Photoelectron Spectroscopic Studies of Model Catalyst Surfaces PDF Download

Author: Stephen Vincent Didziulis
Publisher:
ISBN:
Category :
Languages : en
Pages : 696

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Author: Staffan Andersson
Publisher:
ISBN: 9789155441593
Category : Catalysis
Languages : en
Pages : 48

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Author: Spyridon Zafeiratos
Publisher: World Scientific
ISBN: 180061330X
Category : Science
Languages : en
Pages : 548

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X-ray photoelectron spectroscopy (XPS) has become a standard practice technique, and automated XPS facilities can be found in industry and in universities all over the world. This transformed XPS from an advanced characterization method for dedicated research, to a rather standard analysis technique of surface analysis. The catalyst's surface state is probably the most prominent factor that influences the catalytic performance. It is therefore no surprise that XPS has become an indispensable tool in studies of solid catalysts. It has been directly used to investigate issues such as the surface composition of the active catalyst and reaction and deactivation mechanisms.The objective of this book is to provide a comprehensive overview of the current status and future perspectives of X-ray photoelectron spectroscopy dedicated to catalytic applications, including thermal catalysis, electrocatalysis, and photo(electro)catalysis. The book contains 13 chapters, starting with the necessary introduction of the technique background, including basic phenomena and instrumentation aspects. The second part of the book focuses on the presentation of long-established applications of the technique, such as XPS studies of model catalysts. Finally, the book describes relatively recent developments of this method for cutting-edge surface characterization mainly using synchrotron X-ray radiation.

Author: Franklin Tao
Publisher: John Wiley & Sons
ISBN: 1119845475
Category : Science
Languages : en
Pages : 294

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APPLICATION OF AMBIENT PRESSURE X-RAY PHOTOELECTRON SPECTROSCOPY TO CATALYSIS Authoritative and detailed reference on ambient-pressure x-ray photoelectron spectroscopy for practitioners and researchers starting in the field Application of Ambient Pressure X-ray Photoelectron Spectroscopy to Catalysis introduces a relatively new analytical method and its applications to chemistry, energy, environmental, and materials sciences, particularly the field of heterogeneous catalysis, covering its background and historical development, its principles, the instrumentation required to use it, analysis of data collected with it, and the challenges it faces. The features of this method are described early in the text; the starting chapters provide a base for understanding how AP-XPS tracks crucial information in terms of the surface of a catalyst during catalysis. The second half of this book delves into the specific applications of AP-XPS to fundamental studies of different catalytic reactions. In later chapters, the focus is on how AP-XPS could provide key information toward understanding catalytic mechanisms. To aid in reader comprehension, the takeaways of each chapter are underlined. In Application of Ambient Pressure X-ray Photoelectron Spectroscopy to Catalysis, readers can expect to find detailed information on specific topics such as: Going from surface of model catalyst in UHV to surface of nanoparticle catalyst during catalysis Application of XPS from surface in UHV to surface in gas or liquid phase and fundamentals of X-ray spectroscopy Significance and challenges of studying surface of a catalyst in gaseous phase and instrumentation of ambient pressure X-ray photoelectron spectrometers Experimental methods of AP-XPS studies and difference in data analysis between AP-XPS and high vacuum XPS Ambient Pressure X-Ray Photoelectron Spectroscopy is an ideal resource for entry level researchers and students involved in x-ray photoelectron spectroscopy. Additionally, the text will appeal to scientists in more senior roles in academic and government laboratory institutions in the fields of chemistry, chemical engineering, energy science, and materials science.

Author: J. W. Niemantsverdriet
Publisher: John Wiley & Sons
ISBN: 3527611355
Category : Science
Languages : en
Pages : 344

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Superbly organized and of great pedagogic value, 'Spectroscopy in Catalysis' describes the most important modern analytical techniques used to investigate catalytic surfaces. These include electron, ion, and vibrational spectroscopy, mass spectrometry, temperature-programmed techniques, diffraction, and microscopy. With the focus on practical use, rather than theory, each chapter presents current applications to illustrate the type of information that the technique provides and evaluates its possibilities and limitations, allowing selection of the best catalyst and the correct technique to solve a given problem. This third edition includes significant new developments and case studies, with all the chapters updated by way of recent examples and relevant new literature. For students and for everyone who wants a digestible introduction to catalyst characterization. From reviews of the previous editions: 'This is a truly valuable book ... very useful for industrial practitioners who need to be aware of the type of information that can be obtained from modern surface spectroscopies .... The book has a superb pedagogic value...' Journal of Catalysis '... this is an excellent text on spectroscopies in catalysis and I highly recommend it for ... introductory courses on heterogeneous catalysis or as a general introductory monograph.' Journal of the American Chemical Society

