Tackling Our Energy Challenges in a New Era of Science
Invited article reviews the science behind proton motion in hydrogen-generating catalysts
In their invited review for Chemical Communications, Dr. R. Morris Bullock, Dr. Aaron Appel, and Dr. Monte Helm at Pacific Northwest National Laboratory describe how proton relays and other factors influence catalysts that could store intermittent renewable energy in chemical bonds for later use. They were asked to write this review for a special themed collection in the journal on electrocatalytic hydrogen evolution because of their groundbreaking research in proton movements in reactions that break and form hydrogen. Dr. Jonathan Darmon and Dr. Charles Weiss at PNNL designed artwork that graces the journal's cover.
Simple addition to catalyst's outer edge speeds bond breaking and electron release
Fuel cells could store massive quantities of intermittent solar- or wind-generated energy and release it when needed. The cell can break hydrogen-hydrogen bonds, freeing the electrons to do work. But, fuel cells do not play a major role in our nation's energy economy because they require expensive platinum catalysts. A nickel-based catalyst was revised by the Center for Molecular Electrocalysis to quickly break bonds. The catalyst's speed comes from a second proton relay on the outer edge. With the second relay, the catalyst quickly transforms through three different forms, and the proton goes on its way. Without the relay, the catalyst sticks in one form and moving the proton takes much longer.
Congratulations to the scientists at the Center for Molecular Electrocatalysis, who had their nickel-based catalyst discussed in Inorganic Chemistry, a popular undergraduate college textbook. Students will read about the catalyst, with two seven-membered cyclic diphoshine ligands attached to a nickel atom, that use proton relays to efficiently make H2. Designing catalysts with earth-abundant metals instead of platinum and other rare metals is a critical challenge for upcoming scientists if we are to store intermittent renewable energy and release it when needed. The Center for Molecular Electrocatalysis is an Energy Frontier Research Center funded by the U.S. Department of Energy's Office of Basic Energy Sciences. Pacific Northwest National Laboratory leads the center.
First direct comparison of three nickel-based complexes shows complexes with 2 proton relays outperform those with 4
Wind and other renewable energy sources are limited because the power must be used when it's generated, as it currently cannot be stored. Scientists want to store the energy in compact, easy-to-release chemical bonds. A major challenge is designing an affordable, efficient, and fast catalyst to make the chemical bonds. At the Center for Molecular Electrocatalysis, scientists established that adding proton relays did not increase the catalyst's speed, rather the atoms' arrangement mattered more than the number. The Center is an Energy Frontier Research Center, funded by the U.S. Department of Energy's Office of Basic Energy Sciences and led by Pacific Northwest National Laboratory.
Morris Bullock was quoted in the December 2, 2013, issue of the New York Times
In the December 2 issue of the New York Times, an American daily newspaper that has won 112 Pulitzer Prizes, Dr. Morris Bullock at Pacific Northwest National Laboratory is quoted on the diversity of approaches to the discovery of molecular catalysts as alternatives to precious metals. In the article, "Building a Cheaper Catalyst," writer Douglas Quenqua covers creation of catalysts based on iron and cobalt reported by three teams. These metals could replace precious metals, which have toxicity and cost issues. Bullock is quoted regarding the impact of the diverse recipes used.
Bullock leads the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. He is a Fellow of the Royal Society of Chemistry and American Chemical Society. His work in developing transition metal electrocatalysts has earned him the Royal Society of Chemistry's Homogeneous Catalysis Award in 2013.
Congratulations to Prof. Sharon Hammes-Schiffer, Center for Molecular Electrocatalysis, on being selected as a member of the National Academy of Sciences. A world leader in theoretical and computational chemistry, Hammes-Schiffer studies proton-coupled electron transfer reactions at the Energy Frontier Research Center, funded by DOE's Office of Basic Energy Sciences. She is the Swanlund Professor of Chemistry at the University of Illinois at Urbana-Champaign.
