Colloidal porous gold nanoparticles

Porous Au nanostructures have attracted much attention for their wide uses as catalysts, sensors, actuators and surface-enhanced Raman scattering (SERS) substrates. The synthesis of porous Au nanostructures has mainly relied on dealloying approaches, which generally involve high-temperature treatment to form alloys and subsequent harsh chemical etching. Herein we report on an ambient wet-chemistry method for the synthesis of colloidal porous Au nanoparticles. The synthesis takes advantage of the growth of Au on PbS nanocrystals accompanied by the etching of PbS by the growth solution. The obtained porous Au nanoparticles display a SERS enhancement factor of (1.23 +/- 0.10) x 10(7) on the individual particles under off-resonance excitation and a catalytic activity that is several times those of previously reported porous Au particles and porous Au sheets. Our results will have high impact on many SERS-based analytical and biomedical applications and on the field of Au-based catalysis.