Core−Shell Phase Separation and Structural Transformation of Pt3Sn Alloy Nanoparticles Supported on γ-Al2O3in the Reduction and Oxidation Processes Characterized by In Situ Time-Resolved XAFS

Uemura, Yohei; Inada, Yuji; Bando, Kyoko K.; Sasaki, Takehiko; Kamiuchi, Naoto; Eguchi, Koichi; Yagishita, Akira; Nomura, Masaharu; Tada, Mizuki; Iwasawa, Yasuhiro

doi:10.1021/jp111286b

Cited by 56 publications

(51 citation statements)

References 118 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Besides, a hysteresis loop for the structural changes in the Pt cathode particles in the oxidation and reduction processes is observed. Iwasawa's group [102] also studied the reductive formation and oxidative phase separation of γ-Al 2 O 3 supported Pt 3 Sn nanoparticles during the reduction and oxidation processes at 673 K. Fig. 23a shows a series of time-resolved XANES spectra at Pt L 3 -edge, which were measured every 0.1 s, in the reduction process of the oxidized Pt 3 Sn/γ-Al 2 O 3 catalyst at 673 K under a H 2 pressure of 23.6 kPa.…”

Section: Reviewsmentioning

confidence: 99%

See 1 more Smart Citation

X-ray absorption fine structure spectroscopy in nanomaterials

et al. 2015

View full text Add to dashboard Cite

X-ray absorption fine structure (XAFS) spectroscopy has been widely used for decades in a wide range of scientific fields, including physics, chemistry, biology, materials sciences, environmental sciences, etc. This review article is devoted to the applications of XAFS in nanomaterials. The basic principles of XAFS are briefly described from the view point of practical application, including its theory, data analysis and experiments. Using selected examples from recent literatures, the power of XAFS in determination of local atomic/electronic structures is illustrated for various nanomaterials, covering metal and semiconductor nanoparticles, catalysts, core/shell structures, ultrathin nanosheets, and so on. The utilization of time-resolved XAFS technique is also briefly introduced, for in-situ probing the nucleation/growth processes of nanomaterials and identifying reaction intermediates of nanostructured catalysts under operando conditions.

show abstract

Section: Reviewsmentioning

confidence: 99%

“…Especially, in the study of nanomaterials, with the improvement of the time-resolved XAFS technique, the in-situ probing of the formation processes of nanomaterials Reprinted with permission from Ref. [102]. Copyright 2011, American Chemical Society.…”

Section: Outlook and Perspectivementioning

confidence: 99%

X-ray absorption fine structure spectroscopy in nanomaterials

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The studies of Pt 3 Sn alloy nanoparticles showed these nanoparticles restructure under reducing (H 2 ) or oxidizing (O 2 ) environments 99 in contrast to that in UHV. Their restructuring in H 2 is driven by the low surface energy of Pt and thus a Pt-rich surface is formed.…”

Section: Pt-snmentioning

confidence: 99%

Synthesis, catalysis, surface chemistry and structure of bimetallic nanocatalysts

2012

View full text Add to dashboard Cite

Bimetallic catalysts are one of the main categories of metal catalysts due to the tunability of electronic and geometric structures through alloying a second metal. The integration of a second metal creates a vast number of possibilities for varying the surface structure and composition of metal catalysts toward designing new catalysts. It is well acknowledged that the surface composition, atomic arrangement, and electronic state of bimetallic catalysts could be different from those before a chemical reaction or catalysis based on ex situ studies. Thanks to advances in electron-based surface analytical techniques, the surface chemistry and structure of bimetallic nanoparticles can be characterized under reaction conditions and during catalysis using ambient pressure analytical techniques including ambient pressure XPS, ambient pressure STM, X-ray absorption spectroscopy and others. These ambient pressure studies revealed various restructurings in the composition and arrangement of atoms in the surface region of catalysts under reaction conditions or during catalysis compared to that before reaction. These restructurings are driven by thermodynamic and kinetic factors. The surface energy of the constituent metals and adsorption energy of reactant molecules or dissociated species on a metal component are two main factors from the point of view of thermodynamics. Correlations between the authentic surface structure and chemistry of catalysts during catalysis and simultaneous catalytic performance were built for understanding catalytic mechanisms of bimetallic catalysts toward designing new catalysts with high activity, selectivity, and durability.

show abstract

“…In situ time-resolved XAFS technique in real-time processes enables to determine reaction sequences and structural changes at active metal sites/ensembles in dynamic catalytic processes involving adsorption, diffusion and reactions as reported by our groups in 2000-2011 [27][28][29][30][31][32][33][34][35]. We carried out the world's first successful quick-XAFS (QXAFS) observation and thorough analysis of structural changes of a PEFC Pt/C cathode electrocatalyst in voltage cycling processes (0.4 ¡ 1.0 V vs RHE) and succeeded in deciding six elementary reaction steps and their rate constants in 2007 [14].…”

Section: Introductionmentioning

confidence: 94%

Key Factors Affecting the Performance and Durability of Cathode Electrocatalysts in Polymer Electrolyte Fuel Cells Characterized by In Situ Real Time and Spatially Resolved XAFS Techniques

2014

Self Cite

View full text Add to dashboard Cite

The account article treats with the characterizations of the structural and electronic transformations of Pt/C, Pt 3 Co/C, and Pt 3 Ni/C cathode electrocatalysts in polymer electrolyte fuel cells (PEFCs) involving Pt charging/discharging, Pt-O bond formation/breaking, and Pt-Pt bond breaking/reformation in cathode potential-jump processes and the rate constants of those transformations in the surface reaction sequences on the cathode electrocatalysts by in situ time-resolved X-ray absorption fine structure (XAFS) method. Spatially heterogeneous issue and mechanism for the Pt oxidation and degradation of Pt/C cathode electrocatalyst layers in PEFCs under the operating conditions, which should be uncovered for development of next-generation PEFCs, were also characterized by a scanning nano-XAFS mapping method and a laminography-XAFS method, respectively for 2D and 3D visualizations of Pt chemical species in Pt/C cathode electrocatalyst layers. These XAFS techniques provided new insights into critical issues affecting the performance and property of practical PEFCs under the operating conditions.

show abstract

Core−Shell Phase Separation and Structural Transformation of Pt₃Sn Alloy Nanoparticles Supported on γ-Al₂O₃in the Reduction and Oxidation Processes Characterized by In Situ Time-Resolved XAFS

Cited by 56 publications

References 118 publications

X-ray absorption fine structure spectroscopy in nanomaterials

X-ray absorption fine structure spectroscopy in nanomaterials

Synthesis, catalysis, surface chemistry and structure of bimetallic nanocatalysts

Key Factors Affecting the Performance and Durability of Cathode Electrocatalysts in Polymer Electrolyte Fuel Cells Characterized by In Situ Real Time and Spatially Resolved XAFS Techniques

Contact Info

Product

Resources

About