Measuring changes in wettability and surface area during micro droplet corrosion measurements

We report a new method for directly monitoring dynamic surface wetting that occurs during electrochemical droplet cell corrosion measurements on an Al alloy and Cu galvanic couple. The combination of goniometer potentiostat enabled the in situ observation wettability polarization each metal at interface two metals 0.4 ?L NaCl aqueous droplets. Droplet spreading was heterogeneously metals, where oxygen from surrounding environment diffused into edges reduced cathodic metal, thus increasing this region, while anodic served as sacrificial anode remained constant wetted state. Such inhibited by performing under anaerobic conditions, minimal changes voltammetric response were observed comparison performed air. All voltammetry normalized true area footprint, which measured after evaporation to avoid overestimating current densities. This work highlights potential combined goniometer-electrochemical setup further enhance community's knowledge about interfacial chemistry importance considering evolution micro/nanoscale droplets heterogeneous substrates when estimating rates.