Matteo Cargnello is Assistant Professor of Chemical Engineering and Terman Faculty Fellow. His group research interests are in the preparation and use of uniform and tailored materials for heterogeneous catalysis and photocatalysis and the technological exploitation of nanoparticles and nanocrystals. Reactions of interest are related to sustainable energy generation and use, control of emissions of greenhouse gases, and better utilization of abundant building blocks (methane, biomass). Dr. Cargnello received his Ph.D. in Nanotechnology in 2012 at the University of Trieste (Italy) and he was then a post-doctoral scholar in the Chemistry Department at the University of Pennsylvania (Philadelphia) before joining the Faculty at Stanford.

Academic Appointments

Honors & Awards

  • Catalysis Science Award for Creative Work, Mitsui Chemicals (2020)
  • Mid-Career Nanotechnology Scientific Award, ANNIC (2019)
  • Sloan Research Fellowship, Alfred P. Sloan Foundation (2018)
  • Outstanding Poster Award, Catalysis Gordon Research Conference (2018)
  • Hellman Fellow, Hellman Fellows Fund (2018)
  • Junior award, European Rare Earth and Actinide Society (ERES) (2018)
  • Young Scientist Prize, 16th International Congress on Catalysis, Beijing (China) (2016)
  • Terman Faculty Fellow, Stanford University (2015)
  • Best European PhD Thesis in Catalysis, European Federation of Catalysis Societies (EFCATS) (2013)
  • ENI Award “Debut in Research”, ENI (2013)
  • Levi Award, Italian Chemical Society (SCI) (2012)
  • Inorganic Chemistry Division Award, Italian Chemical Society (SCI) (2012)

Professional Education

  • PhD, University of Trieste, Nanotechnology (2012)

2020-21 Courses

Stanford Advisees

  • Doctoral Dissertation Reader (AC)
    Arun Asundi, Sarah Blair, McKenzie Hubert, Melissa Kreider, Thomas Ludwig, Jimmy Rojas, Joel Schneider, Eduardo Valle
  • Postdoctoral Faculty Sponsor
    Yulian He, Dohyung Kim, Zhenwei Wu
  • Doctoral Dissertation Advisor (AC)
    Aisulu Aitbekova, Angel Yang, Chengshuang Zhou
  • Doctoral Dissertation Co-Advisor (AC)
    Alan Dai, Michael Statt, Julian Vigil
  • Postdoctoral Research Mentor
    Yulian He, Andrew Riscoe

All Publications

  • A General Approach for Monolayer Adsorption of High Weight Loadings of Uniform Nanocrystals on Oxide Supports. Angewandte Chemie (International ed. in English) Kao, K., Yang, A., Huang, W., Zhou, C., Goodman, E. D., Holm, A., Frank, C. W., Cargnello, M. 2021


    Monodispersed metal and semiconductor nanocrystals have attracted great attention in fundamental and applied research due to their tunable size, morphology, and well-defined chemical composition. Utilizing these nanocrystals in a controllable way is highly desirable especially when using them as building blocks for the preparation of nanostructured materials. Their deposition onto oxide materials provide them with wide applicability in many areas, including catalysis. However, so far deposition methods are limited and do not provide control to achieve high particle loadings. This study demonstrates a general approach for the deposition of hydrophobic ligand-stabilized nanocrystals on hydrophilic oxide supports without ligand-exchange. Surface functionalization of the supports with primary amine groups either using an organosilane ((3-aminopropyl)trimethoxysilane) or bonding with aminoalcohols (3-amino-1,2-propanediol) were found to significantly improve the interaction between nanocrystals and supports achieving high loadings (>10 wt. %). The bonding method with aminoalcohols guarantees the opportunity to remove the binding molecules thus allowing clean metal/oxide materials to be obtained, which is of great importance in the preparation of supported nanocrystals for heterogeneous catalysis.

    View details for DOI 10.1002/anie.202017238

    View details for PubMedID 33403788

  • Size-controlled nanocrystals reveal spatial dependence and severity of nanoparticle coalescence and Ostwald ripening in sintering phenomena. Nanoscale Goodman, E. D., Carlson, E. Z., Dietze, E. M., Tahsini, N., Johnson, A., Aitbekova, A., Nguyen Taylor, T., Plessow, P. N., Cargnello, M. 2020


    A major aim in the synthesis of nanomaterials is the development of stable materials for high-temperature applications. Although the thermal coarsening of small and active nanocrystals into less active aggregates is universal in material deactivation, the atomic mechanisms governing nanocrystal growth remain elusive. By utilizing colloidally synthesized Pd/SiO2 powder nanocomposites with controlled nanocrystal sizes and spatial arrangements, we unravel the competing contributions of particle coalescence and atomic ripening processes in nanocrystal growth. Through the study of size-controlled nanocrystals, we can uniquely identify the presence of either nanocrystal dimers or smaller nanoclusters, which indicate the relative contributions of these two processes. By controlling and tracking the nanocrystal density, we demonstrate the spatial dependence of nanocrystal coalescence and the spatial independence of Ostwald (atomic) ripening. Overall, we prove that the most significant loss of the nanocrystal surface area is due to high-temperature atomic ripening. This observation is in quantitative agreement with changes in the nanocrystal density produced by simulations of atomic exchange. Using well-defined colloidal materials, we extend our analysis to explain the unusual high-temperature stability of Au/SiO2 materials up to 800 °C.

