Enhanced photoactive performance of three-layer structured Ag/Cu2O/TiO2 composites with tunable crystal microstructures

Abstract

Three-layer structured composite films consisting of a rutile titanium dioxide (TiO₂) film, a cuprous oxide (Cu₂O) nanofilm, and silver (Ag) particles were successfully prepared through sputtering and annealing procedures. The variations in microstructures and photoactive properties of the composite films were investigated by varying the sputtering duration of Cu₂O and Ag. The photoelectrode made of the Ag particle/Cu₂O/TiO₂ composite films exhibited superior photoelectrochemical and photocatalytic properties in comparison with those of the Cu₂O/TiO₂ bilayer films and pristine TiO₂ film. The surface plasmon resonance of Ag particles promotes the photon absorption capacity of the Ag particle/Cu₂O/TiO₂ composite films. Moreover, the Ag particles on the Cu₂O nanolayer act as effective electron traps, thus preventing recombination of photoinduced carriers under irradiation and prolonging the carrier lifetime, thereby increasing the carrier transfer rate. The Ag particle/Cu₂O/TiO₂ composite film with a surface Ag/(Ag + Cu) atomic ratio of 70.81% exhibits superior photoelectrochemical and photocatalytic properties in comparison with the other Ag particle/Cu₂O/TiO₂ composite films prepared with different Ag sputtering durations. The suitable Ag particle content is an important factor affecting the photoactive performance of the Ag particle/Cu₂O/TiO₂ composite film. The scavenger test results demonstrate that the photodegradation mechanism of the Ag particle/Cu₂O/TiO₂ composite film towards methyl orange solution under irradiation follows a Z-scheme mechanism.