Established 150 years ago by President Abraham Lincoln, the National Academy of Sciences is an official adviser to our nation's government, upon request, in any matter of science or engineering. This prestigious organization furthers science through the election of its members and through original research in the Proceedings of the National Academy of Sciences.
Given two catalysts for the job of turning intermittent wind or solar energy into chemical fuels, scientists chose the material that gets the job done quickly and uses the least energy. A catalyst that quickly produces fuel but uses far more energy than it stores won't get the job. Scientists could measure the overpotential in water but not in other liquids, until Dr. Morris Bullock and Dr. John Roberts devised a quick, elegant technique. This work was done at the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, funded by DOE's Basic Energy Sciences.
Scientists at the Center for Molecular Electrocatalysis demonstrated that matching the proton source's pKa to that of a nickel-based catalyst speeds the conversion of electricity to hydrogen bonds dramatically. Turning electricity into chemical bonds and vice versa is necessary to capture intermittent renewable energy as use-any-time fuel. The Center is an Energy Frontier Research Center, funded by DOE's Office of Basic Energy Sciences, and is led by Pacific Northwest National Laboratory.
Transformations Presents Catalysis and Sustainable Energy
The latest issue of Transformations shows the role of catalysts in making wind, solar and other sustainable energy sources a major part of the nation's energy landscape. Dr. Dan DuBois, Deputy Director of the Center for Molecular Electrocatalysis, shares the three principles involved in creating electrocatalysts, which drive the interconversion of electricity to energy stored in chemical bonds. Learn about this research and much more at the American Chemical Society symposium being held in his honor. Applied and fundamental scientists talk about the power of theory or computational chemistry to break chemistry bottlenecks and settle basic energy questions. Don't miss the latest video – featuring the Center's Dr. Monte Helm and Dr. Morris Bullock.
Given his scientific successes and caring personality, the opportunities to speak at the 1.5-day symposium honoring the career of Dr. Dan DuBois, Pacific Northwest National Laboratory, filled quickly. The event honors DuBois American Chemical Society's Award in Inorganic Chemistry. Dr. Aaron Appel and Dr. Monte Helm at Pacific Northwest National Laboratory, along with Dr. Jenny Yang at the Joint Center for Artificial Photosynthesis, organized the symposium.
Scientists at Center for Molecular Electrocatalysis based at Pacific Northwest National Laboratory developed a fast and efficient iron-based catalyst that splits hydrogen gas to make electricity -- necessary to make fuel cells more economical.
By grafting features analogous to those in Mother Nature's catalysts onto a synthetic catalyst, scientists created a hydrogen production catalyst that is 40% faster than the unmodified catalyst. This study provides foundational information that could, one day, help design and synthesize the catalysts for hydrogen production for fuels, long-lasting electric car batteries, and energy storage from solar and wind farms.
Proton delivery and removal determines if a well-studied catalyst takes its highly productive form or twists into a less useful structure, according to scientists at the Center for Molecular Electrocatalysis, an Energy Frontier Research Center based at Pacific Northwest National Laboratory. The catalyst takes two protons and forms molecular hydrogen, or it can split the hydrogen. The team showed that the most productive isomer, endo/endo, has the key nitrogen-hydrogen bonds pushed close to the nickel center. If the catalyst is in the endo/endo form, the reaction occurs in a fraction of a second. If the catalyst is stuck in another form, the reaction takes days to complete.
Moving four relatively large protons to where they are needed is easier if you build a path, as is being done by scientists at the Center for Molecular Electrocatalysis. The research team has built two iron-based compounds that help protons move from the exterior to where they are needed. Once delivered, the protons bond with molecular oxygen and create water. In previous compounds, the protons often don't arrive in time or go to the wrong place, which leads to forming the unwanted byproduct hydrogen peroxide. The new compounds direct the protons in ways that help separate the two oxygen atoms in O2, and thereby drive the reaction to completion.