    View details for DOI 10.1039/d0nr07960j

    View details for PubMedID 33367382

  • A phytophotonic approach to enhanced photosynthesis ENERGY & ENVIRONMENTAL SCIENCE Kunz, L. Y., Redekop, P., Ort, D. R., Grossman, A. R., Cargnello, M., Majumdar, A. 2020; 13 (12): 4794–4807

    View details for DOI 10.1039/d0ee02960b

    View details for Web of Science ID 000599751100013

  • Dynamics of Copper-Containing Porous Organic Framework Catalysts Reveal Catalytic Behavior Controlled by the Polymer Structure ACS CATALYSIS Wu, Z., Zhang, X., Goodman, E. D., Huang, W., Riscoe, A. R., Yacob, S., Cargnello, M. 2020; 10 (16): 9356–65
  • Enhanced Catalytic Activity for Methane Combustion through in Situ Water Sorption ACS CATALYSIS Huang, W., Zhang, X., Yang, A., Goodman, E. D., Kao, K., Cargnello, M. 2020; 10 (15): 8157–67
  • Chemically Controllable Porous Polymer-Nanocrystal Composites with Hierarchical Arrangement Show Substrate Transport Selectivity CHEMISTRY OF MATERIALS Riscoe, A. R., Wrasman, C. J., Menon, A., Dinakar, B., Goodman, E. D., Kunz, L. Y., Yacob, S., Cargnello, M. 2020; 32 (13): 5904–15
  • Formic acid oxidation boosted by Rh single atoms. Nature nanotechnology Kim, D., Cargnello, M. 2020

    View details for DOI 10.1038/s41565-020-0659-8

    View details for PubMedID 32231269

  • Dilute Pd/Au Alloys Replace Au/TiO2 Interface for Selective Oxidation Reactions ACS CATALYSIS Wrasman, C. J., Riscoe, A. R., Lee, H., Cargnello, M. 2020; 10 (3): 1716–20
  • A Combined Theory-Experiment Analysis of the Surface Species in Lithium-Mediated NH3 Electrosynthesis CHEMELECTROCHEM Schwalbe, J. A., Statt, M. J., Chosy, C., Singh, A. R., Rohr, B. A., Nielander, A. C., Andersen, S. Z., McEnaney, J. M., Baker, J. G., Jaramillo, T. F., Norskov, J. K., Cargnello, M. 2020
  • Design of Organic/Inorganic Hybrid Catalysts for Energy and Environmental Applications. ACS central science Goodman, E. D., Zhou, C., Cargnello, M. 2020; 6 (11): 1916–37


    Controlling selectivity between competing reaction pathways is crucial in catalysis. Several approaches have been proposed to achieve this goal in traditional heterogeneous catalysts including tuning nanoparticle size, varying alloy composition, and controlling supporting material. A less explored and promising research area to control reaction selectivity is via the use of hybrid organic/inorganic catalysts. These materials contain inorganic components which serve as sites for chemical reactions and organic components which either provide diffusional control or directly participate in the formation of active site motifs. Despite the appealing potential of these hybrid materials to increase reaction selectivity, there are significant challenges to the rational design of such hybrid nanostructures. Structural and mechanistic characterization of these materials play a key role in understanding and, therefore, designing these organic/inorganic hybrid catalysts. This Outlook highlights the design of hybrid organic/inorganic catalysts with a brief overview of four different classes of materials and discusses the practical catalytic properties and opportunities emerging from such designs in the area of energy and environmental transformations. Key structural and mechanistic characterization studies are identified to provide fundamental insight into the atomic structure and catalytic behavior of hybrid organic/inorganic catalysts. Exemplary works are used to show how specific active site motifs allow for remarkable changes in the reaction selectivity. Finally, to demonstrate the potential of hybrid catalyst materials, we suggest a characterization-based approach toward the design of biomimetic hybrid organic/inorganic materials for a specific application in the energy and environmental research space: the conversion of methane into methanol.

    View details for DOI 10.1021/acscentsci.0c01046

    View details for PubMedID 33274270

    View details for PubMedCentralID PMC7706093

  • Revealing the structure of a catalytic combustion active-site ensemble combining uniform nanocrystal catalysts and theory insights. Proceedings of the National Academy of Sciences of the United States of America Yang, A. C., Choksi, T., Streibel, V., Aljama, H., Wrasman, C. J., Roling, L. T., Goodman, E. D., Thomas, D., Bare, S. R., Sánchez-Carrera, R. S., Schäfer, A., Li, Y., Abild-Pedersen, F., Cargnello, M. 2020


    Supported metal catalysts are extensively used in industrial and environmental applications. To improve their performance, it is crucial to identify the most active sites. This identification is, however, made challenging by the presence of a large number of potential surface structures that complicate such an assignment. Often, the active site is formed by an ensemble of atoms, thus introducing further complications in its identification. Being able to produce uniform structures and identify the ones that are responsible for the catalyst performance is a crucial goal. In this work, we utilize a combination of uniform Pd/Pt nanocrystal catalysts and theory to reveal the catalytic active-site ensemble in highly active propene combustion materials. Using colloidal chemistry to exquisitely control nanoparticle size, we find that intrinsic rates for propene combustion in the presence of water increase monotonically with particle size on Pt-rich catalysts, suggesting that the reaction is structure dependent. We also reveal that water has a near-zero or mildly positive reaction rate order over Pd/Pt catalysts. Theory insights allow us to determine that the interaction of water with extended terraces present in large particles leads to the formation of step sites on metallic surfaces. These specific step-edge sites are responsible for the efficient combustion of propene at low temperature. This work reveals an elusive geometric ensemble, thus clearly identifying the active site in alkene combustion catalysts. These insights demonstrate how the combination of uniform catalysts and theory can provide a much deeper understanding of active-site geometry for many applications.

