Beneficial Changes in the Mechanism of the Cobalt Catalyzed Hydrogen Evolution Reaction, Induced by Corrole Chelation

Current technologies for mass production of hydrogen gas, needed for fuel cells, synthesis of ammonia and many other purposes, have an enormous carbon footprint. Less than 5% is manufactured by much cleaner water electrolysis, mainly because the electrodes are based on precious platinum. In line with a worldwide effort on replacing platinum by earth abundant metals, the present investigation focuses on electrocatalytic proton reduction by cobalt corroles, via full characterization of a series of complexes and comparison of their properties. The smallest possible and most electron-rich derivative , with H atoms rather than larger and much more electron withdrawing substituents on the macrocycle, provided the best catalytic activity: lowest over potential and largest faradaic efficiency, almost as good as platinum. Mechanism-of-action investigations by experimental and computational analyses exposed that the reason for the superior performance is a new reaction pathway in which protons are activated by singly rather than doubly-reduced cobalt Figure 1