About

Andrew Gellman is the Lord Professor of Chemical Engineering at Carnegie Mellon University, with courtesy appointments in chemistry and materials science. He received his B.Sc. in chemistry from the California Institute of Technology in 1981 and his Ph.D. in chemistry from the University of California at Berkeley in 1985. Following a postdoctoral research position at Cambridge University in England, he began his academic career as an assistant professor of chemistry at the University of Illinois. He joined Carnegie Mellon University’s Department of Chemical Engineering in 1992 and has served as the department head from January 2003 to November 2013. In 2012, he was named co-director of the Wilton E. Scott Institute for Energy Innovation. His research focuses on surface chemistry, with particular emphasis on catalytic surface chemistry, enantioselective chemistry on chiral surfaces, tribology, and high throughput study of alloy surfaces. He has developed experimental methodologies to explore fundamental aspects of surface chemistry and his recent work involves studying enantioselectivity on naturally chiral metal surfaces and developing high throughput methods for alloy surface properties such as catalysis. Gellman has received numerous awards for his research, including the Lifetime Achievement Award in Surface Chemistry/Surface Science from the American Chemical Society in 2026, and has been recognized as a Fellow of the American Chemical Society and the AVS. He has also held distinguished fellowships and awards from organizations such as the Sloan Foundation, Packard Foundation, and the Camille and Henry Dreyfus Foundation.

Research topics

• Materials science
• Chemistry
• Nanotechnology
• Physics
• Computer Science
• Mathematics
• Combinatorial chemistry
• Geometry
• Computational chemistry
• Statistical physics
• Thermodynamics
• Chemical engineering
• Metallurgy
• Chemical physics
• Organic chemistry
• Optoelectronics

Selected publications

• Single-Atom Doping at the Molecule–Metal Interface: How Rh Affects Surface Explosion Kinetics

  The Journal of Physical Chemistry Letters · 2025-04-08

  article

  Controlling chemical reactions at interfaces is central to many fields, including atmospheric, environmental, and biological chemistry as well as catalysis and corrosion. We performed a fundamental study of how catalytically active Rh atoms placed at and above a molecule-metal interface influence the surface reaction kinetics of tartaric acid (TA) decomposition. Specifically, TA decomposition on Cu(100) exhibits autocatalytic decomposition kinetics involving a slow initiation step followed by fast decomposition of the molecular layer. These so-called “surface explosions” are extremely sensitive to initial conditions, making it fundamentally interesting to study how the placement of reactive atoms affects the reaction rate. Temperature-programmed reaction (TPR) experiments reveal that Rh atoms embedded in the Cu(100) surface beneath TA (TA/Rh/Cu) or atop the TA layer (Rh/TA/Cu) reduce the decomposition temperature and modify the reaction rate constants. Isothermal TPR analysis reveals that Rh enhances both the initiation rate constant, ki, and the explosion rate constant, ke, facilitating explosive decomposition at lower temperatures. This result provides evidence that both the initiation and explosion steps occur at the metal-molecule interface and are accelerated by the presence of Rh at this interface. This study illustrates how small amounts of reactive elements may be used to control nonlinear kinetic processes at interfaces.

  PublisherDOI

• In Memory of Gabor Somorjai (1935–2025)

  Catalysis Letters · 2025-11-16

  articleOpen accessCorresponding
  PublisherOA PDFDOI

• The Dual Subsurface Hydrogen (2H’) Mechanism for Ethylene Hydrogenation on Pd

  The Journal of Physical Chemistry C · 2025-08-07

  articleOpen accessSenior authorCorresponding

  A microkinetic model for ethylene hydrogenation on Pd that includes the presence of subsurface hydrogen (H’) was developed by adapting the existing Horiuti–Polanyi framework. This reaction mechanism, known as the Dual Subsurface Hydrogen (2H’) mechanism, is an extension of a reaction model that was initially proposed to resolve inconsistencies in the Langmuir–Hinshelwood mechanism for the H2-D2 exchange reaction. The 2H’ mechanism accurately characterizes surface reactions on Pd-based alloy surfaces by accounting for the presence of H’ in the subsurface, which activates the adsorbed H atoms on the top surface, causing them to react. In this work, we derive a 2H’ mechanism for the hydrogenation of ethylene to ethane and compare the implications of the model to experimental results obtained on a AgxPd1–x Composition Spread Alloy Film (CSAF). The ethylene hydrogenation reaction order in H2 predicted by the 2H’ mechanism, nH2, was consistent with nH2 = 0.69 ± 0.18 measured on Pd within the temperature range 345–405 K. In addition, the 2H’ rate law for ethane production was fit to experimental measurements of ethane production on Pd to estimate the effective hydrogenation rate constant, keff, and the energy barriers for ethylene adsorption and desorption. Kinetic parameter estimation bounded the effective hydrogenation rate constant, keff, to between 1010 and 1014 mol/m2/sec and predicted that the ethylene adsorption energy, ΔEadsE, is on the order of ∼10 kJ/mol. Development of the 2H’ mechanism for more complex reactions, like ethylene hydrogenation, shows the necessity for considering the presence of subsurface hydrogen in properly modeling surface reactions on Pd.

