Understanding the nucleation and growth mechanisms is essential to the rational synthesis of nanocrystals with desired properties. Here we report the development of a molecular probe based on isocyanides for in situ monitoring the deposition of Pt atoms onto the surfaces of colloidal Ag nanocubes by surface-enhanced Raman scattering (SERS). The success relies on the difference in stretching frequency for the NC bond when the isocyanide group binds to the Ag and Pt surfaces, respectively and the coincidence of sites for preferential heterogeneous nucleation and the SERS hot spots at the edges of a Ag nanocube. In a typical process, we titrated H2PtCl6 into an aqueous suspension of Ag nanocubes in the presence of ascorbic acid (AA, as reductant) and polyvinyl pyrrolidone (PVP, as capping agent and colloidal stabilizer) at a slow injection rate at room temperature. The Pt atoms derived from the reduction by AA were directed to be deposited on the {110} facets of Ag nanocubes. By simply controlling the titration volume of Pt4+ precursor at the fixed number of Ag seeds, We confirmed that the deposition of Pt atoms below 1 atomic layer onto the edges of Ag nanocubes during the growth process could be recorded sensitively by SERS. Thus, this new paradigm allows for unprecedented sensitivity, with a detection limit below one monolayer.

Watching submonolayer deposition of platinum on colloidal silver nanocrystals with a molecular probe

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.