Author: Zhongwei Zhu
Publisher:
ISBN:
Category :
Languages : en
Pages : 133

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Surface structure, mobility, and composition of transition metal catalysts were studied by high-pressure scanning tunneling microscopy (HP-STM) and ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) at high gas pressures. HP-STM makes it possible to determine the atomic or molecular rearrangement at catalyst surfaces, particularly at the low-coordinated active surface sites. AP-XPS monitors changes in elemental composition and chemical states of catalysts in response to variations in gas environments. Stepped Pt and Cu single crystals, the hexagonally reconstructed Pt(100) single crystal, and Pt-based bimetallic nanoparticles with controlled size, shape and composition, were employed as the model catalysts for experiments in this thesis. Surface reconstruction at low-coordinated step sites at high gas pressures was first explored on a stepped Pt(557) single crystal surface under O2. At 298 K, 1 Torr of O2 is able to create nanometer-sized clusters that are identified as surface Pt oxide by AP-XPS, which covers the entire Pt(557) surface. On the flat Pt(111) surface under 1 Torr of O2, Pt oxide clusters can form but are mostly accumulated within 2 nm from the steps. The hexagonal oxygen chemisorption pattern is observed on the terraces. At lower pressures such as 10−7 Torr, O2 only adsorbs at the step edges on Pt(557). The majority of the Pt oxide clusters disappear on both Pt(557) and Pt(111) surfaces after O2 is evacuated to the 10−8 Torr range. Quantitative XPS analysis with depth profiles indicates that the Pt oxide formed on Pt(557) is less than 0.6 nm thick and that the Pt oxide concentration at surface together with oxygen coverage varies reversibly with the O2 pressure. The disappearance of Pt oxide clusters upon O2 evacuation is ascribed to reactions of Pt oxide towards H2 and CO in the vacuum background gases. The structure and surface chemistry of the Pt(557) surface was therefore studied under H2-O2 and CO-O2 mixtures. After exposing Pt(557) to approximately 1 Torr of O2 to induce the formation of Pt oxide clusters, H2 was slowly added into the system. Both HP-STM and AP-XPS results show that the Pt oxide coverage decreases with the H2 partial pressure and that all the Pt oxide disappears at H2 partial pressures above 43 mTorr. Pt steps are restored with the removal of Pt oxide clusters. Water is produced in the gas-phase, which co-adsorbs with hydroxyl species on Pt(557). Detailed analysis shows that the consumption of surface Pt oxide is exclusively responsible for the decrease of oxygen coverage on Pt(557). In the coexistence of 1 Torr of CO and 1 Torr of O2, Pt oxide clusters are not observed like under the H2-O2 mixture. Instead, triangular Pt clusters and double-sized terraces induced by CO are observed. Influences of step configuration on the surface restructuring processes were studied on Pt(557) and Pt(332) that differ only in the step orientation. 500 mTorr of CO creates Pt clusters shaped as triangles and parallelograms on Pt(557) and Pt(332), respectively. When 500 mTorr of C2H4 was introduced afterwards, Pt clusters are removed on Pt(332) but preserved on Pt(557). The three-fold hollow sites at the (111) steps enable the Pt(332) surface to accommodate ethylidyne even covered by CO. As a result, kink Pt atoms at the cluster edges are driven to diffuse to form straight steps, so as to admit more ethylidyne at steps. In contrast, Pt(557) has (100) steps on which ethylidyne does not adsorb, therefore keeping the island structure after the introduction of C2H4. When 500 mTorr of C2H4 was added first into the high-pressure cell, a periodic pattern is resolved at step edges on Pt(332). In contrast, some bright species separated by more than 1 nm are observed on Pt(557). Further introducing 500 mTorr of CO does not facilitate the formation of Pt clusters. The structure and mobility under C2H4, H2, and CO were also studied on the Pt(100) surface, whose topmost layer is rearranged into a hexagonal overlayer in vacuum. Under 1 Torr of C2H4, the hexagonal reconstruction is preserved on Pt(100), which is covered by highly mobile adsorbates. Pt atoms on the hexagonal layer can also move as a result of the weakened interaction between the surface layer and the bulk. The mobility is enhanced under 1 Torr of 1:1 C2H4-H2 mixture because the Pt(100)-hex surface is active in ethylene hydrogenation. The surface mobility along with the catalytic reaction is quenched after introducing 3 mTorr of CO. Meanwhile, the hexagonal reconstruction is lifted by the adsorption of CO. At 5 × 10−6 Torr of C2H4, CO from background gases can also adsorb on Pt(100), creating Pt islands that do not revert to the hexagonal surface when the C2H4 pressure was further increased to 1 Torr. In order to understand the effect of substrates on surface reconstruction, the structure of the stepped Cu(557) surface was monitored in equilibrium with high pressures of gases. Cu generally binds to the reducing gases such as CO, H2, and C2H4 weaker than Pt, leading to a lower coverage on Cu than on Pt at the same gas pressure. Accordingly, 12 Torr of CO is required to induce clusters on Cu(557), because higher CO pressures are needed to keep a sufficient amount of CO that can stabilize clusters. At 1 Torr, large terraces with an average width of 23 nm are observed on Cu(557), because of the low diffusion barrier for Cu atoms both on terraces and along the steps. 500 mTorr of H2 results in step coalescence on Cu(557), giving rise to 6 nm wide terraces. C2H4 adsorption at 500 mTorr results in 5 nm large clusters. CO does not change the Cu(557) surface structure while adding into C2H4, but causes the appearance of large terraces while co-adsorbing with H2. Under oxidizing gases, for example 1 Torr of O2, the Cu(557) surface is significantly oxidized, forming thick layers of Cu oxide. Pt-based bimetallic nanoparticle catalysts were also investigated with AP-XPS under reaction conditions to study their surface chemistry. PtFe nanoparticles do not undergo any surface segregation at 298 K when the gas environment changes, but surface Fe atoms are partially reduced under the C2H4-H2 mixture and partially oxidized under O2. Neither does the surface composition of Pt9Co-Co core-shell nanoparticles change while heating under H2 even to 673 K nor do oxidation states. In Pt-Ni systems, at 393 K, Ni is oxidized under O2 and migrates to the surface because Ni is more susceptible to oxidation than Pt. In contrast, when the surface is reduced by H2, Pt segregates to the surface since the surface free energy of Pt is lower. Such segregation does not occur at 353 K owing to the low atomic mobility in lattice.

