Visualizing plasmon-mediated metal deposition and nanoparticle reshaping with liquid-phase transmission electron microscopy

Hot carriers generated by localized surface plasmon resonance (LSPR) in metal nanoparticles can drive chemical reactions such as secondary metal deposition and catalytic reactions. Rationally designing plasmonic nanostructures requires understanding how particle geometry impacts hot carrier reaction dynamics. Here we use liquid-phase transmission electron microscopy (LP-TEM) and an electron radiolysis-resistant solvent to visualize hot carrier-mediated silver deposition and gold nanorod (AuNR) reshaping. AuNRs grew primarily in the transverse direction and displayed tip sharpening and preferential growth at LSPR hotspots. Ex situ white-light illumination produced similar morphological and compositional changes, whereas radiolysis products did not. Growth dynamics relative to electron beam flux and AuNR orientation were consistent with numerical simulations of hot carrier generation. Isolating hot carrier-induced redox processes on AuNRs during LP-TEM enabled quantifying spatially varying hot electron reaction dynamics. This approach is expected to enable quantifying and visualizing a broad range of plasmonic carrier-mediated reactions.