Cavity-Enhanced Catalytic Array for Monitoring Spontaneous Catalytic Dynamics and Applications.

Microdroplets enable catalyst-free reactions via unique interfacial effects, yet current technologies struggle to monitor and quantify reaction kinetics within individual microdroplets. Here, we developed a cavity-enhanced catalysis array that could amplify and resolve catalytic dynamics at the single-microdroplet level. Uniform and stable aqueous microdroplets were confined in a Fabry-Pérot (F-P) cavity, which converted subtle variations in reactant concentration into measurable laser wavelength shifts with high sensitivity (3.08 nM per 10 pm). Integrating the microdroplet array and scanning system, we studied spontaneous catalysis in response to changes in reactant concentration, droplet size, and pH. Results showed that increasing the reactant concentration from 100 to 500 μM accelerated reaction rates by 112%, reaction kinetics correlated positively with surface-to-volume ratio, and weakly acidic conditions accelerated the reaction. These findings deepen our understanding of microdroplet chemistry and establish this platform as a versatile tool for mechanistic studies of green synthesis and biological systems.