High Proton Conductivity Achieved by the Self-Assembly of POM-Based Acid–Base Adduct in SBA-15 over a Wide Range from −40 to 85 °C

Abstract

Almost all proton-conducting materials display poor conductivity at subzero temperatures, which significantly limits their application in cold regions. Thus, effective strategies to achieve high proton conductivity in a wide range from subzero to medium temperatures (−40 to 85 °C) need to be developed. Herein, we prepared proton-conductive materials by encapsulating the acid–base adduct based on Keggin-type H3PW12O40 (HPW) and aminoethanesulfonic acid (C2H7O3NS, HSN) in the linear channels of SBA-15 (named HPW-HSN@SBA-15). The result is the same as we expected: HPW-HSN@SBA-15 exhibits high proton conductivity over a wide temperature range (−40 to 85 °C). The proton conductivity of 75 wt % HPW-HSN@SBA-15 (3HPW-HSN@SBA-15) reaches 0.16 S cm–1 at 85 °C, 97% relative humidity (RH), and 6.8 × 10–5 S cm–1 at −40 °C. The excellent proton conductivity at subzero temperature of HPW-HSN@SBA-15 is mainly attributed to the ultrafast proton transfer with low energy barrier between proton donor (acid group) and proton acceptor (base group) in acid–base adduct without the attendance of water. Furthermore, the proton conductivity cycle test of 3HPW-HSN@SBA-15 demonstrates its good durability and stability.