Plasmonic hot electron transport drives nano-localized chemistry

Abstract

Nanoscale localization of electromagnetic fields near metallic nanostructures underpins the fundamentals and applications of plasmonics. The unavoidable energy loss from plasmon decay, initially seen as a detriment, has now expanded the scope of plasmonic applications to exploit the generated hot carriers. However, quantitative understanding of the spatial localization of these hot carriers, akin to electromagnetic near-field maps, has been elusive. Here we spatially map hot-electron-driven reduction chemistry with 15 nm resolution as a function of time and electromagnetic field polarization for different plasmonic nanostructures. We combine experiments employing a six-electron photo-recycling process that modify the terminal group of a self-assembled monolayer on plasmonic silver nanoantennas, with theoretical predictions from first-principles calculations of non-equilibrium hot-carrier transport in these systems. The resulting localization of reactive regions, determined by hot-carrier transport from high-field regions, paves the way for improving efficiency in hot-carrier extraction science and nanoscale regio-selective surface chemistry.

Plasmon‐Induced Hot Carrier Separation across Dual Interface in Gold–Nickel Phosphide Heterojunction for Photocatalytic Water Splitting

“…Meanwhile, energy transfer can also occur from the TSPR to the LSPR mode, which is promoted by electron–hole pairs . Furthermore, it is suggested that the maximum hot electron flux occurs at the tip of the plasmonic nanostructures and the flux decays exponentially far from the tip . Therefore, the hot electrons with lower energy (generated after multiple scattering) possess longer mean free paths and high energetic electrons remain localized closer to the field hotspots .…”

“…Pure Au NRs were synthesized using the seed‐mediated method originally developed by Murphy and co‐workers, and later modified by El‐Sayed and Nikoobakht . Briefly, seed solution was prepared by adding a freshly prepared, ice‐cold aqueous solution of NaBH 4 (Sigma‐Aldrich, 0.6 mL, 0.01 m ) into a solution of HAuCl 4 ·3H 2 O (Sigma‐Aldrich, 0.025 mL, 0.1 m ) and C 16 TAB (bioreagent grade, Sigma‐Aldrich, 10 mL, 0.1 m ).…”

Mechanistic Studies of Plasmon Chemistry on Metal Catalysts

“…Zhang et al investigated the concentration dependence of pNTP molecules,and observed that azo bond formation had occurred on the sample with high molecular density,a nd that plasmon-induced dissociation from pNTP to thiophenol had occurred for the lower molecular density. [56] The dissociation of the azo bond was induced by the combination of the hot electrons and tunneling electrons,w hich was demonstrated using STM-TERS. reported that the reduction from pNTP to pATPinanacid halide media (HCl, HBr, and HI) was driven by hot-electron transfer.…”

Nanoscale Surface Redox Chemistry Triggered by Plasmon‐Generated Hot Carriers

“…The high sensitivity of SERS is mostly due to the local electromagnetic field enhancement in “hotspots” (nanoscale regions where hot electrons primarily appear). Unfortunately, the enhancement in the randomly distributed hotspots on an SERS substrate can vary enormously.…”