In-situ nanospectroscopic imaging of plasmon-induced two-dimensional [4+4]-cycloaddition polymerization on Au(111)

Feng Shao,Zhilin Yang,Jinggang Lan,Weimin Yang,Yao Zhang,A Dieter Schlüter,Wei Wang,Renato Zenobi

doi:10.1038/s41467-021-24856-5

Abstract

Plasmon-induced chemical reactions (PICRs) have recently become promising approaches for highly efficient light-chemical energy conversion. However, an in-depth understanding of their mechanisms at the nanoscale still remains challenging. Here, we present an in-situ investigation by tip-enhanced Raman spectroscopy (TERS) imaging of the plasmon-induced [4+4]-cycloaddition polymerization within anthracene-based monomer monolayers physisorbed on Au(111), and complement the experimental results with density functional theory (DFT) calculations. This two-dimensional (2D) polymerization can be flexibly triggered and manipulated by the hot carriers, and be monitored simultaneously by TERS in real time and space. TERS imaging provides direct evidence for covalent bond formation with ca. 3.7 nm spatial resolution under ambient conditions. Combined with DFT calculations, the TERS results demonstrate that the lateral polymerization on Au(111) occurs by a hot electron tunneling mechanism, and crosslinks form via a self-stimulating growth mechanism. We show that TERS is promising to be plasmon-induced nanolithography for organic 2D materials.

Highlights

Plasmon-induced chemical reactions (PICRs) have recently become promising approaches for highly efficient light-chemical energy conversion
The monomer MLs were prepared at an air/water interface on a LB trough, which allowed for the controllable transfer of those MLs onto Au(111) with physisorbed molecule/substrate interactions
The different substituent and spatial effects from their molecular structures were shown to affect the catalytic activity of the hot carriers

Summary

Introduction

Plasmon-induced chemical reactions (PICRs) have recently become promising approaches for highly efficient light-chemical energy conversion. We present an in-situ investigation by tip-enhanced Raman spectroscopy (TERS) imaging of the plasmon-induced [4+4]-cycloaddition polymerization within anthracene-based monomer monolayers physisorbed on Au(111), and complement the experimental results with density functional theory (DFT) calculations. This two-dimensional (2D) polymerization can be flexibly triggered and manipulated by the hot carriers, and be monitored simultaneously by TERS in real time and space. The most widely investigated PICRs by TERS include the dimerization of p-aminothiophenol or p-nitrothiophenol[24,29,30], polymerization of dibenzo(1,2)dithiine-3,8-diamine[31], dehydrogenation of 2,13-bis(aldehyde)-[7]thiaheterohelicene[32], crosslinking of benzenemethanethiol[33], deprotonation of 2-pyridinethiol[34], and hydrogenation of chloronitrobenzenethiol[35], which mainly rely on the thiol-anchored self-assembled monolayers (MLs) as the reaction models.

Methods

Results

Conclusion