Tunable Selectivity of Photocatalytic Benzyl Alcohol Transformation over Ag-Ion-Exchanged CdS Nanowires
SeoJin An, Myung Jong Kang, Hangil Lee, Hyun Sung Kim
Abstract
Existing methods for the photocatalytic transformation of aromatic alcohols to value-added products via C–C cross-coupling are inefficient and insufficiently selective. Herein, a series of cadmium sulfide nanowires (CdS NWs) loaded with Ag 2 S (denoted as Ag 2 S@CdS NWs) are constructed via a simple Ag + exchange protocol for the photocatalytic transformation of benzyl alcohol. We successfully demonstrated that the selectivity toward specific products in the photocatalytic transformation of benzyl alcohol over Ag + -exchanged CdS NWs is controlled by varying the amount of exchanged Ag + ions. Notably, the product of the photocatalytic reaction was dependent on the amount of Ag + ions exchanged: with a Ag + exchange of <5 mol %, the C–C coupling product was obtained with >90% selectivity and >95% transformation yield owing to photoinduced electron transfer from the conduction band of CdS to Ag 2 S. Conversely, with a Ag + exchange of >7 mol %, a cocatalyst in which Ag 2 S and Ag are mixed was produced, and benzaldehyde was obtained with >90% selectivity and >90% transformation yield because of photoinduced hole transfer from the valence band of CdS to Ag 2 S/Ag. This study proves that Ag 2 S@CdS NWs can be used as a basis for the development of heterojunction photocatalysts for the conversion of aromatic alcohols into value-added products via C–C cross-coupling reactions or photooxidation toward aromatic aldehyde.