Visualizing Plasmonic Hot Carrier-Mediated Metal Deposition and Nanoparticle Reshaping with Liquid Phase Transmission Electron Microscopy

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