Zisheng Zhang

All Publications

• Enhancing CO Oxidation Rate via Electronic Tuning of CO Binding on Bimetallic Nanoparticle Catalysts. Journal of the American Chemical Society Chung, P. H., Xie, S., Li, X., Mandal, S. C., Zhang, Z., Oh, J., Liu, F., Abild-Pedersen, F., Sánchez-Carrera, R. S., Lizandara-Pueyo, C., Li, Y., Cargnello, M. 2026

  Abstract

  Catalytic CO oxidation on supported metal catalysts, such as platinum, is often promoted by adding a secondary metal, yet the relative importance of interfacial synergy at metal-metal and metal-oxide interfaces over geometric/electronic effects depends on specific systems and can be difficult to disentangle. Existing studies frequently observe electronic promotion alongside interfacial synergy but rarely elucidate how modified CO adsorption translates to a reaction rate change. Here, we use bimetallic Pt-Co catalysts as model systems to disentangle interfacial and electronic contributions. Reaction results show that Pt-Co/Al2O3 catalysts exhibit significantly higher CO oxidation rates than Pt/Al2O3, a 46-fold increase in turnover frequency on Pt3Co1/Al2O3, with less negative reaction order with respect to CO (-0.14 vs -0.57) but comparable order to O2 (0.72 vs 0.80). The kinetic advantage is supported by in situ CO-DRIFTS, revealing weakened CO adsorption on Pt upon Co incorporation. Despite lacking high-density redox sites, the CO oxidation rates on Pt-Co/Al2O3 catalysts are comparable to those on Pt/CeO2, a catalyst known to promote interfacial oxygen exchange. This promotion effect is mirrored in Pt-Ni and Pt-Cu systems, and CO-DRIFTS results confirm a general trend linking weakened CO binding to enhanced rates. Together, these results establish a direct link between reduced CO binding strength and enhanced CO oxidation rates, demonstrating that the rate promotion arises from electronic modification-induced reduced CO coverage rather than from metal oxide interface sites. This work illustrates that the design of a bimetallic catalyst based on electronic structure modifications complements the conventional focus on interfacial active sites.

  View details for DOI 10.1021/jacs.6c10886

  View details for PubMedID 42485209

• CO₍₂₎ Electroreduction on Borated Copper Surfaces: Boron Active Sites, Not Copper ACS CATALYSIS Goswami, A., Zhang, Z., Alexandrova, A. N. 2026

  View details for DOI 10.1021/acscatal.6c02814

  View details for Web of Science ID 001777878300001

• Cation-Limited Hydroxide Anion Diffusion Drives Asymmetric Hydrogen Kinetics on Transition-Metal Decorated Platinum Surface. Journal of the American Chemical Society Wan, C., Zhang, Z., Weng, Z., Sun, Q., Huang, W. H., Liu, E., Chen, Z., Wang, Y., Zhang, A., Ling, Y., Yeh, M. H., Alexandrova, A. N., Jia, Q., Huang, Y., Duan, X. 2026

  Abstract

  Electrocatalytic reactions occur at dynamic, ion-regulated electrochemical interfaces. In electrocatalytic processes such as alkaline hydrogen evolution/oxidation reactions (HER/HOR), which operate at potentials below the electrode's potential of zero charge, electrolyte cations are not mere spectators but profoundly shape reaction behavior. It is generally believed that the alkaline HER and HOR are reversible reactions that share the sluggish Volmer step as their common rate-determining step and therefore exhibit symmetric behavior on Pt-based catalysts. Here, we show that the apparent kinetic symmetry between HER and HOR can be broken on certain transition-metal (TM)-decorated Pt surfaces. Using Ni-decorated Pt as a model system, we show that the formation of Ni-OH species enhances HER kinetics by promoting water dissociation yet paradoxically suppresses HOR kinetics, particularly in highly alkaline electrolytes at potentials above 0.05 V versus the reversible hydrogen electrode. Systematic analyses indicate that abundant TM-OH species drive strong cation accumulation at the outer Helmholtz plane, forming a compact cation layer that pairs with hydroxide anions (OH-) and suppresses their inward diffusion during HOR. Extending this framework across TM-decorated Pt surfaces reveals a systematic trend depending on the TM oxidation potential. Low-oxidation-potential TMs enhance HER but lead to pronounced OH--diffusion-limited HOR. Intermediate TMs promote both HER and HOR, whereas high-oxidation-potential TMs suppress both reactions due to insufficient TM-OH formation. Overall, this work establishes a unified mechanistic framework that links cation accumulation and interfacial OH- transport to distinct HER/HOR kinetics on TM-decorated Pt surfaces in alkaline media, providing design principles for alkaline electrocatalysts.

  View details for DOI 10.1021/jacs.6c03810

  View details for PubMedID 42179157

• O2 Reduction Stimulates Adatom Generation on Cu(111) Catalyzing Hydrogen Evolution. Journal of the American Chemical Society Raciti, D., Zhang, Z., Guo, A., Moffat, T. P. 2026

  Abstract

  Electrochemical mass spectrometry (EC-MS) was used to investigate the coupled dynamics of surface hydride formation, the oxygen reduction reaction (ORR), and the hydrogen evolution reaction (HER) on Cu(111) in perchloric acid. Starting with an Ar-saturated electrolyte, hydride formation proceeds via two overlapping cathodic waves that evolve with cycling due to the restructuring of the electrode surface, associated with the removal of residual oxide species. Grand canonical free-energy calculations indicate that the surface hydride stabilizes pristine terraces against roughening and helps to anneal vacancy-adatom defects introduced during specimen preparation. Introducing controlled amounts of O2 markedly perturbs this behavior, shifting hydride formation to more negative potentials and accelerating HER kinetics, as revealed by EC-MS. Density functional theory and molecular dynamics simulations show that coadsorption of H with ORR intermediates (OH*/OOH*) promotes Cu(111) restructuring through adatom-vacancy formation and subsurface O incorporation. The resulting fluxional adatom sites enhance the HER activity and modulate the ORR kinetics under mixed control. Extended O2 exposure irreversibly restructures the surface and reshapes the hydride formation waves resulting in a lasting imprint on surface reactivity that remains even after returning to nominally O2-free conditions. These findings demonstrate that coupled adsorbates restructure Cu(111) under an electrochemical bias, generating new active sites with direct implications for the performance and stability of Cu electrocatalysts.

