About

Adam Holewinski is an Associate Professor and Graduate Associate Chair in the Department of Chemical and Biological Engineering at the University of Colorado Boulder. His research group focuses on catalysis for sustainability, emphasizing efficient, renewable, and environmentally benign catalytic processes for energy production and the synthesis of commodity and fine chemicals. A particular interest lies in electrochemical routes, which involve the direct interconversion between electrical energy and chemical bonds, enabling the utilization of renewable power sources such as wind and solar. These processes are studied for their higher efficiencies and the ability to achieve different product selectivities compared to thermochemical methods. His work involves fundamental characterization of interactions between molecules and (electro)catalytic surfaces to understand reaction mechanisms, which informs the design and optimization of next-generation catalysts. The research encompasses reactions relevant to fuel cells, batteries, electrolyzers, and electrochemical sensors. Techniques employed include kinetic analysis, quantum chemical calculations, and spectroscopic observations of reactive species and catalyst structures. His group aims to develop reversible air-electrodes for lithium-air batteries, improve electro-oxidation of small organics for low-temperature fuel cells, and control selectivity in chemical synthesis through potential modulation, among other projects. Dr. Holewinski's contributions have been recognized through awards such as the NSF CAREER Award, the CU Boulder Provost’s Faculty Achievement Award, and the Fulbright U.S. Scholar award.

Research topics

• Chemistry
• Organic chemistry
• Physics
• Quantum mechanics
• Materials science
• Process engineering
• Engineering
• Nanotechnology
• Ecology
• Environmental science
• Physical chemistry
• Inorganic chemistry
• Computational chemistry
• Biochemical engineering
• Chemical physics

Selected publications

• Second-order kinetic analysis reveals origins of bifunctional enhancement on alloy electro-oxidation catalysts

  ChemRxiv · 2026-05-04

  articleOpen accessSenior author

  Multi-component electrocatalysts provide wide possibilities to tune reactivity, though the fundamental origins of modification, such as electronic perturbation or bifunctionality, are often ambiguous. Here we demonstrate methods to elucidate operative mechanisms on such materials with microkinetic analysis based on generalized degrees of rate control and second-order kinetic observables. CO electro-oxidation kinetics are analyzed on a series of carbon-supported Ag x Pd 100-x alloys to determine apparent CO and OH – reaction orders, and apparent transfer coefficients (inverse Tafel slopes). Each of these kinetic observables (derivatives of rate) varies across operating conditions, providing a rich dataset with second-order dependencies. The analysis reveals that OH – interacts with Ag sites through only partial charge transfer before coupling to Pd-bound CO. Maximum-likelihood fitting of binding energies, corroborated by grand-canonical density functional theory, also supports electronic effects favoring CO-OH coupling. The observation of non-integer charge transfer steps underscores a broader need for rigorous kinetic characterization beyond Tafel slope analysis.

  PublisherOA PDFDOI

• Final Report for Electro-oxidative valorization of biomass: design strategies for selective and stable catalysis

  2026-05-04

  reportOpen access

  This project aimed to develop a fundamental understanding of the factors that dictate activity and selectivity during electrochemical partial oxidation of multi-carbon organic molecules derived from biomass. Value-adding selective conversions of alcohols to aldehydes, and aldehydes to carboxylic acids were considered, with the ultimate goal to establish general principles for controlling selectivity in organic oxidations. Specific aims involved the use of furfural (FF) and 5-hydoxymethyfurfural (HMF) as model systems and seek to develop knowledge for control of mechanisms that permit selective conversions between oxygenate functional groups with prevention or control of C-C cleavage steps. Another major focus of the work was in achieving these transformations in acidic conditions, which contrasts most existing work (done in base), but is crucial toward compatibility with common pretreatments used to generate small molecules from lignocellulose (e.g. acid hydrolysis or pyrolysis). The work involved well-defined catalyst material synthesis, comparative kinetics, and operando spectroscopies (PI Holewinski), supported by quantum chemical simulations (PI Janik), enabling progress toward efficient, acid-stable oxidation catalysis for biomass upgrading.