    View details for DOI 10.1073/pnas.2002342117

    View details for PubMedID 32554500

  • Nanoscale Spatial Distribution of Supported Nanoparticles Controls Activity and Stability in Powder Catalysts for CO Oxidation and Photocatalytic H2 Evolution. Journal of the American Chemical Society Holm, A., Goodman, E. D., Stenlid, J. H., Aitbekova, A., Zelaya, R., Diroll, B. T., Johnston-Peck, A. C., Kao, K. C., Frank, C. W., Pettersson, L. G., Cargnello, M. 2020; 142 (34): 14481–94


    Supported metal nanoparticles are essential components of high-performing catalysts, and their structures are intensely researched. In comparison, nanoparticle spatial distribution in powder catalysts is conventionally not quantified, and the influence of this collective property on catalyst performance remains poorly investigated. Here, we demonstrate a general colloidal self-assembly method to control uniformity of nanoparticle spatial distribution on common industrial powder supports. We quantify distributions on the nanoscale using image statistics and show that the type of nanospatial distribution determines not only the stability, but also the activity of heterogeneous catalysts. Widely investigated systems (Au-TiO2 for CO oxidation thermocatalysis and Pd-TiO2 for H2 evolution photocatalysis) were used to showcase the universal importance of nanoparticle spatial organization. Spatially and temporally resolved microkinetic modeling revealed that nonuniformly distributed Au nanoparticles suffer from local depletion of surface oxygen, and therefore lower CO oxidation activity, as compared to uniformly distributed nanoparticles. Nanoparticle spatial distribution also determines the stability of Pd-TiO2 photocatalysts, because nonuniformly distributed nanoparticles sinter while uniformly distributed nanoparticles do not. This work introduces new tools to evaluate and understand catalyst collective (ensemble) properties in powder catalysts, which thereby pave the way to more active and stable heterogeneous catalysts.

    View details for DOI 10.1021/jacs.0c03842

    View details for PubMedID 32786792

  • Transition state and product diffusion control by polymer-nanocrystal hybrid catalysts NATURE CATALYSIS Riscoe, A. R., Wrasman, C. J., Herzing, A. A., Hoffman, A. S., Menon, A., Boubnov, A., Vargas, M., Bare, S. R., Cargnello, M. 2019; 2 (10): 852–63
  • Engineering of Ruthenium-Iron Oxide Colloidal Heterostructures Leads to Improved Yields in CO2 Hydrogenation to Hydrocarbons. Angewandte Chemie (International ed. in English) Cargnello, M., Aitbekova, A., Goodman, E., Wu, L., Boubnov, A., Hoffman, A., Genc, A., Cheng, H., Casalena, L., Bare, S. 2019


    Catalytic CO2 reduction to fuels and chemicals is one of the major pursuits in reducing greenhouse gas emissions. One such popular approach utilizes the reverse water-gas shift reaction, followed by Fischer-Tropsch synthesis, and iron is a well-known candidate for this process. Some attempts have been made to modify and improve its reactivity, but resuted in limited success. In this work, using ruthenium-iron oxide colloidal heterodimers we demonstrate that close contact between the two phases promotes the reduction of iron oxide via a proximal hydrogen spillover effect, leading to the formation of ruthenium-iron core-shell structures active for the reaction at significantly lower temperatures than in bare iron catalysts. Furthermore, by engineering the iron oxide shell thickness, we achieve a fourfold increase in hydrocarbon yield compared to the heterodimers. In general, our work shows how rational design of colloidal heterostructures can result in materials with significantly improved catalytic performance in CO2 conversion processes.

    View details for DOI 10.1002/anie.201910579

    View details for PubMedID 31545533

  • Catalyst deactivation via decomposition into single atoms and the role of metal loading NATURE CATALYSIS Goodman, E. D., Johnston-Peck, A. C., Dietze, E. M., Wrasman, C. J., Hoffman, A. S., Abild-Pedersen, F., Bare, S. R., Plessow, P. N., Cargnello, M. 2019; 2 (9): 748–55
  • A Versatile Method for Ammonia Detection in a Range of Relevant Electrolytes via Direct Nuclear Magnetic Resonance Techniques ACS CATALYSIS Nielander, A. C., McEnaney, J. M., Schwalbe, J. A., Baker, J. G., Blair, S. J., Wang, L., Pelton, J. G., Andersen, S. Z., Enemark-Rasmussen, K., Colic, V., Yang, S., Bent, S. F., Cargnello, M., Kibsgaard, J., Vesborg, P. K., Chorkendorff, I., Jaramillo, T. F. 2019; 9 (7): 5797–5802
  • A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements. Nature Andersen, S. Z., Colic, V., Yang, S., Schwalbe, J. A., Nielander, A. C., McEnaney, J. M., Enemark-Rasmussen, K., Baker, J. G., Singh, A. R., Rohr, B. A., Statt, M. J., Blair, S. J., Mezzavilla, S., Kibsgaard, J., Vesborg, P. C., Cargnello, M., Bent, S. F., Jaramillo, T. F., Stephens, I. E., Norskov, J. K., Chorkendorff, I. 2019


