Plasmon Energy Transfer Driven by Electrochemical Tuning of Methylene Blue on Single Gold Nanorods

Abstract

Plasmonic photocatalysis has attracted interest for its potential to generate energy-efficient reactions, but ultrafast internal conversion limits efficient plasmon-based chemistry. Resonance energy transfer (RET) to surface adsorbates offers a way to outcompete internal conversion pathways and also eliminate the need for sacrificial counter-reactions. Herein, we demonstrate RET between methylene blue (MB) and gold nanorods (AuNRs) using in situ single-particle spectroelectrochemistry. During electrochemically driven reversible redox reactions between MB and leucomethylene blue (LMB), we show that the homogeneous line width is broadened when spectral overlap between AuNR scattering and absorption of MB is maximized, indicating RET. Additionally, electrochemical oxidative oligomerization of MB allowed additional dipole coupling to generate RET at lower energies. Time-dependent density functional theory-based simulated absorption provided theoretical insight into the optical properties, as MB molecules were electrochemically oligomerized. Our findings show a mechanism for driving efficient plasmon-assisted processes by RET through the change in the chemical states of surface adsorbates.

Recent Developments in Single-Entity Electrochemistry

“…Lu and Lew conclude that SMEC will allow indirect detection of nonfluorescent electroactive species, with future goals of studying local concentrations, redox states, and electron-transfer kinetics using SMEC. In another example, Oh et al demonstrate the ability to efficiently and controllably induce resonance energy transfer between Au NRs and their surface adsorbate, methylene blue molecules . The redox state of methylene blue can be electrochemically modulated between the oxidized state, which exhibits significant spectral overlap with Au NRs, and the reduced state, which exhibits little to no spectral overlap with Au NRs.…”

“…In another example, Oh et al demonstrate the ability to efficiently and controllably induce resonance energy transfer between Au NRs and their surface adsorbate, methylene blue molecules. 229 The redox state of methylene blue can be electrochemically modulated between the oxidized state, which exhibits significant spectral overlap with Au NRs, and the reduced state, which exhibits little to no spectral overlap with Au NRs. The extent of resonance energy transfer can be found by monitoring changes in the line width of the Au NR’s dark-field scattering spectrum as a function of applied potential, ultimately reporting on SE plasmon damping dynamics while also allowing methylene blue redox chemistry to be indirectly monitored.…”

Photocatalysis on Hybrid Plasmonic Nanomaterials: From Catalytic Mechanism Study at Single-Particle Level to Materials Design

“…The findings give guidance for designing plasmonic metal–molecular photocatalysts. The key for achieving hot-carrier transfer in these metal–molecular systems lies in the hybridization of molecular orbitals and spectral overlap between the plasmonic donor and the molecular acceptor. , …”

“…Recently, Oh et al investigated plasmon damping dynamics in plasmon-enhanced electrocatalytic reactions. The authors obtained line width (Γ), resonance energy (Eres), and intensity (I) from individual Au NRs during electrochemical redox reactions . They observed that the homogeneous line width was broadened when the E res of the Au NRs overlapped with the π → π* transition dipole energy of methylene blue.…”

The impact of a dopant atom on the distribution of hot electrons and holes in Au-doped Ag nano-clusters

“…28 A comprehensive understanding of the mechanisms governing the creation and distribution of HCs is crucial for advancing our knowledge of LSPR-facilitated photocatalysis. 29–42…”