 wt% Au/TiO 2 -CeO 2 and 0.5 wt% Pt/TiO 2 -CeO 2 catalysts were prepared by sol–gel and ultraviolet deposition method. Experimental results show that heterojunction is formed by doping CeO 2 with TiO 2 . The light absorption of materials is redshifted, and the separation of photogenerated electron-hole pairs is enhanced, thereby reducing the load usage of precious metal. The 0.5 wt% Au/TiO 2 -CeO 2 catalyst exhibits optimal performance under visible light irradiation, while the 0.5 wt% Pt/TiO 2 -CeO 2 catalyst exhibits excellent activity under ultraviolet light irradiation. The conversion efficiency in 0.5 wt% Au/TiO 2 -CeO 2 catalytic system under visible light is 97.23 %, and the selectivity can reach 96.91 %. Recycling tests verified the structural stability and reusability of the prepared catalysts. The formation of heterojunction structures can effectively reduce the load of precious metal while maintaining high conversion and selectivity. These findings provide a new pathway for achieving highly selective CAL hydrogenation under mild conditions.