    The electrochemical synthesis of ammonia from nitrogen under mild conditions and using renewable electricity is in principle an attractive alternative1-4 to the demanding, energy-intense Haber-Bosch process, which dominates industrial ammonia production. However, the electrochemical alternative faces considerable scientific and technical challenges5,6 and most experimental studies reported thus far achieve only low selectivities and conversions. In fact, the amount of ammonia produced is usually so small that it is difficult to firmly attribute it to electrochemical nitrogen fixation7-9 and exclude contamination due to ammonia that is either present in air, human breath or ion-conducting membranes9, or generated from labile nitrogen-containing compounds (for example, nitrates, amines, nitrites and nitrogen oxides) that are typically present in the nitrogen gas stream10, in the atmosphere or even the catalyst itself. Although these many and varied sources of potential experimental artefacts are beginning to be recognized and dealt with11,12, concerted efforts to develop effective electrochemical nitrogen reduction processes would benefit from benchmarking protocols for the reaction and from a standardized set of control experiments to identify and then eliminate or quantify contamination sources. Here we put forward such a rigorous procedure that, by making essential use of 15N2, allows us to reliably detect and quantify the electroreduction of N2 to NH3. We demonstrate experimentally the significance of various sources of contamination and show how to remove labile nitrogen-containing compounds present in the N2 gas and how to perform quantitative isotope measurements with cycling of 15N2 gas to reduce both contamination and the cost of isotope measurements. Following this protocol, we obtain negative results when using the most promising pure metal catalysts in aqueous media, and successfully confirm and quantify ammonia synthesis using lithium electrodeposition in tetrahydrofuran13.

    View details for DOI 10.1038/s41586-019-1260-x

    View details for PubMedID 31117118

  • Artificial inflation of apparent photocatalytic activity induced by catalyst-mass-normalization and a method to fairly compare heterojunction systems ENERGY & ENVIRONMENTAL SCIENCE Kunz, L. Y., Diroll, B. T., Wrasman, C. J., Riscoe, A. R., Majumdar, A., Cargnello, M. 2019; 12 (5): 1657–67

    View details for DOI 10.1039/c9ee00452a

    View details for Web of Science ID 000473083100015

  • Colloidal Nanocrystals as Building Blocks for Well-Defined Heterogeneous Catalysts CHEMISTRY OF MATERIALS Cargnello, M. 2019; 31 (3): 576–96
  • Colloidal nanocrystals for heterogeneous catalysis NANO TODAY Losch, P., Huang, W., Goodman, E. D., Wrasman, C. J., Holm, A., Riscoe, A. R., Schwalbe, J. A., Cargnello, M. 2019; 24: 15–47
  • Supported Catalyst Deactivation by Decomposition into Single Atoms Is Suppressed by Increasing Metal Loading. Nature catalysis Goodman, E. D., Johnston-Peck, A. C., Dietze, E. M., Wrasman, C. J., Hoffman, A. S., Abild-Pedersen, F., Bare, S. R., Plessow, P. N., Cargnello, M. 2019; 2


    In the high-temperature environments needed to perform catalytic processes, supported precious metal catalysts severely lose their activity over time. Even brief exposure to high temperatures can lead to significant losses in activity, which forces manufacturers to use large amounts of noble metals to ensure effective catalyst function for a required lifetime. Generally, loss of catalytic activity is attributed to nanoparticle sintering, or processes by which larger particles grow at the expense of smaller ones. Here, by independently controlling particle size and particle loading using colloidal nanocrystals, we reveal the opposite process as a novel deactivation mechanism: nanoparticles rapidly lose activity by high-temperature nanoparticle decomposition into inactive single atoms. This deactivation route is remarkably fast, leading to severe loss of activity in as little as ten minutes. Importantly, this deactivation pathway is strongly dependent on particle density and concentration of support defect sites. A quantitative statistical model explains how for certain reactions, higher particle densities can lead to more stable catalysts.

    View details for DOI 10.1038/s41929-019-0328-1

    View details for PubMedID 32118197

    View details for PubMedCentralID PMC7047889

  • Synthesis of Colloidal Pd/Au Dilute Alloy Nanocrystals and Their Potential for Selective Catalytic Oxidations. Journal of the American Chemical Society Wrasman, C. J., Boubnov, A., Riscoe, A. R., Hoffman, A. S., Bare, S. R., Cargnello, M. 2018


    Selective oxidations are crucial for the creation of valuable chemical building blocks but often require expensive and unstable stoichiometric oxidants such as hydroperoxides and peracids. To date, many catalysts that contain a single type of active site have not been able to attain the desired level of selectivity for partially oxidized products over total combustion. However, catalysts containing multiple types of active sites have proven to be successful for selective reactions. One category of such catalysts is bimetallic alloys, in which catalytic activity and selectivity can be tuned by modifying the surface composition. Traditional catalyst synthesis methods using impregnation struggle to create catalysts with sufficient control over surface chemistry to accurately tune the ensemble size of the desired active sites. Here we describe the synthesis of colloidal nanocrystals of dilute alloys of palladium and gold. We show that when supported on titania (TiO2), tuning the composition of the Pd/Au nanocrystal surface provides a synergistic effect in the selective oxidation of 2-propanol to acetone in the presence of H2 and O2. In particular, we show that certain Pd/Au surface ratios exhibit activity and selectivity far superior to Pd or Au individually. Through precise structural characterization we demonstrate that isolated atoms of Pd exist in the most active catalysts. The synergy between isolated Pd atoms and Au allows for the formation of reactive oxidizing species, likely hydroperoxide groups, responsible for selective oxidation while limiting oxygen dissociation and, thus, complete combustion. This work opens the way to more efficient utilization of scarce noble metals and new options for catalyzed selective oxidations.

