1,3-butadiene hydrogenation, bimetallic catalyst, nuclear magnetic resonance (NMR), isomerization process, parahydrogen-induced polarization (PHIP)

Abstract

In this work, the motions of methylammonium cations (MA) in different phase structures of MAPbCl3 perovskites, including orthorhombic, tetragonal and cubic phases, were studied by solid-state 2H nuclear magnetic resonance (NMR). By a combination of experimental 2H NMR and numerical simulations, the motion models in different phase structures of MAPbCl3 were established in this work. The NMR results disclosed the characteristics of the motions of MA in different phase structures. In the orthorhombic phase, the MA cations are not completely frozen but wobble locally while rapidly rotating around the C-N bond. As the temperature increases, MA cations show various modes of motion in the perovskite lattice. The NMR results also showed that the changes of the motions of MA in different temperatures are not accompanied by the changes of phase structures. The observations in this work will deepen our understanding of the molecular mechanism of the MAPbCl3 phase transitions.

Keywords

• solid-state 2h nmr
• ionic motion
• nmr simulation
• mapbcl3 perovskite