High performance sol-gel synthesized Ce_0.9Sr_0.1(Zr_0.53Ti_0.47)O₄ sensing membrane for a solid-state pH sensor

In this paper, we developed a high-performance solid-state pH sensor using a Ce_0.9Sr_0.1(Zr_0.53Ti_0.47)O₄ (CSZT) membrane through a very simple sol-gel spin-coating process. The structural properties of the CSZT membrane are correlated with its sensing characteristics. The CSZT based EIS sensor exhibited a high pH sensitivity of 92.48 mV pH^-1, which is beyond the Nernst limit (59.4 mV pH^-1), and good reliability in terms of a low hysteresis voltage of 1 mV and a small drift rate of 0.15 mV h^-1. This behaviour is attributed to the incorporation of Sr in the CSZT sensing membrane, which promotes change in the Ce oxidation state from Ce⁴⁺ to Ce³⁺.