Honors & Awards


  • Kavli Energy NanoScience Institute Best Thesis Prize, Kavli Energy NanoScience Institute (2018)
  • MRS Graduate Student Award Silver, MRS (2018)
  • Schmidt Science Fellow Finalist (Inaugural cohort), Schmidt Science Fellows (2018)
  • Gareth Thomas Materials Excellence Award, UC Berkeley (2017)
  • Samsung Scholar, Samsung Scholarship (2012 - 2017)

Professional Education


  • Doctor of Philosophy, University of California Berkeley (2018)
  • Master of Science, University of California Berkeley (2014)

Patents


  • Peidong Yang, Qiao Kong, Dohyung Kim, Chong Liu. "United States Patent 11047055 Method of depositing nanoparticles on an array of nanowires", Jun 29, 2021
  • Peidong Yang, Dohyung Kim. "United States Patent 10704153 Copper nanoparticle structures for reduction of carbon dioxide to multicarbon products", Jul 7, 2020

All Publications


  • Nanoparticle Assembly Induced Ligand Interactions for Enhanced Electrocatalytic CO2 Conversion. Journal of the American Chemical Society Yu, S., Kim, D., Qi, Z., Louisia, S., Li, Y., Somorjai, G. A., Yang, P. 2021

    Abstract

    The microenvironment in which the catalysts are situated is as important as the active sites in determining the overall catalytic performance. Recently, it has been found that nanoparticle (NP) surface ligands can actively participate in creating a favorable catalytic microenvironment, as part of the nanoparticle/ordered-ligand interlayer (NOLI), for selective CO2 conversion. However, much of the ligand-ligand interactions presumed essential to the formation of such a catalytic interlayer remains to be understood. Here, by varying the initial size of NPs and utilizing spectroscopic and electrochemical techniques, we show that the assembly of NPs leads to the necessary ligand interactions for the NOLI formation. The large surface curvature of small NPs promotes strong noncovalent interactions between ligands of adjacent NPs through ligand interdigitation. This ensures their collective behavior in electrochemical conditions and gives rise to the structurally ordered ligand layer of the NOLI. Thus, the use of smaller NPs was shown to result in a greater catalytically effective NOLI area associated with desolvated cations and electrostatic stabilization of intermediates, leading to the enhancement of intrinsic CO2-to-CO turnover. Our findings highlight the potential use of tailored microenvironments for NP catalysis by controlling its surface ligand interactions.

    View details for DOI 10.1021/jacs.1c09777

    View details for PubMedID 34783547

  • Voltage cycling process for the electroconversion of biomass-derived polyols. Proceedings of the National Academy of Sciences of the United States of America Kim, D., Zhou, C., Zhang, M., Cargnello, M. 2021; 118 (41)

    Abstract

    Electrification of chemical reactions is crucial to fundamentally transform our society that is still heavily dependent on fossil resources and unsustainable practices. In addition, electrochemistry-based approaches offer a unique way of catalyzing reactions by the fast and continuous alteration of applied potentials, unlike traditional thermal processes. Here, we show how the continuous cyclic application of electrode potential allows Pt nanoparticles to electrooxidize biomass-derived polyols with turnover frequency improved by orders of magnitude compared with the usual rates at fixed potential conditions. Moreover, secondary alcohol oxidation is enhanced, with a ketoses-to-aldoses ratio increased up to sixfold. The idea has been translated into the construction of a symmetric single-compartment system in a two-electrode configuration. Its operation via voltage cycling demonstrates high-rate sorbitol electrolysis with the formation of H2 as a desired coproduct at operating voltages below 1.4 V. The devised method presents a potential approach to using renewable electricity to drive chemical processes.

