Synergetic Electromagnetic Enhancement and Charger Transfer in Boat-Like Au/PbS/Au Nanohybrids with Increased SERS Activity for Ultrasensitive Molecular Detection

Metal/semiconductor hybrids are ideal substrates for efficient surface-enhanced Raman scattering (SERS) due to the cooperation of electromagnetic field and charge transfer, while it remains a challenge to simultaneously optimize the two enhanced mechanisms to achieve higher SERS improvement. Herein, a boat-like Au/PbS/Au hybrid is synthesized for the first time, which shows improved SERS activity caused by the synergetic effect of huge electromagnetic enhancement and electromagnetic-field-accelerated charge transfer. The boat-like Au/PbS/Au hybrids are prepared by controllably growing the Au shell on the end-exposed Au/PbS nanorods, which has a size-tunable nanocavity at the middle of the nanorod for molecular adsorption and near-field enhancement. As a result, the boat-like Au/PbS/Au hybrids display excellent SERS efficiency on detecting crystal violet under 785 nm excitation, which is much higher than Au nanorod, Au/PbS, and boat-like Au obtained by in situ removing the PbS shell. The detailed comparison of Raman performances of Au/PbS/Au and boat-like Au as well as the numerical simulations and experimental analysis jointly reveal that the synergistic effect of huge near-field enhancement and the accelerated charge transfer between Au, PbS, and Raman molecules are responsible for the prominent SERS performance. The boat-like Au/PbS/Au can efficiently detect 10–10 M of crystal violet and thiram, showing great potential in the fields of pollutant detection and food safety.