Fe-Doped SrCoOx FET Sensors for Extreme Alkaline pH Sensing

The accurate measurement of pH in highly alkaline environments is critical for various industrial applications but remains a complex task. This paper discusses the development of novel Fe-doped SrCoO_x-based FET sensors for the detection of extreme alkaline pH levels. Through a comprehensive investigation of the effects of Fe doping on the structure, electrical properties, and sensing performance of SrCoO_x, we have identified the optimal doping level that significantly enhances the sensor’s performance in highly alkaline conditions. With a Fe doping level of 5 mol %, the sensitivity of the sensor improves to 0.86 lg(Ω)/pH while maintaining the response rate. Further increasing the Fe doping to 10 mol % results in a sensor that demonstrates favorable response time, a suitable pH range, and a linear correlation between lg(R) and pH. The combination of X-ray photoelectron spectroscopy and X-ray diffraction analysis provides insight into the regulation mechanisms of Fe doping on the crystal structure, electronic structure, and oxygen vacancy concentration of SrCoO_x. Our findings indicate that Fe doping leads to an increase in oxygen vacancy concentration and a decrease in the energy barrier for oxygen ion migration, which contributes to the improved sensing performance of the Fe-doped SrCoO_x sensors. Additionally, the study highlights the influence of oxygen vacancy concentration on the electrical properties of SrCoO_x. Precise control over the concentration of oxygen vacancies is crucial for optimizing the sensitivity and response speed of SrCoO_x FET sensors under extreme alkalinity conditions.