  View details for DOI 10.1021/jacs.5c20244

  View details for PubMedID 41671054

• Dopant-Dependent Boron Arrangement and Chemistry of Metal Boride Surface ACS CATALYSIS Zhang, Z., Abild-Pedersen, F. 2026

  View details for DOI 10.1021/acscatal.5c08265

  View details for Web of Science ID 001654472700001

• Non-equilibrium restructurings in catalysis: A chemical space odyssey MRS COMMUNICATIONS Zhang, Z., Zhou, X. 2025

  View details for DOI 10.1557/s43579-025-00902-x

  View details for Web of Science ID 001644159400001

• Unlocking Switchable Reactivity of MBene via Asymmetric Surface Adsorption. The journal of physical chemistry letters Zhang, Z., Abild-Pedersen, F. 2025: 12619-12624

  Abstract

  The Sabatier principle and activity volcano have guided and constrained catalyst design. Surpassing these limitations requires going beyond the static view of catalysis. Here, we propose 2D metal boride (MBene) as a promising model system for dynamic catalysis, exemplified by the nitrogen reduction reaction (N2RR). The surface reactivity of B-rich MBene can be altered by binding organic ligands to the opposite side of the N2RR site. The change in reactivity originates in structural distortions of the metal and boron layers, leading to an energy span of up to 0.8 eV. By cycling the ligands or running a coupled reaction on the opposite side, we could switch between under- and overbinding energetics to surpass the Sabatier limit and access the inverse activity volcano. The reactivity space considering various metals and ligands can be efficiently explored by interpretable machine learning based on geometric descriptors, and promising ligand-bound MBenes for various catalytic scenarios are proposed.

  View details for DOI 10.1021/acs.jpclett.5c03160

  View details for PubMedID 41328668

• Role of Surface Hydroxyls in Atomic-Scale Copper Restructuring during CO Electroreduction. Journal of the American Chemical Society Wei, J., Zhang, Z., Gee, W., Wei, Y., Zhou, Y., Herran, M., Sautet, P., Alexandrova, A. N., Roldan Cuenya, B., Kley, C. S. 2025

  Abstract

  The nanoscale structure of electrocatalyst surfaces governs the selectivity and kinetics of reactions including CO(2) electroreduction (CO(2)R). Yet, their evolution under reaction conditions remains elusive, and the roles of surface hydroxyls (OHad) and the interfacial microenvironment in surface restructuring are poorly understood. Combining electrochemical atomic force microscopy, Raman spectroscopy, and grand canonical modeling, we reveal that OHad acts synergistically with COad to restructure copper (Cu) electrocatalysts during COR. Mixed OHad/COad coverage promotes lifting of surface atoms into metastable states, generating Cu adatoms and nanoclusters at mild cathodic potentials, which aggregate or dissolve at more negative potentials. This restructuring into low-coordinated Cu sites is accompanied by disordering of the interfacial water network. Nanocluster stability depends critically on CO partial pressure, while hydroxyls remain kinetically trapped on the roughened Cu surface. These findings underscore the importance of surface kinetics and interfacial microenvironments in atomic-scale surface restructuring, urging a reassessment of catalytic surface states under realistic conditions.

  View details for DOI 10.1021/jacs.5c14516

  View details for PubMedID 41283916

• AlphaNet: scaling up local-frame-based neural network interatomic potentials NPJ COMPUTATIONAL MATERIALS Yin, B., Wang, J., Du, W., Wang, P., Ying, P., Jia, H., Zhang, Z., Du, Y., Gomes, C., Duan, C., Henkelman, G., Xiao, H. 2025; 11 (1)

  View details for DOI 10.1038/s41524-025-01817-w

  View details for Web of Science ID 001615871100001

• Off-Equilibrium Reactivity of Boron-Enriched Metal Diboride Surfaces in Electroreduction Conditions ACS CATALYSIS Zhang, Z., Abild-Pedersen, F. 2025

  View details for DOI 10.1021/acscatal.5c04054

  View details for Web of Science ID 001526334700001

• Structure Sensitivity and Catalyst Restructuring for CO₂ Electro-reduction on Copper NATURE COMMUNICATIONS Cheng, D., Nguyen, K. C., Sumaria, V., Wei, Z., Zhang, Z., Gee, W., Li, Y., Morales-Guio, C. G., Heyde, M., Roldan Cuenya, B., Alexandrova, A. N., Sautet, P. 2025; 16 (1): 4064

  Abstract

  Cu is the most promising metal catalyst for CO2 electroreduction (CO2RR) to multi-carbon products, yet the structure sensitivity of the reaction and the stability versus restructuring of the catalyst surface under reaction conditions remain controversial. Here, atomic scale simulations of surface energies and reaction pathway kinetics supported by experimental evidence unveil that CO2RR does not take place on perfect planar Cu(111) and Cu(100) surfaces but rather on steps or kinks. These planar surfaces tend to restructure in reaction conditions to the active stepped surfaces, with the strong binding of CO on defective sites acting as a thermodynamic driving force. Notably, we identify that the square motifs adjacent to defects, not the defects themselves, as the active sites for CO2RR via synergistic effect. We evaluate these mechanisms against experiments of CO2RR on ultra-high vacuum-prepared ultraclean Cu surfaces, uncovering the crucial role of step-edge orientation in steering selectivity. Overall, our study refines the structural sensitivity of CO2RR on Cu at the atomic level, highlights the self-activation mechanism and elucidates the origin of in situ restructuring of Cu surfaces during the reaction.

