One-step immobilization of tris(2,2′-bipyridyl)ruthenium(II) via vapor-surface sol–gel deposition towards solid-state electrochemiluminescence detection

A novel method for immobilization of tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)3Cl2) on electrode surfaces based on the vapor-surface sol–gel deposition strategy is first demonstrated in this paper. Ru(bpy)3Cl2 immobilized sol–gel (Ru(bpy)3Cl2/sol–gel) films were characterized by UV–vis spectroscopy and field-emitted scanning electron microscopy (FE-SEM). These results showed that Ru(bpy)3Cl2 was successfully incorporated into the silica sol–gel film. It was found that many irregular Ru(bpy)3Cl2/sol–gel clusters were formed on surfaces through one deposition and thick sol–gel films were observed after further deposition. Electrochemical properties and electrochemiluminescence (ECL) behaviors of Ru(bpy)3Cl2/sol–gel films could be easily adjusted by deposition numbers and time. At last, the Ru(bpy)3Cl2/sol–gel film modified electrode was used for solid-state ECL detection of tripropylamine. The linear range was from 5.8 × 10−8 to 2.4 × 10−4 M with the detection limit of 5 nM, which was three orders of magnitude lower than that from pure Nafion-modified electrodes. The ECL sensor also exhibited high stability, and still remained 92% response after being stored in air for 35 days. This method for immobilization of Ru(bpy)3Cl2 is simple, convenient and low-cost relative to others, so it shows promising applications in solid-state ECL detection.