    View details for DOI 10.1073/pnas.2113382118

    View details for PubMedID 34615713

  • Selective CO2 electrocatalysis at the pseudocapacitive nanoparticle/ordered-ligand interlayer NATURE ENERGY Kim, D., Yu, S., Zheng, F., Roh, I., Li, Y., Louisia, S., Qi, Z., Somorjai, G. A., Frei, H., Wang, L., Yang, P. 2020; 5 (12): 1032-1042
  • Electrochemically scrambled nanocrystals are catalytically active for CO2-to-multicarbons PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Li, Y., Kim, D., Louisia, S., Xie, C., Kong, Q., Yu, S., Lin, T., Aloni, S., Fakra, S. C., Yang, P. 2020; 117 (17): 9194-9201

    Abstract

    Promotion of C-C bonds is one of the key fundamental questions in the field of CO2 electroreduction. Much progress has occurred in developing bulk-derived Cu-based electrodes for CO2-to-multicarbons (CO2-to-C2+), especially in the widely studied class of high-surface-area "oxide-derived" copper. However, fundamental understanding into the structural characteristics responsible for efficient C-C formation is restricted by the intrinsic activity of these catalysts often being comparable to polycrystalline copper foil. By closely probing a Cu nanoparticle (NP) ensemble catalyst active for CO2-to-C2+, we show that bias-induced rapid fusion or "electrochemical scrambling" of Cu NPs creates disordered structures intrinsically active for low overpotential C2+ formation, exhibiting around sevenfold enhancement in C2+ turnover over crystalline Cu. Integrating ex situ, passivated ex situ, and in situ analyses reveals that the scrambled state exhibits several structural signatures: a distinct transition to single-crystal Cu2O cubes upon air exposure, low crystallinity upon passivation, and high mobility under bias. These findings suggest that disordered copper structures facilitate C-C bond formation from CO2 and that electrochemical nanocrystal scrambling is an avenue toward creating such catalysts.

    View details for DOI 10.1073/pnas.1918602117

    View details for Web of Science ID 000530099500017

    View details for PubMedID 32295882

    View details for PubMedCentralID PMC7196911

  • 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

  • Surface and Interface Control in Nanoparticle Catalysis CHEMICAL REVIEWS Xie, C., Niu, Z., Kim, D., Li, M., Yang, P. 2020; 120 (2): 1184-1249

    Abstract

    The surface and interfaces of heterogeneous catalysts are essential to their performance as they are often considered to be active sites for catalytic reactions. With the development of nanoscience, the ability to tune surface and interface of nanostructures has provided a versatile tool for the development and optimization of a heterogeneous catalyst. In this Review, we present the surface and interface control of nanoparticle catalysts in the context of oxygen reduction reaction (ORR), electrochemical CO2 reduction reaction (CO2 RR), and tandem catalysis in three sections. In the first section, we start with the activity of ORR on the nanoscale surface and then focus on the approaches to optimize the performance of Pt-based catalyst including using alloying, core-shell structure, and high surface area open structures. In the section of CO2 RR, where the surface composition of the catalysts plays a dominant role, we cover its reaction fundamentals and the performance of different nanosized metal catalysts. For tandem catalysis, where adjacent catalytic interfaces in a single nanostructure catalyze sequential reactions, we describe its concept and principle, catalyst synthesis methodology, and application in different reactions.

    View details for DOI 10.1021/acs.chemrev.9b00220

    View details for Web of Science ID 000509426800014

    View details for PubMedID 31580651

  • Designing materials for electrochemical carbon dioxide recycling NATURE CATALYSIS Ross, M. B., De Luna, P., Li, Y., Dinh, C., Kim, D., Yang, P., Sargent, E. H. 2019; 2 (8): 648-658
  • Electrocatalytic Rate Alignment Enhances Syngas Generation JOULE Ross, M. B., Li, Y., De Luna, P., Kim, D., Sargent, E. H., Yang, P. 2019; 3 (1): 257-264
  • Strongly Quantum Confined Colloidal Cesium Tin Iodide Perovskite Nanoplates: Lessons for Reducing Defect Density and Improving Stability NANO LETTERS Wong, A., Bekenstein, Y., Kang, J., Kley, C. S., Kim, D., Gibson, N. A., Zhang, D., Yu, Y., Leone, S. R., Wang, L., Alivisatos, A., Yang, P. 2018; 18 (3): 2060-2066

