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Introduction to Surface Chemistry and Catalysis - Ebook download as PDF File . pdf) or read book online. INTRODUCTION TO. SURFACE CHEMISTRY. AND CATALYSIS. GABOR A. SOMORJAI. Department of Chemistry. University of California. Berkeley, California. This revised edition of Introduction to Surface Chemistry and Catalysis reflects this increase of information in virtually every chapter. It emphasizes the modern.

Introduction To Surface Chemistry And Catalysis Pdf

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Introduction to surface chemistry and catalysis. By Gabor A. Somorjai, Wiley, Chichester, UK , XXIV, pp., hardcover, £, ISBN 0‐‐‐5. H.-J. Freund, N. Ernst, M. Bäumer, G. Rupprechter, J. Libuda, H. Kuhlenbeck et al . Pages PDF · Surface Chemistry of Model Oxide-Supported Metal. surfaces, adsorption and catalysis on surfaces, surface science approach to heterogeneous The scope of surface science, surface chemistry in particular, is much wider which includes Introduction to Surface Chemistry and Catalysis by .

This item: Introduction to Surface Chemistry and Catalysis, 2nd Edition. His current research interests include the oxidation of nanoparticles, the compensation effect in heterogeneous catalysis, and sum frequency generation vibrational spectroscopy at interfaces.

The Chemical Physics of Solid Surfaces and Heterogeneous Catalysis

Undetected country. NO YES. Selected type: Added to Your Shopping Cart. Now updated-the current state of development of modern surface science Since the publication of the first edition of this book, molecular surface chemistry and catalysis science have developed rapidly and expanded into fields where atomic scale and molecular information were previously not available.

New to this edition: A discussion of new physical and chemical properties of nanoparticles Ways to utilize new surface science techniques to study properties of polymers, reaction intermediates, and mobility of atoms and molecules at surfaces Molecular-level studies on the origin of the selectivity for several catalytic reactions A microscopic understanding of mechanical properties of surfaces Updated tables of experimental data A new chapter on "soft" surfaces, polymers, and biointerfaces Introduction to Surface Chemistry and Catalysis serves as a textbook for undergraduate and graduate students taking advanced courses in physics, chemistry, engineering, and materials science, as well as researchers in surface science, catalysis science, and their applications.

Experiments with ties for self-assembled monolayers of these nanoscale oxide mixed arrays of polyanions have shown that chemical iden- molecules as model oxide catalysts.

First, they form well- tity can be distinguished on an individual basis using tun- ordered monolayers on surfaces such as graphite [27] and neling spectroscopy, in effect demonstrating one can probe a silver [28]. Second, they exhibit novel electronic signatures reactive surface on a site-by-site basis [35]. We have also that can be used to identify individual molecules in these shown for the first time that ordered monolayers can be monolayers and to predict their redox properties.

By cou- We were one of the first two groups to demonstrate pling redox-active metal centers with redox-active HPAs, that ordered HPA monolayers could be formed on graphite one may improve both activity and selectivity for various surfaces by deposition from solution and imaged in air metal-catalyzed oxidation processes. Previous studies pro- with molecular resolution by scanning tunneling microscopy vide precedents for this strategy in terms of catalyst perfor- STM [29,30].

Tunneling spectroscopy measurements on mance [45], but it remains to connect this with molecular individual HPA molecules revealed current peaks, referred level control of surface redox properties that these ordered to as negative differential resistance NDR , in their current- HPA monolayers suggest is feasible.

Acrylic acid yields over supported HPA catalysts, plotted as a func- Fig. Oxidations were carried out by Keggin ions with different heteroatoms and framework compositions. Open squares denote heteropoly- redox properties of HPAs, including reduction potentials acids; filled squares are HPA catalysts for which some protons have been from electrochemical measurements, and NDR peak volt- exchanged.

For example, one with different heteroatoms and framework transition metal most often encounters volcano plots as means to correlate constituents. Reduction potential measurements shown in the activity of different catalysts for single reactions involv- Fig. As we have of formic acid on metals: activity initially increases with in- shown [34], the use of NDR peak potentials circumvents this creasing heat of formation of the metal formate or the metal problem.

