About

Susannah Scott is a Distinguished Professor in the Department of Chemistry & Biochemistry at the University of California, Santa Barbara. Her specialization includes Inorganic & Organometallic Materials Chemistry, Physical Chemistry, Molecular Design & Synthesis, and Energy, Catalysis & Green Chemistry. She received her Ph.D. in Inorganic Chemistry from Iowa State University in 1991 and completed postdoctoral studies at the Institut de recherches sur la catalyse in Lyon, France, supported by a NATO Postdoctoral Fellowship. She joined the faculty of the University of Ottawa in 1994, where she was named to a Canada Research Chair in Catalyst Design, before moving to UCSB in 2002. Her research focuses on fundamental and applied surface chemistry and catalysis, aiming to understand interactions and transformations of molecules at gas-solid interfaces by creating highly uniform active sites. Her work involves synthesizing molecular precursors and anchoring them onto solid supports to investigate catalytic processes, including ethylene polymerization, olefin metathesis, biomass conversion, and polymer upcycling. She has received numerous awards, including the NSERC Women’s Faculty Award, the Polanyi Prize in Chemistry, a Cottrell Scholars Award, and a Union Carbide Innovation Award.

Research topics

• Organic chemistry
• Chemistry
• Composite material
• Materials science
• Polymer chemistry
• Chemical engineering

Selected publications

• Majority Ga(I) Sites in H ₂ –Activated Ga/γ-Al ₂ O ₃ and Ga/ZSM5 Catalysts Exhibit Distinctive XANES and Anomalous EXAFS Behavior

  ACS Catalysis · 2026-01-15

  articleSenior authorCorresponding

  Ga-containing oxides are selective catalysts for high-temperature hydrocarbon reactions such as alkane dehydrogenation. The active sites are proposed to have an oxidation state of either +1 or +3, and bear a combination of hydride and alkyl ligands, in addition to oxygen-donor ligands associated with the support. Activating a Ga/γ-Al2O3 or Ga/ZSM5 catalyst in H2 at or above 473 K causes the Ga K-edge to (1) shift decisively to lower energy, and (2) increase significantly in its white line intensity. Taken together, these behaviors are shown to be signatures for Ga(III) reduction. The extent of Ga(I) formation, assessed by quantitative XANES analysis, varies with temperature, H2 pressure, and the nature of the support. H2 also causes strong suppression of the EXAFS amplitude. The origin of the latter phenomenon was investigated by analyzing Ga(I) EXAFS signatures in two well-defined model compounds: mixed-valent Ga2Cl4 and Ga(I)-β″-Al2O3. Theoretical simulations show the EXAFS “invisibility” of Ga(I)at noncryogenic temperatures is a direct result of very large vibrational amplitudes. Due to its valence electron configuration and largely unhybridized 4p orbitals, Ga(I) forms very long, labile bonds whose mean-squared relative displacements (σ2) are an order of magnitude higher compared to those associated with the much shorter, stronger bonds of Ga(III). Consequently, EXAFS signals for materials with a mixture of Ga oxidation states are virtually devoid of structural information about the Ga(I) sites, being dominated instead by scattering paths involving residual Ga(III) sites. At elevated reaction temperatures in the H2-activated catalysts, hydrides are minority species, accompanying the majority Ga(I) sites. These insights set the stage for quantitative analysis of Ga speciation during alkane dehydrogenation, and elucidation of the structure(s) of the active sites. Furthermore, they have broad implications for the use of X-ray absorption spectroscopy to extract structure–property relations for catalysts and other materials containing Ga(I) or other weakly bonded, highly dynamic metal ions.

  PublisherDOI

• Revisiting glucose isomerization and epimerization catalyzed by Cr-MIL-101 in aqueous phase: Kinetics and deactivation mechanism

  Journal of Catalysis · 2025-06-08

  articleCorresponding
  PublisherDOI

• Monitoring Depolymerization in Mesopores Using Dynamic Properties of Polymeric Melt Accessed via Dielectric Spectroscopy

