Highly efficient hydrogen evolution by decomposition of formic acid using an iridium catalyst with 4,4′-dihydroxy-2,2′-bipyridine

Abstract

The efficient evolution of CO-free hydrogen by the decomposition of formic acid using iridium catalyst with 4,4′-dihydroxy-2,2′-bipyridine as a ligand in H₂O was demonstrated. The highest catalytic activity (turnover frequency (TOF) of up to 14000 h⁻¹ at 90 °C) and an almost complete consumption of formic acid were obtained for the catalytic system. Furthermore, it was found that hydrogen could be generated even at elevated pressures. We discuss the possibility of a cycle for CO₂ as a hydrogen carrier by combining the decomposition of formic acid (evolution of H₂) with the hydrogenation of bicarbonate (fixation of CO₂ and storage of H₂) using the iridium catalyst.