    View details for PubMedID 30220200

  • Deconvoluting Transient Water Effects on the Activity of Pd Methane Combustion Catalysts INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH Huang, W., Goodman, E. D., Losch, P., Cargnello, M. 2018; 57 (31): 10261–68
  • In Situ X-ray Scattering Guides the Synthesis of Uniform PtSn Nanocrystals. Nano letters Wu, L., Fournier, A. P., Willis, J. J., Cargnello, M., Tassone, C. J. 2018


    Compared to monometallic nanocrystals (NCs), bimetallic ones often exhibit superior properties due to their wide tunability in structure and composition. A detailed understanding of their synthesis at the atomic scale provides crucial knowledge for their rational design. Here, exploring the Pt-Sn bimetallic system as an example, we study in detail the synthesis of PtSn NCs using in situ synchrotron X-ray scattering. We show that when Pt(II) and Sn(IV) precursors are used, in contrast to a typical simultaneous reduction mechanism, the PtSn NCs are formed through an initial reduction of Pt(II) to form Pt NCs, followed by the chemical transformation from Pt to PtSn. The kinetics derived from the in situ measurements shows fast diffusion of Sn into the Pt lattice accompanied by reordering of these atoms into intermetallic PtSn structure within 300 s at the reaction temperature (280 °C). This crucial mechanistic understanding enables the synthesis of well-defined PtSn NCs with controlled structure and composition via a seed-mediated approach. This type of in situ characterization can be extended to other multicomponent nanostructures to advance their rational synthesis for practical applications.

    View details for PubMedID 29812947

  • Low-Temperature Restructuring of CeO2-Supported Ru Nanoparticles Determines Selectivity in CO2 Catalytic Reduction. Journal of the American Chemical Society Aitbekova, A., Wu, L., Wrasman, C. J., Boubnov, A., Hoffman, A. S., Goodman, E. D., Bare, S. R., Cargnello, M. 2018; 140 (42): 13736–45


    CO2 reduction to higher value products is a promising way to produce fuels and key chemical building blocks while reducing CO2 emissions. The reaction at atmospheric pressure mainly yields CH4 via methanation and CO via the reverse water-gas shift (RWGS) reaction. Describing catalyst features that control the selectivity of these two pathways is important to determine the formation of specific products. At the same time, identification of morphological changes occurring to catalysts under reaction conditions can be crucial to tune their catalytic performance. In this contribution we investigate the dependency of selectivity for CO2 reduction on the size of Ru nanoparticles (NPs) and on support. We find that even at rather low temperatures (210 °C), oxidative pretreatment induces redispersion of Ru NPs supported on CeO2 and leads to a complete switch in the performance of this material from a well-known selective methanation catalyst to an active and selective RWGS catalyst. By utilizing in situ X-ray absorption spectroscopy, we demonstrate that the low-temperature redispersion process occurs via decomposition of the metal oxide phase with size-dependent kinetics, producing stable single-site RuO x/CeO2 species strongly bound to the CeO2 support that are remarkably selective for CO production. These results show that reaction selectivity can be heavily dependent on catalyst structure and that structural changes of the catalyst can occur even at low temperatures and can go unseen in materials with less defined structures.

    View details for PubMedID 30252458

  • High-temperature crystallization of nanocrystals into three-dimensional superlattices NATURE Wu, L., Willis, J. J., McKay, I., Diroll, B. T., Qin, J., Cargnello, M., Tassone, C. J. 2017; 548 (7666): 197-+


    Crystallization of colloidal nanocrystals into superlattices represents a practical bottom-up process with which to create ordered metamaterials with emergent functionalities. With precise control over the size, shape and composition of individual nanocrystals, various single- and multi-component nanocrystal superlattices have been produced, the lattice structures and chemical compositions of which can be accurately engineered. Nanocrystal superlattices are typically prepared by carefully controlling the assembly process through solvent evaporation or destabilization or through DNA-guided crystallization. Slow solvent evaporation or cooling of nanocrystal solutions (over hours or days) is the key element for successful crystallization processes. Here we report the rapid growth (seconds) of micrometre-sized, face-centred-cubic, three-dimensional nanocrystal superlattices during colloidal synthesis at high temperatures (more than 230 degrees Celsius). Using in situ small-angle X-ray scattering, we observe continuous growth of individual nanocrystals within the lattices, which results in simultaneous lattice expansion and fine nanocrystal size control due to the superlattice templates. Thermodynamic models demonstrate that balanced attractive and repulsive interparticle interactions dictated by the ligand coverage on nanocrystal surfaces and nanocrystal core size are responsible for the crystallization process. The interparticle interactions can also be controlled to form different superlattice structures, such as hexagonal close-packed lattices. The rational assembly of various nanocrystal systems into novel materials is thus facilitated for both fundamental research and for practical applications in the fields of magnetics, electronics and catalysis.

    View details for PubMedID 28759888

  • Systematic Identification of Promoters for Methane Oxidation Catalysts Using Size- and Composition-Controlled Pd-Based Bimetallic Nanocrystals. Journal of the American Chemical Society Willis, J. J., Goodman, E. D., Wu, L., Riscoe, A. R., Martins, P., Tassone, C. J., Cargnello, M. 2017; 139 (34): 11989–97


    Promoters enhance the performance of catalytic active phases by increasing rates, stability, and/or selectivity. The process of identifying promoters is in most cases empirical and relies on testing a broad range of catalysts prepared with the random deposition of active and promoter phases, typically with no fine control over their localization. This issue is particularly relevant in supported bimetallic systems, where two metals are codeposited onto high-surface area materials. We here report the use of colloidal bimetallic nanocrystals to produce catalysts where the active and promoter phases are colocalized to a fine extent. This strategy enables a systematic approach to study the promotional effects of several transition metals on palladium catalysts for methane oxidation. In order to achieve these goals, we demonstrate a single synthetic protocol to obtain uniform palladium-based bimetallic nanocrystals (PdM, M = V, Mn, Fe, Co, Ni, Zn, Sn, and potentially extendable to other metal combinations) with a wide variety of compositions and sizes based on high-temperature thermal decomposition of readily available precursors. Once the nanocrystals are supported onto oxide materials, thermal treatments in air cause segregation of the base metal oxide phase in close proximity to the Pd phase. We demonstrate that some metals (Fe, Co, and Sn) inhibit the sintering of the active Pd metal phase, while others (Ni and Zn) increase its intrinsic activity compared to a monometallic Pd catalyst. This procedure can be generalized to systematically investigate the promotional effects of metal and metal oxide phases for a variety of active metal-promoter combinations and catalytic reactions.