    Abstract

    Within the last several years, metal halide perovskites such as methylammonium lead iodide, CH3NH3PbI3, have come to the forefront of scientific investigation as defect-tolerant, solution-processable semiconductors that exhibit excellent optoelectronic properties. The vast majority of study has focused on Pb-based perovskites, which have limited applications because of their inherent toxicity. To enable the broad application of these materials, the properties of lead-free halide perovskites must be explored. Here, two-dimensional, lead-free cesium tin iodide, (CsSnI3), perovskite nanoplates have been synthesized and characterized for the first time. These CsSnI3 nanoplates exhibit thicknesses of less than 4 nm and exhibit significant quantum confinement with photoluminescence at 1.59 eV compared to 1.3 eV in the bulk. Ab initio calculations employing the generalized gradient approximation of Perdew-Burke-Ernzerhof elucidate that although the dominant intrinsic defects in CsSnI3 do not introduce deep levels inside the band gap, their concentration can be quite high. These simulations also highlight that synthesizing and processing CsSnI3 in Sn-rich conditions can reduce defect density and increase stability, which matches insights gained experimentally. This improvement in the understanding of CsSnI3 represents a step toward the broader challenge of building a deeper understanding of Sn-based halide perovskites and developing design principles that will lead to their successful application in optoelectronic devices.

    View details for DOI 10.1021/acs.nanolett.8b00077

    View details for Web of Science ID 000427910600069

    View details for PubMedID 29504759

  • Copper nanoparticle ensembles for selective electroreduction of CO2 to C-2-C-3 products PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Kim, D., Kley, C. S., Li, Y., Yang, P. 2017; 114 (40): 10560-10565

    Abstract

    Direct conversion of carbon dioxide to multicarbon products remains as a grand challenge in electrochemical CO2 reduction. Various forms of oxidized copper have been demonstrated as electrocatalysts that still require large overpotentials. Here, we show that an ensemble of Cu nanoparticles (NPs) enables selective formation of C2-C3 products at low overpotentials. Densely packed Cu NP ensembles underwent structural transformation during electrolysis into electrocatalytically active cube-like particles intermixed with smaller nanoparticles. Ethylene, ethanol, and n-propanol are the major C2-C3 products with onset potential at -0.53 V (vs. reversible hydrogen electrode, RHE) and C2-C3 faradaic efficiency (FE) reaching 50% at only -0.75 V. Thus, the catalyst exhibits selective generation of C2-C3 hydrocarbons and oxygenates at considerably lowered overpotentials in neutral pH aqueous media. In addition, this approach suggests new opportunities in realizing multicarbon product formation from CO2, where the majority of efforts has been to use oxidized copper-based materials. Robust catalytic performance is demonstrated by 10 h of stable operation with C2-C3 current density 10 mA/cm2 (at -0.75 V), rendering it attractive for solar-to-fuel applications. Tafel analysis suggests reductive CO coupling as a rate determining step for C2 products, while n-propanol (C3) production seems to have a discrete pathway.

    View details for DOI 10.1073/pnas.1711493114

    View details for Web of Science ID 000412130500043

    View details for PubMedID 28923930

    View details for PubMedCentralID PMC5635920

  • Control of Architecture in Rhombic Dodecahedral Pt-Ni Nanoframe Electrocatalysts JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Becknell, N., Son, Y., Kim, D., Li, D., Yu, Y., Niu, Z., Lei, T., Sneed, B. T., More, K. L., Markovic, N. M., Stamenkovic, V. R., Yang, P. 2017; 139 (34): 11678-11681

