Novel Ag-Cu bimetallic alloy decorated near-infrared responsive three-dimensional rod-like architectures for efficient photocatalytic water purification.

In this paper, novel silver-copper bimetallic alloy (Ag-Cu) nanoparticles (NPs) decorated β-NaYF4: Yb3+, Tm3+@TiO2 ("@" means TiO2 supported on NaYF4: Yb3+, Tm3+, marked as NYFT) micro-rods were successfully synthesized through a surfactant-assistant sol-gel method and H2 reduction process for the first time. In NYFT@Ag-Cu composite, efficient energy transfer from β-NaYF4: Yb3+, Tm3+ (NYF) to TiO2 and metal NPs was confirmed. Under near-infrared (NIR) light irradiation, Ag-Cu alloy supported NYFT exhibited significantly enhanced photocatalytic activity in comparison with other samples, and water disinfection involving 100% inactivation of bacteria was realized within 8 h. The strengthened photocatalytic activity was assigned to the synergistic effect of up-conversion (UC) material and alloy NPs. Some reasons for the improved photocatalytic activity were systematically investigated and a probable mechanism for NIR-responsive photocatalysis was elucidated.