Creating single-atom Pt-ceria catalysts by surface step decoration

Dvořák, Filip; Camellone, Matteo Farnesi; Tovt, Andrii; Tran, Nguyen Dung; Negreiros, Fábio R.; Vorokhta, Mykhailo; Škála, Tomáš; Matolı́nová, Iva; Mysliveček, Josef; Matolín, Vladimı́r; Fabris, Stefano

doi:10.1038/ncomms10801

Cited by 428 publications

(247 citation statements)

References 47 publications

Supporting

Mentioning

231

Contrasting

Order By: Relevance

“…The energy dispersive X‐ray spectroscopic (EDS) result in Figure 2 d shows the presence of Pt in the NTs (see Figure S2 for the EDS maps of Co, Mn, O, P, and Ni), and the Pt weight percentage is 1.6 %. AR HAADF imaging performed by aberration‐corrected scanning TEM (STEM) indicates that a plenty of single Pt atoms are well dispersed on the NTs (Figures 2 e and Figure S3), similar to those reported,10a,10c, 12, 13, 18 and no Pt crystal grains/particles are found. Further, the electron diffraction pattern in Figure 2 f demonstrates that the NTs contain the crystal grains of Ni(OH) 2 , CoP and Co 2 P, but no diffraction spots from Pt crystals are present, according to the standard crystallographic data of Joint Committee on Powder Diffraction Standards.…”

supporting

confidence: 84%

Potential‐Cycling Synthesis of Single Platinum Atoms for Efficient Hydrogen Evolution in Neutral Media

et al. 2017

View full text Add to dashboard Cite

Single‐atom catalysts (SACs) have exhibited high activities for the hydrogen evolution reaction (HER) electrocatalysis in acidic or alkaline media, when they are used with binders on cathodes. However, to date, no SACs have been reported for the HER electrocatalysis in neutral media. We demonstrate a potential‐cycling method to synthesize a catalyst comprising single Pt atoms on CoP‐based nanotube arrays supported by a Ni foam, termed PtSA‐NT‐NF. This binder‐free catalyst is centimeter‐scale and scalable. It is directly used as HER cathodes, whose performances at low and high current densities in phosphate buffer solutions (pH 7.2) are comparable to and better than, respectively, those of commercial Pt/C. The Pt mass activity of PtSA‐NT‐NF is 4 times of that of Pt/C, and its electrocatalytic stability is also better than that of Pt/C. This work provides a large‐scale production strategy for binder‐free Pt SAC electrodes for efficient HER in neutral media.

show abstract

supporting

confidence: 84%

Potential‐Cycling Synthesis of Single Platinum Atoms for Efficient Hydrogen Evolution in Neutral Media

et al. 2017

View full text Add to dashboard Cite

show abstract

“…This pathway was calculated to be exothermic for Pt 9 A very similar local PtO 4 structure emerges upon Pt adsorption at the steps of the CeO 2 Ĳ111) surface. 22 The thermodynamics of segregation and the corresponding atomic and electronic structures of Pt on stepped CeO 2 Ĳ111) were investigated by density functional calculations. 22 Different adsorption sites were considered ( Fig.…”

Section: Parameters Controlling Proton Exchange Membrane Fuel Cell Pementioning

confidence: 99%

“…22 The thermodynamics of segregation and the corresponding atomic and electronic structures of Pt on stepped CeO 2 Ĳ111) were investigated by density functional calculations. 22 Different adsorption sites were considered ( Fig. 7) including oxygen vacancies (a), regular sites (b) and Pt clusters (c) on the CeO 2 Ĳ111) terrace, and the two low-energy one-monolayer-high steps labeled as step I (d, f) and step II (e, g) on stoichiometric (denoted S) and non-stoichiometric (with excess of oxygen, denoted O) surfaces.…”

Section: Parameters Controlling Proton Exchange Membrane Fuel Cell Pementioning

confidence: 99%

“…21,22,98 In particular, Pt 2+ species were prepared either on the surface of nanostructured ceria films 21 or on stepped CeO 2 Ĳ111) surfaces. 22 The first approach employed codeposition of Pt and Ce metal in an oxygen atmosphere onto a well-ordered CeO 2 Ĳ111) buffer layer at low temperature. The use of a 1.5 nm thick buffer layer was necessary to minimize the influence of the Cu(111) substrate on the structure of the Pt-CeO 2 film.…”

