Electron paramagnetic resonance spectroscopy: toward the path of dihydrogen isotopologue detection in porous materials

Abstract

Electron paramagnetic resonance (EPR) spectroscopy is a powerful method to characterize the local framework structure of nanoporous materials during the dihydrogen isotopologue adsorption process. It also allows for exploring the adsorption sites of the dihydrogen isotopes and monitoring their desorption characteristics on the microscopic scale. The paramagnetic spin probes in the form of transition metal ions or organic radicals are required for EPR spectroscopy and are introduced either at the framework lattice position or in the pores of the metal–organic frameworks. This review highlights current advancements within the field of dihydrogen isotopologue detection as well as key findings related to the versatility of in situ continuous wave EPR and pulsed EPR experiments as toolkits for monitoring the adsorption–desorption process of dihydrogen isotopologues from the perspective of the framework as well as studying the host–guest interactions based on high-resolution advantages offered by using a pulsed EPR approach.