An Electrochromic Ag-Decorated WO3−x Film with Adjustable Defect States for Electrochemical Surface-Enhanced Raman Spectroscopy

Abstract

Electrochemical surface-enhanced Raman scattering (EC-SERS) spectroscopy is an ultrasensitive spectro-electrochemistry technique that provides mechanistic and dynamic information on electrochemical interfaces at the molecular level. However, the plasmon-mediated photocatalysis hinders the intrinsic electrochemical behavior of molecules at electrochemical interfaces. This work aimed to develop a facile method for constructing a reliable EC-SERS substrate that can be used to study the molecular dynamics at electrochemical interfaces. Herein, a novel Ag-WO3−x electrochromic heterostructure was synthesized for EC-SERS. Especially, the use of electrochromic WO3−x film suppresses the influence of hot-electrons-induced catalysis while offering a reliable SERS effect. Based on this finding, the real electrochemical behavior of p-aminothiophenol (PATP) on Ag nanoparticles (NPs) surface was revealed for the first time. We are confident that metal-semiconductor electrochromic heterostructures could be developed into reliable substrates for EC-SERS analysis. Furthermore, the results obtained in this work provide new insights not only into the chemical mechanism of SERS, but also into the hot-electron transfer mechanism in metal-semiconductor heterostructures.

Influence of Adsorption of para‐Aminothiophenol on Trap States and Recombination Kinetics at Plasmonic Ag‐TiO2 Heterostructure Interfaces

“…Recombination processes usually occur at the trap states of the semiconductor, such as interstitial atoms, vacancies, and grain boundaries [29] . Moreover, the trap states in semiconductor materials can act as electron donors or electron acceptors [30] . Therefore, recombination involving traps which is one of the most important mechanisms in semiconductors, had been extensively studied [29] .…”

“…[29] Moreover, the trap states in semiconductor materials can act as electron donors or electron acceptors. [30] Therefore, recombination involving traps which is one of the most important mechanisms in semiconductors, had been extensively studied. [29] Jung et al studied the photoluminescence (PL) spectra of anatase TiO 2 nanoparticles after calcination at different temperatures and found that PL intensity increased with the increase of calcination temperature, which was owing to the reduction of trap states.…”