Precise Tailoring of Mesoporous Silica-Coated Gold Nanorods for Laser Ignition at 1064 nm

The plasmon-induced photothermal effect is often regarded as one of the most intriguing features of Au nanorods (AuNRs). The spectral matching of absorption and excitation determines the optical absorption quantity and the photothermal conversion efficiency, which is essential for practical applications. Although the dimensional tunability of monodisperse AuNRs has already been accessible, the fine-tuning of AuNRs with longitudinal surface plasmon resonance (LSPR) at a desired wavelength to match the excitation is still challenging because of inferior reproducibility and synthetic complexity. In this work, using hydroquinone as both a cosurfactant and a reductant, we propose a synthetic strategy toward AuNRs with excellent linear tunability of LSPR peaks from 530 to 1200 nm via simply altering the dosage of silver nitrate. Given that the laser wavelength for ignition is 1064 nm, the LSPR wavelength of AuNRs could be exactly controlled at 1064 nm for maximum photothermal performance. Afterward, the as-prepared AuNRs were coated with a dendritic mesoporous silica shell for plasmonic stability and loading explosive molecules. As a proof of concept, the laser ignitability could be achieved only in the presence of AuNRs with LSPR wavelength approaching 1064 nm, highlighting the importance of spectral matching in photothermal conversion-assisted laser ignition.