UC Irvine

IrOx thin films are useful as pH sensors in a multitude of applications. However, fabrication is prone to contamination and performance is highly variable, so a high level of control throughout the fabrication and use cycle is required. Assuming a clean production cycle, calibration control can be achieved by simple polarization routines within specific voltage ranges. However, the extension of this technique into different solutions and applications is limited by mechanistic understanding. The presumed mechanism, based on our own surface chemistry investigations, it that the redox state mixtures and species ratio changes theorized by others are indeed taking place. Attempts were made to further interrogate mechanism, in terms of depth direction and interfacial interactions, but experimental preparation requires more time investment. In total, this work presents several application studies, resulting performance variability thereof, demonstration of performance control, and an exploration of correlated physical mechanisms.