The authors acknowledge National Science Foundation grant CHE- 1214068 for supporting this research project.

1. Preparação de GMS <ol><li> Use todos os produtos químicos no processo seguinte como recebidos. </li><li> Preparar 75 ml de 2 M de solução de ácido clorídrico (HCl). Pesar 2,0 g de poli (etilenoglicol) -bloco-poli (propileno glicol) -bloco-poli (etileno-glicol) (P123, PM = 5800) e transferir para o preparado 75 ml de solução 2 M de HCl. À TA, aplicar agitação magnética à solução a uma velocidade de 350 r / min, até que esteja completamente dissolvido P123. A solução ficará claro. </li><li> Pesar 4 g de tetraetoxissilano (TEOS, PM = 208,33) num pequeno vaso de reacção e transferência de 180 uL de cloreto de bis [3- (trietoxissilil) propil] -tetrasulfide (TESPTS, PM = 538,94) para dentro do frasco. Lentamente agitar o frasco para misturar os dois produtos químicos. Num outro frasco, pesar 38 mg de ácido cloroáurico (HAuCl 4, 99,90%) e dissolver em 1 ml de água Dl. </li><li> Aumentar a temperatura da solução P123 a 35 ° C num banho de óleo com temperatura controlada por termopar. </li><li> Adicione toda a mistura de TEOS eTESPTS preparado no passo 1.3 para a solução P123, e manter a solução em agitação magnética vigorosa de 700 r / min. Manter a solução agitar durante 2 min, depois adicionar toda a solução de HAuCl 4, preparado no passo 1.3, gota a gota dentro de 30 seg. </li><li> Manter a solução em agitação a 700 r / min durante 24 horas a 35 ° C. </li><li> Após 24 horas, transferir a solução para um frasco e armazenar selado num forno regulado a 100 ° C durante 72 h. Isso é chamado de processamento hidrotérmico. </li><li> Após o processamento hidrotérmico, filtrar a solução com um papel de filtração # 1 e sob uma pressão negativa de um funil, em seguida, lava-se com água duas vezes e etanol três vezes para remover o HCl restante. Durante cada processo de lavagem, adicionar água ou etanol 1 cm acima sólido e esperar que o material secar. </li><li> Transferir precipitação a partir de filtração para um cadinho de material cerâmico e calcinado a 550 ° C durante 4 h. Definir o programa de rampa como se segue: 25 ° C a 550 ° C durante 2 horas, manter a 550 ° C durante 4h, depois deixar a amostra permanecer no forno com a porta fechada até que a temperatura desce abaixo de 40 ° C. </li><li> Após calcinação, transferir o produto para um frasco de vidro com uma espátula de plástico. O material sintetizado tem uma cor vermelha. </li></ol> 2. A reacção catalítico, a oxidação do álcool benzílico <ol><li> Uma vez que a oxidação do álcool benzílico é uma reacção em fase líquida sem um solvente separado, medida 5 ml de álcool benzílico (99,8%) e transferi-lo para um balão de 25 ml de três tubuladuras, em seguida, pesar 10 mg de catalisador de GMS e adicionar a benzilo álcool. </li><li> Defina-se um banho de óleo com temperatura controlada com agitação magnética para garantir um controlo preciso e uniforme da temperatura da reacção. </li><li> Colocar o balão com álcool benzílico e o catalisador para o banho de óleo, em seguida, ajustar a temperatura para 100 ° C e agita-se a 150 r / min. </li><li> O caudal de gás de oxigénio com 99,9% de pureza para o balão a 2 ml / min controlados por um controlador de fluxo de massa. </li><li> Quando otemperatura do banho de óleo atinge 100 ° C e estabilize, introduzir gás de oxigénio para o balão de três tubuladuras. </li><li> Manter constante a taxa de fluxo de oxigénio e de temperatura, e deixar a reacção prosseguir durante 6 horas. </li><li> Após a reacção, filtra-se o produto com um papel de filtração # 1. Recolher a fase líquida e transferência de uma alíquota para um frasco de cromatografia em fase gasosa (GC). No frasco de GC, misturar ácido acético quatro partes para HPLC, para cada uma parte de amostra (Por exemplo, use 36 amostras ul e 144 ul de ácido acético.) Coloque o frasco em um amostrador automático cromatógrafo a gás para análise. Lavar o precipitado sólido no papel de filtro com água desionizada e etanol, em seguida deixar secar ao ar. Recolhe-se o