Synergistic Effects for Enhanced Catalysis in a Dual Single-Atom Catalyst

Herein, we develop a non-selective charge compensation strategy to prepare multi-single-atom doped carbon (MSAC) in which a sodium p-toluenesulfonate (PTS-Na) doped polypyrrole (S-PPy) polymer is designed to anchor discretionary mixtures of multiple metal cations, including iron (Fe3+), cobalt (Co3+), ruthenium (Ru3+), palladium (Pd2+), indium (In3+), iridium (Ir2+), and platinum (Pt2+) . As illustrated in Figure 1, the carbon surface can be tuned with different level of compositional complexities, including unary Pt1@NC, binary (MSAC-2, (PtFe)1@NC), ternary (MSAC-3, (PtFeIr)1@NC), quaternary (MSAC-4, (PtFeIrRu)1@NC), quinary (MSAC-5, (PtFeIrRuCo)1@NC), senary (MSAC-6, (PtFeIrRuCoPd)1@NC), and septenary (MSAC-7, (PtFeIrRuCoPdIn)1@NC) samples. The structural evolution of carbon surface dictates the activities of both ORR and HER. The senary MSAC-6 achieves the ORR mass activity of 18.1 A·mgmetal-1 at 0.9 V (Vs reversible hydrogen electrode (RHE)) over 30K cycles, which is 164 times higher than that of commercial Pt/C. The quaternary MSAC-4 presented a comparable HER catalytic capability with that of Pt/C. These results indicate that the highly complexed carbon surface can enhance its ability over general electrochemical catalytic reactions. The mechanisms regarding of the ORR and HER activities of the alternated carbon surface are also theoretically and experimentally investigated in this work, showing that the synergistic effects amongst the co-doped atoms can activate or inactivate certain single-atom sites.

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Tunable Carbon Surface from Mono- to Multi-Metallic Single Atoms

10.26434/chemrxiv.12264083.v1 ◽

2020 ◽

Author(s):

Weihong Lai ◽

Heng Wang ◽

Quan jiang ◽

Zichao Yan ◽

Hanwen Liu ◽

...

Keyword(s):

Synergistic Effects ◽

Structural Evolution ◽

Charge Compensation ◽

Catalytic Reactions ◽

Single Atom ◽

Carbon Surface ◽

Hydrogen Electrode ◽

Single Atoms ◽

Mass Activity ◽

Co Doped

Herein, we develop a non-selective charge compensation strategy to prepare multi-single-atom doped carbon (MSAC) in which a sodium p-toluenesulfonate (PTS-Na) doped polypyrrole (S-PPy) polymer is designed to anchor discretionary mixtures of multiple metal cations, including iron (Fe3+), cobalt (Co3+), ruthenium (Ru3+), palladium (Pd2+), indium (In3+), iridium (Ir2+), and platinum (Pt2+) . As illustrated in Figure 1, the carbon surface can be tuned with different level of compositional complexities, including unary Pt1@NC, binary (MSAC-2, (PtFe)1@NC), ternary (MSAC-3, (PtFeIr)1@NC), quaternary (MSAC-4, (PtFeIrRu)1@NC), quinary (MSAC-5, (PtFeIrRuCo)1@NC), senary (MSAC-6, (PtFeIrRuCoPd)1@NC), and septenary (MSAC-7, (PtFeIrRuCoPdIn)1@NC) samples. The structural evolution of carbon surface dictates the activities of both ORR and HER. The senary MSAC-6 achieves the ORR mass activity of 18.1 A·mgmetal-1 at 0.9 V (Vs reversible hydrogen electrode (RHE)) over 30K cycles, which is 164 times higher than that of commercial Pt/C. The quaternary MSAC-4 presented a comparable HER catalytic capability with that of Pt/C. These results indicate that the highly complexed carbon surface can enhance its ability over general electrochemical catalytic reactions. The mechanisms regarding of the ORR and HER activities of the alternated carbon surface are also theoretically and experimentally investigated in this work, showing that the synergistic effects amongst the co-doped atoms can activate or inactivate certain single-atom sites.

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Intrinsic Descriptors for Coordination Environment and Synergistic Effects of Metal and Environment in Single-Atom-Catalyzed Carbon Dioxide Electroreduction

The Journal of Physical Chemistry C ◽

10.1021/acs.jpcc.1c04637 ◽

2021 ◽

Author(s):

Hao Yuan ◽

Zhenyu Li

Keyword(s):

Carbon Dioxide ◽

Synergistic Effects ◽

Single Atom ◽

Coordination Environment ◽

Carbon Dioxide Electroreduction

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Synthetic strategies of supported atomic clusters for heterogeneous catalysis

Nature Communications ◽

10.1038/s41467-020-19571-6 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Hongpan Rong ◽

