Highlights
- Demonstrates super-Nernstian sensitivity of −73.64 mV/pH for accurate readings.
- Rapid response kinetics with an 18.16 s stabilization time for quick assessments.
- Exceptional stability and minimal signal drift under varying ionic strength conditions.
- Cost-effective and easy to fabricate, ideal for reliable marine pH monitoring.
Abstract
The pH level is a critical factor influencing the growth and development of marine life, environmental shifts, and various industrial and agricultural production activities. Consequently, there is an urgent requirement for a high-precision ocean pH sensor to accurately assess the pH levels in seawater. The pH-sensitive electrode was fabricated using a polyimide substrate coated with an electrodeposited iridium oxide thin film. This iridium oxide-based electrode demonstrated exceptional pH-sensing performance, including a super-Nernstian sensitivity of −73.64 mV/pH, rapid response kinetics (18.16 s stabilization time), and excellent stability across repeated pH cycling tests (3↔6 and 8↔10). Furthermore, the sensor exhibited strong resistance to environmental interference, with a linear temperature coefficient of −1.6 mV/°C and minimal signal drift (<5 mV) under varying ionic strength conditions. Practical validation through pH measurements in standardized buffer solutions and complex real-world samples confirmed its measurement reliability. Leveriting the advantages of cost-effectiveness and straightforward fabrication, this electroplated iridium oxide thin film presents a compelling solution for marine pH monitoring applications, particularly in scenarios requiring high stability and tolerance to fluctuating environmental parameters.
Sun Y., He P., Xu Z., Qin G., Liu R., Chen B., Sun X. & Dong Y., 2025. Iridium oxide thin film flexible ocean pH sensor based on electroplating deposition process. Microchemical Journal 215: 114454. doi: 10.1016/j.microc.2025.114454. Article (subscription required).