  Macromolecules · 2025-10-17

  article

  Traditional design principles for heterogeneous catalysis guide the use of catalytic particles with mesosized (∼2–50 nm) pores to increase the number of surface-active sites by way of an increased surface area. However, the entry of long-chain polymers into such pores may be significantly limited by the size and entanglement of polymers in the melt state, thereby decreasing the number of accessible sites. Assessment of catalyst performance from traditional reactor-based studies averages over intrapore reaction events as well as reactions on the surface of a particle, resulting in an inability to distinguish between differences in site accessibility and activity. Techniques that assess the intrapore performance can inform the design of future heterogeneous catalysts for polymer upcycling. In this work, we demonstrate the use of broadband dielectric spectroscopy to monitor depolymerization of a polymer melt within mesopores via changes in the segmental relaxation time scale of amorphous polymer chains. In particular, we highlight the use of an anodic aluminum oxide (AAO) membrane as a readily available model for catalyst pores with a well-characterized pore morphology. The decrease in the segmental relaxation (α-relaxation) time of the melt with increasing chain scission emerges as a measure of the extent of polymer deconstruction inside mesopores. To demonstrate the utility of this technique, we demonstrate the decomposition of two commercial poly(propylene carbonate) polymers with different decomposition rates within mesopores. As the polymers depolymerize, their segmental relaxation time decreases as the molecular weight decreases (as predicted by the Fox–Flory equation). The BDS-measured change in segmental relaxation time mirrors the expected trend based on change in molecular weight measured by size exclusion chromatography.

  PublisherDOI

• Isopotential Electron Titration: Hydrogen Adsorbate-Metal Charge Transfer

  ACS Central Science · 2025-09-15 · 4 citations

  articleOpen access

  The extent of charge transfer between an adsorbate and thermocatalytic surface plays a key role in determining catalytic activity, but direct and quantitative measures have remained elusive. Here, we report the method of isopotential electron titration (IET), an approach that directly measures charge transfer between adsorbates and catalytic surfaces. Charge transfer between Pt and adsorbed hydrogen adatoms was investigated using a catalytic condenser, where the Pt surface was separated from a p-type silicon layer by a hafnia dielectric film. By forcing the Pt and Si layers into isopotential conditions, charge transfer between the adsorbate and Pt surface was titrated through an external circuit. Hydrogen atoms donated electrons to Pt upon adsorption, which was quantitatively reversed upon desorption. Across a temperature range of 125-200 °C (surface hydrogen fractional coverages of 80-100%), the charge transferred to Pt by an adsorbed hydrogen atom was measured to be 0.19 ± 0.01% |e|/H. Bader charge analysis of the extent of charge transfer was in agreement with experimental measurements, with a calculated net donation of 0.4% |e|/H. The ability to experimentally quantify surface charge transfer provides an electronic-based approach to characterize catalytic surfaces, the adsorbed moieties residing on them, and the chemical reactions they accelerate.

  PublisherDOI

• Contributors

  Elsevier eBooks · 2025-01-01

  book-chapter
  PublisherDOI

• Isopotential Electron Titration: Hydrogen Metal-Adsorbate Charge Transfer

  ChemRxiv · 2025-04-06 · 1 citations

  preprintOpen access

  The extent of charge transfer between an adsorbate and thermocatalytic surface plays a key role in determining binding energy and catalytic activity, but direct and quantitative measures have remained elusive. Here, we report the method of isopotential electron titration (IET), an approach that directly measures charge transfer between adsorbates and catalytic surfaces. Charge transfer between Pt and adsorbed hydrogen adatoms was investigated using a catalytic condenser architecture, where the Pt surface was separated from a p-type silicon layer by a hafnia dielectric film. By forcing the Pt and Si layers into isopotential conditions, excess charge resulting from transfer between adsorbate and Pt surface was titrated through an external circuit. Hydrogen atoms donated electrons to Pt upon adsorption, adopting a partial positive charge on the surface, which was quantitatively reversed upon their thermal desorption from the surface. Across a temperature range of 125 -200 °C and hydrogen partial pressures of 0.005 - 1 atm, consistent with a surface hydrogen fractional coverage of 80-100%, the charge transferred to Pt by an adsorbed H atom was measured to be 1.89 ± 0.05 mmol e- mol Pt-1. Bader charge analysis of the extent of charge transfer was comparable to experimental measurements, with a calculated net donation of 4 mmol e- mol Pt-1 by adsorbed hydrogen. The ability to experimentally quantify surface charge transfer events provides an electronic-based approach to understand and characterize catalytic surfaces, the adsorbed moieties residing on them, and the chemical reactions they accelerate.

