Reconstruction of Ag/Au NCs

The purified Ag–Au–Ag NR solution (2 mL) was mixed with different volumes of H₂O₂ (0.03 wt % in water) in a 10 mL plastic tube and followed by 5 min ultrasonic treatment. Then, the mixture was allowed to stand without disturbance at room temperature. After 24 h, the supernatant liquid was taken out carefully using a plastic dropper and discarded, and then the precipitates were dispersed in 1 mL of water. Because no organics were added, further purification was not needed.