Facet-Controlled Electrosynthesis of Nanoparticles by Combinatorial Screening in Scanning Electrochemical Cell Microscopy

Controlled synthesis of faceted nanoparticles on the surface without explicit use of ligands has gained attention due to their potential applications in electrocatalysis and sensing. Electrodeposition is a desirable method, but controlling the size, spatial distribution, and morphology of the nanoparticles requires extensive optimization. Here, we report spatially resolved synthesis of shape-controlled Pt nanoparticles and fast screening of synthesis conditions in scanning electrochemical cell microscopy (SECCM) using pulse potentials. Screening occurs at individual ~µm2 areas isolated in SECCM, allowing multiple conditions to be screened in one mapping experiment. The screening reveals that the formation of (100) facets in Pt nanoparticles is sensitive to the upper and lower potential limits in the square-wave potential pulse. The facet control is explained by the facet-dependent migration effect from the concurrent hydrogen evolution reaction during Pt deposition. Moreover, the density and size of nanoparticles can also be controlled. This approach paves the way for automated synthesis and characterization of single-facet metallic nanoparticles, offering great potential for advancements in electrocatalysis and sensor applications.