About

Ezra Clark is an Early Career Assistant Professor in the Department of Chemical Engineering at Penn State University. His research focuses on energy and environment, interfaces and surfaces, materials and nanotechnology, separations and transport, and systems engineering. His specific interest areas include heterogeneous electrocatalysis, electrochemical reaction mechanisms and kinetics, electrochemical surface science, organic electrosynthesis, carbon dioxide utilization, electronic structure engineering of intermetallic electrocatalysis, operando electrochemical spectroscopy, and electrochemical mass spectrometry. Dr. Clark earned his Bachelor of Science in Chemical Engineering from the University of Louisville in 2012 and completed his Ph.D. in Chemical Engineering at the University of California at Berkeley in 2018. His work involves advancing understanding and development of electrochemical processes related to energy conversion and environmental sustainability, with a particular emphasis on electrochemical reduction of carbon dioxide and related catalytic systems.

Research topics

• Materials science
• Chemistry
• Inorganic chemistry
• Composite material
• Physical chemistry
• Chemical engineering
• Nanotechnology
• Chromatography
• Photochemistry
• Thermodynamics
• Physics
• Organic chemistry
• Metallurgy
• Nuclear engineering
• Engineering

Selected publications

• Rigor and Reproducibility in Electrocatalysis: Best Practices for Operando Studies

  ChemRxiv · 2026-04-17

  articleOpen access

  Operando measurements have rapidly expanded the scope of electrocatalysis by enabling direct observation of catalytic interfaces under working conditions and by linking structural, compositional, and spectroscopic observables to activity and selectivity. Yet the growth of operando methods has outpaced the adoption of broadly shared experimental standards, creating persistent challenges in reproducibility, interpretation, and comparison across laboratories and platforms. This Perspective synthesizes discussions from the 2025 National Science Foundation Workshop on Rigor and Reproducibility in Electrocatalysis and outlines a practical framework for the rigorous use of operando measurements in electrocatalysis. We highlight three recurring needs: careful implementation of complex methods to avoid overinterpretation; recognition that (subtle) differences in reactor architecture, hydrodynamics, and electrical boundary conditions can alter apparent kinetics and selectivity; and transparent reporting standards that enable meaningful cross-comparison without constraining measurement-specific cell innovation. Focusing on widely used techniques (including X-ray and vibrational spectroscopies, mass spectrometry, and electron microscopy) we discuss technique-specific pitfalls, cross-validation strategies, and recurring platform-agnostic considerations such as mass transport, current distribution, temporal-resolution mismatches, and catalyst evolution. This Perspective aims to strengthen the mechanistic inference and improve the reproducibility, comparability, and predictive value of operando electrocatalysis research.

  PublisherDOI

• Elucidating the Origins of Electrocatalytic Phenomena Using Steady State Isotopic Transient Kinetic Analysis

  ACS Catalysis · 2026-03-19 · 1 citations

  articleOpen accessSenior authorCorresponding

  Intrinsic electrocatalytic activity is the ratio between the steady state coverage of reaction intermediates and their surface lifetimes. Thus, electrocatalytic activity is promoted by either increasing the steady state coverage of reaction intermediates, reducing their surface lifetimes, or some combination of both. Unfortunately, there is a lack of techniques for measuring these parameters. This manuscript demonstrates that these parameters can be quantified simultaneously by performing steady state isotopic transient kinetic analysis (SSITKA). SSITKA is performed by rapidly changing the isotopic composition of the reactant and measuring the isotopic transient of the corresponding product using a mass spectrometer. The observed product isotopic transient is used to calculate the coverage of intermediates and their surface lifetimes. Electrochemical SSITKA (eSSITKA) is demonstrated and validated using methanol (MeOH) oxidation to CO2 over Pt as a test reaction. The insights provided by these measurements are leveraged to explain the origins of the potential-dependent rate of MeOH oxidation in the low overpotential regime. This technique can be used to investigate any electrochemical reaction or electrocatalyst material that evolves a volatile product. Thus, this method is broadly applicable to the field of electrocatalysis and will facilitate the elucidation of a variety of different electrocatalytic phenomena.

  PublisherDOI

• Amniotic Fluid Inflammatory Profile is Altered by Prenatal Cigarette Smoke Exposure

