Jason F. Weaver
Ph.D., 1998, Stanford University
Ph : 352-392-0869
331 Chemical Engineering Building
Surface Chemistry of Metals and Metal Oxides
Reaction Kinetics and Catalysis
Oxide Thin Films
Our research focuses on advancing the molecular-level understanding of chemical reactions occurring on solid surfaces. Such reactions are fundamental to heterogeneous catalysis and semiconductor processing, yet remain poorly understood at the molecular level. My students and I investigate surface chemical reactions using a wide array of analysis methods based on ultrahigh vacuum (UHV) surface chemistry and physics, including methods that provide information about surface reaction kinetics, adsorbed intermediates, atomic-scale surface structure and the chemical states of adsorbed molecules and atoms of the solid. We also make rigorous comparisons between our experimental data and predictions of molecular simulations, and find that this approach is a powerful way in which to identify the elementary processes governing surface chemical reactions.
Growth and Surface Chemistry of Oxide Thin Films
We are investigating the growth and chemical properties of oxide thin films that develop on the surfaces late transition metals during oxidation catalysis. This work is motivated by findings that metal oxide layers form on metallic catalysts that are operating in oxygen-rich environments, and that such oxide layers can play a decisive role in determining catalytic performance. In our research, we produce oxide thin films in UHV by oxidizing metallic surfaces using beams of plasma-generated oxygen atoms. This approach allows us to investigate oxide films under well-controlled conditions, and thereby gain detailed insights for understanding the growth and surface chemical properties of oxides that are central to several catalytic applications, such as the catalytic combustion of natural gas, exhaust gas remediation in automobiles, fuel cell catalysis and selective oxidation processes. We also investigate the catalytic behavior of oxide thin films using in situ synchrotron-based techniques, which affords comparisons between the results of our model UHV studies and the behavior of working catalysts. Key topics on which we have focused include the mechanisms for Pt and Pd oxidation and the adsorption and activation of small molecules, particularly alkanes, on well-defined Pt and Pd oxide surfaces. Our work has provided new understanding of the surface chemical properties of late transition-metal oxides, and continues to clarify the microscopic origins of the reactivity of this important class of materials.
Catalysis by Doped Oxides
We are also studying oxidation chemistry on rare earth oxide surfaces. Our main goals are to determine fundamental structure-reactivity relationships of rare earth oxide surfaces and develop methods for tuning the oxide selectivity toward promoting partial vs. complete oxidation reactions. We are particularly interested in understanding how to modify these surfaces to achieve high selectivity toward the oxidative coupling of methane to C2 products, while avoiding complete oxidation. We are exploring how metallic dopants influence the reducibility and catalytic properties of rare earth oxides. The ultimate aim is to establish rational strategies for modifying catalytic performance by incorporating metallic dopants into the structure of a host oxide.
Recent Publications
1. 1. "CO oxidation on PdO(101) during temperature programmed reaction spectroscopy: Role of oxygen vacancies", F. Zhang, L. Pan, T. Li, J. Diulus, A. Asthagiri and J.F. Weaver, J. Phys. Chem. C 118 (2014) 28647-28661.
2. 2. "Oxidation of a Tb2O3(111) thin film on Pt(111) by gas-phase oxygen atoms", W. Cartas, R. Rai, A. Sathe, A. Schaefer and J.F. Weaver, J. Phys. Chem. C 118 (2014) 20916-20926.
3 3. "Intrinsic ligand effect governing the catalytic activity of Pd oxide thin films", N.M. Martin, M. Van den Bossche, A. Hellman, H. Grönbeck, C. Hakanoglu, J. Gustafson, S. Blomberg, N. Johanson, Z. Liu, S. Axnanda, J.F. Weaver, and E. Lundgren, ACS Catal. 4 (2014) 3330-3334.
4. 4. "Alkane activation on crystalline metal oxide surfaces", J.F. Weaver, C. Hakanoglu, A. Antony and A. Asthagiri, Chem. Soc. Rev. 43 (2014) 7536-7547.
5. 5. "Surface chemistry of late transition metal oxides", J.F. Weaver, Chem. Rev. 113 (2013) 4164-4215.