  PublisherOA PDFDOI

• Quantification of [MTBD][beti] loading and its effects on Pt/HSC electrode performance in hydrogen fuel cells

  Journal of Power Sources · 2026-02-07

  articleOpen access

  High surface area carbon-supported platinum catalysts (Pt/HSC) are widely used in polymer electrolyte membrane fuel cells but often suffer from limited proton and oxygen transport within porous domains. To address these challenges, we integrate the ionic liquid [MTBD][beti] into Pt/HSC catalyst layers using two deposition methods—one-pot and sequential deposition—to tune IL distribution within micropores and mesopores. A combination of ex situ and in operando techniques were employed to elucidate electrode structure–performance relationships across a range of IL loadings. Sequential deposition achieved more efficient pore filling and higher IL retention at lower IL:C ratios, enabling enhanced proton conductivity and protection of active sites. Compared to the IL-free Pt/HSC, IL-modified electrodes demonstrated up to 28% improvement in mass activity and enhanced high-current-density performance under low relative humidity, while maintaining comparable performance under humidified conditions. Electrochemical impedance spectroscopy and CO displacement experiments reveal that improvements are linked to reduced ionic resistance and lower sulfonate adsorption on Pt sites, rather than changes in electrochemical surface area. However, excessive IL loading leads to mass transport losses. These results highlight the importance of selective pore filling and efficient IL distribution in achieving kinetic gains without compromising ionic and gas transport. • Sequential deposition improves IL deposition efficiency and pore filling. • Up to 28% boost in mass activity with minimal IL loading. • E x situ and in operando characterization to describe local distribution of IL within electrode. • ILs reduce sulfonate adsorption on Pt sites and enhance ionic conductivity at low RH. • Excess IL worsens gas transport causing non-monotonic performance trend with IL loading.

  PublisherDOI

• Synthesis of Solid-Solution Mn_<i>x</i>Zn_1–<i>x</i>O Nanoparticles and their Electrochemical Oxidation of Furfural

  Inorganic Chemistry · 2025-08-20

  article

  Electrochemical valorization of biomass-derived substrates has become a prominent area of research due to its potential to produce value-added products from renewable feedstocks in a more sustainable way. First-row transition-metal electrodes are compelling candidates for these conversions due to their stability, abundance, and cost-effectiveness. Herein, we report on the colloidal synthesis of MnxZn1–xO (x = 0.3–0.7) nanoparticles and their electrocatalytic activity toward furfural oxidation. We find that the hindrance of a MnO impurity can be achieved by leveraging the oxidation state of the Mn precursor. The MnxZn1–xO composition closely follows the ratio of precursors, with all of the nanoparticles having a wurtzite structure as determined by ICP-MS and PXRD, respectively. XANES and XPS revealed the presence of Mn in different oxidation states, with the ratio of these varying based on the composition. When comparing the electrocatalytic activity of the monometallic and bimetallic oxides for furfural oxidation, a decrease in current density was observed with increasing Zn content. We find that the MnxZn1–xO nanoparticles favor the formation of the 6 e– oxidation product 5-hydroxy-2(5H)-furanone, while both monometallic oxides primarily yield CO2 and other deeply oxidized products. These findings can contribute toward the design and synthesis of more active and selective electrocatalysts.

  PublisherDOI

• Recyclable Electrocatalytically Active Suspensions Based on TEMPO Polymediators and Carbon Nanotubes

  ECS Meeting Abstracts · 2025-07-11

  article

  In recent years, there has been a substantial focus on developing lignocellulose-derived platform chemicals since lignocellulosic biomass is the most abundant renewable feedstock and considerably cheaper than crude oil. [1] Secondary dehydration products including furans, most notably furfural and 5-(hydroxymethyl)furfural (HMF), can be used for synthesis of numerous organic commodity chemicals, which find their application as pharmaceuticals, food additives and monomers for renewable plastics. [2] Despite this, traditional thermal catalytic approaches have fallen short of practicality due to needs of expensive oxidants and/or large heat input. [3] Electrochemistry is an attractive alternative in terms of sustainability and economic viability, since reactions can be operated under ambient conditions using electricity as an environmentally benign oxidant, often leading to improved selectivity and energy efficiency. [4] To overcome activation barriers, electrocatalysts are typically employed. Heterogeneous electrocatalysis is often associated with good stability but limited selectivity, whereas homogeneous approaches provide well-defined active sites and reaction profiles at the cost of lower turnover numbers. Furthermore, homogeneous electrocatalysis implies additional separation steps. To overcome the separation issue, several methods have been developed over the last decades, including soluble polymediators, [5] and TEMPO-modified electrodes [6] . Herein, we present a new approach, in which multi-walled carbon nanotubes (MWCNTs) combined with TEMPO-polymediators are being employed as a multifunctional suspension for electrocatalytic oxidation of alcohols. The system constitutes a hybrid between homogeneous and heterogeneous electrocatalysis, wherein a conductive nanoparticle is transported to the electrode by convection, where it is electrically charged upon contact, then interacting with the catalyst in the solution. Compared to the homogeneous-only approaches, mass transfer is considerably improved. In other words, electrocatalysis is not limited to the electrode surface − the electrode is rather dispersed over the electrolyte solution, thereby ensuring larger electrochemically active surface area and thus better interaction between catalyst and substrate. Furthermore, polymediator-MWCNTs-system can be simply recycled using filtration or dialysis. The results of electroanalytic and synthetic studies will be presented in this contribution. [1] A. Corma, S. Iborra, A. Velty, Chem. Rev. 2007 , 107 , 2411-2502. [2] A. H. Motagamwala, W. Won, C. Sener, D. M. Alonso, C. T. Maravelias, J. A. Dumesic, Sci. Adv. 2018 , 4 , eaap9722. [3] (a) J. J. Bozell, G. R. Petersen, Green Chem. 2010 , 12 ; (b) K. Yan, G. Wu, T. Lafleur, C. Jarvis, Renew. Sust. Energ. Rev. 2014 , 38 , 663-676. [4] R. Francke, R. D. Little, Chem. Soc. Rev. 2014 , 43 , 2492-2521. [5] N. Mohebbati, A. Prudlik, A. Scherkus, A. Gudkova, R. Francke, ChemElectroChem 2021 , 8 , 3837-3843. [6] (a) Y. Kashiwagi, H. Ono, T. Osa, Chem. Lett. 1993 , 22 , 257-260; (b) A. Das, S. S. Stahl, Angew. Chem. Int. Ed. Engl. 2017 , 56 , 8892-8897.