    View details for PubMedID 28800226

  • Elucidating the synergistic mechanism of nickel-molybdenum electrocatalysts for the hydrogen evolution reaction MRS COMMUNICATIONS Mckay, I. S., Schwalbe, J. A., Goodman, E. D., Willis, J. J., Majumdar, A., Cargnello, M. 2016; 6 (3): 241-246
  • Polycatenar Ligand Control of the Synthesis and Self-Assembly of Colloidal Nanocrystals JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Diroll, B. T., Jishkariani, D., Cargnello, M., Murray, C. B., Donnio, B. 2016; 138 (33): 10508-10515


    Hydrophobic colloidal nanocrystals are typically synthesized and manipulated with commercially available ligands, and surface functionalization is therefore typically limited to a small number of molecules. Here, we report the use of polycatenar ligands derived from polyalkylbenzoates for the direct synthesis of metallic, chalcogenide, pnictide, and oxide nanocrystals. Polycatenar molecules, branched structures bearing diverging chains in which the terminal substitution pattern, functionality, and binding group can be independently modified, offer a modular platform for the development of ligands with targeted properties. Not only are these ligands used for the direct synthesis of monodisperse nanocrystals, but nanocrystals coated with polycatenar ligands self-assemble into softer bcc superlattices that deviate from conventional harder close-packed structures (fcc or hcp) formed by the same nanocrystals coated with commercial ligands. Self-assembly experiments demonstrate that the molecular structure of polycatenar ligands encodes interparticle spacings and attractions, engineering self-assembly, which is tunable from hard sphere to soft sphere behavior.

    View details for DOI 10.1021/jacs.6b04979

    View details for Web of Science ID 000382181900025

    View details for PubMedID 27472457

  • Revealing particle growth mechanisms by combining high-surface-area catalysts made with monodisperse particles and electron microscopy conducted at atmospheric pressure JOURNAL OF CATALYSIS Zhang, S., Cargnello, M., Cai, W., Murray, C. B., Graham, G. W., Pan, X. 2016; 337: 240-247
  • Engineering titania nanostructure to tune and improve its photocatalytic activity PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Cargnello, M., Montini, T., Smolin, S. Y., Priebe, J. B., Jaen, J. J., Doan-Nguyen, V. V., Mckay, I. S., Schwalbe, J. A., Pohl, M., Gordon, T. R., Lu, Y., Baxter, J. B., Brueckner, A., Fornasiero, P., Murray, C. B. 2016; 113 (15): 3966-3971


    Photocatalytic pathways could prove crucial to the sustainable production of fuels and chemicals required for a carbon-neutral society. Electron-hole recombination is a critical problem that has, so far, limited the efficiency of the most promising photocatalytic materials. Here, we show the efficacy of anisotropy in improving charge separation and thereby boosting the activity of a titania (TiO2) photocatalytic system. Specifically, we show that H2 production in uniform, one-dimensional brookite titania nanorods is highly enhanced by engineering their length. By using complimentary characterization techniques to separately probe excited electrons and holes, we link the high observed reaction rates to the anisotropic structure, which favors efficient carrier utilization. Quantum yield values for hydrogen production from ethanol, glycerol, and glucose as high as 65%, 35%, and 6%, respectively, demonstrate the promise and generality of this approach for improving the photoactivity of semiconducting nanostructures for a wide range of reacting systems.

    View details for DOI 10.1073/pnas.1524806113

    View details for Web of Science ID 000373762400034

    View details for PubMedID 27035977

    View details for PubMedCentralID PMC4839447

  • Substitutional doping in nanocrystal superlattices NATURE Cargnello, M., Johnston-Peck, A. C., Diroll, B. T., Wong, E., Datta, B., Damodhar, D., Doan-Nguyen, V. V., Herzing, A. A., Kagan, C. R., Murray, C. B. 2015; 524 (7566): 450-?
  • Efficient Removal of Organic Ligands from Supported Nanocrystals by Fast Thermal Annealing Enables Catalytic Studies on Well-Defined Active Phases JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Cargnello, M., Chen, C., Diroll, B. T., Doan-Nguyen, V. V., Gorte, R. J., Murray, C. B. 2015; 137 (21): 6906-6911


    A simple yet efficient method to remove organic ligands from supported nanocrystals is reported for activating uniform catalysts prepared by colloidal synthesis procedures. The method relies on a fast thermal treatment in which ligands are quickly removed in air, before sintering can cause changes in the size and shape of the supported nanocrystals. A short treatment at high temperatures is found to be sufficient for activating the systems for catalytic reactions. We show that this method is widely applicable to nanostructures of different sizes, shapes, and compositions. Being rapid and effective, this procedure allows the production of monodisperse heterogeneous catalysts for studying a variety of structure-activity relationships. We show here results on methane steam reforming, where the particle size controls the CO/CO2 ratio on alumina-supported Pd, demonstrating the potential applications of the method in catalysis.

