Constructing surface synergistic effect in Cu-Cu2O hybrids and monolayer H1.4Ti1.65O4·H2O nanosheets for selective cinnamyl alcohol oxidation to cinnamaldehyde

Abstract

A multifunctional photocatalyst is constructed based on Cu-Cu2O hybrid and monolayer H1.4Ti1.65O4·H2O nanosheets via an in situ photo-deposition process (Cu-Cu2O/TNS). The prepared sample enables the oxidation of cinnamyl alcohol to cinnamaldehyde with over 95% of selectivity under visible light irradiation using molecule O2 as the oxidant. In situ FTIR spectra suggest that the Lewis acid sites in TNS would selectively adsorbed the hydroxyl of cinnamyl alcohol forming surface CO∙∙∙TiO coordination species. UV-DRS spectra reveal that light adsorption of TNS can be extended to visible light region due to the interface charges transfer from COH to TiO via the surface coordination, resulting in the activation of OH in alcohol. In situ ESR further indicates that directional interface charge transfer induces the charge enrichment in Ti atoms of TiO6, facilitating O2 adsorption. XAFS results reveal that the hybrid electronic states of Cu-Cu2O efficiently improve the interface electronic transfer kinetics to inhibit the intramolecular hydrogen transfer for dominating the selectivity towards cinnamaldehyde. This work highlights the synergistic effect of surface coordination-activation-photocatalysis for selective photosynthesis of fine chemicals.