Studies of metal oxide Ta2O5 CeO2 thin films for applications as electrochemical ph sensing techniques

Abstract

In the present study, thin films of Ta2O5 and CeO2 were used to fabricate electrochemical pH sensor. The optical constants and thickness of Ta2O5 deposited films were theoretically estimated by deploying the envelope method. The thin films of Ta2O5 and CeO2 were fabricated using electron beam evaporation on glass electrodes. These films were further characterized using XRD, CCI and FE-SEM techniques for their structure, roughness and surface morphology, respectively. The XRD spectra of the coated electrodes confirm the fabrication of the thin films and FESEM micrograph of these thin films confirm the stability of sensing layer after its immersion in harsh solvents. Repeatable electrochemical response of the electrode was observed in 1.0-12.0 and 1.0-14.0pH range solutions for Ta2O5 and CeO2 sensing films respectively, which indicates them as potential electrode material for pH sensing. The reliability of the fabricated sensors was also validated with tap water which indicates that the presence of other ions in solution, does not affect the performance of the sensors. It can be concluded from the present research work that the response time of Ta2O5 based pH sensor is shorter as compared to that based on CeO2. The pH detection range is wider for CeO2 based pH sensor as compared to that of Ta2O5 based sensor. The cyclic voltammetry curves show the good sensitivity and stability of both the sensors. The fabricated CeO2 based pH sensors exhibit better performance than those reported earlier. newline