Author: J. L. G. Fierro
Publisher: Elsevier Publishing Company
ISBN:
Category : Science
Languages : en
Pages : 402

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Surface spectroscopic techniques / J.L.G. Fierro -- Electronic structure and composition of surfaces / J. Alvarez, M.C. Asensio -- Surface groups on oxides / B.A. Morrow -- Characterization of catalyst structures by extended x-ray absorbtion spectroscopy / J.C. Conesa, P. Esteban, H. Dexpert, D. Bazin -- Characterisation of heterogeneous catalysts by Mössbauer spectroscopy / F.J. Berry.

Author: W Delgass
Publisher: Elsevier
ISBN: 0323154697
Category : Science
Languages : en
Pages : 352

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Spectroscopy in Heterogeneous Catalysis deals with the applications of spectroscopy in heterogeneous catalysis. The concepts and capabilities of a particular technique, experimental procedures, and examples of all proven or potentially important applications are discussed. The use of spectroscopic measurements in guiding empirical approaches to applied problems and to fundamental studies of the chemical identity of catalytic surfaces is also described. This book is comprised of eight chapters and begins with a discussion on the scope of spectroscopy in catalysis and applications of spectroscopy to zeolite catalysts. The following chapters focus on infrared spectroscopy, with emphasis on the theory and interpretation of infrared spectra; Raman spectroscopy and the theory of the Raman effect; diffuse reflectance and photoacoustic spectroscopies; and Mössbauer spectroscopy. Electron spin resonance spectroscopy and nuclear magnetic resonance spectroscopy are also considered. The final chapter is devoted to X-ray photoelectron spectroscopy (XPS) and its application to core electrons, along with the experimental equipment and procedures used. The applications of XPS to studies of surface behavior and catalyst composition and chemistry are outlined. This monograph will be a useful resource for physicists, researchers, and potential researchers in heterogeneous catalysis.

Author: Shi-Gang Sun
Publisher: Elsevier
ISBN: 0080489060
Category : Science
Languages : en
Pages : 559

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Book Description
In-Situ Spectroscopic Studies of Adsorption at the Electrode and Electrocatalysis is a new reference on in-situ spectroscopic techniques/applications, fundamentals of electrocatalysis at molecule level, and progresses within electrochemical surface science. Presenting both essential background knowledge at graduate level and original research within the fields of spectroscopy, electrochemistry, and surface science. Featuring 15 chapters by prominent worldwide scholars, based on their recent progress in different aspects of in-situ spectroscopy studies, this book will appeal to a wide audience of scientists. In summary this book is highly suitable for graduates learning basic concepts and advanced applications of in-situ spectroscopy, electrocatalysis and electrode adsorptions. * Written by the most active scientists in the fields of spectroscopy, electrochemistry and surface science* Essential background knowledge for graduate students* A modern reference of cutting-edge scientific research

Author: Tery Lynn Barr
Publisher: ASTM International
ISBN: 9780803102774
Category : Science
Languages : en
Pages : 220

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