Robert Baker received a BS degree from Brigham Young University in 2007 and a MS degree from Brigham Young University in 2008. He received his PhD from Gabor Somorjai at the University of California, Berkeley in 2012 where his dissertation research focused on electronic activation of surface chemical reactions at the metal-support interface. From 2012 to 2014 he performed postdoctoral research with Stephen Leone studying ultrafast electron dynamics and interfacial charge transfer in metal oxides using transient x-ray absorption spectroscopy. He has been an assistant professor at The Ohio State University since July 2014. He has received the Air Force Office of Scientific Research Young Investigator Award and the Department of Energy Early Career Award.
Ultrafast Soft X-Ray Spectroscopy
Ultrafast Transient Absorption
The element, oxidation state, and spin state specificity of soft x-ray spectroscopy coupled with the ultrafast temporal resolution provides a powerful experimental technique for investigating charge transfer dynamics in a wide range of systems. The coherent soft x-ray pulses created by tabletop high harmonic generation provide femtosecond broadband pulses in the energy range of tens to hundreds of eV. This energy range is well suited for M-edge spectroscopy of transition metals. In particular, transition metal oxides are important in catalysis, but element specific charge transfer kinetics in these systems are not well understood. Current investigation includes charge transfer dynamics of single and mixed metal oxides because of their different catalytic properties for CO2 reduction and water oxidation. Understanding the charge transfer dynamics will have significant impact on the design of future catalytic systems. Femtosecond time resolution as well as element, oxidation state, and spin state specificity provides valuable insight into the charge transfer dynamics of these solid-state systems.
Nonlinear Soft X-Ray Spectroscopy
Direct observation of surface electronic structure at working electrode–electrolyte interfaces has the potential to greatly advance current understanding of electrochemical systems and reveal the material properties that govern efficiency and selectivity during electrochemical catalysis. Toward this goal, we have constructed a high harmonic generation soft x-ray light source for nonlinear spectroscopy. Of particular interest is the development soft x-ray sum frequency generation spectroscopy as a probe of electronic structure and charge carrier dynamics at active interfaces. The goal of this work is to extend traditional SFG spectroscopy from the infrared to the soft x-ray spectral region in order to serve as a powerful probe of electronic structure and element specific carrier dynamics at active electrochemical interfaces.
The ability to convert sunlight and electricity to chemical energy is at the heart of energy conversion and storage. We are developing new materials capable of selective CO2 reduction as well as efficient water oxidation. Our efforts focus on identifying the relationship between the electronic structure of mixed metal and metal oxide catalysts and their catalytic performance. These efforts rely on in-house ultrafast and non-linear soft x-ray spectroscopy, which allows us to probe the electronic structure of active interfaces and make real-time observations of carrier excitation, thermalization, separation, and injection during an electrocatalytic reaction event.
Designing catalyst surfaces to achieve high selectivity is important for the efficient processing of petroleum products. Perhaps more importantly, selective catalysis is critical for developing renewable routes for synthesis of numerous commercially important chemicals. We are actively working to develop a more complete mechanistic understanding of surface chemical reactions that will inform the design of new efficient catalysts for renewable energy conversion and green chemical synthesis.
We are currently interested in accepting new students.
A complete list of publications can be found here.
A. Cirri, J. Husek, S. Biswas, and L. R. Baker , “Achieving Surface Sensitivity in Ultrafast XUV Spectroscopy: M2,3-Edge Reflection–Absorption of Transition Metal Oxides,”
Journal of Physical Chemistry C , 2017 , DOI: 10.1021/acs.jpcc.7b05127.
Y. Mueanngern, X. Yang, Y. Tang, F. Tao, and L. R. Baker , “Catalysis at Multiple Length Scales: Crotonaldehyde Hydrogenation at Nanoscale and Mesoscale Interfaces in Platinum–Cerium Oxide Catalysts,”
Journal of Physical Chemistry C , 2017 , DOI: 10.1021/acs.jpcc.7b03886.
X. Yang, E. A. Fugate, Y. Mueanngern, L. R. Baker , “Photo-Electrochemical CO 2 Reduction to Acetate on Iron–Copper Oxide Catalysts,”
ACS Catalysis, 2017 , 7, 177–180.
X. Yang, Y. Mueanngern, Q. A. Baker, L. R. Baker , “Crotonaldehyde Hydrogenation on Platinum–Titanium Oxide and Platinum–Cerium Oxide Catalysts: Selective C=O Bond Hydrogenation Requires Platinum Sites Beyond the Oxide–Metal
Interface,” Catalysis Science & Technology , 2016 ,
6 , 6824–6835.
J. Y. Park, L. R. Baker , and G. A. Somorjai, “The Role of Hot Electrons and Metal-Oxide Interfaces in Surface Chemistry and Catalytic Reactions,”
Chemical Reviews , 2015 , 115 , 2781–2817.
L. R. Baker , C. M. Jiang, S. T. Kelly, J. M. Lucas, J. Vura-Weis, M. K. Gilles, A. P. Alivisatos, and S. R. Leone, “Charge Carrier Dynamics of Photoexcited Co 3 O 4 in Methanol: Extending
High Harmonic Transient Absorption Spectroscopy to Liquid Environments,”
Nano Letters , 2014 , 14 , 5883–5890.
C. M. Jiang, L. R. Baker , J. M. Lucas, J. Vura-Weis, A. P. Alivisatos, and S. R. Leone, “Characterization of Photo-Induced Charge Transfer and Hot Carrier Relaxation Pathways in Spinel Cobalt Oxide (Co 3 O 4 ),”
Journal of Physical Chemistry C , 2014 ,
118 , 22774–22784.
G. Kennedy, L. R. Baker , and G. A. Somorjai, “Selective Amplification of C=O Bond Hydrogenation on Pt by an Active TiO 2 Support: Catalytic Reaction and Sum Frequency Generation Vibrational Spectroscopy
Studies of Crotonaldehyde Hydrogenation,” Angewandte Chemie International Edition ,
2014 , 53 , 3405–3408.
L. R. Baker , G. Kennedy, M. Van Spronsen, A. Hervier, X. Cai, S. Chen, L. Wang, and G. A. Somorjai, “Furfuraldehyde Hydrogenation on Titanium Oxide-Supported Platinum Nanoparticles Studied by Sum Frequency Generation Vibrational
Spectroscopy: Acid–Base Catalysis Explains the Molecular Origin of Strong Metal–Support Interactions,”
Journal of American Chemical Society , 2012 ,
134 , 14208–14216.