  American Journal of Respiratory and Critical Care Medicine · 2025-05-01

  article

  Abstract Introduction: Fetal breathing movements permit the exchange of fetal lung fluid with amniotic fluid (AF), maintains optimal lung distention, and is vital for pulmonary cell differentiation and lung development. Elevated IL-1β, IL-5, and TNF-α in AF promotes offspring airway hyperreactivity and induces fetal lung inflammation, all of which are associated with chronic lung disease. Therefore, AF composition, and factors that alter it, may directly impact the developing lungs and could affect disease risk. AF may link the external environment and the developing lungs. Previously, we reported that the AF has a unique cytokine/chemokine profile when compared to maternal blood (MB), cord blood (CB), and placenta (PL). But whether this profile can be modified by external stimuli is unknown. Prenatal exposure to cigarette smoke (CS) increases risk for chronic lung disease; therefore, we hypothesize that maternal CS exposure alters the AF cytokine/chemokine profile. Methods: Matched AF, MB, CB, and PL were collected from patients undergoing a term caesarean delivery. Information on CS exposure was collected by questionnaire, and cotinine levels were measured using a direct ELISA to confirm exposure. Protein was isolated from PL samples using a RIPA buffer, and then all samples were assayed for 99 cytokines/chemokines using a multiplex array. Profiles were compared using partial least squares-discriminant analysis (PLS-DA) and differential abundance analysis. Data is presented as mean±SD. Results: There were no significant differences in the clinical measurements or demographics between cotinine negative or positive samples (Table 1). Gestational age was trending lower for cotinine positive samples and may require adjustment in downstream analyses. 27% of AF samples (n=22) had detectable cotinine (51.04±11.90 ng/mL) at levels 1.62-fold higher than CB (31.52±22.78 ng/mL, p<0.01) and 1.45-fold higher than MB (35.13±24.46 ng/mL, p<0.05). Cotinine was undetected in all PL samples. Cotinine-positive AF samples have higher levels of IP-10 (7552.08±6143.49 vs. 690.20±1103.64 pg/mL, p<0.001), CXCL9 (838.85±635.83 vs. 250.73±193.06 pg/mL, p<0.005), IL-10 (7.81±3.52 vs. 4.02±2.23 pg/mL, p<0.01), and IL-6 (992.37±557.50 vs. 513.23±430.35 pg/mL, p<0.05) relative to cotinine-negative samples. These cytokines did not differ in the CB cotinine-positive relative to -negative samples. Conclusions: CS exposure alters the AF profile, increasing the abundance of both pro- and anti-inflammatory mediators. Additionally, prenatal CS exposure leads to cotinine bioaccumulation in AF. These results provide evidence that the AF composition can be influenced and may be an important communication pathway between the external environment and the developing lungs.

  PublisherDOI

• Investigating the Origins of the pH-Dependent Oxidation of Glycerol over Platinum Using Differential Electrochemical Mass Spectrometry

  The Journal of Physical Chemistry C · 2024-06-25 · 7 citations

  articleOpen accessSenior authorCorresponding

  The glycerol oxidation reaction (GOR) to give CO2 could be harnessed to produce energy in a direct glycerol fuel cell. However, state-of-the-art electrocatalysts for this reaction exhibit poor voltage and current efficiency. Thus, there is a need to develop superior electrocatalysts for this process. However, rational electrocatalyst design is difficult due to the complicated reaction mechanism, which is poorly understood. In the present study, differential electrochemical mass spectrometry is utilized to investigate the mechanism of glycerol oxidation over Pt. This is accomplished by investigating the products formed during the electrochemical oxidation of glycerol and various potential reaction intermediates during cyclic voltammetry in acidic and alkaline media. Mass spectrometric cyclic voltammograms showed that the m/z = 44 signal, assigned to CO2, was detected during GOR over a Pt electrode in a 0.5 M H2SO4 solution. At electrode potentials greater than 1.0 V vs RHE, the m/z = 29 signal was also detected, suggesting the formation of formic acid (FA) by C–C bond cleavage reaction. The influence of electrolyte pH on the adsorption of glycerol and its various potential oxidation products on Pt(110) and Pt(100) active sites were investigated. Glycerol, glyceraldehyde, dihydroxyacetone, and FA were oxidized at an overpotential of ca. 0.7 V in 0.5 M H2SO4. However, the oxidation of most of the species potentially derived from glycerol required a higher overpotential (>1.0 V), providing an explanation for the low GOR kinetics in acidic media. Conversely, glyceric acid, hydroxypyruvic acid, mesoxalic acid, and glycolic acid were oxidized to CO2 at an overpotential of 0.5 V in alkaline media. Thus, alkaline media facilitates GOR kinetics by enabling intermediate oxidation products to remain adsorbed to the electrode surface.

  PublisherOA PDFDOI

• Preventing Alloy Electrocatalyst Segregation in Air Using Sacrificial Passivating Overlayers

  The Journal of Physical Chemistry C · 2024-01-02

  articleOpen access1st author

  Many alloy electrocatalysts, including intermetallics, are exceptionally sensitive to segregation in air due to the electronic dissimilarity of the constituent metals. We demonstrate that even alloys with strong cohesive energies rapidly segregate upon air exposure, completely burying the less reactive constituent metal beneath the surface. To circumvent this issue, we develop and validate a new experimental approach for bridging the pressure gap between electronic structure characterization performed under ultrahigh vacuum and electrocatalytic activity testing performed under ambient conditions. This method is based on encapsulation of the alloy surface with a sacrificial passivating overlayer of aluminum oxide. These passivating overlayers protect the underlying material from segregation in the air and can be completely and rapidly removed in an alkaline electrochemical environment under potential control. We demonstrate that alloy surfaces prepared, protected, and introduced into the electrolyte in this manner exhibit near-surface compositions consistent with those of the bulk material despite prior air exposure. We also demonstrate that this protection scheme does not alter the electrocatalytic activity of benchmark electrocatalysts. Implementation of this approach will enable reliable correlations between the electrocatalytic activity measured under ambient conditions and the near-surface electronic structure measured under ultrahigh vacuum.

