Honors and Awards

• Eastman Lectureship, Dept. of Chemical Engineering, Univ. of South Carolina, 2016
• Honorary Professorship, 111 Program, Tongji Univ., Shanghai, P. R. China, 2013-2017
• EaStCHEM International Visiting Fellowship lecturer, U. of Edinburgh & St. Andrews, Scotland 2008
• George A. Olah Award in Hydrocarbon or Petroleum Chemistry, Amer. Chem. Soc. (ACS) 2007
• Fellow of the American Association for the Advancement of Science (AAAS), 2004
• University de Paris-Sud, Professeur Invite', Orsay, France, 2001
• Osaka Nat'l Res. Inst., AIST Guest Researcher Awards, Osaka, Japan, 1999 and 2000
• Keynote Address, Brazilian Vacuum Society Annual Conf., Sao Jose dos Campos, Brazil, 2000
• Fellow of the American Vacuum Society (AVS), 1999
• Distinguished Alumnus of Emporia State University, 1998
• Fellow of the American Physical Society (APS), 1996

Research Interests

“Life at the edge” - Surfaces are where the action is!

Interfacial processes and surface chemistry are at the heart of a wide range of technologies, e.g., those associated with the chemical and petroleum industries, functioning of batteries and fuel cells, production of microelectronic devices, and design and fabrication of sensors and diagnostic devices. In addition, surfaces play key roles in heterogeneous processes in environmental and atmospheric chemistry, and are central to developments in nanoscience and technology by modifying and controlling properties of nanoparticles and electrical contacts.

Our research primarily involves novel materials and processes for sustainable energy applications, with an emphasis on investigating and understanding chemical reactions at surfaces. We seek to synthesize and understand advanced materials with novel properties, discover methods to alter and control surface chemistry and processes, and develop new catalysts and processes for efficient synthesis of nanomaterials, chemicals, and fuels. We often employ the well-defined and controllable conditions of ultrahigh vacuum to obtain fundamental information, which can often be directly compared with theory, and use a wide array of surface-sensitive analytical techniques for materials characterization and an atomic scale view, including high-resolution X-ray photoelectron spectroscopy (HR-XPS), low energy ion scattering (LEIS), infrared reflection-absorption spectroscopy (IRAS), temperature programmed desorption (TPD) mass spectroscopy, and scanning tunneling microscopy (STM). We also conduct experiments under in-situ (in a working environment) and operando (during operational measurement) conditions, e.g., utilizing gas and liquid cells adapted for infrared and Raman spectroscopy, transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS). We operate laboratories and use facilities on campus and at the Princeton Plasma Physics Laboratory (PPPL), which is a U.S. Department of Energy national laboratory managed by Princeton University with the primary aim to harness and accelerate the development of fusion energy. 

Current research activities include investigations of:

(i) High temperature plasma-materials interactions (PMI) for fusion energy systems, e.g., fundamental studies of the surface properties and deuterium retention in solid and liquid metal plasma-facing components (PFCs) for improved plasma performance and PFC development in the National Spherical Tokamak-Upgrade (NSTX-U), and the erosion, re-deposition, and recycling of lithium-coated PFCs in the Lithium Tokamak Experiment-β (LTX-β).

(ii) Low temperature plasma-materials interactions for plasma-assisted combustion and plasma-assisted catalysis, e.g., experiments and modeling of ammonia synthesis, ammonia decomposition, and dry methane reforming (DRM), and methane decomposition to produce hydrogen and carbon nanotubes in an innovative arc reactor with molten electrodes. Also, surface science experiments probing atomic layer etching and control of plasma-surface interactions for future applications of diamond electronic and quantum devices and sensors.

(iii) Electrochemistry, electrocatalysis, photoelectrocatalysis, and plasmonic catalysis, e.g., investigations of binary transition-metal oxide electrocatalysts for the oxygen evolution reaction (OER), transition metal atom-decorated/doped 2D materials for electrocatalysis, surface chemistry and heterogeneous processes in electrocatalytic CO₂ and N₂ reduction, and fundamental studies of CO₂ removal to form mineralized carbonates from seawater. In addition, materials characterization for the development of an integrated process for scalable manufacturing of high-performance battery cathode active materials in lithium ion batteries (LIBs), and fundamental studies of current collectors for reservoir-free solid state batteries.

(iv) Heterogeneous catalysis, e.g., the surface chemistry and reactions for bimetallic gold catalysts for green chemistry and sustainability, and for bimetallic nickel catalysts for propane dehydrogenation to propylene.

(v) Environmental remediation utilizing innovative materials science approaches, in particular enhancing transport and delivery of ferrihydrite nanoparticles via polymer encapsulation for the bioremediation of toxic perfluoroalkyl and polyfluoroalkyl substances (PFAS) in contaminated sediments.