Shufang Ji ◽

Jiatao Zhang ◽

Dingsheng Wang ◽

Yadong Li

Keyword(s):

Catalytic Properties ◽

Synergistic Effects ◽

Atomic Clusters ◽

Atomic Level ◽

Single Atom ◽

Metal Metal ◽

Intermediate States ◽

Relationship Of ◽

Metal Bonds ◽

Structure Properties

AbstractSupported atomic clusters with uniform metal sites and definite low-nuclearity are intermediate states between single-atom catalysts (SACs) and nanoparticles in size. Benefiting from the presence of metal–metal bonds, supported atomic clusters can trigger synergistic effects among every metal atom, which contributes to achieving unique catalytic properties different from SACs and nanoparticles. However, the scalable and precise synthesis and atomic-level insights into the structure–properties relationship of supported atomic clusters is a great challenge. This perspective presents the latest progress of the synthesis of supported atomic clusters, highlights how the structure affects catalytic properties, and discusses the limitations as well as prospects.

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Single-atom nanozymes

Science Advances ◽

10.1126/sciadv.aav5490 ◽

2019 ◽

Vol 5 (5) ◽

pp. eaav5490 ◽

Cited By ~ 111

Author(s):

Liang Huang ◽

Jinxing Chen ◽

Linfeng Gan ◽

Jin Wang ◽

Shaojun Dong

Keyword(s):

Active Sites ◽

Synergistic Effects ◽

Theoretical Calculations ◽

Experimental Studies ◽

Size Composition ◽

Underlying Mechanism ◽

Catalytic Performance ◽

Axial Ligand ◽

Single Atom ◽

Active Centers

Conventional nanozyme technologies face formidable challenges of intricate size-, composition-, and facet-dependent catalysis and inherently low active site density. We discovered a new class of single-atom nanozymes with atomically dispersed enzyme-like active sites in nanomaterials, which significantly enhanced catalytic performance, and uncovered the underlying mechanism. With oxidase catalysis as a model reaction, experimental studies and theoretical calculations revealed that single-atom nanozymes with carbon nanoframe–confined FeN5 active centers (FeN5 SA/CNF) catalytically behaved like the axial ligand–coordinated heme of cytochrome P450. The definite active moieties and crucial synergistic effects endow FeN5 SA/CNF with a clear electron push-effect mechanism, as well as the highest oxidase-like activity among other nanozymes (the rate constant is 70 times higher than that of commercial Pt/C) and versatile antibacterial applications. These suggest that the single-atom nanozymes have great potential to become the next-generation nanozymes.

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Single Atom Image Contrast in Fixed Beam Dark Field Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051840 ◽

1974 ◽

Vol 32 ◽

pp. 366-367

Author(s):

Wah Chi

Keyword(s):

Scattering Amplitude ◽

Present Report ◽

Dark Field ◽

Image Contrast ◽

Single Atom ◽

Optical Theorem ◽

Hartree Fock ◽

Heavy Atoms ◽

Beam Stop ◽

Fixed Beam

Resolution and contrast are the important factors to determine the feasibility of imaging single heavy atoms on a thin substrate in an electron microscope. The present report compares the atom image characteristics in different modes of fixed beam dark field microscopy including the ideal beam stop (IBS), a wire beam stop (WBS), tilted illumination (Tl) and a displaced aperture (DA). Image contrast between one Hg and a column of linearly aligned carbon atoms (representing the substrate), are also discussed. The assumptions in the present calculations are perfectly coherent illumination, atom object is represented by spherically symmetric potential derived from Relativistic Hartree Fock Slater wave functions, phase grating approximation is used to evaluate the complex scattering amplitude, inelastic scattering is ignored, phase distortion is solely due to defocus and spherical abberation, and total elastic scattering cross section is evaluated by the Optical Theorem. The atom image intensities are presented in a Z-modulation display, and the details of calculation are described elsewhere.

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Atomic Spectroscopy in the FIM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100145157 ◽

1986 ◽

Vol 44 ◽

pp. 758-761

Author(s):

J. J. Hren ◽

S. D. Walck

Keyword(s):

Electron Microscope ◽

Electric Fields ◽

Atom Probe ◽

Atomic Spectroscopy ◽

Single Atom ◽

Statistical Sampling ◽

Commercial Instrument ◽

Available Technology ◽

High Electric Fields ◽

Field Ion Microscope

The field ion microscope (FIM) has had the ability to routinely image the surface atoms of metals since Mueller perfected it in 1956. Since 1967, the TOF Atom Probe has had single atom sensitivity in conjunction with the FIM. “Why then hasn't the FIM enjoyed the success of the electron microscope?” The answer is closely related to the evolution of FIM/Atom Probe techniques and the available technology. This paper will review this evolution from Mueller's early discoveries, to the development of a viable commercial instrument. It will touch upon some important contributions of individuals and groups, but will not attempt to be all inclusive. Variations in instrumentation that define the class of problems for which the FIM/AP is uniquely suited and those for which it is not will be described. The influence of high electric fields inherent to the technique on the specimens studied will also be discussed. The specimen geometry as it relates to preparation, statistical sampling and compatibility with the TEM will be examined.

