Mechanochemical activation of 2D MnPS₃ for sub-attomolar sensing

Molecular detection is important in biosensing, food safety, and environmental surveillance. The high biocompatibility, superior mechanical stability, and low cost make plasmon-free surface-enhanced Raman scattering (SERS) a promising sensing technique, the ultrahigh sensitivity of which is urgently pursued for realistic applications. As a proof of concept, we report a mechanochemical strategy, which combines the wrinkling and chemical functionalization, to fabricate a plasmon-free SERS platform based on 2D MnPS₃ with a sub-attomolar detection limit. In detail, the formation of wrinkles in 2D MnPS₃ enables a SERS substrate of the material to detect trace methylene blue molecules. The mechanism is experimentally revealed that the wrinkled structures contribute to the improvement of light-matter coupling. On this basis, decorating a wrinkled MnPS₃ which has absorbed methylene blue with histamine dihydrochloride further lowers the detection limit to 10^-19 M. Because the amino groups in histamine dihydrochloride molecules are crosslinkers that create more pathways to promote charge transfer between these substances. This work provides a guidance for the design of SERS sensors with single-molecule-level sensitivity.