  View details for DOI 10.1038/s41467-025-59267-3

  View details for Web of Science ID 001479703200027

  View details for PubMedID 40307245

  View details for PubMedCentralID PMC12043938

• Reorganizing the Pt Surface Water Structure for Highly Efficient Alkaline Hydrogen Oxidation Reaction. Journal of the American Chemical Society Wan, C., Zhang, Z., Wang, S., Sun, Q., Liu, E., Pu, H., Zhang, A., Chen, Z., Shah, A. H., Fu, X., Alexandrova, A. N., Jia, Q., Huang, Y., Duan, X. 2025

  Abstract

  The hydrogen oxidation reaction (HOR) in alkaline electrolytes exhibits markedly slower kinetics than that in acidic electrolytes. This poses a critical challenge for alkaline exchange membrane fuel cells (AEMFCs). The slower kinetics in alkaline electrolytes is often attributed to the more sluggish Volmer step (hydrogen desorption). It has been shown that the alkaline HOR activity on the Pt surface can be considerably enhanced by the presence of oxophilic transition metals (TMs) and surface-adsorbed hydroxyl groups on TMs (TM-OHad), although the exact role of TM-OHad remains a topic of active debates. Herein, using single-atom Rh-tailored Pt nanowires as a model system, we demonstrate that hydroxyl groups adsorbed on the Rh sites (Rh-OHad) can profoundly reorganize the Pt surface water structure to deliver a record-setting alkaline HOR performance. In situ surface characterizations, together with theoretical studies, reveal that surface Rh-OHad could promote the oxygen-down water (H2O↓) that favors more hydrogen bond with Pt surface adsorbed hydrogen (H2O↓···Had-Pt) than the hydrogen-down water (OH2↓). The H2O↓ further serves as the bridge to facilitate the formation of an energetically favorable six-membered-ring transition structure with neighboring Pt-Had and Rh-OHad, thus reducing the Volmer step activation energy and boosting HOR kinetics.

  View details for DOI 10.1021/jacs.5c00775

  View details for PubMedID 40130907

• GOCIA: a grand canonical global optimizer for clusters, interfaces, and adsorbates. Physical chemistry chemical physics : PCCP Zhang, Z., Gee, W., Lavroff, R. H., Alexandrova, A. N. 2024

  Abstract

  Restructuring of surfaces and interfaces plays a key role in the activation and/or deactivation of a wide spectrum of heterogeneous catalysts and functional materials. The statistical ensemble representation can provide unique atomistic insights into this fluxional and metastable realm, but constructing the ensemble is very challenging, especially for the systems with off-stoichiometric reconstruction and varying coverage of mixed adsorbates. Here, we report GOCIA, a versatile global optimizer for exploring the chemical space of these systems. It features the grand canonical genetic algorithm (GCGA), which bases the target function on the grand potential and evolves across the compositional space, as well as many useful functionalities, with implementation details explained. GOCIA has been applied to various systems in catalysis, from clusters to surfaces and from thermal to electrocatalysis.

  View details for DOI 10.1039/d4cp03801k

  View details for PubMedID 39687986

• Cu-Supported ZnO under Conditions of CO2Reduction to Methanol: Why 0.2 ML Coverage? The journal of physical chemistry letters Lavroff, R. H., Cummings, E., Sawant, K., Zhang, Z., Sautet, P., Alexandrova, A. N. 2024: 11745-11752

  Abstract

  By hydrogenating carbon dioxide to value-added products such as methanol, heterogeneous catalysts can lower greenhouse gas emissions and generate alternative liquid fuels. The most common commercial catalyst for the reduction of CO2 to methanol is Cu/ZnO/Al2O3, where ZnO improves conversion and selectivity toward methanol. The structure of this catalyst is thought to be Zn oxy(hydroxyl) overlayers on the nanometer scale on Cu. In the presence of CO2 and H2 under reaction conditions, the Cu substrate itself can be restructured and/or partially oxidized at its interface with ZnO, or the Zn might be reduced, possibly completely to a CuZn alloy, making the exact structure and stoichiometry of the active site a topic of active debate. In this study, we examine Zn3 clusters on Cu(100) and Cu(111), as a subnano model of the catalyst. We use a grand canonical genetic algorithm to sample the system structure and stoichiometry under catalytic conditions: T of 550 K, initial partial pressures of H2 of 4.5 atm and CO2 of 0.5 atm, and 1% conversion. We uncover a strong dependence of the catalyst stoichiometry on the surface coverage. At the optimal 0.2 ML surface coverage, chains of Zn(OH) form on both Cu surfaces. On Cu(100), the catalyst has many thermally accessible metastable minima, whereas on Cu(111), it does not. No oxidation or reconstruction of the Cu is found. However, at a lower coverage of Zn, Zn3 clusters take on a metallic form on Cu(100), and slightly oxidized Zn3O on Cu(111), while the surface uptakes H to form a variety of low hydrides of Cu. We thus hypothesize that the 0.2 ML Zn coverage is optimal, as found experimentally, because of the stronger yet incomplete oxidation afforded by Zn at this coverage.

  View details for DOI 10.1021/acs.jpclett.4c02908

  View details for PubMedID 39547933

• H and CO Co-Induced Roughening of Cu Surface in CO₂ Electroreduction Conditions JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Zhang, Z., Gee, W., Sautet, P., Alexandrova, A. N. 2024; 146 (23): 16119-16127

  Abstract

  The dynamic restructuring of Cu has been observed under electrochemical conditions, and it has been hypothesized to underlie the unique reactivity of Cu toward CO2 electroreduction. Roughening is one of the key surface phenomena for Cu activation, whereby numerous atomic vacancies and adatoms form. However, the atomic structure of such surface motifs in the presence of relevant adsorbates has remained elusive. Here, we explore the chemical space of Cu surface restructuring under coverage of CO and H in realistic electroreduction conditions, by combining grand canonical DFT and global optimization techniques, from which we construct a potential-dependent grand canonical ensemble representation. The regime of intermediate and mixed CO and H coverage─where structures exhibit some elevated surface Cu─is thermodynamically unfavorable yet kinetically inevitable. Therefore, we develop a quasi-kinetic Monte Carlo simulation to track the system's evolution during a simulated cathodic scan. We reveal the evolution path of the system across coverage space and identify the accessible metastable structures formed along the way. Chemical bonding analysis is performed on the metastable structures with elevated Cu*CO species to understand their formation mechanism. By molecular dynamics simulations and free energy calculations, the surface chemistry of the Cu*CO species is explored, and we identify plausible mechanisms via which the Cu*CO species may diffuse or dimerize. This work provides rich atomistic insights into the phenomenon of surface roughening and the structure of involved species. It also features generalizable methods to explore the chemical space of restructuring surfaces with mixed adsorbates and their nonequilibrium evolution.

