Substitution of vanadium into the framework of mesoporous MCM-41 molecular sieves has been achieved; these materials were found to be very efficient catalysts for the selective oxidation of large organic molecules using hydrogen peroxide.

By applying a multitude of experimental techniques including ¹H, ¹⁴N, ²⁰⁷Pb NMR and ¹²⁷I NMR/NQR, tracer diffusion, reaction cell and doping experiments, as well as stoichiometric variation, conductivity, and polarization experiments, iodine ions are unambiguously shown to be the mobile species in CH₃NH₃PbI₃, with iodine vacancies shown to represent the mechanistic centers under equilibrium conditions. Pb²⁺ and CH₃NH₃⁺ ions do not significantly contribute to the long range transport (upper limits for their contributions are given), whereby the latter exhibit substantial local motion. The decisive electronic contribution to the mixed conductivity in the experimental window stems from electron holes. As holes can be associated with iodine orbitals, local variations of the iodine stoichiometry may be fast and enable light effects on ion transport.