    Abstract

    Platinum-based alloys are known to demonstrate advanced properties in electrochemical reactions that are relevant for proton exchange membrane fuel cells and electrolyzers. Further development of Pt alloy electrocatalysts relies on the design of architectures with highly active surfaces and optimized utilization of the expensive element, Pt. Here, we show that the three-dimensional Pt anisotropy of Pt-Ni rhombic dodecahedra can be tuned by controlling the ratio between Pt and Ni precursors such that either a completely hollow nanoframe or a new architecture, the excavated nanoframe, can be obtained. The excavated nanoframe showed ∼10 times higher specific and ∼6 times higher mass activity for the oxygen reduction reaction than Pt/C, and twice the mass activity of the hollow nanoframe. The high activity is attributed to enhanced Ni content in the near-surface region and the extended two-dimensional sheet structure within the nanoframe that minimizes the number of buried Pt sites.

    View details for DOI 10.1021/jacs.7b05584

    View details for Web of Science ID 000409286000011

    View details for PubMedID 28787139

  • Tunable Cu Enrichment Enables Designer Syngas Electrosynthesis from CO2 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Ross, M. B., Cao Thang Dinh, Li, Y., Kim, D., De Luna, P., Sargent, E. H., Yang, P. 2017; 139 (27): 9359-9363

    Abstract

    Using renewable energy to recycle CO2 provides an opportunity to both reduce net CO2 emissions and synthesize fuels and chemical feedstocks. It is of central importance to design electrocatalysts that both are efficient and can access a tunable spectrum of products. Syngas, a mixture of carbon monoxide (CO) and hydrogen (H2), is an important chemical precursor that can be converted downstream into small molecules or larger hydrocarbons by fermentation or thermochemistry. Many processes that utilize syngas require different syngas compositions: we therefore pursued the rational design of a family of electrocatalysts that can be programmed to synthesize different designer syngas ratios. We utilize in situ surface-enhanced Raman spectroscopy and first-principles density functional theory calculations to develop a systematic picture of CO* binding on Cu-enriched Au surface model systems. Insights from these model systems are then translated to nanostructured electrocatalysts, whereby controlled Cu enrichment enables tunable syngas production while maintaining current densities greater than 20 mA/cm2.

    View details for DOI 10.1021/jacs.7b04892

    View details for Web of Science ID 000405642400040

    View details for PubMedID 28660764

  • through Atomic Ordering Transformations of AuCu Nanoparticles. Journal of the American Chemical Society Kim, D., Xie, C., Becknell, N., Yu, Y., Karamad, M., Chan, K., Crumlin, E. J., Nørskov, J. K., Yang, P. 2017

    Abstract

    Precise control of elemental configurations within multimetallic nanoparticles (NPs) could enable access to functional nanomaterials with significant performance benefits. This can be achieved down to the atomic level by the disorder-to-order transformation of individual NPs. Here, by systematically controlling the ordering degree, we show that the atomic ordering transformation, applied to AuCu NPs, activates them to perform as selective electrocatalysts for CO2 reduction. In contrast to the disordered alloy NP, which is catalytically active for hydrogen evolution, ordered AuCu NPs selectively converted CO2 to CO at faradaic efficiency reaching 80%. CO formation could be achieved with a reduction in overpotential of ∼200 mV, and catalytic turnover was enhanced by 3.2-fold. In comparison to those obtained with a pure gold catalyst, mass activities could be improved as well. Atomic-level structural investigations revealed three atomic gold layers over the intermetallic core to be sufficient for enhanced catalytic behavior, which is further supported by DFT analysis.

