Plasmon-Driven C─B Bond Cleavage: Role of Metal Nanobipyramids' Sharpness

Anisotropic metal nanostructures are emerging as groundbreaking photocatalytic platforms by leveraging nanoscale light-matter interactions, which facilitate unprecedented charge carrier generation and convert photon energy to chemical energy. The present study demonstrates the comparative photocatalytic performance toward the plasmon-driven protodeboronation reactions by employing gold nanobipyramids (Au NBPs) and silver-coated gold nanobipyramids (Au@Ag NBPs) as photocatalysts using the molecular fingerprint technique, surface-enhanced Raman spectroscopy (SERS). With the aid of a plasmonic hotspot, 4-mercaptophenyl boronic acid (4-MPBA) was transformed into benzenethiol (BT) under 633 nm laser irradiation. Our investigations revealed that Au NBPs with sharp tips exhibited remarkable catalytic efficiency, achieving a 65% yield within 5 min, whereas Ag-coated (Au@Ag) NBPs with a small tip curvature radius exhibited enhanced SERS signals with relatively lower yields (44%-55%) and extended reaction times. Surprisingly, Au@Ag NBPs with a large tip curvature radius were found to completely suppress the catalytic activity. Mechanistic pathway was extracted through temperature-dependent studies (30-90 °C), which indicates that hot charge carriers, rather than photothermal effects, trigger the bond cleavage. This work provides valuable insights into structure-activity relationships in plasmon-enhanced photocatalysis and establishes Au NBPs as promising candidates for efficient protodeboronation reactions.