Synergistic effect of upconversion and plasmons in NaYF4:Yb3+, Er3+, Tm3+@TiO2-Ag composites for MO photodegradation

Structure-based rational design of photocatalysts to enable combination of nanocomponents of radically different properties for enhanced solar energy utilization is a very challenging task. Herein, we integrated up-conversion material NaYF4:Yb3+, Er3+, Tm3+ with TiO2 shells and Ag nanoparticles to synthesise a new class of materials with good stability, broadband absorption from ultraviolet to near infrared, and excellent photocatalytic activity. Structure analysis proved that intimate contact between the NaYF4: Yb3+, Er3+, Tm3+ core and the TiO2 shell and between the TiO2 shell and Ag NPs is the reason for the enhanced photocatalytic activity. Furthermore, the materials also showed exceptionally high stability and reusability under similar experimental conditions. All these results reveal that hierarchical core-shell microspheres exhibit great prospects for developing efficient solar photocatalysts.