Sensitive and Homogeneous Surface‐Enhanced Raman Scattering Detection Using Heterometallic Interfaces on Metal–Organic Framework‐Derived Structure

Abstract

AbstractHere the use of heterometallic interfaces on metal–organic framework‐derived structures as surface‐enhanced Raman scattering (SERS)‐active substrates is investigated for sensitive and homogeneous SERS detection. Zeolitic imidazole framework‐67 (ZIF‐67) is grown on a conductive glass substrate via chemical bath deposition, followed by carbonization and oxidation to form ZIF‐67‐derived Co3O4 (ZIF‐67‐CO). For the sensitive and homogeneous SERS analysis, ZIF‐67‐CO is converted to the heterometallic interface Au–Ag@ZIF‐67‐derived Co3O4 (denoted as Au–Ag@ZIF‐67‐CO) via electrodeposition and successive chemical grafting. The optical properties of Au–Ag@ZIF‐67‐CO indicate a uniform and large‐scale distribution of both metals on the surface. Raman signals from the substrate are evenly enhanced based on the Raman intensity and shift mapping over a large area. Due to the multiple absorption bands of the Au–Ag@ZIF‐67‐CO substrate, signal enhancement can also be achieved with two different laser sources (532 and 785 nm) that are frequently used in SERS. As a result, concentration‐dependent and fingerprint SERS signals of small molecules such as 1,2‐bis‐(4‐pyridyl) ethylene, Nile blue A, and 1,1′‐diethyl‐2,2′‐cyanine iodide are obtained, and their signal enhancement factors are 104–105. Collectively, the use of heterometallic‐interfaced ZIF‐67‐CO will be a beneficial approach for collecting reproducible SERS signals of various target analytes.