个人简介

B.A., 1996, Univ. of Texas M.S., 2000, Univ. of Massachusetts Ph.D., 2006, California Institute of Technology Postdoctoral Fellow, Northwestern Univ. 2006-2008 AwardOrganizationDivisionLevel CodeType CodeStart DateEnd Date Camille Dreyfus Teacher-Scholar AwardProfessionalHonors2013 National Science Foundation, CAREER awardProfessionalHonors2012 Alfred P. Sloan Research FellowshipProfessionalFellowship2012 Department of Energy, Early Career Research Program awardProfessionalHonors2011

研究领域

Inorganic Materials Physical

(Research Description PDF - 880 kb) Hamann Group Research: There is a LOT of energy from sunlight striking the Earth’s surface: approximately 1017 Joules/second. For comparison, the averaged worldwide energy demand is approximately 1013 Joules/second. The Hamann group is engaged in interdisciplinary research to address basic science issues related to new methods and materials for utilizing this incredible resource to produce electricity and chemical fuels. Of specific interest are regenerative and non-regenerative photoelectrochemical cells, including dye-sensitized solar cells and thin-film absorber photocatalytic systems. In addition, we are interested in the use of ammonia as an energy (hydrogen) carrier and are investigating the electrocatalytic synthesis and electrolysis of ammonia. Dye Sensitized Solar Cells: We are investigating the fundamental role of the relevant dye-sensitized solar cell, DSSC, components (redox shuttle, photoanode and sensitizer) involved in key efficiency-determining processes. Ultra-fast electron injection from a photoexcited sensitizer into a photoanode produces a charge separated state with typically high quantum efficiency. We are primarily interested in the subsequent processes of dye regeneration and recombination which control the efficiency of charge collection. We systematically vary the components involved in each reaction and interrogate them with a series of photoelectrochemical measurements. The general lessons learned will ultimately be used to develop design rules for next generation DSSCs comprised of molecules and materials which are capable of overcoming the kinetic and energetic constraints of current generation cells. Thin Film Absorber Solar Cells: We are interested in exploring the use of thin films to overcome the problems associated with short collection length materials. One absorbing material of current interest is α-Fe2O3 (hematite). Hematite is an attractive material for solar energy conversion due to the abundance of iron in the earth’s crust, the extremely low cost, chemical stability and environmental harmlessness. In addition, hematite has been shown to be a promising water oxidation photocatalyst in a fuel-forming (non-regenerative) photoelectrochemical cells. We are currently elucidating the rate limiting steps as well as water oxidation mechanism on the electrode surface. Additional topics of recent interest include understanding the effect of substrate and underlayer materials, incorporation of dopants, and surface layers (e.g. catalysts) on the water oxidation efficiency. Additional oxide, nitride and oxynitride semiconductor materials are also under current investigation. Ammonia Electrocatalysis: Nitrogen is the most abundant gas in Earth’s atmosphere and water is the most abundant liquid on Earth’s surface; combining the catalytic reduction of N2 with the oxidation of H2O to produce NH3 offers a route to scalable renewable energy storage. Liquid ammonia has an energy density comparable to methanol, and the stored chemical energy can in principle be used to generate electricity or H2 on demand. The electrolysis of liquid NH3 has received limited attention to date, however. We are therefore exploring the electrocatalytic conversion of liquid NH3 to H2. We are also engaged on a broader collaborative effort to develop and investigate new electro-catalysts based on earth-abundant materials for NH3 synthesis and electrolysis.

