A novel carbonate ion-selective electrode based on pine-leaf porous silver nanoparticles/polyaniline composites as the solid contact for marine monitoring

The design of carbonate-selective electrodes with high sensitivity, stability, and selectivity holds significant potential for applications in marine environmental monitoring. In this study, a novel pine-leaf porous structure carbonate ion-selective electrode was prepared with a solid contact layer of silver nanoparticles/polyaniline (AgNPs@PANI) using a two-step electrochemical method involving electropolymerized PANI and electrodeposited AgNPs. The novel structure provides additional charge transport paths and a larger contact area for carbonate ions passing through the selective membrane, thereby enhancing the membrane's carbonate-responsive performance. The results indicate that the GE/AgNPs@PANI/CO32−-ISE demonstrates a near-Nernst response (−29.5 ± 0.2 mV per decade) to carbonate ions over a wide concentration range (10−1–10−6 M) as well as a low carbonate detection limit (1.15 × 10−7 M), with excellent performance in terms of response speed (5.5 s), reversibility (1.35 mV), long-term potential stability (0.17 mV h−1), and selectivity. The developed electrode was applied to the detection of carbonate in real seawater using the standard addition method, and the average recovery was found to be 95–105%. Meanwhile, the results of carbonate ion detection in real samples using this electrode were largely consistent with those obtained by potentiometric titration, demonstrating significant practicality in marine chemistry research.