NDR peak voltages can be measured in air for in- oxide as a generic surrogate , passes through a maximum for dividual molecules, either in the surface monolayers or de- platinum, and then decreases for metals with progressively posited on the STM tip [44]. Such a level of surface chem- higher heats of formation of their formates [49].

The usual ical characterization in principle permits one to map redox explanation is that for metals with heats of formation of the active centers site-by-site on model catalyst surfaces in or- intermediate less than that of the optimum catalyst, forma- der to develop structure-function relationships for these ma- tion of the intermediate is rate determining; for metals on the terials.

It also offers the prospect of using single molecule opposite slope of the volcano, reaction of the surface inter- spectra of HPAs in air as predictive tools in oxidation catal- mediate is rate determining. For example, Fig. These suggest idation. If oxidation activities. Reaction networks in oxidation catalysis rate determining, activity will begin to decrease as the re- duction potential increases.

Then, as for other single reaction Before one examines correlations of single molecule tun- processes, catalyst activity will exhibit volcano behavior. Chemical catalysis is most often interested in partial M. At mini- How then should we expect the performance of oxidation mum, such processes must be described as sequential reac- catalysts to vary as we vary their reduction potentials?

The alyst reoxidation is not rate limiting, the activity of a family optimum catalyst will no longer necessarily be the one that of catalysts for a single reaction would be expected to exhibit exhibits the highest rate for conversion of A to B, but rather increasing activity with increasing reduction potential.

In practice, selective oxida- provided that the catalysts exhibited similar surface areas tions are often characterized by triangular or series-parallel site densities and experiments were conducted at similar reaction networks. These add a parallel nonselective step, contact times. The target ity and yield would still increase monotonically with catalyst is a catalyst that minimizes the impact of these nonselective reduction potential subject to the same assumptions above , steps while promoting the desired partial oxidation reaction.

In that case selectivity would again be constant, but constant. For a purely sequential reaction reactant concentrations of the two parallel reactions are the network, activity for oxidation of A will increase with in- same. For series reactions, selectivity will fall monotonically creasing catalyst reduction potential, selectivity to B may be with increasing conversion, and yield will pass through a expected to decrease, and yield of B will pass through a max- maximum at intermediate conversion, if both reactions in the imum i.

Thus when results a range of catalysts that range from the inactive but selective, are evaluated from different catalysts, it is often preferable to the active but nonselective.

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When sup- complicated. Indeed it has lectivity and yield vs reduction potential will be qualitatively been claimed that supporting heteropolyacids on their alkali similar to that outlined for purely series processes, but with salts increases their stability at elevated temperatures [51].

This as- Unsupported HPAs are not as robust. Although phospho- sumes that relatively inactive catalysts nonreducible mate- tungstates are more stable than phosphomolybdate Keggin rials in the case of oxidation catalysts will still be selective. This is par- different nonselective from the point of view of oxidation ticularly evident when vanadium is incorporated into the catalysis reaction paths.

For example, nonreducible metal framework of a phosphomolybdate Keggin ion [54]. A re- oxides often catalyze acid or base reactions. This work concluded that the active state ity will begin to decrease as reduction potential increases. In of the HPA was a partially reduced oligomer of polyanions such a case reaction selectivity will exhibit volcano behavior bridged by vanadyl groups [55].

We consider below five case studies involving the use of The scale of NDR peak potentials obtained from tun- supported HPAs to oxidize propane, butane, and isobutyric neling spectra of more than 40 HPAs [34], illustrated in acid, and bulk HPAs to oxidize isobutane and acetaldehyde Fig.

Relationships between catalyst perfor- this family of oxidation catalysts. As one examines oxida- mance and single molecule spectra obtained with the STM tion processes that demand stronger or weaker oxidation cat- are explored for these five cases. Additional examples for alysts, one might expect to see emerging the various pat- which such relationships may be developed, including the terns discussed above for the dependence of activity, selec- oxidations of acrolein and ethylene with supported HPAs, tivity, and yield on reduction potential or NDR peak volt- and the oxidation of methane in the liquid phase by dissolved age.

One can then hope to identify the reduction potential or HPAs, will be the subject of future communications. While experiments are and spectroscopic measurements on supported HPA mono- needed that specifically target construction of volcano plots layers, to the extent that the latter reflect molecular proper- such as that illustrated in Fig.