  View details for DOI 10.1021/jacs.4c03515

  View details for Web of Science ID 001237235700001

  View details for PubMedID 38815275

• Synthesis and characterization of low-dimensional N-heterocyclic carbene lattices SCIENCE Qie, B., Wang, Z., Jiang, J., Zhang, Z., Jacobse, P. H., Lu, J., Li, X., Liu, F., Alexandrova, A. N., Louie, S. G., Crommie, M. F., Fischer, F. R. 2024; 384 (6698): 895-901

  Abstract

  The covalent interaction of N-heterocyclic carbenes (NHCs) with transition metal atoms gives rise to distinctive frontier molecular orbitals (FMOs). These emergent electronic states have spurred the widespread adoption of NHC ligands in chemical catalysis and functional materials. Although formation of carbene-metal complexes in self-assembled monolayers on surfaces has been explored, design and electronic structure characterization of extended low-dimensional NHC-metal lattices remains elusive. Here we demonstrate a modular approach to engineering one-dimensional (1D) metal-organic chains and two-dimensional (2D) Kagome lattices using the FMOs of NHC-Au-NHC junctions to create low-dimensional molecular networks exhibiting intrinsic metallicity. Scanning tunneling spectroscopy and first-principles density functional theory reveal the contribution of C-Au-C π-bonding states to dispersive bands that imbue 1D- and 2D-NHC lattices with exceptionally small work functions.

  View details for DOI 10.1126/science.adm9814

  View details for Web of Science ID 001253631400002

  View details for PubMedID 38781380

• Platinum Surface Water Orientation Dictates Hydrogen Evolution Reaction Kinetics in Alkaline Media JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Shah, A., Zhang, Z., Wan, C., Wang, S., Zhang, A., Wang, L., Alexandrova, A. N., Huang, Y., Duan, X. 2024; 146 (14): 9623-9630

  Abstract

  The fundamental understanding of sluggish hydrogen evolution reaction (HER) kinetics on a platinum (Pt) surface in alkaline media is a topic of considerable debate. Herein, we combine cyclic voltammetry (CV) and electrical transport spectroscopy (ETS) approaches to probe the Pt surface at different pH values and develop molecular-level insights into the pH-dependent HER kinetics in alkaline media. The change in HER Tafel slope from ∼110 mV/decade in pH 7-10 to ∼53 mV/decade in pH 11-13 suggests considerably enhanced kinetics at higher pH. The ETS studies reveal a similar pH-dependent switch in the ETS conductance signal at around pH 10, suggesting a notable change of surface adsorbates. Fixed-potential calculations and chemical bonding analysis suggest that this switch is attributed to a change in interfacial water orientation, shifting from primarily an O-down configuration below pH 10 to a H-down configuration above pH 10. This reorientation weakens the O-H bond in the interfacial water molecules and modifies the reaction pathway, leading to considerably accelerated HER kinetics at higher pH. Our integrated studies provide an unprecedented molecular-level understanding of the nontrivial pH-dependent HER kinetics in alkaline media.

  View details for DOI 10.1021/jacs.3c12934

  View details for Web of Science ID 001192382700001

  View details for PubMedID 38533830

• Coverage-Induced Cation Dehydration and Migration for Enhanced CO-CO Coupling on Cu Electrocatalysts ACS CATALYSIS Yan, H., Zhang, Z., Wang, Y. 2024; 14 (5): 3596-3605

  View details for DOI 10.1021/acscatal.3c05812

  View details for Web of Science ID 001173731700001

• Modeling Interfacial Dynamics on Single Atom Electrocatalysts: Explicit Solvation and Potential Dependence ACCOUNTS OF CHEMICAL RESEARCH Zhang, Z., Li, J., Wang, Y. 2024; 57 (2): 198-207

  Abstract

  ConspectusSingle atom electrocatalysts, with noble metal-free composition, maximal atom efficiency, and exceptional reactivity toward various energy and environmental applications, have become a research hot spot in the recent decade. Their simplicity and the isolated nature of the atomic structure of their active site have also made them an ideal model catalyst system for studying reaction mechanisms and activity trends. However, the state of the single atom active sites during electrochemical reactions may not be as simple as is usually assumed. To the contrary, the single atom electrocatalysts have been reported to be under greater influence from interfacial dynamics, with solvent and electrolyte ions perpetually interacting with the electrified active center under an applied electrode potential. These complexities render the activity trends and reaction mechanisms derived from simplistic models dubious.In this Account, with a few popular single atom electrocatalysis systems, we show how the change in electrochemical potential induces nontrivial variation in the free energy profile of elemental electrochemical reaction steps, demonstrate how the active centers with different electronic structure features can induce different solvation structures at the interface even for the same reaction intermediate of the simplest electrochemical reaction, and discuss the implication of the complexities on the kinetics and thermodynamics of the reaction system to better address the activity and selectivity trends. We also venture into more intriguing interfacial phenomena, such as alternative reaction pathways and intermediates that are favored and stabilized by solvation and polarization effects, long-range interfacial dynamics across the region far beyond the contact layer, and the dynamic activation or deactivation of single atom sites under operation conditions. We show the necessity of including realistic aspects (explicit solvent, electrolyte, and electrode potential) into the model to correctly capture the physics and chemistry at the electrochemical interface and to understand the reaction mechanisms and reactivity trends. We also demonstrate how the popular simplistic design principles fail and how they can be revised by including the kinetics and interfacial factors in the model. All of these rich dynamics and chemistry would remain hidden or overlooked otherwise. We believe that the complexity at an electrochemical interface is not a curse but a blessing in that it enables deeper understanding and finer control of the potential-dependent free energy landscape of electrochemical reactions, which opens up new dimensions for further design and optimization of single atom electrocatalysts and beyond. Limitations of current methods and challenges faced by the theoretical and experimental communities are discussed, along with the possible solutions awaiting development in the future.

