Ppm-level Cu dopant on ultrathin Pd nanosheets/TiO2 for highly enhanced photocatalytic alcoholysis of epoxides

Abstract

Photocatalysis provides a new avenue for organic synthesis, to which catalyst design at atomic level holds the key. Herein, the first case of ppm-level (39 ppm) Cu dopant based photocatalyst has been successfully constructed as Cu1Pd200/TiO2, in which Cu element dopes ultrathin Pd nanosheets (thickness of 2 nm) with atomic dispersion using TiO2 as the semiconductor host. The alcoholysis of styrene oxide, as a model reaction, can produce valuable β-alkoxy alcohols, conventionally requiring corrosive strong acids or harsh reaction conditions. The presence of ppm-level Cu atoms in Cu1Pd200/TiO2 can boost alcoholysis with a quite high reaction rate of 176 mmol·g−1·h−1 at room temperature under light illumination (100 mW·cm2), which is 6 times and 17 times higher than Pd/TiO2 and bare TiO2, respectively. Moreover, the Cu-doped photocatalyst presents excellent stability without deactivation after ten cycles. Based on X-ray photoelectron spectroscopy, infrared spectroscopy and control experiments, this unexpected photocatalytic behavior mainly origins from the electron transfer effect and unique chemisorption of epoxides owing to Cu dopant.