Section: Stability As a Function Of Noble Metal Loadingmentioning

confidence: 99%

See 1 more Smart Citation

Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

Lykhach

Bruix

Fabris

et al. 2017

Catal. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

The concept of single atom catalysis offers maximum noble metal efficiency for the development of lowcost catalytic materials. Among possible applications are catalytic materials for proton exchange membrane fuel cells. In the present review, recent efforts towards the fabrication of single atom catalysts on nanostructured ceria and their reactivity are discussed in the prospect of their employment as anode catalysts.The remarkable performance and the durability of the ceria-based anode catalysts with ultra-low Pt loading result from the interplay between two states associated with supported atomically dispersed Pt and subnanometer Pt particles. The occurrence of these two states is a consequence of strong interactions between Pt and nanostructured ceria that yield atomically dispersed species under oxidizing conditions and sub-nanometer Pt particles under reducing conditions. The square-planar arrangement of four O atoms on {100} nanoterraces has been identified as the key structural element on the surface of the nanostructured ceria where Pt is anchored in the form of Pt 2+ species. The conversion of Pt 2+ species to subnanometer Pt particles is triggered by a redox process involving Ce 3+ centers. The latter emerge due to either oxygen vacancies or adsorption of reducing agents. The unique properties of the sub-nanometer Pt particles arise from metal-support interactions involving charge transfer, structural flexibility, and spillover phenomena. The abundance of specific adsorption sites similar to those on {100} nanoterraces determines the ideal (maximum) Pt loading in Pt-CeO x films that still allows reversible switching between the atomically dispersed Pt and sub-nanometer particles yielding high activity and durability during fuel cell operation.

show abstract

“…Neyman and coworkers 15 proposed that Pt 2+ cations could be stabilized within so-called Pt-O 4 nanopockets. Using a combination of STM, XPS and DFT, Dvorak et al 16 demonstrated that such nanopockets can exist at step edges on CeO 2 (111). Specifically, they found that Pt 2+ dominates for samples with a high step density (Fig 2g-i), whereas flat, oxygen vacancy rich samples promote the formation of metallic clusters on the terraces (Figs 2d-f).…”

mentioning

confidence: 99%

Unravelling single atom catalysis: The surface science approach

Parkinson

2017

Chinese Journal of Catalysis

View full text Add to dashboard Cite

Understanding the fundamental mechanisms of single-atom catalysis (SAC) is important to design systems with improved performance and stability. This is problematic, however, because singleatom active sites are extremely difficult to characterize with existing experimental techniques. Over the last 40 years, surface science has provided the fundamental insights to understand heterogeneous catalysis, but model systems in which metal atoms are stable on well-characterized metal-oxide substrates at reaction temperatures are scarce. In this perspective, I discuss what is already known about isolated metal atoms adsorbed on model metal-oxide surfaces, and how this information can be used to understand SAC. A key issue is that, although the highly-idealised model systems studied in surface science may not be representative of a real working catalyst, they do very much resemble what can be calculated using state-of-the-art theoretical modelling. Thus, surface science offers an opportunity to rigorously benchmark the theoretical approach to modelling SAC in future. Perhaps more excitingly, several groups have developed model systems where metal adatoms remain stable at elevated temperatures. To date however, there has been no clear demonstration of catalytic activity. The perspective closes with a brief discussion of the prospect for STM experiments under realistic reaction conditions. Main TextThe rapidly emerging field of single-atom catalysis (SAC) aims to slash the precious metal loading in heterogeneous catalysts by replacing metal nanoparticles with so-called "single-atom" active sites 1 . While there are many reports of active SAC systems, the topic remains somewhat controversial because it is very difficult to characterize a system based on single atoms, and to distinguish between these and subnano particles 2 . In practice, most groups use aberration-corrected transmission electron microscopy (TEM) to demonstrate the atomic dispersion, sometimes supplemented by XANES, which can rule out significant metal-metal bonding 1 . The activity of the catalyst is then tested, and although some mechanistic information can be drawn by in-situ techniques such as IRAS, the catalytic mechanism is proposed largely on the basis of theoretical calculations. Such calculations are based on an idealised model of the system, in which both the support structure and active site geometry are assumed. Thus, a one-to-one correspondence between the experimental and theoretical results is difficult to prove.Traditionally, surface science has provided mechanistic information to understand heterogeneous catalysis. The idea is to strip away the complexity of a real catalyst and study well-defined singlecrystal samples in a highly-controlled ultrahigh vacuum (UHV) environment. This way, the adsorption of individual reactants can be studied in detail, and an understanding of the basic interactions can be built up. The downside of the approach is that the highly idealised model system may not be as representative of the real catalyst as o...

show abstract

Creating single-atom Pt-ceria catalysts by surface step decoration

Cited by 428 publications

References 47 publications

Potential‐Cycling Synthesis of Single Platinum Atoms for Efficient Hydrogen Evolution in Neutral Media

Potential‐Cycling Synthesis of Single Platinum Atoms for Efficient Hydrogen Evolution in Neutral Media

Oxide-based nanomaterials for fuel cell catalysis: the interplay between supported single Pt atoms and particles

Unravelling single atom catalysis: The surface science approach

Contact Info

Product

Resources

About