  View details for DOI 10.1021/acs.accounts.3c00589

  View details for Web of Science ID 001181652500001

  View details for PubMedID 38166366

• Tracking Active Phase Behavior on Boron Nitride during the Oxidative Dehydrogenation of Propane Using Operando X-ray Raman Spectroscopy. Journal of the American Chemical Society Cendejas, M. C., Paredes Mellone, O. A., Kurumbail, U., Zhang, Z., Jansen, J. H., Ibrahim, F., Dong, S., Vinson, J., Alexandrova, A. N., Sokaras, D., Bare, S. R., Hermans, I. 2023

  Abstract

  Hexagonal boron nitride (hBN) is a highly selective catalyst for the oxidative dehydrogenation of propane (ODHP) to propylene. Using a variety of ex situ characterization techniques, the activity of the catalyst has been attributed to the formation of an amorphous boron oxyhydroxide surface layer. The ODHP reaction mechanism proceeds via a combination of surface mediated and gas phase propagated radical reactions with the relative importance of both depending on the surface-to-void-volume ratio. Here we demonstrate the unique capability of operando X-ray Raman spectroscopy (XRS) to investigate the oxyfunctionalization of the catalyst under reaction conditions (1 mm outer diameter reactor, 500 to 550 °C, P = 30 kPa C3H8, 15 kPa O2, 56 kPa He). We probe the effect of a water cofeed on the surface of the activated catalyst and find that water removes boron oxyhydroxide from the surface, resulting in a lower reaction rate when the surface reaction dominates and an enhanced reaction rate when the gas phase contribution dominates. Computational description of the surface transformations at an atomic-level combined with high precision XRS spectra simulations with the OCEAN code rationalize the experimental observations. This work establishes XRS as a powerful technique for the investigation of light element-containing catalysts under working conditions.

  View details for DOI 10.1021/jacs.3c08679

  View details for PubMedID 37931025

• Kinetic pathways of fast lithium transport in solid electrolyte interphases with discrete inorganic components ENERGY & ENVIRONMENTAL SCIENCE Yu, Y., Koh, H., Zhang, Z., Yang, Z., Alexandrova, A. N., Agarwal, M., Stach, E. A., Xie, J. 2023; 16 (12): 5904-5915

  View details for DOI 10.1039/d3ee02048g

  View details for Web of Science ID 001086837000001

• Off-Stoichiometric Restructuring and Sliding Dynamics of Hexagonal Boron Nitride Edges in Conditions of Oxidative Dehydrogenation of Propane JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Zhang, Z., Hermans, I., Alexandrova, A. N. 2023; 145 (31): 17265-17273

  Abstract

  Boron-containing materials, such as hexagonal boron nitride (h-BN), recently shown to be active and selective catalysts for the oxidative dehydrogenation of propane (ODHP), have been shown to undergo significant surface oxyfunctionalization and restructuring. Although experimental ex situ studies have probed the change in chemical environment on the surface, the structural evolution of it under varying reaction conditions has not been established. Herein, we perform global optimization structure search with a grand canonical genetic algorithm to explore the chemical space of off-stoichiometric restructuring of the h-BN surface under ambient as well as ODHP-relevant conditions. A grand canonical ensemble representation of the surface is established, and the predicted 11B solid-state NMR spectra are consistent with previous experimental reports. In addition, we investigated the relative sliding of h-BN sheets and how it influences the surface chemistry with ab initio molecular dynamics simulations. The B-O linkages on the edges are found to be significantly strained during the sliding, causing the metastable sliding configurations to have higher reactivity toward the activation of propane and water.

  View details for DOI 10.1021/jacs.3c04613

  View details for Web of Science ID 001039718300001

  View details for PubMedID 37506379

• Electrochemical Carbon Dioxide Capture and Concentration CHEMICAL REVIEWS Zito, A. M., Clarke, L. E., Barlow, J. M., Bim, D., Zhang, Z., Ripley, K. M., Li, C., Kummeth, A., Leonard, M. E., Alexandrova, A. N., Brushett, F. R., Yang, J. Y. Y. 2023; 123 (13): 8069-8098

  Abstract

  Electrochemical carbon capture and concentration (eCCC) offers a promising alternative to thermochemical processes as it circumvents the limitations of temperature-driven capture and release. This review will discuss a wide range of eCCC approaches, starting with the first examples reported in the 1960s and 1970s, then transitioning into more recent approaches and future outlooks. For each approach, the achievements in the field, current challenges, and opportunities for improvement will be described. This review is a comprehensive survey of the eCCC field and evaluates the chemical, theoretical, and electrochemical engineering aspects of different methods to aid in the development of modern economical eCCC technologies that can be utilized in large-scale carbon capture and sequestration (CCS) processes.

  View details for DOI 10.1021/acs.chemrev.2c00681

  View details for Web of Science ID 001013700500001

  View details for PubMedID 37343385

• Engineering Single-Atom Electrocatalysts for Enhancing Kinetics of Acidic Volmer Reaction JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Cao, H., Wang, Q., Zhang, Z., Yan, H., Zhao, H., Yang, H., Liu, B., Li, J., Wang, Y. 2023; 145 (24): 13038-13047

  Abstract

  The design of active and low-cost electrocatalyst for hydrogen evolution reaction (HER) is the key to achieving a clean hydrogen energy infrastructure. The most successful design principle of hydrogen electrocatalyst is the activity volcano plot, which is based on Sabatier principle and has been used to understand the exceptional activity of noble metal and design of metal alloy catalysts. However, this application of volcano plot in designing single-atom electrocatalysts (SAEs) on nitrogen doped graphene (TM/N4C catalysts) for HER has been less successful due to the nonmetallic nature of the single metal atom site. Herein, by performing ab initio molecular dynamics simulations and free energy calculations on a series of SAEs systems (TM/N4C with TM = 3d, 4d, or 5d metals), we find that the strong charge-dipole interaction between the negatively charged *H intermediate and the interfacial H2O molecules could alter the transition path of the acidic Volmer reaction and dramatically raise its kinetic barrier, despite its favorable adsorption free energy. Such kinetic hindrance is also experimentally confirmed by electrochemical measurements. By combining the hydrogen adsorption free energy and the physics of competing interfacial interactions, we propose a unifying design principle for engineering the SAEs used for hydrogen energy conversion, which incorporates both thermodynamic and kinetic considerations and allows going beyond the activity volcano model.