  PublisherDOI

• Temperature Effects on the Surface CO Population during CO₂ Electroreduction over Copper

  ACS Catalysis · 2025-05-13 · 10 citations

  articleOpen access

  In industrial implementations, CO2 electrolyzers will likely operate at high temperatures due to heat transfer limitations, but the effects of temperature on surface reactions involved in CO2 electroreduction remain elusive and heavily based on inference from product analysis. In this study, we used surface-enhanced infrared absorption spectroscopy (SEIRAS) to deconvolute temperature-dependent phenomena affecting the CO population on copper between 20 and 80 °C. We show that CO coverage and migration to defect sites increase between 20 and 45 °C and decrease between 45 and 80 °C, suggesting that increasing temperature favors a CO hydrogenation route to C1 products over a CO coupling route to C2+ products. C1 and C2+ product formation rates have 1.28 and 1.95 order dependence on the concentration of CO on defect sites, respectively, indicating that these are the active sites for product formation between 20 and 80 °C. Thus, increasing temperature has a direct effect on the CO conversion route to C1 and C2+ products beyond just controlling local CO2 availability, mass transport, and elementary reaction rates. These findings provide a deeper understanding of the underlying reaction mechanism at elevated temperatures, which is a key step in rationalizing product distribution and in designing solutions for enhanced C2+ production in CO2 electrolyzers.

  PublisherDOI

• Quasi-In-Situ Analysis of Electrode Top Atomic Layers via High-Sensitivity Low-Energy Ion Scattering and Potential-Controlled Sample Transfer

  Chemistry of Materials · 2025-06-04

  preprintOpen access

  Electrocatalytic reactions involve interfacial interactions between the surfaces of electrodes and reactive species at an electrolyte interface. There are presently no universal or unambiguous methods to directly assay the active top atomic layer composition that influences the reactivity of these electrodes under relevant operating conditions. Low-energy ion scattering (LEIS) spectroscopy is a surface characterization technique that yields compositional analysis of the outermost atomic layer of a material, but it must be performed in ultrahigh vacuum (UHV). Application of LEIS measurements to electrochemical materials that are removed from ambient liquid-phase environments thus leaves an open question as to whether the surface that is transferred to UHV is truly the surface that manifested during the electrochemical reaction. Toward the goal of preserving the active surface state, we developed a sample transfer workflow for LEIS enabling air-free removal and drying of an electrode from an electrochemical cell while maintaining control of the potential using an auxiliary electrode. The potential-controlled emersion method was demonstrated to give distinct potential-dependent surface compositions for a Cu–Pd alloy relative to removal after uncontrolled return to open-circuit potential. A Cu-enriched surface was found at anodic potential and a Pd-enriched surface at cathodic potential, suggesting that the approach can be used to retain representative atomic configurations during transfer. Since adsorbates will often persist from the reaction environment, conventional sample pretreatment methods for removal, including atomic O and atomic H exposure, were also contrasted. Both methods were found to differ with results from incidental low-dose depth profiling by the LEIS primary ion source, which removes adventitious species and surface atoms during the course of repeated measurements. These depth profiles were found to be sensitive to sample history and thus qualitatively informative, despite the possible changes induced by ion damage. The results exhibit (i) the need for complete control over the polarization state of the sample at all times (no excursions to open circuit during transfer) and (ii) the utility of low-dose depth profiling to capture changes in the near-surface composition.