    View details for DOI 10.1021/jacs.7b03516

    View details for PubMedID 28551991

  • Ultrathin Epitaxial Cu@Au Core-Shell Nanowires for Stable Transparent Conductors JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Niu, Z., Cui, F., Yu, Y., Becknell, N., Sun, Y., Khanarian, G., Kim, D., Dou, L., Dehestani, A., Schierle-Arndt, K., Yang, P. 2017; 139 (21): 7348-7354

    Abstract

    Copper nanowire networks are considered a promising alternative to indium tin oxide as transparent conductors. The fast degradation of copper in ambient conditions, however, largely overshadows their practical applications. Here, we develop the synthesis of ultrathin Cu@Au core-shell nanowires using trioctylphosphine as a strong binding ligand to prevent galvanic replacement reactions. The epitaxial overgrowth of a gold shell with a few atomic layers on the surface of copper nanowires can greatly enhance their resistance to heat (80 °C), humidity (80%) and air for at least 700 h, while their optical and electrical performance remained similar to the original high-performance copper (e.g., sheet resistance 35 Ω sq-1 at transmittance of ∼89% with a haze factor <3%). The precise engineering of core-shell nanostructures demonstrated in this study offers huge potential to further explore the applications of copper nanowires in flexible and stretchable electronic and optoelectronic devices.

    View details for DOI 10.1021/jacs.7b02884

    View details for Web of Science ID 000402691800032

    View details for PubMedID 28482149

  • Room-Temperature Dynamics of Vanishing Copper Nanoparticles Supported on Silica NANO LETTERS Kim, D., Becknell, N., Yu, Y., Yang, P. 2017; 17 (4): 2732-2737

    Abstract

    In heterogeneous catalysis, a nanoparticle (NP) system has immediate chemical surroundings with which its interaction needs to be considered, as nanoparticles are typically loaded onto certain supports. Beyond what is known about these interactions, dynamic atomic interactions between the nanoparticle and support could result from the increased energetics at the nanoscale. Here, we show that the dynamic response of atoms in copper nanoparticles to the underlying silica support at room temperature and ambient atmosphere results in the complete disappearance of supported nanoparticles over the course of only a few weeks. A quantitative study of copper nanoparticles at various size regimes (6-17 nm) revealed the significance of size-dependent nanoparticle energetics to the interaction with the support. Extended X-ray absorption fine structure is used to show that copper atoms could readily diffuse into the support to be locally surrounded by oxygen and silicon with structurally disordered outer coordination shells. Increased energetic states at the nanoscale and the energetically favorable configuration of individual copper atoms within silica, identified through EXAFS, are suggested as the cause of nanoparticle disappearance. This unexpected observation opens up new questions as to how nanoparticles interact with surrounding environments that could fundamentally change our conventional view of supported nanoparticle systems.

    View details for DOI 10.1021/acs.nanolett.7b00942

    View details for Web of Science ID 000399354500090

    View details for PubMedID 28293956

  • Structure-Sensitive CO2 Electroreduction to Hydrocarbons on Ultrathin 5-fold Twinned Copper Nanowires NANO LETTERS Li, Y., Cui, F., Ross, M. B., Kim, D., Sun, Y., Yang, P. 2017; 17 (2): 1312-1317

    Abstract

    Copper is uniquely active for the electrocatalytic reduction of carbon dioxide (CO2) to products beyond carbon monoxide, such as methane (CH4) and ethylene (C2H4). Therefore, understanding selectivity trends for CO2 electrocatalysis on copper surfaces is critical for developing more efficient catalysts for CO2 conversion to higher order products. Herein, we investigate the electrocatalytic activity of ultrathin (diameter ∼20 nm) 5-fold twinned copper nanowires (Cu NWs) for CO2 reduction. These Cu NW catalysts were found to exhibit high CH4 selectivity over other carbon products, reaching 55% Faradaic efficiency (FE) at -1.25 V versus reversible hydrogen electrode while other products were produced with less than 5% FE. This selectivity was found to be sensitive to morphological changes in the nanowire catalyst observed over the course of electrolysis. Wrapping the wires with graphene oxide was found to be a successful strategy for preserving both the morphology and reaction selectivity of the Cu NWs. These results suggest that product selectivity on Cu NWs is highly dependent on morphological features and that hydrocarbon selectivity can be manipulated by structural evolution or the prevention thereof.

