Characteristics of Pd/Nafion oxygen sensor modified with polypyrrole by chemical vapor deposition

In this study, Pd/Nafion electrodes were prepared by impregnation-reduction methods in sensing oxygen. To prolong the electrode's life in practical use, a polypyrrole (PPy) film was chemically deposited onto the Pd/Nafion electrode. The sensitivities of PPy-modified Pd/Nafion electrodes are 0.00671 and 0.0117 µA/ppm obtained in O2 concentration regions of 0–5000 and 5000–50,000 ppm, respectively. Generally, the response time and the recovery time decreases and increases significantly with increasing O2 concentrations. After continuous aging tests for 48 h, the sensitivities of the Pd/Nafion and the PPy-modified Pd/Nafion electrodes decrease by 97% and 53%, respectively.