Iridium–NHC-based catalyst for ambient pressure storage and low temperature release of H2via the CO2/HCO2H couple

Abstract

A hybrid N-heterocyclic carbene (NHC) ligand-based iridium catalyst system has been demonstrated in ambient-pressure CO₂-hydrogenation and low-temperature HCO₂H-dehydrogenation processes. High catalytic activity with TOF values of up to 58 h⁻¹ at 30 °C and 1 atm pressure for hydrogenation and up to 100 000 h⁻¹ at 90 °C for dehydrogenation has been achieved with this promising catalyst. The newly-introduced strategy of using an imidazolylidene-based strongly sigma-donating abnormal NHC ligand partnering with a proton-responsive ligand framework within the catalyst suggested a key guideline in this chemistry involving dual activity toward chemical hydrogen storage/delivery processes.