UiO-66 Particles Decorated with Ag/Au Nanoparticles as SERS Sensors for Detecting Harmful Patina in Trace Analysis of Ancient Bronze Art

Quantitative analysis of harmful patina components on the surface of bronzeware is crucial as patina can corrode artifacts. Surface-enhanced Raman spectroscopy (SERS) has a common application in surface analysis. However, there exists an absence of documented investigations concerning the quantitative analysis of detrimental patina, particularly the chloride patina. To achieve high sensitivity in targeting harmful patina, we report a fabrication method for constructing Ag/Au alloys in the pores and on the surface of UiO-66 (zirconium 1,4-dicarboxybenzene metal–organic framework) nanomaterials, resulting in Ag/Au/UiO-66 nanoparticle monolayers formed by self-assembly at the oil–water interface. By incorporating them onto the surface of PVA hydrogel, we obtained SERS sensor devices with excellent flexibility, outstanding optical transparency, and ultrahigh activity. These sensor devices efficiently sample irregular surfaces and detect micrometer-scale specimen. They significantly enhance the Raman characteristic peaks of measured objects, facilitating precise analysis of the patina composition on the surface of bronze artifacts. The Raman peak at 118 cm–1 was boosted from 367 to 11,909 for detecting harmful patina, and the enhancement factor of the SERS substrate was calculated to be 3.6 ×1010 for detecting the Raman peak of rhodamine 6G (R6G), which could be easily detected at 610 cm–1 at a concentration of 10–13 mol/L (M). The Raman peaks at 610 cm–1 from the SERS substrate could also be readily detected. By grafting the organic fluorescent group amino-MQAE onto the surface of Ag/Au/UiO-66 nanoparticles (NPs), the content of harmful patina on the surface of bronze artifacts treated for different durations was indirectly determined. These results indicate the successful construction of the Ag/Au alloy on the surface of UiO-66 NPs, resulting in SERS sensor devices with excellent flexibility, optical transparency, and ultrahigh sensitivity.