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September 2013

Moving Protons at the Speed of Life

How two researchers are tackling energy transport and storage, one particle at a time

Samantha Horvath

As critically acclaimed reporter Diane Sawyer once put it, "Fun is getting paid to learn things." That's just what Molly O'Hagan and Mike Mock are doing.

How does a particle that's one million-millionth the size of a marble change how we treat an English garden? A Ferrari? Well, at first glance, probably very little. But looking deeper, the key to making both free of fossil fuels is how protons, tiny positively charged particles, are used. A garden often needs fertilizer, which is produced from ammonia, which itself is derived from fossil fuels. A car needs gasoline, and the hope is to, one day, replace the common combustion engine with renewable fuels. These ideas and others are the lofty goals of the Center for Molecular Electrocatalysis.

Two of the Center's rising stars are researchers Molly O'Hagan and Michael Mock. O'Hagan uses spectroscopic techniques to understand proton mobility in hydrogen oxidation and/or production catalysts for use in fuel cells, and Mock addresses alternative ways to produce ammonia. They're working to understand the flow of protons and electrons in processes of critical importance to energy transformation reactions and, perhaps even more important, they're having fun while they're at it!

Far from stereotypical. Unlike the comedic stereotypes that we often see on television, O'Hagan and Mock are proof that scientists are multi-faceted, engaging people. Mock is an avid tennis player and has been playing since he was 4 years old. O'Hagan takes to the quieter side of life and enjoys reading. Her favorite author is English novelist Nick Hornby, author of High FidelityAbout a Boy, and Fever Pitch. She also enjoys going out to nearby wineries around southwest Washington to find her latest favorite. Her wine of choice? A petite Syrah.

In addition to her background in chemistry, O'Hagan also speaks Spanish. As an undergraduate at the University of Wisconsin, River Falls, she minored in Spanish and even worked as a server in a Mexican restaurant. After encouragement from her undergraduate advisor, O'Hagan studied abroad for a semester, doing inorganic chemistry research in Zaragoza, Spain. When asked if she still speaks Spanish, O'Hagan laments with a chuckle, "If you don't use it, you lose it!"

Mock, who likes to ride his bike to work when time allows, graduated from the University of Delaware and has been with the Center since its inception in 2009. O'Hagan received her doctorate in biochemistry also from the University of Delaware and joined Pacific Northwest National Laboratory (PNNL), where the Center is based, afterwards. O'Hagan and Mock graduated from the same research group at the University of Delaware, but their focuses were quite diverse, biochemistry vs. organometallic chemistry, and both began as postdoctoral fellows at PNNL before transitioning to their permanent positions.

Speeding up the handoff of protons. The research that Mock and O'Hagan are doing hinges on chemical compounds with very specific properties. These bio-inspired catalysts have an important feature termed proton relays, which act much like sprinters in a baton relay race. Arm-like molecular groups pass the baton (or proton) to and from the catalyst's active site, the place where all the action (chemistry) happens. These catalysts have another crucial trait in that the active sites are Earth-abundant transition metals, such as nickel, iron, and chromium, which make them much cheaper to produce and, ultimately, for the public to buy because they are readily available.

With a diversified set of experimental techniques available to her, O'Hagan has found a niche using spectroscopy to look at catalysts designed to perform proton reduction and hydrogen oxidation, the two key chemical reactions occurring in hydrogen fuel cells. O'Hagan's research focuses on understanding how efficient the proton relays are at both accepting or delivering protons to the surrounding solution and delivering or removing protons from the metal center. Enhancing both processes is an important aspect of designing more efficient catalysts. As the summer draws to a close, she and her postdoc Jianbo Hou are getting some amazing results.

"These types of experiments are essential to optimizing proton delivery because they can directly probe how proton movement changes with varying catalyst structure and solution," O'Hagan explained.

The making of ammonia. Mock's scientific passion is looking for renewable ways to produce ammonia, which is the world's primary feedstock for the synthesis of agricultural fertilizer. The current industrial process is costly because it utilizes hydrogen as a raw material, which is produced from fossil sources, and requires high temperatures and pressures of nitrogen and hydrogen to produce ammonia in large yields.

"The development of an efficient catalyst for nitrogen reduction to ammonia by the addition of protons and electrons with Earth-abundant transition metals is a significant challenge," Mock pointed out.

Mock spends much of his time collaborating, answering questions, and working with researchers on the nitrogen reduction effort. He and his colleagues, who have been working diligently on this project, have had a recent breakthrough in the chemistry. "Our recent discovery is exciting because we identified chromium as a candidate for the development of a catalytic nitrogen reduction system." Previously, only tungsten and molybdenum, members of the same group on the periodic table, were thought to be viable candidates.

On a more personal note. As if tackling issues related to our nation's energy crisis weren't enough, O'Hagan and Mock were married in 2009 and welcomed their son Odin, now 10 months old, into their lives late last year. Even though they are part of the same Center, O'Hagan and Mock work on very different projects, and their varied skill sets tend to put them in complementary roles. As the Center's Deputy Director Monte Helm said, "There are staff and postdocs at PNNL who don't know they're married."

As one might imagine, "It's great to able to share what your spouse does all day," O'Hagan supplements, "but we actually talk very little about work while we are at home."

Mock sums it all up nicely, "PNNL and the Center have been an ideal work environment where our complementary expertise is well suited for the complex problems of developing electrocatalysts for energy storage and for Molly and me to develop our professional careers as scientists."

Closing in. While the implementation of these catalysts in large-scale processes is still in the fundamental stages, thanks to O'Hagan, Mock, and all of the researchers at the Center, it's well on its way to becoming a reality and then those protons really will be moving at the speed of life.

About the author(s):

  • Samantha Horvath is a postdoctoral research associate with the Hammes-Schiffer research group at the University of Illinois at Urbana-Champaign. She and the other group members focus on understanding proton and electron coupled motion through theoretical simulations and models and is part of the Center for Molecular Electrocatalysis. Outside of the lab Sam enjoys hosting dinner parties for friends and volunteering at local animal shelters.

Disclaimer: The opinions in this newsletter are those of the individual authors and do not represent the views or position of the Department of Energy.