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.