Visualizing Phase Boundaries with Electrogenerated Chemiluminescence

Abstract

Reactivity at phase boundaries is central to many areas of chemistry, from synthesis to heterogeneous catalysis. New tools are necessary to gain a more detailed understanding of processes occurring at these boundaries. We describe a series of experiments to visualize phase boundaries using electrogenerated chemiluminescence (ECL) on glassy carbon electrodes. By taking advantage of the solubilities of the ECL luminophore and the coreactant in different liquid phases, we demonstrate that the interface of various phases (i.e., the boundaries formed between a water microdroplet, 1,2-dichloroethane, and a glassy carbon electrode and the boundaries formed between an oxygen bubble, water, and a glassy carbon electrode) can be evaluated. We measured microdroplet contact radii, the three-phase boundary thickness, and growth dynamics of electrogenerated O 2 bubbles. These experimental tools and the fundamental knowledge they yield will find applications in biology, nanoscience, synthesis, and energy storage and conversion, where understanding phase boundary chemistry is essential.

Electrochemiluminescence with semiconductor (nano)materials

“…Since metal-based QDs are toxic, it is important to use low-toxicity, eco-friendly alternatives to develop QD-ECL emitters. Undoubtedly, the versatility offered by the combination of ECL with SC (nano)materials opens a wide range of opportunities to develop new ultrasensitive (bio)sensing and imaging applications, especially in point-of-care testing, conned and multiphase systems, 178,228,229 biological assays, and microscopy of cellular and subcellular structures.…”

Electrogenerated chemiluminescence detection of single entities

“…63 To obtain more understanding of phase boundaries, Dick and co-workers described the measurements of imaging phase boundaries using ECL on glassy carbon electrodes. 64 The selective imaging of the two-dimensional contact interface for individual micrometer water droplets suspended in 1,2-dichloroethane may be achieved by selectively dissolving the ECL luminophore and coreactant in the water microdroplets to make ECL reaction only proceed in the aqueous phase. These ECL imaging experiments capture the entirety of the water/ electrode boundary to provide contrast with the oil phase, which allowed quantication of the boundary thickness of 9 AE 3 mm, the microdroplet contact radii, as well as the growth dynamics of electrogenerated O 2 bubbles (Fig.…”

Enabling practical nanoparticle electrodeposition from aqueous nanodroplets

“…45 Our group expanded the use of nanodropletmediated electrodeposition to electrosynthesize high entropy alloy nanoparticles along with several fundamental studies regarding growth kinetics of single nanoparticles 33,34 and reactivity at the three-phase boundary. [35][36][37] One of the greatest drawbacks of electrodeposition from water nanodroplets is the complicated ion transfer mechanisms necessary to maintain electroneutrality during nanoparticle formation. For instance, the reduction of chloroplatinic acid liberates six chloride anions.…”