Oxidation of propane to acrylic acid 2. Details of the oxidation procedure are given One of the key issues in attempting to correlate catalytic in US Patent 6,, Results of these runs are given in performance with spectroscopy of model systems obtained Table 1 and form the basis of the volcano plot shown in ex situ is the stability of HPAs under catalytic reaction Fig.

Even if one observes intact Keggin ions before vs NDR peak potential to this correlation. It is apparent and after reaction as is often the case [50,51] , there is no from these additional data that the catalyst activity increases guarantee that they operate in an intact state. However, their as the reduction potential increases NDR peak potential retention or recovery of a Keggin structure suggests that a becomes less negative , as expected.

The selectivity is quite close connection exists between their working and initial low for the least active catalyst, suggesting that parallel states, and that the characteristics of the latter may therefore reactions control the selectivity for catalysts with insufficient provide useful correlating or predictive tools.

The number of samples peaks might give superior performance. As shown in Fig. Oxidation of n-butane to maleic and acetic acids peaks above ca. He noted that the Table 2 and Fig. Table 3 and Fig.

Although activity trends are unclear compare the yields of these n-butane oxidation products as from this limited data set, both yield and selectivity increase a function of the NDR peak potential of the HPA that was as the reduction potential increases.

Again this suggests supported. Oxidation activities beyond those of the HPAs represented in Table 3 would be required to produce significant overoxidation of the acid products of butane oxidation. Isobutane oxidation selectivity and yield to methacrylic acid MAA Fig.

Oxidation of acetaldehyde to acetic acid 2. Table 4 and Fig. The trend selectivity. Conversion, selectivity, and yield all rise rapidly NDR value, followed by a continuing monotonic increase above this threshold, and for the limited data available, ap- that may or may not plateau. Summary with higher NDR peak potentials.

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Given the relatively high and invariant conversions reached with the phosphomolyb- Taken together, the results of these five case studies com- date HPAs in this study, it is not surprising that selectiv- bining NDR peak potentials measured for HPA monolay- ity and yield do not vary significantly among this family ers by STM, with literature data for catalyst performance, of catalysts.

More meaningful comparisons would require clearly show that less negative NDR peaks are associated data to be obtained at lower conversions, where differences with higher activity in oxidation catalysis.

This is consistent between active and selective catalysts might be better re- with our previous demonstrations that NDR peak potentials solved.

Conversion, selectivity, and yield for oxidative dehydrogenation of Fig. Relative oxidation rates for conversion of acetaldehyde to acetic acid isobutyric acid to methacrylic acid from [50] vs HPA NDR peak potential.

The advantage of the would indicate that the HPA-catalyzed oxidation of acrolein comprehensive and nearly continuous scale of HPA NDR should be more efficient than propylene and the latter in turn peak potentials is that it provides the tools to examine trends would be more efficient than that of propane. Such trends may be used to interpret the structure of polyoxometalate salt. In the sequence of oxidation steps tak- the reaction networks, as outlined earlier, to correlate cata- ing propane to acrylic acid, conversion increases and the re- lyst performance with independently measured redox prop- quired operating temperature decreases when one starts with erties, and to predict or select the optimum catalyst for the each successive oxidation product in the sequence, just as reaction of interest.

While the results to date are not suf- expected. For example, extrapolation of the yield Metal oxides hold great promise for the molecular-level and selectivity curves in Figs. This is in reasonable accord with the order of alysts, on the same scale. Negative differential resis- etaldehyde. A similar picture is provided by comparing the tance features in the tunneling spectra correlate well with conversion of different reactants with a single HPA.

HPA [32] M. Kaba, I. Song, M. Barteau, J. Song, R. Shnitser, J. Cowan, C. Hill, M. Barteau, Inorg. They may serve as the prototype of single site heterogeneous [34] I.

Song, J. Lyons, M. Barteau, Catal. Today, in press. B Kinne, M.

Barteau, Surf. References [37] I. Kaba, M. Cordatos, T.