    View details for DOI 10.1021/jacs.5b03333

    View details for Web of Science ID 000355890600025

    View details for PubMedID 25961673

  • Dynamic structural evolution of supported palladium-ceria core-shell catalysts revealed by in situ electron microscopy. Nature communications Zhang, S., Chen, C., Cargnello, M., Fornasiero, P., Gorte, R. J., Graham, G. W., Pan, X. 2015; 6: 7778-?


    The exceptional activity for methane combustion of modular palladium-ceria core-shell subunits on silicon-functionalized alumina that was recently reported has created renewed interest in the potential of core-shell structures as catalysts. Here we report on our use of advanced ex situ and in situ electron microscopy with atomic resolution to show that the modular palladium-ceria core-shell subunits undergo structural evolution over a wide temperature range. In situ observations performed in an atmospheric gas cell within this temperature range provide real-time evidence that the palladium and ceria nanoparticle constituents of the palladium-ceria core-shell participate in a dynamical process that leads to the formation of an unanticipated structure comprised of an intimate mixture of palladium, cerium, silicon and oxygen, with very high dispersion. This finding may open new perspectives about the origin of the activity of this catalyst.

    View details for DOI 10.1038/ncomms8778

    View details for PubMedID 26160065

    View details for PubMedCentralID PMC4510970

  • Substitutional doping in nanocrystal superlattices. Nature Cargnello, M., Johnston-Peck, A. C., Diroll, B. T., Wong, E., Datta, B., Damodhar, D., Doan-Nguyen, V. V., Herzing, A. A., Kagan, C. R., Murray, C. B. 2015; 524 (7566): 450–53


    Doping is a process in which atomic impurities are intentionally added to a host material to modify its properties. It has had a revolutionary impact in altering or introducing electronic, magnetic, luminescent, and catalytic properties for several applications, for example in semiconductors. Here we explore and demonstrate the extension of the concept of substitutional atomic doping to nanometre-scale crystal doping, in which one nanocrystal is used to replace another to form doped self-assembled superlattices. Towards this goal, we show that gold nanocrystals act as substitutional dopants in superlattices of cadmium selenide or lead selenide nanocrystals when the size of the gold nanocrystal is very close to that of the host. The gold nanocrystals occupy random positions in the superlattice and their density is readily and widely controllable, analogous to the case of atomic doping, but here through nanocrystal self-assembly. We also show that the electronic properties of the superlattices are highly tunable and strongly affected by the presence and density of the gold nanocrystal dopants. The conductivity of lead selenide films, for example, can be manipulated over at least six orders of magnitude by the addition of gold nanocrystals and is explained by a percolation model. As this process relies on the self-assembly of uniform nanocrystals, it can be generally applied to assemble a wide variety of nanocrystal-doped structures for electronic, optical, magnetic, and catalytic materials.

    View details for PubMedID 26310766

  • Solution-Phase Synthesis of Titanium Dioxide Nanoparticles and Nanocrystals CHEMICAL REVIEWS Cargnello, M., Gordon, T. R., Murray, C. B. 2014; 114 (19): 9319-9345

    View details for DOI 10.1021/cr500170p

    View details for Web of Science ID 000343017900003

    View details for PubMedID 25004056

  • Enhanced Energy Transfer in Quasi-Quaternary Nanocrystal Superlattices ADVANCED MATERIALS Cargnello, M., Diroll, B. T., Gaulding, E. A., Murray, C. B. 2014; 26 (15): 2419-2423


    Quasi-quaternary nanocrystal superlattices are assembled by using exclusively core-shell particles as building blocks. The assemblies show an enhancement of energy-transfer from cadmium selenide-based core-shell quantum dots to gold-iron oxide core-shell nanocrystals compared to random mixtures of the same components.

    View details for DOI 10.1002/adma.201304136

    View details for Web of Science ID 000334181400019

    View details for PubMedID 24357329

  • Control of Metal Nanocrystal Size Reveals Metal-Support Interface Role for Ceria Catalysts SCIENCE Cargnello, M., Doan-Nguyen, V. V., Gordon, T. R., Diaz, R. E., Stach, E. A., Gorte, R. J., Fornasiero, P., Murray, C. B. 2013; 341 (6147): 771-773


    Interactions between ceria (CeO2) and supported metals greatly enhance rates for a number of important reactions. However, direct relationships between structure and function in these catalysts have been difficult to extract because the samples studied either were heterogeneous or were model systems dissimilar to working catalysts. We report rate measurements on samples in which the length of the ceria-metal interface was tailored by the use of monodisperse nickel, palladium, and platinum nanocrystals. We found that carbon monoxide oxidation in ceria-based catalysts is greatly enhanced at the ceria-metal interface sites for a range of group VIII metal catalysts, clarifying the pivotal role played by the support.

    View details for DOI 10.1126/science.1240148

    View details for Web of Science ID 000323122200043

    View details for PubMedID 23868919

  • Exceptional Activity for Methane Combustion over Modular Pd@CeO2 Subunits on Functionalized Al2O3 SCIENCE Cargnello, M., Delgado Jaen, J. J., Hernandez Garrido, J. C., Bakhmutsky, K., Montini, T., Calvino Gamez, J. J., Gorte, R. J., Fornasiero, P. 2012; 337 (6095): 713-717


    There is a critical need for improved methane-oxidation catalysts to both reduce emissions of methane, a greenhouse gas, and improve the performance of gas turbines. However, materials that are currently available either have low activity below 400°C or are unstable at higher temperatures. Here, we describe a supramolecular approach in which single units composed of a palladium (Pd) core and a ceria (CeO(2)) shell are preorganized in solution and then homogeneously deposited onto a modified hydrophobic alumina. Electron microscopy and other structural methods revealed that the Pd cores remained isolated even after heating the catalyst to 850°C. Enhanced metal-support interactions led to exceptionally high methane oxidation, with complete conversion below 400°C and outstanding thermal stability under demanding conditions.

