Ionic Liquid-Regulated Interfacial Microenvironment Enables Highly Efficient Electrochemiluminescence

The efficiency of electrochemiluminescence (ECL) is often limited by insufficient electron transfer and reactant accumulation on electrode surfaces. Herein, tunable ionic liquid (IL)-based microdomains were assembled on gold electrodes to enhance the ECL of the Ru(bpy)₃²⁺/triethylamine (TEA) system in neutral solution. By varying the alkyl chain length of ILs, the interfacial microdomain size was systematically controlled, leading to pronounced differences in ECL enhancement. The smallest microdomains yielded a 20-fold enhancement in ECL compared with the bare electrode, whereas the largest microdomains showed only a 6-fold enhancement. Electrochemical and ECL measurements show that the IL microdomains accelerate the oxidation kinetics of TEA and increase the interfacial accumulation of Ru(bpy)₃²⁺. Similar amplification behavior was observed for ILs with different counteranions and in tripropylamine (TPrA)- and luminol-based ECL systems, indicating the generality of this IL-regulated interfacial engineering strategy. This work provides a promising approach for enhancing ECL efficiency, which supports high-performance ECL sensing technologies.