    View details for DOI 10.1021/acs.nanolett.6b05287

    View details for Web of Science ID 000393848800101

    View details for PubMedID 28094953

  • Plasmon-Enhanced PhotoCatalytic CO2 Conversion within Metal Organic Frameworks under Visible Light JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Choi, K., Kim, D., Rungtaweevoranit, B., Trickett, C. A., Barmanbek, J., Alshammari, A. S., Yang, P., Yaghi, O. M. 2017; 139 (1): 356-362

    Abstract

    Materials development for artificial photosynthesis, in particular, CO2 reduction, has been under extensive efforts, ranging from inorganic semiconductors to molecular complexes. In this report, we demonstrate a metal-organic framework (MOF)-coated nanoparticle photocatalyst with enhanced CO2 reduction activity and stability, which stems from having two different functional units for activity enhancement and catalytic stability combined together as a single construct. Covalently attaching a CO2-to-CO conversion photocatalyst ReI(CO)3(BPYDC)Cl, BPYDC = 2,2'-bipyridine-5,5'-dicarboxylate, to a zirconium MOF, UiO-67 (Ren-MOF), prevents dimerization leading to deactivation. By systematically controlling its density in the framework (n = 0, 1, 2, 3, 5, 11, 16, and 24 complexes per unit cell), the highest photocatalytic activity was found for Re3-MOF. Structural analysis of Ren-MOFs suggests that a fine balance of proximity between photoactive centers is needed for cooperatively enhanced photocatalytic activity, where an optimum number of Re complexes per unit cell should reach the highest activity. Based on the structure-activity correlation of Ren-MOFs, Re3-MOF was coated onto Ag nanocubes (Ag⊂Re3-MOF), which spatially confined photoactive Re centers to the intensified near-surface electric fields at the surface of Ag nanocubes, resulting in a 7-fold enhancement of CO2-to-CO conversion under visible light with long-term stability maintained up to 48 h.

    View details for DOI 10.1021/jacs.6b11027

    View details for Web of Science ID 000392036900054

    View details for PubMedID 28004911

  • Anisotropic phase segregation and migration of Pt in nanocrystals en route to nanoframe catalysts NATURE MATERIALS Niu, Z., Becknell, N., Yu, Y., Kim, D., Chen, C., Kornienko, N., Somorjai, G. A., Yang, P. 2016; 15 (11): 1188-+

    Abstract

    Compositional heterogeneity in shaped, bimetallic nanocrystals offers additional variables to manoeuvre the functionality of the nanocrystal. However, understanding how to manipulate anisotropic elemental distributions in a nanocrystal is a great challenge in reaching higher tiers of nanocatalyst design. Here, we present the evolutionary trajectory of phase segregation in Pt-Ni rhombic dodecahedra. The anisotropic growth of a Pt-rich phase along the 〈111〉 and 〈200〉 directions at the initial growth stage results in Pt segregation to the 14 axes of a rhombic dodecahedron, forming a highly branched, Pt-rich tetradecapod structure embedded in a Ni-rich shell. With longer growth time, the Pt-rich phase selectively migrates outwards through the 14 axes to the 24 edges such that the rhombic dodecahedron becomes a Pt-rich frame enclosing a Ni-rich interior phase. The revealed anisotropic phase segregation and migration mechanism offers a radically different approach to fabrication of nanocatalysts with desired compositional distributions and performance.

    View details for DOI 10.1038/NMAT4724

    View details for Web of Science ID 000386377000015

    View details for PubMedID 27525570

  • Directed Assembly of Nanoparticle Catalysts on Nanowire Photoelectrodes for Photoelectrochemical CO2 Reduction NANO LETTERS Kong, Q., Kim, D., Liu, C., Yu, Y., Su, Y., Li, Y., Yang, P. 2016; 16 (9): 5675-5680

