摘要
A monolayer-MoS 2 /ZnO-microtube heterostructure is fabricated for SERS detection. • Deep defects and optical resonances promote SERS performance in monolayer-MoS 2. • A limit of detection of 10 −12 M with an enhancement factor of 2.4 × 10 7 is realized. • Monolayer-MoS 2 /ZnO-microtube heterostructure is reusable by photodegradation. Two-dimensional transition metal dichalcogenides (2D-TMDCs) have attracted considerable attention as substrate enhancers for surface-enhanced Raman spectroscopy (SERS) due to their extraordinary chemical stability and spatial homogeneity. Unfortunately, the enhancement factors of 2D-TMDCs are limited by weak optical confinement within the atomically-thick layer. Construction of 2D-TMDCs/semiconductor-microcavity heterostructures significantly boosts the light confinement by optical resonances as well as charge-transfer (CT) resonances by energy-level alignment, by which the SERS performance is improved. Here we fabricate a monolayer-MoS 2 /ZnO-microtube (ML-MoS 2 /ZnO-MT) heterostructures, of which the ML-MoS 2 was capped onto the ZnO-MT via van der Waals forces. The deep-defect level in ZnO-MT grown by optical vapor supersaturated precipitation provide an extra CT channel transferring carriers to ML-MoS 2 for chemical enhancement. Meanwhile, the Fabry-Perot resonances supported in the ZnO-MT promote exciton, molecule and CT resonances as well as fluorescence resonance energy transfer between ML-MoS 2 and analyte molecules, by which a SERS enhancement factor of 2.4 × 10 7 with the limit of detection down to 10 −12 M for methylene blue is achieved. The ML-MoS 2 /ZnO-MT also exhibits the pronounced catalytic behavior, enabling the SERS heterostructure reusable by photodegradation of analyte molecules under 5-min ultraviolet irradiation. This work provides a new approach for highly-sensitive and recyclable plasmon-free SERS substrates for trace detection. Download: Download high-res image (69KB) Download: Download full-size image
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