Quantum Effects Enter Semiconductor-Based SERS: Multiresonant MoO₃·xH₂O Quantum Dots Enabling Direct, Sensitive SERS Detection of Small Inorganic Molecules

Abstract

There is keen research interest in building highly effective semiconductor-based surface-enhanced Raman scattering (SERS) platforms, due to their selectivity for many probe molecules and suitability for complex scenario applications. However, current tuning approaches have not yet been successful in creating semiconductor-based SERS sensors for small inorganic molecules, due to the challenge of creating sufficient SERS enhancement in semiconductors. Here, we demonstrate the use of MoO 3 •xH 2 O quantum dots (QDs), to achieve direct and sensitive fingerprinting of the inorganic species hydrazine, which is a first attempt in semiconductor-based SERS research, as well as various other probe molecules. The resulting SERS platform that uses QDs with average size of 2.2 nm could successfully detect the signal of hydrazine with a limit of detection estimated to be around 4 × 10 −5 M, significantly lowering the detectable concentration by at least 1000-fold, in sharp contrast to the weak performance of 10 and 100 nm particles, demonstrating that quantum size effect triggered by small particle size below the Bohr radius is crucially responsible for high SERS activity. The significantly enhanced SERS activity is a result of vibronically coupled multipathway, highly efficient charge-transfer resonances induced by the divergence of energy states in quantum-sized MoO 3 •xH 2 O. This is a proof-of-concept demonstration of the exploitation of quantum size effect, toward significantly enhanced intrinsic SERS activity in semiconductor-based SERS materials.

Construction of Ultrasensitive Surface‐Enhanced Raman Scattering Substates Based on TiO2 Aerogels

“…[ 24 ] This is another evidence of CM mechanism induced by the CT process due to the Herzberg−Teller coupling term. [ 25 ]…”

“…[24] This is another evidence of CM mechanism induced by the CT process due to the Herzberg−Teller coupling term. [25] To clarified aerogels effect in SERS activity, a series of experiments were conducted. First of all, the SERS effect of TiO 2 -a1 aerogels was also examined under 633 nm (1.95 eV) and 785 nm (1.58 eV) laser excitation, further shown very weak SERS signal (Figure 3c).…”

New Trends in Nanoarchitectured SERS Substrates: Nanospaces, 2D Materials, and Organic Heterostructures

“…The active utilization of organic semiconductors was inspired by the electronic properties of inorganic semiconductors (ZnO, TiO 2 , lnAs/GaAs, graphene, and CuTe) studied by Usta and Demirel. [110,157] They showed that p-type benzothiophene-based polymer 2,7-dioctyl [1]benzothieno[3,2-b]- [1]benzothiophene (C8-BTBT) in combination with Au thin film could be an efficient plasmonic heterostructure (Figure 14d-1). [106] C8-BTBT was deposited on a Si wafer by chemical vapor deposition followed by sputtering of an Au nanolayer.…”

Significant surface-enhanced Raman scattering effect of Ag-loaded iron hydroxide enabled by coordination effect between Ag and hydroxyl group

“…Therefore, it is of great significance to develop efficient and sensitive detection methods. As a fast and effective spectroscopic technique, SERS features the capability of detecting the vibrational fingerprints of trace molecules 4,5 The excellent performance promotes its wide-spread application in different fields, such as biological, pharmaceutical, contaminant, and toxin detection fields. [6][7][8] It is imperative to design SERS substrates with high performance for the trace detection of PAAB.…”