  View details for DOI 10.1021/jacs.2c13418

  View details for Web of Science ID 001008499500001

  View details for PubMedID 37285479

• Hydrogen Evolution on Electrode-Supported Pt<i>_n</i> Clusters: Ensemble of Hydride States Governs the Size Dependent Reactivity ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Zhang, Z., Masubuchi, T., Sautet, P., Anderson, S. L., Alexandrova, A. N. 2023; 62 (20): e202218210

  Abstract

  We report the size-dependent activity and stability of supported Pt1,4,7,8 for electrocatalytic hydrogen evolution reaction, and show that clusters outperform polycrystalline Pt in activity, with size-dependent stability. To understand the size effects, we use DFT calculations to study the structural fluxionality under varying potentials. We show that the clusters can reshape under H coverage and populate an ensemble of states with diverse stoichiometry, structure, and thus reactivity. Both experiment and theory suggest that electrocatalytic species are hydridic states of the clusters (≈2 H/Pt). An ensemble-based kinetic model reproduces the experimental activity trend and reveals the role of metastable states. The stability trend is rationalized by chemical bonding analysis. Our joint study demonstrates the potential- and adsorbate-coverage-dependent fluxionality of subnano clusters of different sizes and offers a systematic modeling strategy to tackle the complexities.

  View details for DOI 10.1002/anie.202218210

  View details for Web of Science ID 000969620200001

  View details for PubMedID 36920979

• Molecular design of redox carriers for electrochemical CO₂ capture and concentration CHEMICAL SOCIETY REVIEWS Barlow, J. M., Clarke, L. E., Zhang, Z., Bim, D., Ripley, K. M., Zito, A., Brushett, F. R., Alexandrova, A. N., Yang, J. Y. 2022; 51 (20): 8415-8433

  Abstract

  Developing improved methods for CO2 capture and concentration (CCC) is essential to mitigating the impact of our current emissions and can lead to carbon net negative technologies. Electrochemical approaches for CCC can achieve much higher theoretical efficiencies compared to the thermal methods that have been more commonly pursued. The use of redox carriers, or molecular species that can bind and release CO2 depending on their oxidation state, is an increasingly popular approach as carrier properties can be tailored for different applications. The key requirements for stable and efficient redox carriers are discussed in the context of chemical scaling relationships and operational conditions. Computational and experimental approaches towards developing redox carriers with optimal properties are also described.

  View details for DOI 10.1039/d2cs00367h

  View details for Web of Science ID 000857446200001

  View details for PubMedID 36128984

• Modeling the Potential-Dependent Kinetics of CO2 Electroreduction on Single-Nickel Atom Catalysts with Explicit Solvation ACS CATALYSIS Zhao, H., Cao, H., Zhang, Z., Wang, Y. 2022

  View details for DOI 10.1021/acscatal.2c02383

  View details for Web of Science ID 000859445300001

• Inverse molecular design of alkoxides and phenoxides for aqueous direct air capture of CO₂ PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhang, Z., Kummeth, A. L., Yang, J. Y., Alexandrova, A. N. 2022; 119 (25): e2123496119

  Abstract

  Aqueous direct air capture (DAC) is a key technology toward a carbon negative infrastructure. Developing sorbent molecules with water and oxygen tolerance and high CO2 binding capacity is therefore highly desired. We analyze the CO2 absorption chemistries on amines, alkoxides, and phenoxides with density functional theory calculations, and perform inverse molecular design of the optimal sorbent. The alkoxides and phenoxides are found to be more suitable for aqueous DAC than amines thanks to their water tolerance (lower pKa prevents protonation by water) and capture stoichiometry of 1:1 (2:1 for amines). All three molecular systems are found to generally obey the same linear scaling relationship (LSR) between [Formula: see text] and [Formula: see text], since both CO2 and proton are bonded to the nucleophilic (alkoxy or amine) binding site through a majorly [Formula: see text] bonding orbital. Several high-performance alkoxides are proposed from the computational screening. Phenoxides have comparatively poorer correlation between [Formula: see text] and [Formula: see text], showing promise for optimization. We apply a genetic algorithm to search the chemical space of substituted phenoxides for the optimal sorbent. Several promising off-LSR candidates are discovered. The most promising one features bulky ortho substituents forcing the CO2 adduct into a perpendicular configuration with respect to the aromatic ring. In this configuration, the phenoxide binds CO2 and a proton using different molecular orbitals, thereby decoupling the [Formula: see text] and [Formula: see text]. The [Formula: see text] trend and off-LSR behaviors are then confirmed by experiments, validating the inverse molecular design framework. This work not only extensively studies the chemistry of the aqueous DAC, but also presents a transferrable computational workflow for understanding and optimization of other functional molecules.

  View details for DOI 10.1073/pnas.2123496119

  View details for Web of Science ID 000900734500016

  View details for PubMedID 35709322

  View details for PubMedCentralID PMC9231474

• Potential-Dependent Free Energy Relationship in Interpreting theElectrochemical Performance of CO₂Reduction on Single AtomCatalysts ACS CATALYSIS Cao, H., Zhang, Z., Chen, J., Wang, Y. 2022; 12 (11): 6606-6617

  View details for DOI 10.1021/acscatal.2c01470

  View details for Web of Science ID 000810516000031

• Ensemble representation of catalytic interfaces: soloists, orchestras, and everything in-between CHEMICAL SCIENCE Lavroff, R. H., Morgan, H. W. T., Zhang, Z., Poths, P., Alexandrova, A. N. 2022; 13 (27): 8003-8016

  Abstract

  Catalytic systems are complex and dynamic, exploring vast chemical spaces on multiple timescales. In this perspective, we discuss the dynamic behavior of fluxional, heterogeneous thermal and electrocatalysts and the ensembles of many isomers which govern their behavior. We develop a new paradigm in catalysis theory in which highly fluxional systems, namely sub-nano clusters, isomerize on a much shorter timescale than that of the catalyzed reaction, so macroscopic properties arise from the thermal ensemble of isomers, not just the ground state. Accurate chemical predictions can only be reached through a many-structure picture of the catalyst, and we explain the breakdown of conventional methods such as linear scaling relations and size-selected prevention of sintering. We capitalize on the forward-looking discussion of the means of controlling the size of these dynamic ensembles. This control, such that the most effective or selective isomers can dominate the system, is essential for the fluxional catalyst to be practicable, and their targeted synthesis to be possible. It will also provide a fundamental lever of catalyst design. Finally, we discuss computational tools and experimental methods for probing ensembles and the role of specific isomers. We hope that catalyst optimization using chemically informed descriptors of ensemble nature and size will become a new norm in the field of catalysis and have broad impacts in sustainable energy, efficient chemical production, and more.

