Insights into Interfacial Proton Transport in Protonic Ceramic Conductors

Abstract

Understanding the mechanism of proton conduction at the interface of materials enables the development of a new generation of protonic ceramic conductors at low temperatures (< 300 °C) through water absorption and proton transport on the interface. In-situ Raman spectroscopy was performed on water-saturated, porous, and nanostructured TiO2 membranes directly observe the isotope exchange reactions suggested a Grotthuss-type proton transport and faster isotope exchange rate at 175 °C than that at 25 °C with a corresponding activation energy of 9 kJ mol-1. Comparing to traditional high-temperature protonic ceramic conductors through bulk transport, water absorption on the interface in simple oxides system has higher proton mobility and similar proton concentration, indicating the interface is a facile route for proton transport. In addition, the measured hydrogen isotope exchange rates in nanostructured BCZYYb by in-situ Raman spectroscopy in the temperature range of 100-300 °C were comparable or even higher than that in fully dense BCZYYb in the range of 400-600 °C, suggesting the possibility of using the nanostructured BCZYYb membrane as an electrolyte materials in protonic ceramic fuel cells at low temperatures (<300 °C).