    Abstract

    Reducing carbon dioxide with a multicomponent artificial photosynthetic system, closely mimicking nature, represents a promising approach for energy storage. Previous works have focused on exploiting light-harvesting semiconductor nanowires (NW) for photoelectrochemical water splitting. With the newly developed CO2 reduction nanoparticle (NP) catalysts, direct interfacing of these nanocatalysts with NW light absorbers for photoelectrochemical reduction of CO2 becomes feasible. Here, we demonstrate a directed assembly of NP catalysts on vertical NW substrates for CO2-to-CO conversion under illumination. Guided by the one-dimensional geometry, well-dispersed assembly of Au3Cu NPs on the surface of Si NW arrays was achieved with facile coverage tunability. Such Au3Cu NP decorated Si NW arrays can readily serve as effective CO2 reduction photoelectrodes, exhibiting high CO2-to-CO selectivity close to 80% at -0.20 V vs RHE with suppressed hydrogen evolution. A reduction of 120 mV overpotential compared to the planar (PL) counterpart was observed resulting from the optimized spatial arrangement of NP catalysts on the high surface area NW arrays. In addition, this system showed consistent photoelectrochemical CO2 reduction capability up to 18 h. This simple photoelectrode assembly process will lead to further progress in artificial photosynthesis, by allowing the combination of developments in each subfield to create an efficient light-driven system generating carbon-based fuels.

    View details for DOI 10.1021/acs.nanolett.6b02321

    View details for Web of Science ID 000383412100053

    View details for PubMedID 27494433

  • A Molecular Surface Functionalization Approach to Tuning Nanoparticle Electrocatalysts for Carbon Dioxide Reduction JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Cao, Z., Kim, D., Hong, D., Yu, Y., Xu, J., Lin, S., Wen, X., Nichols, E. M., Jeong, K., Reimer, J. A., Yang, P., Chang, C. J. 2016; 138 (26): 8120-8125

    Abstract

    Conversion of the greenhouse gas carbon dioxide (CO2) to value-added products is an important challenge for sustainable energy research, and nanomaterials offer a broad class of heterogeneous catalysts for such transformations. Here we report a molecular surface functionalization approach to tuning gold nanoparticle (Au NP) electrocatalysts for reduction of CO2 to CO. The N-heterocyclic (NHC) carbene-functionalized Au NP catalyst exhibits improved faradaic efficiency (FE = 83%) for reduction of CO2 to CO in water at neutral pH at an overpotential of 0.46 V with a 7.6-fold increase in current density compared to that of the parent Au NP (FE = 53%). Tafel plots of the NHC carbene-functionalized Au NP (72 mV/decade) vs parent Au NP (138 mV/decade) systems further show that the molecular ligand influences mechanistic pathways for CO2 reduction. The results establish molecular surface functionalization as a complementary approach to size, shape, composition, and defect control for nanoparticle catalyst design.

    View details for DOI 10.1021/jacs.6b02878

    View details for Web of Science ID 000379455600017

    View details for PubMedID 27322487

  • Metal-Organic Frameworks for Electrocatalytic Reduction of Carbon Dioxide JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Kornienko, N., Zhao, Y., Kiley, C. S., Zhu, C., Kim, D., Lin, S., Chang, C. J., Yaghi, O. M., Yang, P. 2015; 137 (44): 14129-14135

    Abstract

    A key challenge in the field of electrochemical carbon dioxide reduction is the design of catalytic materials featuring high product selectivity, stability, and a composition of earth-abundant elements. In this work, we introduce thin films of nanosized metal-organic frameworks (MOFs) as atomically defined and nanoscopic materials that function as catalysts for the efficient and selective reduction of carbon dioxide to carbon monoxide in aqueous electrolytes. Detailed examination of a cobalt-porphyrin MOF, Al2(OH)2TCPP-Co (TCPP-H2 = 4,4',4″,4‴-(porphyrin-5,10,15,20-tetrayl)tetrabenzoate) revealed a selectivity for CO production in excess of 76% and stability over 7 h with a per-site turnover number (TON) of 1400. In situ spectroelectrochemical measurements provided insights into the cobalt oxidation state during the course of reaction and showed that the majority of catalytic centers in this MOF are redox-accessible where Co(II) is reduced to Co(I) during catalysis.

