Optical humidity sensing, proton-conducting sol―gel glass monolith

Abstract An integrated, crack-free glass monolith is prepared via a modified sol–gel approach. It has an accessible network of channels consisting of anisotropic pores of widths ca. 20–50 nm and lengths ca. 100–250 nm. The glass monolith exhibits a transparency change based on humidity, which is utilized as a basis for optical humidity measurements. On the other hand, the glass monolith shows high proton conduction in humid atmosphere, and its proton conductivity reaches a value of 0.12 S cm −1 at 30 °C and 80% relative humidity.