  PublisherOA PDFDOI

• Mechanically Accelerated Depolymerization of Entangled Linear Polymer Melts

  Macromolecules · 2025-11-05

  article

  Mechanical forces can enhance the chemical depolymerization of synthetic polymers when shear flow accelerates chain scission. To quantify the extent of mechanically accelerated scission, the effect of simple shear flow (duration and strength) with low Weissenberg and Deborah numbers was investigated by considering the impact of applied work in both simple shear and shear dominated mixed flows. Hydrogenated polyisoprene was chosen as a model linear, entangled system. The conditions (strain amplitude, frequency, and shearing time) necessary to increase chain scission were assessed in the rubbery melt. Isothermal scission versus work curves were superposed by applying shift factors aT,S, whose Arrhenius-like temperature dependence provide an apparent energy barrier for chain scission of ∼110 kJ/mol, which is likely a combination of the activation energy of viscosity and bond energy. These results provide a base for quantifying the impact of shear on depolymerization of polymer melts and highlight the connection between viscous dissipation and scission chemistry.

  PublisherDOI

• Heterogeneous catalytic epimerization of <scp>d</scp> -glucose to <scp>d</scp> -mannose by a tin-organic framework

  Reaction Chemistry & Engineering · 2025-09-17 · 2 citations

  articleOpen access

  Epimerization of d -glucose into d -mannose catalyzed by tin-organic frameworks was performed. Separation of the obtained mixture of d -glucose and d -mannose using crystallization and adsorption was examined.

  PublisherOA PDFDOI

• Revisiting Glucose Isomerization and Epimerization Catalyzed by Cr-Mil-101 in Aqueous Phase: Kinetics and Deactivation Mechanism

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Anionic Surfactants from Reactive Separation of Hydrocarbons Derived from Polyethylene Upcycling

  Langmuir · 2025-02-04 · 5 citations

  articleOpen access

  Chemical upcycling of polyethylene (PE) to long-chain alkylaromatics through tandem hydrocracking/aromatization has potential to provide value-added chemicals. However, the liquid product is a complex mixture of alkanes, alkylbenzenes, and polyaromatics, limiting its direct usability. The most valuable component of the product mixture is the alkylbenzenes because of their potential as precursors to anionic surfactants. In this study, a one-pot reactive separation is described. Sulfonating the product mixture from PE upcycling with silica sulfuric acid followed by neutralization with sodium hydroxide yields sodium alkylbenzenesulfonates (up to 93 mol % selectivity), along with a separate phase of lubricant-range hydrocarbons as a coproduct. Compared to petroleum-based sodium dodecylbenzenesulfonates, the reported PE-derived surfactant molecules show competitive physicochemical properties, including surface tension and interfacial tension. According to life cycle assessment, the described reaction strategy demonstrates 20% lower greenhouse gas emissions, when considering uses for the coproducts of PE upcycling, compared to conventional linear alkylbenzenesulfonates (LAS) manufacturing directly from petrochemical feedstocks.

  PublisherDOI

Recent grants

• SusChEM: Directing the distribution of biomass-derived molecules in porous materials

  NSF · $345k · 2015–2019

• Collaborative Research: SusChEM: Designing Catalytic Interfaces to Promote Selective Lignin Depolymerization

  NSF · $225k · 2016–2020

• PIRE: Advancing the US-China Partnership in Electron Chemistry and Catalysis at Interfaces

  NSF · $4.0M · 2010–2018

• NER: Perovskite Reservoirs for Precious Metal Nanoparticles

  NSF · $100k · 2005–2007

• A Synthetic Approach to Active Site Deconvolution in Supported Cr Catalysts for Olefin Polymerization

  NSF · $350k · 2005–2009

Frequent coauthors

• Laurent Delevoye

  Unité de catalyse et de chimie du solide de Lille

  36 shared

• Régis M. Gauvin

  Institut de Recherche de Chimie Paris

  34 shared

• Mostafa Taoufik

  Centre National de la Recherche Scientifique

  32 shared

• Long Qi

  Iowa State University

  29 shared

• Anthony J. Crisci

  Massachusetts Institute of Technology

  27 shared

• Jean‐Marie Basset

  King Abdullah University of Science and Technology

  26 shared

• Jeroen A. van Bokhoven

  ETH Zurich

  25 shared

• James A. Dumesic

  University of Wisconsin–Madison

  23 shared

Awards & honors

• Canada Research Chair in Catalyst Design
• NSERC Women’s Faculty Award (1994-1999)
• Polanyi Prize in Chemistry (1994)
• Cottrell Scholars Award (1997)
• Union Carbide Innovation Award (1998)