PNNL

Abstract

Efficient production of molecular hydrogen for storage of energy from renewable sources is crucial for the development of wind and solar power. Hydrogenase enzymes in nature catalyze H2 production using earth-abundant metals (iron and nickel) using precise delivery of protons to the metal center. Here we report a synthetic nickel complex containing proton relays, [Ni(PPh2NC6H4OH2)2](BF4)2 (PPh2NC6H4OH2 = 1,5-bis(p-hydroxyphenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane), that catalyzes the production of H2 in an aqueous environment with turnover frequencies of 750-170,000 s-1 at directly measured overpotentials of 310-470 mV. The remarkable performance of this catalyst in aqueous environments exceeds the requirements necessary for molecular catalytic production of H2 by energy derived from photovoltaic solar cells. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.