Proton-conducting zirconium phosphate glass thin films

Abstract

Fast proton-conducting glasses, if developed, would have immense potential for use as membranes in fuel cells, gas sensors, and water electrolysis because the protons in phosphate glasses are highly mobile, and accordingly, these glasses have high proton conductivities. It is noteworthy that the conductivity increases with the P2O5 content of the reported phosphate glasses. This result strongly supports the idea of proton hopping through hydrogen-bonded non-bridging oxygen (NBO) which stems from the P2O5 network in the phosphate glasses. In this study, zirconium phosphate glass thin films with various phosphorus contents were fabricated by spin-on-glass (SOG) technique. The conductivity of the fabricated thin films was maximum 3.16×10−5 S/cm at temperatures of 350°C even in the absence of humidity. The observed conductivity of the zirconium phosphate glass thin films is attributable to the fast thermal diffusion of protons through non-bridging oxygen (NBO). The proton mobility was analyzed on the basis of IR absorption patterns.