  View details for DOI 10.1039/d2sc01367c

  View details for Web of Science ID 000817912600001

  View details for PubMedID 35919426

  View details for PubMedCentralID PMC9278157

• Pseudo-adsorption and long-range redox coupling during oxygen reduction reaction on single atom electrocatalyst NATURE COMMUNICATIONS Chen, J., Zhang, Z., Yan, H., Xia, G., Cao, H., Wang, Y. 2022; 13 (1): 1734

  Abstract

  Fundamental understanding of the dynamic behaviors at the electrochemical interface is crucial for electrocatalyst design and optimization. Here, we revisit the oxygen reduction reaction mechanism on a series of transition metal (M = Fe, Co, Ni, Cu) single atom sites embedded in N-doped nanocarbon by ab initio molecular dynamics simulations with explicit solvation. We have identified the dissociative pathways and the thereby emerged solvated hydroxide species for all the proton-coupled electron transfer (PCET) steps at the electrochemical interface. Such hydroxide species can be dynamically confined in a "pseudo-adsorption" state at a few water layers away from the active site and respond to the redox event at the catalytic center in a coupled manner within timescale less than 1 ps. In the PCET steps, the proton species (in form of hydronium in neutral/acidic media or water in alkaline medium) can protonate the pseudo-adsorbed hydroxide without needing to travel to the direct catalyst surface. This, therefore, expands the reactive region beyond the direct catalyst surface, boosting the reaction kinetics via alleviating mass transfer limits. Our work implies that in catalysis the reaction species may not necessarily bind to the catalyst surface but be confined in an active region.

  View details for DOI 10.1038/s41467-022-29357-7

  View details for Web of Science ID 000777408600028

  View details for PubMedID 35365615

  View details for PubMedCentralID PMC8975818

• Molecular Design of Dispersed Nickel Phthalocyanine@Nanocarbon Hybrid Catalyst for Active and Stable Electroreduction of CO₂ JOURNAL OF PHYSICAL CHEMISTRY C Zhang, Z., Wang, Y. 2021; 125 (25): 13836-13849

  View details for DOI 10.1021/acs.jpcc.1c02508

  View details for Web of Science ID 000670787500013

• Hydrogen Evolution on Restructured B-Rich WB: Metastable Surface States and Isolated Active Sites ACS CATALYSIS Zhang, Z., Cui, Z., Jimenez-Izal, E., Sautet, P., Alexandrova, A. N. 2020; 10 (23): 13867-13877

  View details for DOI 10.1021/acscatal.0c03410

  View details for Web of Science ID 000598140200010

• Molecular engineering of dispersed nickel phthalocyanines on carbon nanotubes for selective CO(2)reduction NATURE ENERGY Zhang, X., Wang, Y., Gu, M., Wang, M., Zhang, Z., Pan, W., Jiang, Z., Zheng, H., Lucero, M., Wang, H., Sterbinsky, G. E., Ma, Q., Wang, Y., Feng, Z., Li, J., Dai, H., Liang, Y. 2020

  View details for DOI 10.1038/s41560-020-0667-9

  View details for Web of Science ID 000558156800001

• Why Boron Nitride is such a Selective Catalyst for the Oxidative Dehydrogenation of Propane ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Venegas, J. M., Zhang, Z., Agbi, T. O., McDermott, W. P., Alexandrova, A., Hermans, I. 2020; 59 (38): 16527-16535

  Abstract

  Boron-containing materials, and in particular boron nitride, have recently been identified as highly selective catalysts for the oxidative dehydrogenation of alkanes such as propane. To date, no mechanism exists that can explain both the unprecedented selectivity, the observed surface oxyfunctionalization, and the peculiar kinetic features of this reaction. We combine catalytic activity measurements with quantum chemical calculations to put forward a bold new hypothesis. We argue that the remarkable product distribution can be rationalized by a combination of surface-mediated formation of radicals over metastable sites, and their sequential propagation in the gas phase. Based on known radical propagation steps, we quantitatively describe the oxygen pressure-dependent relative formation of the main product propylene and by-product ethylene. Free radical intermediates most likely differentiate this catalytic system from less selective vanadium-based catalysts.

  View details for DOI 10.1002/anie.202003695

  View details for Web of Science ID 000548426700001

  View details for PubMedID 32573006

• Ensembles of Metastable States Govern Heterogeneous Catalysis on Dynamic Interfaces ACCOUNTS OF CHEMICAL RESEARCH Zhang, Z., Zandkarimi, B., Alexandrova, A. N. 2020; 53 (2): 447-458