  PublisherOA PDFDOI

• Atomistic modeling of kinetic surface segregation mechanisms in CuAu binary alloys: A first-principles study

  Materials Today Communications · 2025-07-31

  article
  PublisherDOI

• Surface Segregation Across Ternary Alloy Composition Space: Cu X Ag Y Au1- X - Y

  SSRN Electronic Journal · 2024-01-01

  preprintOpen access1st authorCorresponding
  PublisherDOI

• Oxidative corrosion resistance of a Cr Fe Ni1-- composition spread alloy film (CSAF) in dry air

  Applied Surface Science · 2024-05-25 · 2 citations

  articleOpen accessSenior authorCorresponding
  PublisherOA PDFDOI

• Surface Segregation Studies in Ternary Noble Metal Alloys: Comparing DFT and Machine Learning with Experimental Data

  ChemPhysChem · 2024-03-22 · 4 citations

  articleOpen access

  Surface segregation, whereby the surface composition of an alloy differs systematically from the bulk, has historically been hard to study, because it requires experimental and modeling methods that span alloy composition space. In this work, we study surface segregation in catalytically relevant noble and platinum-group metal alloys with a focus on three ternary systems: AgAuCu, AuCuPd, and CuPdPt. We develop a data set of 2478 fcc slabs with those compositions including all three low-index crystallographic orientations relaxed with Density Functional Theory using the PBEsol functional with D3 dispersion corrections. We fine-tune a machine learning model on this data and use the model in a series of 1800 Monte Carlo simulations spanning ternary composition space for each surface orientation and ternary chemical system. The results of these simulations are validated against prior experimental surface segregation data collected using composition spread alloy films for AgAuCu and AuCuPd. Our findings reveal that simulations conducted using the (110) orientation most closely match experimentally observed surface segregation trends, and while predicted trends qualitatively match observation, biases in the PBEsol functional limit numeric accuracy. This study advances understanding of surface segregation and the utility of computational studies and highlights the need for further improvements in simulation accuracy.

  PublisherOA PDFDOI

• H₂–D₂ Exchange Activity and Electronic Structure of Ag_<i>x</i>Pd_1–<i>x</i> Alloy Catalysts Spanning Composition Space

  ACS Catalysis · 2024-07-08 · 3 citations

  articleOpen accessSenior authorCorresponding

  can be explained by a reduction in the availability of surface Pd at high Ag compositions.

  PublisherDOI

• Atomic-scale origin of the enantiospecific decomposition of tartaric acid on chiral copper surfaces

  Chemical Communications · 2024-01-01 · 3 citations

  article

  The origin of the enantiospecific decomposition of L- and D-tartaric acid on chiral Cu surfaces is elucidated on a structure-spread domed Cu(110) crystal by spatially resolved XPS and atomic-scale STM imaging. Extensive enantiospecific surface restructuring leads to the formation of surfaces vicinal to Cu(14,17,2) which are responsible for the enantiospecificity.

  PublisherDOI

• Structure Sensitive Reaction Kinetics of Chiral Molecules on Intrinsically Chiral Surfaces

  The Journal of Physical Chemistry C · 2024-08-13 · 2 citations

  articleOpen accessSenior authorCorresponding

  surfaces. The second model introduces the use of chiral cubic harmonic functions to capture the symmetry constraints of the face-centered cubic Cu structure. The model using 58 generalized coordination numbers has a fitting error similar to that of the model using only 5 cubic harmonic functions. The two models predict maxima in the enantiospecificity on surfaces with very similar surface orientations. The models developed in this work are applicable for any enantiospecific reaction happening on any chiral material with a cubic lattice structure, opening the way to understanding the surface structure sensitivity of the enantiospecific reaction kinetics.

  PublisherDOI

Recent grants

• Subsurface Hydrogen in a Alloy Hydrogenation Catalysis

  NSF · $467k · 2020–2024

• Collaborative Research: High Throughput Structure Sensitive Surface Chemistry

  NSF · $370k · 2010–2013

• Collaborative Research: Structure Sensitive Surface Chemistry - Enantioselectivity on Chiral Surfaces

  NSF · $345k · 2018–2021

• MRI: Deveopment of an Apparatus for Deposition of Multi-component Thin Films with Lateral Composition Gradients

  NSF · $635k · 2009–2012

• Collaborative Research: Structure Sensitive Surface Chemistry - Small Molecule Activation and Spillover

  NSF · $371k · 2021–2026

Frequent coauthors

• James B. Miller

  111 shared

• Nisha Shukla

  Dr. BMN College of Home Science

  28 shared

• Petro Kondratyuk

  Carnegie Mellon University

  26 shared

• E. Charles H. Sykes

  Tufts University

  26 shared

• Gábor A. Somorjai

  University of California, Berkeley

  22 shared

• Esteban Broitman

  SKF (Netherlands)

  20 shared

• G.A. Somorjai

  20 shared

• Bryan D. Morreale

  Sandia National Laboratories

  17 shared

Education

• B.S., Chemistry

  California Institute of Technology

  1981

• Ph.D., Chemistry

  University of California, Berkeley

  1985

Awards & honors

• Lifetime Achievement Award in Surface Chemistry/Surface Scie…
• Fellow of the American Chemical Society (2011)
• Fellow of the AVS (2012)
• Welch Foundation Lectureship (Texas - 2001)
• Zeneca Fellowship (University of Cambridge - 2000)