  PublisherOA PDFDOI

• A Versatile Electrochemical Cell for <i>Operando</i> XAS

  ChemCatChem · 2024-04-03 · 9 citations

  articleOpen access

  Abstract In situ and operando X‐ray absorption spectroscopy (XAS) provides fundamental insight into the working principles of electrocatalysts and is an important tool for future catalyst development. However, the design of an operando XAS electrocatalytic cell is not facile, and researchers designing cells, whether new cells or modifications to previous cells, often spend many hours on cell design before obtaining high‐quality XAS data. Here, we describe the design, with engineering drawings, and operation of a versatile XAS cell with options for gas flow, electrolyte flow, pH monitoring, temperature monitoring, and the ability to handle many catalyst forms (any catalyst that can be deposited onto a conductive X‐ray transparent substrate). We benchmarked XAS spectra collected using the new experimental cell to a previous cell design showing its ability to produce quality XAS data. We demonstrate the viability of this cell by providing insight into electrocatalysts by studying cation effects and show the tetrabutylammonium cation prevents bulk oxidation of copper. We hope the availability of this cell allows researchers to convert time typically spent on cell design to time spent on breakthroughs in electrocatalysis.

  PublisherOA PDFDOI

• Differential electrochemical mass spectrometry (DEMS) cell

  OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) · 2023-04-28

  articleOpen access1st authorCorresponding

  The present invention provides for a differential electrochemical mass spectrometry (DEMS) cell comprising a working electrode chamber configured such that an electrolyte enters the working electrode chamber through a channel running through the working electrode.

  PublisherOA PDF

• Enhancing carbon utilization

  Nature Energy · 2023-02-14 · 1 citations

  article1st authorCorresponding
  PublisherDOI

• Tuning Surface Reactivity and Electric Field Strength via Intermetallic Alloying

  ACS Energy Letters · 2023-09-27 · 11 citations

  articleOpen access1st author

  reduction to multicarbon products, involve the formation of dipolar and polarizable transition states during the rate-determining step. Systematic and independent control over surface reactivity and electric field strength would accelerate the discovery of highly active electrocatalysts for these reactions by providing a means of reducing the transition state energy through field stabilization. Herein, we demonstrate that intermetallic alloying enables independent and systematic control over d-band energetics and work function through the variation of alloy composition and oxophilic constituent identity, respectively. We identify several intermetallic phases exhibiting properties that should collectively yield higher intrinsic activity for CO reduction compared to conventional Cu-based electrocatalysts. However, we also highlight the propensity of these alloys to segregate in air as a significant roadblock to investigating their electrocatalytic activity.

  PublisherDOI

• (Invited) Investigations of Electrochemical CO₂ Reduction with Differential Electrochemical Mass Spectrometry

  ECS Meeting Abstracts · 2023-08-28

  article1st authorCorresponding

  Differential electrochemical mass spectrometry (DEMS) is an analytical technique wherein an electrochemical reactor is interfaced with a mass spectrometer using a pervaporation membrane. This configuration enables volatile electrochemical reaction products to be continuously collected, identified, and quantified during steady state and dynamic polarization. The capabilities of this analytical technique are highly dependent on the design of the electrochemical reactor and how it is interfaced to the mass spectrometer. This presentation will introduce a variety of different DEMS cell designs and will compare their capabilities and limitations in terms of product sensitivity, product quantifiability, and time response. These comparisons will be illustrated through a series of vignettes investigating the electrocatalysis of CO 2 reduction over Cu, Ag, and Au. This reaction is particularly difficult to investigate with DEMS since many of the reaction products yield identical mass fragments upon electron impact ionization. A general strategy for deconvoluting the extent to which a given product contributes to the observed mass ion currents will be presented. The utilization of DEMS for the direct observation of both the composition of the local reaction environment and the transient formation of intermediate reaction products will be discussed, as well as how these insights can be leveraged to guide rational electrocatalyst design. Finally, a new type of DEMS setup capable of quantifying the steady state surface coverage and surface lifetimes of electrochemical reaction intermediates will be presented. Figure 1

  PublisherDOI

Frequent coauthors

• Alexis T. Bell

  188 shared

• Joaquin Resasco

  60 shared

• Stefan Ringe

  54 shared

• Amber Walton

  University of Minnesota

  43 shared

• Thomas F. Jaramillo

  37 shared

• Christopher Hahn

  36 shared

• Karen Chan

  Technical University of Denmark

  36 shared

• Youngkook Kwon

  Korea University of Science and Technology

  30 shared

Labs

• Ezra Clark LabPI

Education

• Doctor of Philosophy , Chemical and Biomolecular Engineering

  University of California Berkeley

  2018

• Bachelor of Science, Chemical Engineering

  University of Louisville

  2012

Awards & honors

• Outstanding Engineering Alumni Award
• Early Career Alumni Recognition Award
• Alumni Achievement Award
• Alumni Fellow Award