Recyclable MXene film as SERS sensor with high sensitivity and flexibility adjusted with ZnO quantum dots

Abstract

Developing flexible substrates with high sensitivity, good reproducibility and recyclability is a major challenge in surface enhanced Raman scattering (SERS) research. Herein, we prepare a recyclable Ti₃C₂ MXene/ZnO quantum dots (Ti₃C₂/ZnO) heterostructure film as an efficient SERS sensor with remarkable flexibility using vacuum assisted filtration technique. Benefiting from the more charge transfer (CT) paths, higher CT efficiency provided by oxygen vacancies (OVs) in ZnO QDs and Schottky barrier between Ti₃C₂ and ZnO QDs, the limit of detection (LOD) for 4-mercaptopyridine (4-MPY) molecules was as low as 1×10⁻⁷ M. In addition, the prepared flexible SERS film provided uniform and stable signals for both temporal (storage at room temperature for 60 days) and spatial (RSD = 10.7 %) scales due to the optimal distribution of ZnO QDs in the macroscopic assembly of Ti₃C₂/ZnO hybrid with excellent reliability and durability. Moreover, the prepared novel flexible SERS sensor achieved self-cleaning by photocatalytically degrading methylene blue (MB) residues extracted from the surface of orange peels and showed exceptional reusability during the detection process. Thus, this high-efficiency and low-cost flexible recyclable SERS sensor may be useful for the in-situ molecular detection in food security and environmental protection.