fig4

Figure 4. (A and B) Interfacial water structure probed by in-situ ATR-SEIRAS on GDEs with D79 and D520 (The peaks for weakly and strongly hydrogen-bonded water are shown in red and blue, respectively); (C and D) Normalized band intensities at ~3,250 and ~3,380 cm^-1 for GDEs with D79 and D520; (E and F) Schematic diagram of the Grotthuss mechanism and the vehicle mechanism for proton transport; (G) Schematic diagram of strongly and weakly hydrogen bond networks. (Red and white spheres denote O and H atoms. Solid and dashed lines represent intramolecular O-H bonds and intermolecular O-H···O hydrogen bonds, respectively).