Proton-Conductive Membranes Doped with Orthophosphoric Acid Based on Inorganic-Organic Hybrid Materials

• Published in: Journal of the American Ceramic Society Vol. 88; no. 12; pp. 3427 - 3432
• Main Authors: Huang, Sheng Jian, Lee, Hoi Kwan, Lee, Yong Su, Kang†, Won Ho
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Science Inc 01.12.2005; Blackwell; Wiley Subscription Services, Inc
• Subjects: Acids; Ceramics; Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Complexation; Conductivity; Diffraction; Exact sciences and technology; General and physical chemistry; Humidity; Membranes; Precursors; Protons; Relative humidity; Sol gel process; X-rays; Relative humidity; Scanning electron microscopy; Phosphoric acid; Porous membrane; Sol gel process; Hybrid material; Preparation; Proton conductivity; Membrane
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1551-2916.2005.00621.x

A series of proton‐conductive inorganic–organic hybrid membranes doped with phosphoric acid (H3PO4) have been prepared by the sol–gel process with 3‐glycidoxypropyltrimethoxysilane (GPTMS), 3‐aminopropyltriethoxysilane (APTES), and tetraethoxysilane (TEOS) as precursors. High proton conductivity of 3.0 × 10−3 S/cm with a composition of 50TEOS–30GPTMS–20APTES–50H3PO4 was obtained at 120°C under 50% relative humidity (RH). The differential thermal analysis curve showed that thermal stability of membrane is significantly enhanced by the presence of an SiO2 framework up to 250°C. X‐ray ray diffraction revealed that the gels were amorphous. Infrared spectra showed a good complexation of H3PO4 in the matrix. The porous hybrid membrane, characterized by scanning electron microscopy, shows humidity‐dependent conduction, and the conductivity under 75% relative humidity was significantly improved by addition of APTES due to the increase in the concentration of the defective site in the hybrid matrix.