近期论文

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Hamann, T.W.; "Perovskites take lead in solar hydrogen race." Science 345, 1566 (2014) *Science 345, 1593 (2014), by Luo, Grätzel and co-workers Young, K.M.H., Hamann, T.W.; "Enhanced photocatalytic water oxidation efficiency with Ni(OH)2 catalysts deposited on α-Fe2O3 via ALD." Chem. Commun., 2014, 50 (63) 8727-8730 Kronawitter, C.X., Zegkinoglou, I., Shen, S.H., Liao, P., Cho, I.S., Zandi, O., Lashgari, K., Westin, G., Guo, J.H., Himpsel, F.J., Carter, E.A., Zheng, X.L., Hamann, T.W., Koel, B.E., Mao, S.S., Vayssieres, L.; "On Theoretical and Experimental Titanium Incorporation into Hematite Nanostructures" Energy Environ. Sci., 2014, 7, 3100-3121 Soman, S., Xie, Y., Hamann, T.W.; "Cyclometalated sensitizers for DSSCs employing cobalt redox shuttles" Polyhedron, 2014, 82, 139–147 *special edition "Molecular Materials for Solar Energy Conversion" edited by Ed Constable Zandi, O., Hamann, T.W.; "Enhanced Photovoltage Through Selective Surface State Removal" J. Phys. Chem. Lett. 2014, 5 (9), 1522–1526 *Live Slide Presentation Klahr, B.M.; Hamann, T.W.; "Water Oxidation on Hematite Photoelectrodes: Insight on the Nature and Identity of Surface States through In-situ Spectroelectrochemistry" J. Phys. Chem. C 2014, 118 (19), 10393–10399 Zandi, O., Beardslee, J.A., Hamann, T.W.; "Substrate Dependent Water Splitting with Ultrathin α-Fe2O3 Electrodes" J. Phys. Chem. C 2014, 118 (30), 16494–16503 *Michael Gratzel Festschrift Hamann, T.W.; "Water splitting: An adaptive junction." Nature Materials 2014, 13, 3–4 *Nature Materials 13, 81–86 (2014), by Lin and Boettcher Young, K.M.H., Klahr, B.M., Zandi, O., Hamann, T.W.; "Photocatalytic Water Oxidation with Hematite Electrodes." Catalysis Science & Technology, 2013, 3, 1660-1671 Riha, S.C., Klahr, B.M., Tyo, E.C., Seifert, S., Vajda S., Pellin, M.J., Hamann, T.W., Martinson, A.B.F.; "Atomic Layer Deposition of a Sub-monolayer Catalyst for the Enhanced Photoelectrochemical Performance of Water Oxidation with Hematite." ACS Nano 2013, 7 (3), 2396–2405 Xie, Y., Hamann, T.W.; "Fast Low Spin Cobalt Complex Redox Shuttles for Dye-Sensitized Solar Cells." J. Phys. Chem. Lett., 2013, 4, 328–332 Zandi, O., Klahr, B.M., Hamann, T.W.; "Highly Photoactive Ti-doped α-Fe2O3 Thin Film Electrodes; Resurrection of the Dead Layer." Energy Environ. Sci., 2013, 6, 634–642 Ondersma, J.W.; Hamann, T.W.; "Recombination and Redox Couples in Dye-Sensitized Solar Cells." Coordination Chemistry Reviews 2013, 257, 1533–1543 Ondersma, J.W.; Hamann, T.W.; "Conduction Band Energy Determination by Variable Temperature Spectroelectrochemistry." Energy Environ. Sci. 2012, 5 (11), 9476–9480 Klahr, B.M., Gimenez S., Fabregat-Santiago, F., Bisquert, J., Hamann, T.W.; "Photoelectrochemical and Impedance Spectroscopic Investigation of Water Oxidation with "Co-Pi" coated Hematite Electrodes." J. Am. Chem. Soc. 2012, 134 (40), 16693–16700 *Nature Chemistry 4, 965–967 (2012), News and Views, by Daniel Gamelin Hamann, T.W.; "Splitting Water with Rust: Hematite Photoelectrochemistry." Dalton Trans., 2012, 41, 7830–7834 Klahr, B.M., Gimenez S., Fabregat-Santiago, F., Bisquert, J., Hamann, T.W.; "Electrochemical and Photoelectrochemical Investigation of Water Oxidation with Hematite Electrodes." Energy Environ. Sci. 2012, 5 (6), 7626–1636 Klahr, B.M., Gimenez S., Fabregat-Santiago, F., Hamann, T.W., Bisquert, J.; "Water oxidation at hematite photoelectrodes: the role of surface states." J. Am. Chem. Soc. 2012, 134 (9), 4294–4302 Hamann, T.W.; "The End of Iodide? Cobalt Complex Redox Shuttles in DSSCs." Dalton Trans., 2012, 41 (11), 3111–3115 Ondersma, J.W.; Hamann, T.W.; " Spatially-Resolved Sources of Dark Current in Nanoparticle TiO2 Electrodes." Langmuir 2011, 27 (21), 13361–13366