New nanostructured heterogeneous catalysts with increased selectivity and stability.

In this perspective, several examples of work from our laboratory are reported where colloidal or self-assembly chemistry has been used to design new catalysts with specific properties. In the first, platinum nanoparticles with well-defined shapes have been dispersed on a high-surface-area silica support in order to take advantage of the structure sensitivity exhibited by the interconversion between the cis and trans isomers of olefins. The second case involves the use of dendrimers as scaffolding structures to prepare catalysts with small platinum nanoparticles of well-defined size. Reduced sintering of metal nanoparticles on supported catalysts is accomplished in our third example via their encapsulation inside a layer of mesoporous silica deposited on top, after metal dispersion, and etched using a newly developed surface-protection process. The final project refers to the use of yolk@shell metal-oxide systems as nanoreactors for photocatalysis. In all those examples, new synthetic nanotechnology has been directed to address a specific issue in catalysis previously identified by surface-science studies.

[1]  Ilkeun Lee,et al.  The Stereoselectivity of the Dehydrogenation of Alkyl Groups on Pt(111) Single-Crystal Surfaces , 2011 .

[2]  Francisco Zaera,et al.  Dendrimer-based synthesis of Pt catalysts for hydrocarbon conversion , 2011 .

[3]  Ilkeun Lee,et al.  Surface‐Protected Etching of Mesoporous Oxide Shells for the Stabilization of Metal Nanocatalysts , 2010 .

[4]  Zhong-lin Chen,et al.  Magnetically recoverable core-shell nanocomposites with enhanced photocatalytic activity. , 2010, Chemistry.

[5]  F. Zaera,et al.  Adsorption properties of supported platinum catalysts prepared using dendrimers. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[6]  Ilkeun Lee,et al.  Catalytic conversion of olefins on supported cubic platinum nanoparticles: Selectivity of (1 0 0) versus (1 1 1) surfaces , 2010 .

[7]  F. Zaera.  The New Materials Science of Catalysis: Toward Controlling Selectivity by Designing the Structure of the Active Site , 2010 .

[8]  R. Crooks,et al.  Adsorption of Carbon Monoxide on Dendrimer-Encapsulated Platinum Nanoparticles: Liquid versus Gas Phase , 2010 .

[9]  Gabor A. Somorjai,et al.  Advancing the frontiers in nanocatalysis, biointerfaces, and renewable energy conversion by innovations of surface techniques. , 2009, Journal of the American Chemical Society.

[10]  F. Zaera,et al.  Conversion of cis- and trans-2-butene with Deuterium on a Pd/Fe3O4 model catalyst , 2009 .

[11]  F. Zaera.  Regio-, stereo-, and enantioselectivity in hydrocarbon conversion on metal surfaces. , 2009, Accounts of chemical research.

[12]  D. Mozaffarian,et al.  Trans fatty acids: effects on metabolic syndrome, heart disease and diabetes , 2009, Nature Reviews Endocrinology.

[13]  Younan Xia,et al.  Shape-controlled synthesis of platinum nanocrystals for catalytic and electrocatalytic applications , 2009 .

[14]  G. Somorjai,et al.  Thermally stable Pt/mesoporous silica core-shell nanocatalysts for high-temperature reactions. , 2009, Nature materials.

[15]  Ilkeun Lee,et al.  Tuning selectivity in catalysis by controlling particle shape. , 2009, Nature materials.

[16]  F. Zaera,et al.  Origin of the selectivity for trans-to-cis isomerization in 2-butene on Pt(111) single crystal surfaces. , 2008, Journal of the American Chemical Society.

[17]  Ilkeun Lee,et al.  Synthesis of heterogeneous catalysts with well shaped platinum particles to control reaction selectivity , 2008, Proceedings of the National Academy of Sciences.

[18]  Hyunjoon Song,et al.  Precise tuning of porosity and surface functionality in Au@SiO2 nanoreactors for high catalytic efficiency , 2008 .

[19]  Ilkeun Lee,et al.  Thermal Chemistry of 1,4-Difluoro-2-butenes on Pt(111) Single-Crystal Surfaces , 2008 .

[20]  Tierui Zhang,et al.  Permeable silica shell through surface-protected etching. , 2008, Nano letters.

[21]  H. Freund,et al.  Isomerization and Hydrogenation of cis-2-Butene on Pd Model Catalyst , 2008 .

[22]  G. Somorjai,et al.  Dendrimer templated synthesis of one nanometer Rh and Pt particles supported on mesoporous silica: catalytic activity for ethylene and pyrrole hydrogenation. , 2008, Nano letters.

