Selective photocatalytic conversion of benzyl alcohol to benzaldehyde or deoxybenzoin over ion-exchanged CdS

Abstract

The visible light absorbing CdS nanoparticles were partially modified with Au2S and Ag2S via a simple cation exchange process to prepare hetemstructure photocatalysts (denoted as Au2S@CdS and Ag2S@CdS), which were employed for the conversion of aromatic alcohols to valued-added products, such as benzaldehyde and C-C coupling products, including deoxybenzoin and hydrobenzoin. When Au 2 S@CdS was used as the photocatalyst, benzaldehyde was obtained as the main product with a selectivity of 99%, and when Ag2S@CdS was used as the photocatalyst, deoxybenzoin was obtained as the main product with a selectivity of 95%. The critical photo-generated electron and hole transfer occurring during the photocatalytic reaction was systemically investigated by performing various control experiments and using in-situ high-resolution X-ray photoelectron spectroscopy. In addition, with the photocatalytic system proposed in this study, benzyl alcohol could be photoconverted into benzaldehyde or deoxybenzoin almost completely with high selectivity by altering the cocatalyst component via simple ion exchange.