Direct printing of micropatterned plasmonic Au nanoparticle/MoS₂ heterostructure for ultrasensitive surface-enhanced Raman spectroscopy sensing

Abstract

Molybdenum disulfide (MoS₂) has attracted a wide range of research attention due to its distinct electronic structures and the great potential for use in emerging microelectronic and photonic devices. However, the development of MoS₂-based micro-electronic/photonic devices lags far behind expectations mainly because of the lack of efficient microfabrication technology. Here, a high-resolution precision photoreduction technology is presented for directly printing MoS₂ micropatterns that can be decorated into gold nanoparticle (AuNP)/ MoS₂ heterostructure for ultrasensitive surface-enhanced Raman spectroscopy (SERS) sensing. Micropatterns of MoSₓ nanoparticles are initially grown toward a target size in a light-controlled manner and then transformed into a micropatterned pure MoS₂ nanofilm through thermal annealing. Thereafter, size and gap-controlled AuNPs are grown selectively on the surface of MoS₂ to form a self-aligned AuNP/MoS₂ heterostructure with desired optical properties. Thanks to both electromagnetic and chemical enhancements, the directly printed plasmonic AuNP/ MoS₂ substrate can greatly enhance Raman signals to detect crystal violet (CV) and 4-mercaptobenzoic acid (4-MBA) at 10⁻¹² m under the excitation of 785-nm laser. This multiscale-engineered plasmonic AuNP/MoS₂ substrate is rapidly printed without relying on expensive and time-consuming nanofabrication processes, offering a new technical approach for future development of MoS₂-based micro-devices and sensing platforms.