[23]  G. Ertl.  Reactions at surfaces: from atoms to complexity (Nobel Lecture). , 2008, Angewandte Chemie.

[24]  Hyunjoon Song,et al.  A Nanoreactor Framework of a Au@SiO2 Yolk/Shell Structure for Catalytic Reduction of p‐Nitrophenol , 2008 .

[25]  Ilkeun Lee,et al.  Infrared spectroscopy characterization of the chemistry of C4 hydrocarbons on Pt(111) single-crystal surfaces , 2007 .

[26]  P. Kamat.  Meeting the Clean Energy Demand: Nanostructure Architectures for Solar Energy Conversion , 2007 .

[27]  S. Kuwabata,et al.  Ligand-free platinum nanoparticles encapsulated in a hollow porous carbon shell as a highly active heterogeneous hydrogenation catalyst. , 2006, Angewandte Chemie.

[28]  Francisco Zaera,et al.  Organic chemistry on solid surfaces , 2006 .

[29]  Feng Lu,et al.  Nanoparticles as recyclable catalysts: the frontier between homogeneous and heterogeneous catalysis. , 2005, Angewandte Chemie.

[30]  Ilkeun Lee,et al.  Selectivity in platinum-catalyzed cis-trans carbon-carbon double-bond isomerization. , 2005, Journal of the American Chemical Society.

[31]  H. Zeng,et al.  Size tuning, functionalization, and reactivation of Au in TiO2 nanoreactors. , 2005, Angewandte Chemie.

[32]  M. El-Sayed,et al.  Catalysis with transition metal nanoparticles in colloidal solution: nanoparticle shape dependence and stability. , 2005, The journal of physical chemistry. B.

[33]  Prashant V Kamat,et al.  Charge separation and catalytic activity of Ag@TiO2 core-shell composite clusters under UV-irradiation. , 2005, Journal of the American Chemical Society.

[34]  Ilkeun Lee,et al.  Thermal chemistry of C4 hydrocarbons on Pt(111): Mechanism for double-bond isomerization. , 2005, The journal of physical chemistry. B.

[35]  Richard M Crooks,et al.  Synthesis, characterization, and applications of dendrimer-encapsulated nanoparticles. , 2005, The journal of physical chemistry. B.

[36]  B. D. Chandler,et al.  Decomposition and Activation of Pt-Dendrimer Nanocomposites on a Silica Support , 2004 .

[37]  H. Hah,et al.  New synthetic route for preparing rattle-type silica particles with metal cores. , 2004, Chemical communications.

[38]  T. Risse,et al.  Cluster, facets, and edges: site-dependent selective chemistry on model catalysts. , 2003, Chemical record.

[39]  F. Zaera.  Surface Chemistry of Hydrocarbon Fragments on Transition Metals: Towards Understanding Catalytic Processes , 2002 .

[40]  Younan Xia,et al.  Synthesis and Self-Assembly of Au@SiO2 Core−Shell Colloids , 2002 .

[41]  B. Gates.  Models of metal catalysts: beyond single crystals , 2000 .

[42]  G. Somorjai,et al.  The Flexible Surface: Molecular Studies Explain the Extraordinary Diversity of Surface Chemical Properties , 1998 .

[43]  Paul Mulvaney,et al.  Synthesis of Nanosized Gold−Silica Core−Shell Particles , 1996 .

[44]  G. Bond.  Strategy of research on supported metal catalysts. Problems of structure-sensitive reactions in the gas phase , 1993 .

[45]  D. Goodman,et al.  High pressure catalytic reactions over single-crystal metal surfaces , 1991 .

[46]  G. Somorjai,et al.  Surface science studies of catalysis: classification of reactions , 1986 .

[47]  G. Somorjai,et al.  Surface structure and temperature dependence of n-hexane skeletal rearrangement reactions catalyzed over platinum single crystal surfaces: Marked structure sensitivity of aromatization , 1984 .

[48]  G. Somorjai,et al.  Heterogeneous catalysis on the molecular scale , 1982 .

[49]  G. Somorjai,et al.  SURFACE STRUCTURE AND TEMPERATURE DEPENDENCE OF LIGHT-ALKANE SKELETAL REARRANGEMENT REACTIONS CATALYZED OVER PLATINUM SINGLE-CRYSTAL SURFACES , 1982 .

[50]  J. M. Thomas,et al.  Introduction to the principles of heterogeneous catalysis , 1967 .