A cathodically polarized PANI-based lead ion-selective electrode: achieving high stability with antibiofouling...

Solid-state contact ion-selective electrodes (SC-ISEs) are an efficacious means of monitoring heavy metal contamination. Instability of the electrode potential is a key factor limiting their development, with biofouling in real water samples posing a significant challenge to maintaining stability. Therefore, addressing biofouling is crucial for optimizing solid-state ion-selective electrodes. In this work, high stability and antibiofouling capability in a solid-state contact lead ion-selective electrode (SC-Pb²⁺-ISE) based on polyaniline (PANI) was achieved through cathodic polarization. Specifically, PANI played a dual role in the ion-selective membrane (ISM) as an ion-to-electron transducer and antifouling agent. Given the excellent electrochemical performance of PANI, the prepared electrode (GC/PANI-Pb²⁺-ISM) demonstrated a remarkable antibiofouling efficiency of 98.2% under a cathodic polarization of -0.2 V. Furthermore, a standard deviation of standard potential (E^θ) as low as ± 0.5 mV was realized successfully. The excellent chrono-potentiometric stability of 17.0 ± 2.9 μV/s was also demonstrated. The electrode maintained a Nernstian response slope of 30.7 ± 0.2 (R² = 0.998) after applying a cathode potential (-0.2 V) for 30 min. The developed GC/PANI-Pb²⁺-ISM electrode is suitable for practical applications in real environmental water sample monitoring.