  Abstract

  Heterogeneous catalysis is at the heart of the chemical industry. Being able to tune and design efficient catalysts for processes of interest is of the utmost importance, and for this, a molecular-level understanding of heterogeneous catalysts is the first step and indeed a prime focus of modern catalysis research. For a long time, the single most thermodynamically stable structure of the catalytic interface attained under the reaction conditions had been envisioned as the reactive phase. However, some catalytic interfaces continue to undergo structural dynamics in the steady state, triggered by high temperatures and pressures and binding and changing reagents. Among particularly dynamic interfaces are such widely used catalysts as crystalline and amorphous surfaced supporting (sub)nanometallic clusters. Recently, it became clear that this dynamic fluxionality causes the supported clusters to populate many distinct structural and stoichiometric states under catalytic conditions. Hence, the catalytic interface should be viewed as an evolving statistical ensemble of many structures (rather than one structure). Every member in the ensemble contributes to the properties of the catalyst differently, in proportion to its probability of being populated. This new notion flips the established paradigm and calls for a new theory, new modeling approaches, operando measurements, and updated design strategies. The statistical ensemble nature of surface-supported subnanocluster catalysts can be exemplified by oxide-supported and adsorbate-covered Pt, Pd, Cu, and CuPd clusters, which are catalytic toward oxidative and nonoxidative dehydrogenation. They have access to a variety of 3D and quasi-2D shapes. The compositions of their thermal ensembles are dependent on the cluster size, leading to size-specific catalytic activities and the famous "every atom counts" phenomenon. The support and adsorbates affect catalyst structures, and the state of the reacting species causes the ensemble to change in every reaction intermediate. The most stable member of the ensemble dominates the thermodynamic properties of the corresponding intermediate, whereas the kinetics can be determined by more active but less populated metastable catalyst states, and that suggests that many earlier studies might have overlooked the actual active sites. Both effects depend on the relative time scales of catalyst restructuring and reaction dynamics. The catalyst may routinely operate off-equilibrium. Ensemble phenomena lead to surprising exceptions from established rules of catalysis, such as scaling relations and Arrhenius behavior. Catalyst deactivation is also an ensemble property, and its extent of mitigation can be predicted through the new paradigm. These findings were enabled by advances in theory, such as global optimization and subsequent utilization of multiple local minima and pathways sampling as well as operando catalyst characterization. The fact that the per-site and per-species resolution is needed for the description and prediction of catalyst properties gives theory the central role in catalysis research, as most experiments provide ensemble-average information and cannot detect the crucial minority species that may be responsible for the catalytic activity.

  View details for DOI 10.1021/acs.accounts.9b00531

  View details for Web of Science ID 000514759600014

  View details for PubMedID 31977181

• Phthalocyanine Precursors To Construct Atomically Dispersed Iron Electrocatalysts ACS CATALYSIS Wang, Y., Wang, M., Zhang, Z., Wang, Q., Jiang, Z., Lucero, M., Zhang, X., Li, X., Gu, M., Feng, Z., Liang, Y. 2019; 9 (7): 6252-6261

  View details for DOI 10.1021/acscatal.9b01617

  View details for Web of Science ID 000474812400046

• Comparison of TiO₂ and g-C₃N₄ 2D/2D nanocomposites from three synthesis protocols for visible-light induced hydrogen evolution CATALYSIS SCIENCE & TECHNOLOGY Zhong, R., Zhang, Z., Luo, S., Zhang, Z., Huang, L., Gu, M. 2019; 9 (1): 75-85

  View details for DOI 10.1039/c8cy00965a

  View details for Web of Science ID 000454918600022

• Dynamic Phase Diagram of Catalytic Surface of Hexagonal Boron Nitride under Conditions of Oxidative Dehydrogenation of Propane JOURNAL OF PHYSICAL CHEMISTRY LETTERS Zhang, Z., Jimenez-Izal, E., Hermans, I., Alexandrova, A. N. 2019; 10 (1): 20-25

  Abstract

  Partially oxidized surfaces of hexagonal boron nitride (hBN) and several metal borides are unexpectedly excellent catalysts for oxidative dehydrogenation of alkanes to olefins, but the nature of the active site(s) on these B-containing interfaces remains elusive. We characterize the surface of the partially oxidized B-rich hBN surface under reaction conditions from first principles. The interface has thermal access to multiple different stoichiometries and multiple structures of each stoichiometry. The size of the thermal ensemble is composition-dependent. The phase diagram of the interface constructed on the basis of the statistical ensembles of many accessible states is very different from the one based on global minima. Phase boundaries shift and blur, and phases consist of several stoichiometries and structures. The BO layer transiently exposes the reactive -B═O motifs in the metastable states. The fluxionality and structural diversity emerging under reaction conditions must be taken into account in theoretically descriptions of the catalytic interface.

  View details for DOI 10.1021/acs.jpclett.8b03373

  View details for Web of Science ID 000455168800004

  View details for PubMedID 30557024

• Covalently bonded 2D/2D O-g-C₃N₄/TiO₂ heterojunction for enhanced visible-light photocatalytic hydrogen evolution APPLIED CATALYSIS B-ENVIRONMENTAL Zhong, R., Zhang, Z., Yi, H., Zeng, L., Tang, C., Huang, L., Gu, M. 2018; 237: 1130-1138

  View details for DOI 10.1016/j.apcatb.2017.12.066

  View details for Web of Science ID 000442973700115

• Nickel bis(dithiolene) complexes for electrocatalytic hydrogen evolution: A computational study JOURNAL OF ORGANOMETALLIC CHEMISTRY Zhang, Z., Yang, T., Qin, P., Dang, L. 2018; 864: 143-147

  View details for DOI 10.1016/j.jorganchem.2018.03.007

  View details for Web of Science ID 000432598600019

• Highly selective and active CO₂ reduction electro-catalysts based on cobalt phthalocyanine/carbon nanotube hybrid structures NATURE COMMUNICATIONS Zhang, X., Wu, Z., Zhang, X., Li, L., Li, Y., Xu, H., Li, X., Yu, X., Zhang, Z., Liang, Y., Wang, H. 2017; 8: 14675

  Abstract

  Electrochemical reduction of carbon dioxide with renewable energy is a sustainable way of producing carbon-neutral fuels. However, developing active, selective and stable electrocatalysts is challenging and entails material structure design and tailoring across a range of length scales. Here we report a cobalt-phthalocyanine-based high-performance carbon dioxide reduction electrocatalyst material developed with a combined nanoscale and molecular approach. On the nanoscale, cobalt phthalocyanine (CoPc) molecules are uniformly anchored on carbon nanotubes to afford substantially increased current density, improved selectivity for carbon monoxide, and enhanced durability. On the molecular level, the catalytic performance is further enhanced by introducing cyano groups to the CoPc molecule. The resulting hybrid catalyst exhibits >95% Faradaic efficiency for carbon monoxide production in a wide potential range and extraordinary catalytic activity with a current density of 15.0 mA cm-2 and a turnover frequency of 4.1 s-1 at the overpotential of 0.52 V in a near-neutral aqueous solution.

  View details for DOI 10.1038/ncomms14675

  View details for Web of Science ID 000395727800001

  View details for PubMedID 28272403

  View details for PubMedCentralID PMC5344970