Evaluation of mesoporous borosilicate glass–ceramic composites as frits in reference electrodes

The development of new mesoporous frits for reference electrodes to overcome the limitations of cross-contamination and screening effect is essential for many electrochemical measurements. Available frit-based reference electrodes (e.g., mesoporous, microporous) still suffer from cross-contamination and/or errors in electrochemical measurements. In this work, a mesoporous glass–ceramic composite is prepared to mitigate such limitations. Mesoporous glass–ceramic frits were prepared from low-cost materials (i.e., borosilicate and kaolin) at relatively low temperatures (750–850 °C). The prepared glass–ceramic frits were characterized using scanning electron microscopy (SEM), impedance measurements, and nitrogen sorption isotherms. The developed mesoporous glass–ceramic composites are characterized by a high chemical resistance against corrosive materials and a low thermal expansion. Reference electrodes constructed with the developed mesoporous glass–ceramic frits exhibited a low flow rate of 0.002 ± 0.001 to 0.41 ± 0.06 μL h(−1) and high potential stability as well as very small potential drift of −2.4 ± 0.2 to −4.9 ± 0.2 μV h(−1). Mesoporous glass–ceramic based reference electrodes exhibited average potential variations of 13 ± 3 mV over the concentration range of 1 mM to 0.1 M KCl. This indicates that mesoporous glass–ceramic frit-based reference electrodes exhibited a much lower flow rate compared to available microporous frit-based reference electrodes. Moreover, the developed mesoporous ceramic-based reference electrodes exhibited a 4–15-fold improvement in potential variations and a large improvement in potential stability in comparison with the reported mesoporous-frit-based reference electrodes.