Atomic layer deposited TiO2 ultrathin layer on Ag_ZnO nanorods for stable and efficient photocatalytic degradation of RhB

Abstract

Highly stable and active TiO2-coated Ag-modified ZnO nanorods supported on stainless steel mesh (xTi@Ag_ZnO-SS) were successfully synthesized in this work. A low-temperature one-pot hydrothermal method was used to grow Ag_ZnO on stainless steel mesh, and subsequently, an atomic layer deposition (ALD) technique was applied to deposit a TiO2 layer on the surface of Ag_ZnO-SS. The addition of Ag-enhanced photoactivity via favored charge carrier transfer and the TiO2 layer improved stability through suppressed corrosion under UV irradiation, which was demonstrated by cycling performance for RhB photodegradation in two aspects: morphology and photoactivity. After 10 cycles (2 h/cycle) RhB degradation tests under UV irradiation, all the TiO2-protected ZnO materials maintained more intact nanorods structure and more than 80% of the initial photoactivity in the 1st cycle, whereas the ZnO materials without TiO2 coating were drastically deconstructed and only had 56% of initial photodegradation ability. Comprehensive study indicated that thicker TiO2 layers resulted in higher stability but lower photoactivity due to the inhibited charge transfer. The developed TiO2@Ag_ZnO nanorods immobilized on stainless steel mesh demonstrated a promising strategy for the design of highly stable and active photocatalysts endowed with great industrial scalability and practicality.