Selective hydrogenation of 1,3-butadiene on platinum–copper alloys at the single-atom limit

Lucci, Felicia R.; Liu, Jilei; Marcinkowski, Matthew D.; Yang, Ming; Allard, Lawrence F.; Flytzani‐Stephanopoulos, Maria; Sykes, E. Charles H.

doi:10.1038/ncomms9550

Cited by 499 publications

(579 citation statements)

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“…In several cases it has been shown that by doping the coinage metals with PGMs at very low molar fractions, such that these more reactive metals disperse as isolated single atoms in the surface layer of the host material, the activity of the coinage metal surface can be dramatically enhanced whilst retaining excellent reaction selectivity [11][12][13][14][15][16][17][18][19][20][21][22][23][24]. These single atom alloys (SAAs) of Sykes and co-workers exhibit tolerance to CO [18] and have been employed to catalyse hydrogenation [16][17][18][19][20], dehydrogenation [22,23], C-H activation and hydrosilylation [25] reactions with high activity and selectivity, as extended model surfaces and/or as real catalyst nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

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Carbon Monoxide Poisoning Resistance and Structural Stability of Single Atom Alloys

et al. 2018

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Platinum group metals (PGMs) serve as highly active catalysts in a variety of heterogeneous chemical processes. Unfortunately, their high activity is accompanied by a high affinity for CO and thus, PGMs are susceptible to poisoning. Alloying PGMs with metals exhibiting lower affinity to CO could be an effective strategy toward preventing such poisoning. In this work, we use density functional theory to demonstrate this strategy, focusing on highly dilute alloys of PGMs (Pd, Pt, Rh, Ir and Ni) with poison resistant coinage metal hosts (Cu, Ag, Au), such that individual PGM atoms are dispersed at the atomic limit forming single atom alloys (SAAs). We show that compared to the pure metals, CO exhibits lower binding strength on the majority of SAAs studied, and we use kinetic Monte Carlo simulation to obtain relevant temperature programed desorption spectra, which are found to be in good agreement with experiments. Additionally, we consider the effects of CO adsorption on the structure of SAAs. We calculate segregation energies which are indicative of the stability of dopant atoms in the bulk compared to the surface layer, as well as aggregation energies to determine the stability of isolated surface dopant atoms compared to dimer and trimer configurations. Our calculations reveal that CO adsorption induces dopant atom segregation into the surface layer for all SAAs considered here, whereas aggregation and island formation may be promoted or inhibited depending on alloy constitution and CO coverage. This observation suggests the possibility of controlling ensemble effects in novel catalyst architectures through CO-induced aggregation and kinetic trapping.

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Section: Introductionmentioning

confidence: 99%

“…These single atom alloys (SAAs) of Sykes and co-workers exhibit tolerance to CO [18] and have been employed to catalyse hydrogenation [16][17][18][19][20], dehydrogenation [22,23], C-H activation and hydrosilylation [25] reactions with high activity and selectivity, as extended model surfaces and/or as real catalyst nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Carbon Monoxide Poisoning Resistance and Structural Stability of Single Atom Alloys

et al. 2018

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“…28 A recent study revealed a direct link between single crystal and nanoparticle catalysts of Pt−Cu SAAs which show high activity and selectivity for butadiene hydrogenation to butenes, demonstrating transferability from the model study to the catalytic reaction under practical conditions. 29 Using the opposite approach, Besenbacher et al found that adding small amounts of Au to Ni(111) tempered surface reactivity and reduced catalyst coking and transferred this result to a real catalyst. 30,31 In the current work, we have alloyed small amounts of Ni into Au(111) to produce SAAs and demonstrated their potential for increasing the binding strength of adsorbates using CO as a probe molecule.…”

Section: Introductionmentioning

confidence: 99%

Preparation, Structure, and Surface Chemistry of Ni–Au Single Atom Alloys

et al. 2016

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Ni/Au is an alloy combination that while, immiscible in the bulk, exhibits a rich array of surface geometries that may offer improved catalytic properties. It has been demonstrated that the addition of small amounts of Au to Ni tempers its reactivity and reduces coking during the steam reforming of methane. Herein, we report the first successful preparation of dilute Ni−Au alloys (up to 0.04 ML) in which small amounts of Ni are deposited on, and alloyed into, Au(111) using physical vapor deposition. We find that the surface structure can be tuned during deposition via control of the substrate temperature. By adjusting the surface temperature in the 300−650 K range, we are able to produce first Ni islands, then mixtures of Ni islands and Ni−Au surface alloys, and finally, when above 550 K, predominantly island-free Ni−Au single atom alloys (SAAs). Low-temperature scanning tunneling microscopy (STM) combined with density functional theory calculations confirm that the Ni−Au SAAs formed at high temperature correspond to Ni atoms exchanged with surface Au atoms. Ni−Au SAAs form preferentially at the elbow regions of the Au(111) herringbone reconstruction, but at high coverage also appear over the whole surface. To investigate the adsorption properties of Ni−Au SAAs, we studied the adsorption and desorption of CO using STM which allowed us to determine at which atomic sites the CO adsorbs on these heterogeneous alloys. We find that small amounts of Ni in the form of single atoms increases the reactivity of the substrate by creating single Ni sites in the Au surface to which CO binds significantly more strongly than Au. These results serve as a guide in the design of surface architectures that combine Au's weak binding and selective chemistry with localized, strong binding Ni atom sites that serve to increase reactivity.

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“…Recently, several studies [27][28][29][30][31][32][33][34][35][36][37] have provided incontrovertible proof that individual atoms are indeed capable of effecting a number of catalytic reactions, especially selective hydrogenations, as well as the water-gas shift reaction:…”

Section: Single-atom Heterogeneous Catalystsmentioning

confidence: 99%

Reflections on the value of electron microscopy in the study of heterogeneous catalysts

Thomas

2017

Proc. R. Soc. A.

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Electron microscopy (EM) is arguably the single most powerful method of characterizing heterogeneous catalysts. Irrespective of whether they are bulk and multiphasic, or monophasic and monocrystalline, or nanocluster and even single-atom and on a support, their structures in atomic detail can be visualized in two or three dimensions, thanks to high-resolution instruments, with sub-Ångstrom spatial resolutions. Their topography, tomography, phase-purity, composition, as well as the bonding, and valence-states of their constituent atoms and ions and, in favourable circumstances, the short-range and long-range atomic order and dynamics of the catalytically active sites, can all be retrieved by the panoply of variants of modern EM. The latter embrace electron crystallography, rotation and precession electron diffraction, X-ray emission and high-resolution electron energy-loss spectra (EELS). Aberration-corrected (AC) transmission (TEM) and scanning transmission electron microscopy (STEM) have led to a revolution in structure determination. Environmental EM is already playing an increasing role in catalyst characterization, and new advances, involving special cells for the study of solid catalysts in contact with liquid reactants, have recently been deployed.

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Selective hydrogenation of 1,3-butadiene on platinum–copper alloys at the single-atom limit

Cited by 499 publications

References 56 publications

Carbon Monoxide Poisoning Resistance and Structural Stability of Single Atom Alloys

Carbon Monoxide Poisoning Resistance and Structural Stability of Single Atom Alloys

Preparation, Structure, and Surface Chemistry of Ni–Au Single Atom Alloys

Reflections on the value of electron microscopy in the study of heterogeneous catalysts

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