sólido seco com uma espátula de catalisador reciclado. </li><li> Repetir o mesmo procedimento experimental do passo 2.3 a 2.7 com catalisador reciclado três vezes. Em cada repetição, ajustar a quantidade de álcool benzílico para coincidir com o rácio descrito no passo 2.2. </li></ol> 3. Thermal Tratamento de GMS para Teste de Estabilidade térmica <ol><li> Pesar três porções de 300 mg separadas de GMS sintetizados, e armazená-los em frascos de vidro. Estes são marcados como lote 1, lote 2 e 3. Mantenha lote lote 1 como grupo controle, e colocar em lotes 2 e 3 de lote em uma fornalha para o processamento térmico. </li><li> Programa do forno como se segue para o processamento a 400 ° C: rampa de 25 ° C a 400 ° C em 0,5 horas, mantida a 400 ° C durante 4 horas, deixar a amostra permanecer no forno com a porta fechada até que as quedas de temperatura abaixo de 40 ° C. Coloque lote 2 em um cadinho e iniciar o programa. </li><li> Programa do forno como se segue para o processamento a 650 ° C: rampa de 25 ° C a 650 ° C em 0,75 horas, manutenção a 650 ° C durante 4 horas, deixar a amostra permanecer no forno com a porta fechada até que a temperatura desce abaixo do 40 ° C. Coloque lote 3 em um cadinho e iniciar o programa. </li></ol> 4. CaracterizaçãoMateriais de GMS 21,22 <ol><li> No instrumento fisiossorção, desgaseifica GMS materiais com o seguinte programa: 90 ° C durante 60 min e, em seguida, a 350 ° C durante 480 min. Executar análise completa-isotérmica sobre os materiais desgaseificados para obter dados fisiossorção. </li><li> Dispersar amostra GMS em uma grade TEM carbono holey 200-mesh e observar a amostra sob um microscópio eletrônico de transmissão. Restringir ampliação sob 44,000X para proteger o material. </li><li> DRX correr com Cu Ka radiação (λ = 1,5418 Å). Set tensão de tubo de 45 kV e corrente do tubo de 40 mA. Recolhe intensidade na gama 2θ entre 10 ° e 90 ° com um tamanho de passo de 0,008 ° e um tempo de medição de 5 segundos em cada passo. </li></ol>

<ol>
	<li>Liguras, D. K., Kondarides, D. I., Verykios, X. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+hydrogen+for+fuel+cells+by+steam+reforming+of+ethanol+over+supported+noble+metal+catalysts.">Production of hydrogen for fuel cells by steam reforming of ethanol over supported noble metal catalysts.</a> Appl. Catal. B-Environ. 43 (4), 345-354 (2003).</li><li>Gelin, P., Primet, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complete+oxidation+of+methane+at+low+temperature+over+noble+metal+based+catalysts:+a+review.">Complete oxidation of methane at low temperature over noble metal based catalysts: a review.</a> Appl. Catal. B-Environ. 39 (1), 1-37 (2002).</li><li>Lu, S. F., Pan, J., Huang, A. B., Zhuang, L., Lu, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Alkaline+polymer+electrolyte+fuel+cells+completely+free+from+noble+metal+catalysts.">Alkaline polymer electrolyte fuel cells completely free from noble metal catalysts.</a> Proc. Natl. Acad. Sci. U. S. A. 105 (52), 20611-20614 (2008).</li><li>Ma, C. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Catalytic+oxidation+of+benzyl+alcohol+on+Au+or+Au&#8211;Pd+nanoparticles+confined+in+mesoporous+silica.">Catalytic oxidation of benzyl alcohol on Au or Au&#8211;Pd nanoparticles confined in mesoporous silica.</a> Applied Catalysis B: Environmental. 92 (1-2), 202-208 (2009).</li><li>Bamwenda, G. R., Tsubota, S., Nakamura, T., Haruta, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+the+preparation+methods+on+the+catalytic+activity+of+platinum+and+gold+supported+on+TiO2+for+CO+oxidation.">The influence of the preparation methods on the catalytic activity of platinum and gold supported on TiO2 for CO oxidation.</a> Catalysis Letters. 44 (1-2), 83-87 (1997).</li><li>Brown, K. R., Walter, D. G., Natan, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Seeding+of+colloidal+Au+nanoparticle+solutions.+2.">Seeding of colloidal Au nanoparticle solutions. 2.</a> Improved control of particle size. 12 (2), 306-313 (2000).