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Field ion microscope investigations of atomic processes at surfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153117 ◽

1989 ◽

Vol 47 ◽

pp. 228-229

Author(s):

G. L. Kellogg ◽

P. R. Schwoebel

Keyword(s):

Single Crystal ◽

Crystal Surface ◽

Linear Chain ◽

Atom Probe ◽

Nucleation And Growth ◽

Single Atom ◽

Initial Structure ◽

Atomic Processes ◽

Single Crystal Surfaces ◽

Field Ion Microscope

Although no longer unique in its ability to resolve individual single atoms on surfaces, the field ion microscope remains a powerful tool for the quantitative characterization of atomic processes on single-crystal surfaces. Investigations of single-atom surface diffusion, adatom-adatom interactions, surface reconstructions, cluster nucleation and growth, and a variety of surface chemical reactions have provided new insights to the atomic nature of surfaces. Moreover, the ability to determine the chemical identity of selected atoms seen in the field ion microscope image by atom-probe mass spectroscopy has increased or even changed our understanding of solid-state-reaction processes such as ordering, clustering, precipitation and segregation in alloys. This presentation focuses on the operational principles of the field-ion microscope and atom-probe mass spectrometer and some very recent applications of the field ion microscope to the nucleation and growth of metal clusters on metal surfaces.The structure assumed by clusters of atoms on a single-crystal surface yields fundamental information on the adatom-adatom interactions important in crystal growth. It was discovered in previous investigations with the field ion microscope that, contrary to intuition, the initial structure of clusters of Pt, Pd, Ir and Ni atoms on W(110) is a linear chain oriented in the <111> direction of the substrate.

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Morphology of High-Performance Rigid-Rod Polymer Fibers and Molecular Composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015366x ◽

1989 ◽

Vol 47 ◽

pp. 338-339

Author(s):

W.W. Adams ◽

S. J. Krause

Keyword(s):

Tensile Strength ◽

High Performance ◽

Liquid Crystalline ◽

Molecular Level ◽

Synergistic Effects ◽

Tensile Modulus ◽

Commercial Development ◽

The Matrix ◽

Molecular Composites ◽

Rigid Rod

Rigid-rod polymers such as PBO, poly(paraphenylene benzobisoxazole), Figure 1a, are now in commercial development for use as high-performance fibers and for reinforcement at the molecular level in molecular composites. Spinning of liquid crystalline polyphosphoric acid solutions of PBO, followed by washing, drying, and tension heat treatment produces fibers which have the following properties: density of 1.59 g/cm3; tensile strength of 820 kpsi; tensile modulus of 52 Mpsi; compressive strength of 50 kpsi; they are electrically insulating; they do not absorb moisture; and they are insensitive to radiation, including ultraviolet. Since the chain modulus of PBO is estimated to be 730 GPa, the high stiffness also affords the opportunity to reinforce a flexible coil polymer at the molecular level, in analogy to a chopped fiber reinforced composite. The objectives of the molecular composite concept are to eliminate the thermal expansion coefficient mismatch between the fiber and the matrix, as occurs in conventional composites, to eliminate the interface between the fiber and the matrix, and, hopefully, to obtain synergistic effects from the exceptional stiffness of the rigid-rod molecule. These expectations have been confirmed in the case of blending rigid-rod PBZT, poly(paraphenylene benzobisthiazole), Figure 1b, with stiff-chain ABPBI, poly 2,5(6) benzimidazole, Fig. 1c A film with 30% PBZT/70% ABPBI had tensile strength 190 kpsi and tensile modulus of 13 Mpsi when solution spun from a 3% methane sulfonic acid solution into a film. The modulus, as predicted by rule of mixtures, for a film with this composition and with planar isotropic orientation, should be 16 Mpsi. The experimental value is 80% of the theoretical value indicating that the concept of a molecular composite is valid.

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Recent advancement in the electrocatalytic synthesis of ammonia

Nanoscale ◽

10.1039/d0nr01359e ◽

2020 ◽

Vol 12 (15) ◽

pp. 8065-8094 ◽

Cited By ~ 6

Author(s):

Xudong Wen ◽

Jingqi Guan

Keyword(s):

Metal Oxide ◽

Oxide Catalysts ◽

Single Atom ◽

Metal Oxide Catalysts ◽

Metal Free ◽

Recent Advancement ◽

Nanocomposite Catalysts

Different kinds of electrocatalysts used in NRR electrocatalysis (including single atom catalysts, metal oxide catalysts, nanocomposite catalysts, and metal free catalysts) are introduced.

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