Scientists have long been puzzled by nature's ability to use cheap and plentiful building blocks – iron, nickel and sulfur – to achieve the catalytic performance seen in rare and expensive metals. In particular, two enzymes – iron-iron hydrogenase and nickel-iron hydrogenase – function as hydrogen processors, much like platinum.
"Nature relies on a very elaborate architecture to support its own 'hydrogen economy,' " said Thomas B. Rauchfuss, a professor of chemistry and corresponding author of the paper. "We cracked that design by generating mock-ups of the catalytic site to include the substrate hydrogen atom."
The researchers' model of the nickel-iron complex is the first to include a bridging hydride ligand, an essential component of the catalyst.
"By better understanding the mechanism in the nickel-iron hydrogenase active site, we are learning how to develop new kinds of synthetic catalysts that may be useful in other applications," said graduate student Bryan E. Barton, lead author of the paper.