Improved electrodeposited iridium oxide pH sensor fabricated on etched titanium substrates

Area of Science:

• Electrochemistry
• Materials Science
• Analytical Chemistry

Background:

• Development of reliable solid-state pH sensors is crucial for various applications.
• Existing sensors often face challenges with fabrication time, cost, and performance.

Purpose of the Study:

• To develop an improved solid-state pH sensor with enhanced characteristics.
• To optimize the fabrication process for reduced time and cost.
• To evaluate the sensor's performance in a flow injection analysis system.

Main Methods:

• Anodic electrodeposition of iridium oxide film on acid-etched titanium substrate.
• Optimization of electrodeposition solution (IrCl4, H2O2, K2C2O4, K2CO3) and heating to 90°C.
• Protection of the pH-sensing layer with Nafion and a microporous polyester membrane.
• Integration of the sensor into a flow injection analysis (FIA) system.

Main Results:

• Achieved excellent adhesion and reproducibility of the iridium oxide pH-sensing layer.
• Reduced sensor preparation time from 3 days to 10 minutes.
• Demonstrated a super-Nernstian response (-73.7 ± 1.2 mV/pH unit) over a wide pH range (1.5-11.5).
• Obtained linear peak height dependence on sample pH (2-11) in the FIA system.

Conclusions:

• The improved solid-state pH sensor offers significant advantages in fabrication speed, cost, and performance.
• The sensor is suitable for accurate pH monitoring in flow injection analysis.
• This technology holds promise for advancing electrochemical sensing applications.