    View details for DOI 10.1126/science.1222887

    View details for Web of Science ID 000307354500049

    View details for PubMedID 22879514

  • Multiwalled Carbon Nanotubes Drive the Activity of Metal@oxide Core-Shell Catalysts in Modular Nanocomposites JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Cargnello, M., Grzelczak, M., Rodriguez-Gonzalez, B., Syrgiannis, Z., Bakhmutsky, K., La Parola, V., Liz-Marzan, L. M., Gorte, R. J., Prato, M., Fornasiero, P. 2012; 134 (28): 11760-11766


    Rational nanostructure manipulation has been used to prepare nanocomposites in which multiwalled carbon nanotubes (MWCNTs) were embedded inside mesoporous layers of oxides (TiO(2), ZrO(2), or CeO(2)), which in turn contained dispersed metal nanoparticles (Pd or Pt). We show that the MWCNTs induce the crystallization of the oxide layer at room temperature and that the mesoporous oxide shell allows the particles to be accessible for catalytic reactions. In contrast to samples prepared in the absence of MWCNTs, both the activity and the stability of core-shell catalysts is largely enhanced, resulting in nanocomposites with remarkable performance for the water-gas-shift reaction, photocatalytic reforming of methanol, and Suzuki coupling. The modular approach shown here demonstrates that high-performance catalytic materials can be obtained through the precise organization of nanoscale building blocks.

    View details for DOI 10.1021/ja304398b

    View details for Web of Science ID 000306457900068

    View details for PubMedID 22716042

  • Nonaqueous Synthesis of TiO2 Nanocrystals Using TiF4 to Engineer Morphology, Oxygen Vacancy Concentration, and Photocatalytic Activity JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Gordon, T. R., Cargnello, M., Paik, T., Mangolini, F., Weber, R. T., Fornasiero, P., Murray, C. B. 2012; 134 (15): 6751-6761


    Control over faceting in nanocrystals (NCs) is pivotal for many applications, but most notably when investigating catalytic reactions which occur on the surfaces of nanostructures. Anatase titanium dioxide (TiO(2)) is one of the most studied photocatalysts, but the shape dependence of its activity has not yet been satisfactorily investigated and many questions still remain unanswered. We report the nonaqueous surfactant-assisted synthesis of highly uniform anatase TiO(2) NCs with tailorable morphology in the 10-100 nm size regime, prepared through a seeded growth technique. Introduction of titanium(IV) fluoride (TiF(4)) preferentially exposes the {001} facet of anatase through in situ release of hydrofluoric acid (HF), allowing for the formation of uniform anatase NCs based on the truncated tetragonal bipyramidal geometry. A method is described to engineer the percentage of {001} and {101} facets through the choice of cosurfactant and titanium precursor. X-ray diffraction studies are performed in conjunction with simulation to determine an average NC dimension which correlates with results obtained using electron microscopy. In addition to altering the particle shape, the introduction of TiF(4) into the synthesis results in TiO(2) NCs that are blue in color and display a broad visible/NIR absorbance which peaks in the infrared (λ(max) ≈ 3400 nm). The blue color results from oxygen vacancies formed in the presence of fluorine, as indicated by electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) studies. The surfactants on the surface of the NCs are removed through a simple ligand exchange procedure, allowing the shape dependence of photocatalytic hydrogen evolution to be studied using monodisperse TiO(2) NCs. Preliminary experiments on the photoreforming of methanol, employed as a model sacrificial agent, on platinized samples resulted in high volumes of evolved hydrogen (up to 2.1 mmol h(-1) g(-1)) under simulated solar illumination. Remarkably, the data suggest that, under our experimental conditions, the {101} facets of anatase are more active than the {001}.

    View details for DOI 10.1021/ja300823a

    View details for Web of Science ID 000302887300038

    View details for PubMedID 22444667

  • Synthesis of Dispersible Pd@CeO2 Core-Shell Nanostructures by Self-Assembly JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Cargnello, M., Wieder, N. L., Montini, T., Gorte, R. J., Fornasiero, P. 2010; 132 (4): 1402-1409


    A methodology is described for the preparation of Pd@CeO(2) core-shell nanostructures that are easily dispersible in common organic solvents. The method involves the synthesis of Pd nanoparticles protected by a monolayer of 11-mercaptoundecanoic acid (MUA). The carboxylic groups on the nanoparticle surfaces are used to direct the self-assembly of a cerium(IV) alkoxide around the metal particles, followed by the controlled hydrolysis to form CeO(2). The characterization of the nanostructures by means of different techniques, in particular by electron microscopy, allowed us to demonstrate the nature of core-shell systems, with CeO(2) nanocrystals forming a shell around the MUA-protected Pd core. Finally, an example of the use of these nanostructures as flexible precursors for the preparation of heterogeneous catalysts is reported by investigating the reactivity of Pd@CeO(2)/Al(2)O(3) nanocomposites toward CO oxidation, water-gas shift (WGS), and methanol steam reforming reactions. Together with CO adsorption data, these observations suggest the accessibility of the Pd phase in the nanocomposites.

    View details for DOI 10.1021/ja909131k

    View details for Web of Science ID 000275084800058

    View details for PubMedID 20043676