    View details for DOI 10.1021/jacs.5b08212

    View details for Web of Science ID 000364727600025

    View details for PubMedID 26509213

  • Covalent organic frameworks comprising cobalt porphyrins for catalytic CO2 reduction in water SCIENCE Lin, S., Diercks, C. S., Zhang, Y., Kornienko, N., Nichols, E. M., Zhao, Y., Paris, A. R., Kim, D., Yang, P., Yaghi, O. M., Chang, C. J. 2015; 349 (6253): 1208-1213

    Abstract

    Conversion of carbon dioxide (CO2) to carbon monoxide (CO) and other value-added carbon products is an important challenge for clean energy research. Here we report modular optimization of covalent organic frameworks (COFs), in which the building units are cobalt porphyrin catalysts linked by organic struts through imine bonds, to prepare a catalytic material for aqueous electrochemical reduction of CO2 to CO. The catalysts exhibit high Faradaic efficiency (90%) and turnover numbers (up to 290,000, with initial turnover frequency of 9400 hour(-1)) at pH 7 with an overpotential of -0.55 volts, equivalent to a 26-fold improvement in activity compared with the molecular cobalt complex, with no degradation over 24 hours. X-ray absorption data reveal the influence of the COF environment on the electronic structure of the catalytic cobalt centers.

    View details for DOI 10.1126/science.aac8343

    View details for Web of Science ID 000360968400039

    View details for PubMedID 26292706

  • Artificial Photosynthesis for Sustainable Fuel and Chemical Production ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Kim, D., Sakimoto, K. K., Hong, D., Yang, P. 2015; 54 (11): 3259-3266

    Abstract

    The apparent incongruity between the increasing consumption of fuels and chemicals and the finite amount of resources has led us to seek means to maintain the sustainability of our society. Artificial photosynthesis, which utilizes sunlight to create high-value chemicals from abundant resources, is considered as the most promising and viable method. This Minireview describes the progress and challenges in the field of artificial photosynthesis in terms of its key components: developments in photoelectrochemical water splitting and recent progress in electrochemical CO2 reduction. Advances in catalysis, concerning the use of renewable hydrogen as a feedstock for major chemical production, are outlined to shed light on the ultimate role of artificial photosynthesis in achieving sustainable chemistry.

    View details for DOI 10.1002/anie.201409116

    View details for Web of Science ID 000350766100010

    View details for PubMedID 25594933

  • Synergistic geometric and electronic effects for electrochemical reduction of carbon dioxide using gold-copper bimetallic nanoparticles NATURE COMMUNICATIONS Kim, D., Resasco, J., Yu, Y., Asiri, A., Yang, P. 2014; 5: 4948

    Abstract

    Highly efficient and selective electrochemical reduction of carbon dioxide represents one of the biggest scientific challenges in artificial photosynthesis, where carbon dioxide and water are converted into chemical fuels from solar energy. However, our fundamental understanding of the reaction is still limited and we do not have the capability to design an outstanding catalyst with great activity and selectivity a priori. Here we assemble uniform gold-copper bimetallic nanoparticles with different compositions into ordered monolayers, which serve as a well-defined platform to understand their fundamental catalytic activity in carbon dioxide reduction. We find that two important factors related to intermediate binding, the electronic effect and the geometric effect, dictate the activity of gold-copper bimetallic nanoparticles. These nanoparticle monolayers also show great mass activities, outperforming conventional carbon dioxide reduction catalysts. The insights gained through this study may serve as a foundation for designing better carbon dioxide electrochemical reduction catalysts.

    View details for DOI 10.1038/ncomms5948

    View details for Web of Science ID 000342984800004

    View details for PubMedID 25208828

  • Simple and cost-effective reduction of graphite oxide by sulfuric acid CARBON Kim, D., Yang, S., Kim, Y., Jung, H., Park, C. 2012; 50 (9): 3229-3232