Bunleisen, J. Stubenrauch, J. Vohs, R. Gorte, [38] M. A 15 J. Hilaire, X. Researchers have devoted a great deal of efforts to finding Pt-free electrocatalysts, including Ru 2 , transition metal disulfides 3 , 4 , 5 , 6 , metal carbides 7 , 8 , and metal phosphides 9 , For example, Mahmood et al.

Therefore, earth-abundant catalysts such as MoS2 have attracted intense research interest due to their low cost and high availability. Despite the discovery of relatively cheap electrocatalysts for HER, they are currently not viable for water splitting because they exhibit either higher overpotentials or poorer stability than Pt-based catalysts 2 , 6. For practical industrial uses, the performance of electrocatalysts at large current densities is critical.

Therefore, developing electrocatalysts that perform well at high current densities is critical for large-scale use.

To this end, Chen et al. We note that these catalysts either have large overpotentials or are only suitable for a specific pH for HER at high current densities. Developing catalysts that work well in a wide pH range is important not only for an understanding of the different HER mechanisms in acidic and alkaline media, but also for use in different pH conditions based on specific needs.

This is therefore another important issue to be addressed, especially when considering the slow water dissociation kinetics in an alkaline medium for most catalysts such as Pt and MoS2, which results in poorer catalytic activity in alkaline than in acidic media 17 , 18 , 19 , Many efforts have been devoted to improve the HER performance of electrocatalysts in alkaline media 3 , 4 , 19 , 21 , Subbaraman et al.

Later, other metal hydroxides such as Co OH 2 have also been shown to work as water dissociation promoters in alkaline media 18 , 22 , 23 , 24 , However, species that can work as kinetic promoters for water dissociation are few and are mainly limited to metal hydroxides and oxyhydroxides. Overall, the challenges in designing catalysts that work well over a range of pH values at high current densities stem from the fact that HER involves electron transfer and redistribution at liquid—solid—gas interfaces, which becomes complicated at large current densities and in different pH conditions Specifically, features of a catalyst may affect electron transfer rate, the amount and exposure of active sites, accessibility of catalytic surfaces to reactants, bonding strength with hydrogen, and water dissociation kinetics, and thus would influence their HER performance at high current densities.

Here, we address these challenges by developing electrocatalysts with an optimized morphology and surface chemistry. Based on these studies, an efficient catalyst for HER at high current density over a range of pH values is synthesized.

This catalyst has many advantages. First, the aligned MoS2 nanosheets have many exposed active sites that benefit in-plane electron transfer. Second, the spherical morphology has roughness at both the micro- and nano-scales, and this is necessary for access of reactants and release of hydrogen bubbles 27 , Third, the Mo2C nanoclusters change the surface chemistry of the MoS2 catalysts.

Experimental and theoretical investigations show that Mo2C modified by surface oxygen groups formed during the HER not only promotes the interfacial mass transfer of reactants and hydrogen gas bubbles on MoS2, but also speeds up the water dissociation and hydrogen absorption kinetics, resulting in decent HER performance at high current densities.

Insets in c and e are enlarged views and the corresponding fast Fourier transform FFT pattern, respectively.

The images d and e are enlarged views of the squares outlined in red and blue in c. The scale bars are 5 nm in c and 0.

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At the microscale, there are a large number of microspheres with a narrow diameter distribution of 1. The inset of Fig. Such a structure can pump liquid-phase electrolyte onto the catalytic surface because of the strong capillary forces As a result it reduces gas—solid interface adhesion and promotes the release of hydrogen bubbles from the catalyst surface 30 , which is critical for HER involving high current densities.

In addition, the aligned MoS2 nanosheets have a large number of exposed catalytically active edge sites.The pass energy was 20 eV and energy step size was 0.

Surface Chemistry and Catalysis

You will also find a description of one example of autocatalysis - a reaction which is catalysed by one of its products. Open squares denote heteropoly- redox properties of HPAs, including reduction potentials acids; filled squares are HPA catalysts for which some protons have been from electrochemical measurements, and NDR peak volt- exchanged.

Schlogl, Appl. Idriss, M. The hydrogen was ultrapure; it had been passed through the Pd-Ag thimble of a RSI cornmercial purifier. Oxidation of acetaldehyde to acetic acid 2. A 11 Barteau, Langmuir 18 Martinez, M.

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