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

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−1at 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 CO2as a hydrogen carrier by combining the decomposition of formic acid (evolution of H2) with the hydrogenation of bicarbonate (fixation of CO2and storage of H2) using the iridium catalyst. [ABSTRACT FROM AUTHOR]