Heavy doping of H- ion in 12CaO • 7Al2O3

12CaO center dot 7Al(2)O(3) (C12A7, mayenite), which has a nanoscale porous structure that can accommodate extraframework species such as hydride (H-), oxide (O2-), hydroxide (OH-) ions, and electrons, has been doped with H- ions to investigate its effects as dominant extraframework species. Chemical doping with CaH2 enables the concentration of H- ions to reach almost the theoretical maximum. The concentration of H- ions is characterized by optical absorption intensity ascribed to photoionization of H- ions, and H-1 magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy. Persistent electron generation, which is accompanied by the formation of an F+ absorption band and electrical conductivity, by irradiation with ultraviolet light at room temperature increases as the H- ion doping increases until it reaches half the theoretical maximum and then decreases as the H- ion concentration increases further. This dependence indicates that both H- and O2- ions are necessary for the generation of persistent electrons. (C) 2011 Elsevier Inc. All rights reserved.