Energy Research

Our research has helped to understand the redox reactions of important small molecules like N2, CO2, and hydrocarbons. We often use strategies that are inspired by natural enzymes, in particular the ways that inexpensive metals can be used.

In previous times, we developed nickel catalysts for the reduction of protons to hydrogen (H2through collaboration with Richard Eisenberg and Todd Krauss at the University of Rochester. These experiments used a light-harvesting molecule (“chromophore”), an electron donor, and a catalyst to produce H2. Using photophysical and electrochemical methods, we made several advances in understanding the stability and reactivity of catalysts with cobalt and nickel. Using CdSe quantum dots, we developed the first homogeneous systems that can form H2 for weeks without decomposition.

However, in the long run, hydrogen is not a very convenient energy-storing molecule since it is difficult to store and has low energy density. Our current goal is to take advantage of our expertise on N2 reduction to store energy instead in NH3, an exciting frontier in carbon-free energy storage. (See a recent article at this link.) This requires adapting our N2-reducing compounds to perform at milder potentials, with good catalytic turnover, with the electrons coming from an electrode. We have two independent efforts along these lines: one on bimolecular N2 splitting together with Alan Goldman (Rutgers), Faraj Hasanayn (American University Beirut) and Alex Miller (UNC Chapel Hill) supported by funding from the National Science Foundation, and another on tethered complexes for mononuclear N2 activation as part of the DOE-funded CHASE Solar Hub based at UNC Chapel Hill.

In a separate direction in our lab, we are pursuing catalytic reactions to activate hydrocarbons and couple them with N2 to form N-containing organic compounds (see illustration above). This exciting area combines C-H activation and N-N activation, and forms C-N bonds from abundant resources. This direction in the lab is funded by a grant from the Department of Energy.


Relevant Publications

Sean F. McWilliams, Daniel L. J. Broere, Connor J. V. Halliday, Samuel M. Bhutto, Brandon Q. Mercado, Patrick L. Holland
Coupling Dinitrogen and Hydrocarbons through Aryl Migration    
Nature  2020584, 221-226.  Chem. Eng. News "Research of the Year"
Gannon P. Connor, Brandon Q. Mercado, Hannah M. C. Lant, James M. Mayer, Patrick L. Holland
Chemical oxidation of a coordinated PNP-pincer ligand forms unexpected Re-nitroxide complexes with reversal of nitride reactivity
Inorg. Chem.  201958, 10791-10801.  
Amit Das, Zhiji Han, William W. Brennessel, Patrick L. Holland, Richard Eisenberg
Nickel Complexes for Robust Light-Driven and Electrocatalytic Hydrogen Production from Water
ACS Catal.  20155, 1397-1406.  
Zhiji Han, Luxi Shen, William W. Brennessel, Patrick L. Holland, Richard Eisenberg
Nickel Pyridylthiolate Complexes for the Photocatalytic Production of Hydrogen from Aqueous Solutions in Noble-Metal-Free Systems
J. Am. Chem. Soc.  2013135, 14659-14669.  
Zuofeng Chen, Christopher R. K. Glasson, Patrick L. Holland, Thomas J. Meyer
Electrogenerated polypyridyl ruthenium hydride and ligand activation for water reduction to hydrogen and acetone to iso-propanol
Phys. Chem. Chem. Phys.  201315, 9503-9507.  
Zhiji Han, Fen Qiu, Richard Eisenberg, Patrick L. Holland, Todd D. Krauss
Robust Photogeneration of H2 in Water Using Semiconductor Nanocrystals and a Nickel Catalyst
Science  2012338, 1321 1324.  
Christopher R. K. Glasson, Wenjing Song, Dennis L. Ashford, Aaron Vannucci, Zuofeng Chen, Javier J. Concepcion, Patrick L. Holland, Thomas J. Meyer
Self-Assembled Bilayers on Indium-Tin Oxide (SAB-ITO) Electrodes: A Design for Chromophore-Catalyst Photoanodes
Inorg. Chem.  201251, 8637-8639.  
William R. McNamara, Zhiji Han, Chih-Juo Yin, William W. Brennessel, Patrick L. Holland, Richard Eisenberg
Cobalt-Dithiolene Complexes for the Photocatalytic and Electrocatalytic Reduction of Protons in Aqueous Solutions
Proc. Natl. Acad. Sci. USA   2012109, 15594-15599.  
Zhiji Han, William R. McNamara, Min-Sik Eum, Patrick L. Holland, Richard Eisenberg
A Nickel Thiolate Catalyst for the Long-Lived Photocatalytic Production of Hydrogen in a Noble-Metal-Free System
Angew. Chem. Int. Ed.   201251, 1667-1670.  
Theresa M. McCormick, Zhiji Han, David J. Weinberg, Patrick L. Holland, Richard Eisenberg
The Impact of Ligand Exchange in Hydrogen Production from Cobaloxime-Containing Photocatalytic Systems
Inorg. Chem.  201150, 10660-10666.  
William R. McNamara, Zhiji Han, Paul J. Alperin, William W. Brennessel, Patrick L. Holland, Richard Eisenberg
Cobalt-Dithiolene Complex for the Photocatalytic and Electrocatalytic Reduction of Protons
J. Am. Chem. Soc.  2011133, 5123-5132.  
Matthew P. McLaughlin, Theresa M. McCormick, Richard Eisenberg, Patrick L. Holland
A stable molecular nickel catalyst for the homogeneous photogeneration of hydrogen in aqueous solution
Chem. Commun.   201147, 7989-7981.  
Azwana R. Sadique, William W. Brennessel, Patrick L. Holland
A diketiminate-bound diiron complex with a bridging carbonate ligand
Acta Cryst. C  200965, m174-m176.  
Azwana R. Sadique, William W. Brennessel, and Patrick L. Holland
Reduction of COto CO Using Low-Coordinate Iron: Formation of a Four-Coordinate Iron Dicarbonyl Complex and a Bridging Carbonate Complex
Inorg. Chem.   200847, 784-786.