  PublisherDOI

• Platinum–Ruthenium Alloys Are Not Bifunctional CO Electro-Oxidation Catalysts: A Kinetic Analysis

  ACS Energy Letters · 2025-12-23 · 1 citations

  articleSenior authorCorresponding

  Electro-oxidation of CO is a common kinetic bottleneck in many types of fuel cells and organic electrosynthesis processes. Alloys of Pt and Ru are often used as anode catalysts, with high activity attributed to bifunctionality; this suggests that Ru preferentially activates water to form surface hydroxyl groups that can react with Pt-bound CO. However, rigorous kinetic measurements have not confirmed this assertion under steady-state electro-oxidation conditions. Here, CO electro-oxidation is analyzed using several commercial Pt/C and Pt100-xRux/C nanoparticle catalysts in acidic and alkaline electrolytes. Kinetic observables including apparent transfer coefficients and reaction orders are measured and evaluated using a degree of rate control analysis. The kinetic observables for both Pt and PtRu alloys are most consistent with competitive adsorption and Langmuir–Hinshelwood coupling across a single site-type, rather than two distinct sites. Therefore, the role of Ru in CO electro-oxidation is assigned to be a purely electronic effect.

  PublisherDOI

• Using Pore Window Size to Control Selectivity for Acetylene Hydrogenation on Pd@LTA Zeolite Catalysts

  ACS Catalysis · 2025-07-14 · 4 citations

  articleCorresponding

  Selective hydrogenation of acetylene in ethylene-rich streams is important for industrial applications of ethylene and is commonly performed on Pd-based catalysts. To improve the ethylene selectivity, we incorporated highly dispersed Pd into 4A, a Linde type A zeolite with a pore size of ∼4 Å, with the assistance of mercaptosilanes. Reaction studies indicated that incorporation of Pd within the zeolite (Pd@4A) resulted in higher ethylene selectivity compared to deposition on the external surface of the zeolite (Pd/4A), even at high acetylene conversions near 99%. Pressure decay adsorption measurements showed that diffusion was markedly faster for acetylene compared to ethylene within the 4A. To test the hypothesis that pore (window) size determined selectivity, the Pd@4A zeolite pore size was further modified by variable loadings of NaOH. Breakthrough curve measurements and kinetic adsorption studies indicated that the ethylene diffusion rate decreased with increasing deposition of NaOH, suggesting that accessibility of ethylene to the encapsulated Pd within the LTA zeolite was hindered. The NaOH-modified zeolites exhibited a higher ethylene selectivity (∼80% under 93% acetylene conversion). However, excessive NaOH loading led to a low activity. This strategy provides an avenue for enhancing the selectivity by tuning the accessibility of active sites inside of the porous material.

  PublisherDOI

• Advances in electrosynthesis for a greener chemical industry

  Green Chemistry · 2024-01-01 · 4 citations

  articleOpen access

  This themed collection gathers together articles on advances in electrosynthesis for a greener chemical industry.

  PublisherOA PDFDOI

Recent grants

• Collaborative Research: SusChEM: Manipulation of Reaction Selectivity in the electrochemical environment for biomass-to-chemicals conversions

  NSF · $430k · 2017–2020

• Mixed Ion Electron Conductor (MIEC) Cascade Electrodes for High Density Energy Storage in Li2O2

  NSF · $343k · 2018–2022

• CAREER: Understanding Bifunctionality in Organic Electro-oxidation Catalysis

  NSF · $651k · 2020–2025

Frequent coauthors

• J. Will Medlin

  University of Colorado Boulder

  27 shared

• Joseph C. Hasse

  University of Colorado System

  15 shared

• Nathanael C. Ramos

  14 shared

• Francisco Willian de Souza Lucas

  University of Colorado Boulder

  14 shared

• Alex Roman

  University of Colorado Boulder

  13 shared

• Adam Baz

  University of Colorado System

  10 shared

• Miles A. Sakwa‐Novak

  Global Thermostat (United States)

  9 shared

• Suljo Linic

  University of Michigan–Ann Arbor

  8 shared

Education

• Other

  University of Michigan

  2007

• Ph.D.

  University of Michigan

  2013

• Other, Postdoctoral Research

  Georgia Tech

  2015

Awards & honors

• Fulbright U.S. Scholar (2023)
• Journal of Catalysis Early Career Board (2023)
• CU Boulder Provost’s Faculty Achievement Award (2022)
• CU College of Engineering Dean’s Performance Award -- Outsta…
• Class of Influential Researchers: Industrial & Engineering C…