</li><li>Niesz, K., Grass, M., Somorjai, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Precise+control+of+the+Pt+nanoparticle+size+by+seeded+growth+using+EO13PO30EO13+triblock+copolymers+as+protective+agents.">Precise control of the Pt nanoparticle size by seeded growth using EO13PO30EO13 triblock copolymers as protective agents.</a> Nano Lett. 5 (11), 2238-2240 (2005).</li><li>Yuranov, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pd/SiO2+catalysts:+synthesis+of+Pd+nanoparticles+with+the+controlled+size+in+mesoporous+silicas.">Pd/SiO2 catalysts: synthesis of Pd nanoparticles with the controlled size in mesoporous silicas.</a> J. Mol. Catal. A-Chem. 192, 1-2 (2003).</li><li>Brinas, R. P., Hu, M. H., Qian, L. P., Lymar, E. S., Hainfeld, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gold+nanoparticle+size+controlled+by+polymeric+Au(I)+thiolate+precursor+size.">Gold nanoparticle size controlled by polymeric Au(I) thiolate precursor size.</a> J. Am. Chem. Soc. 130 (3), 975-982 (2008).</li><li>Zhu, H. G., Liang, C. D., Yan, W. F., Overbury, S. H., Dai, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+of+highly+active+silica-supported+Au+catalysts+for+CO+oxidation+by+a+solution-based+technique.">Preparation of highly active silica-supported Au catalysts for CO oxidation by a solution-based technique.</a> J. Phys. Chem. B. 110 (22), 10842-10848 (2006).</li><li>Gabaldon, J. P., Bore, M., Datye, A. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesoporous+silica+supports+for+improved+thermal+stability+in+supported+Au+catalysts.">Mesoporous silica supports for improved thermal stability in supported Au catalysts.</a> Top. Catal. 44 (1-2), 253-262 (2007).</li><li>Li, F. B., Li, X. Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+enhancement+of+photodegradation+efficiency+using+Pt-TiO2+catalyst.">The enhancement of photodegradation efficiency using Pt-TiO2 catalyst.</a> Chemosphere. 48 (10), 1103-1111 (2002).</li><li>Sakthivel, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancement+of+photocatalytic+activity+by+metal+deposition:+characterisation+and+photonic+efficiency+of+Pt,+Au+and+Pd+deposited+on+TiO2+catalyst.">Enhancement of photocatalytic activity by metal deposition: characterisation and photonic efficiency of Pt, Au and Pd deposited on TiO2 catalyst.</a> Water Res. 38 (13), 3001-3008 (2004).</li><li>Jia, C. G., Wang, Y. P., Feng, H. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparation+and+Catalytic+Properties+Of+Polymer-Supported+Fe-Co-Cu+And+Fe-Co-Au+Pentametallic+Clusters.">Preparation and Catalytic Properties Of Polymer-Supported Fe-Co-Cu And Fe-Co-Au Pentametallic Clusters.</a> React. Polym. 18 (3), 203-211 (1992).</li><li>Yu, X. Q., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduced+graphene+oxide+supported+Au+nanoparticles+as+an+efficient+catalyst+for+aerobic+oxidation+of+benzyl+alcohol.">Reduced graphene oxide supported Au nanoparticles as an efficient catalyst for aerobic oxidation of benzyl alcohol.</a> Appl. Surf. Sci. 280, 450-455 (2013).</li><li>Xu, Y. Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Au@Pt+core-shell+nanoparticles+supported+on+multiwalled+carbon+nanotubes+for+methanol+oxidation.">Au@Pt core-shell nanoparticles supported on multiwalled carbon nanotubes for methanol oxidation.</a> Catal. Commun. 13 (1), 54-58 (2011).</li><li>Baker, C. O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Size+Control+of+Gold+Nanoparticles+Grown+on+Polyaniline+Nanofibers+for+Bistable+Memory+Devices.">Size Control of Gold Nanoparticles Grown on Polyaniline Nanofibers for Bistable Memory Devices.</a> ACS Nano. 5 (5), 3469-3474 (2011).</li><li>Wei, G. -. T., Yang, Z., Lee, C. Y., Yang, H. Y., Wang, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aqueous&#8722;Organic+Phase+Transfer+of+Gold+Nanoparticles+and+Gold+Nanorods+Using+an+Ionic+Liquid.">Aqueous&#8722;Organic Phase Transfer of Gold Nanoparticles and Gold Nanorods Using an Ionic Liquid.</a> J. Am. Chem. Soc. 126 (16), 5036-5037 (2004).</li><li>Gadenne, B., Hesemann, P., Moreau, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Supported+ionic+liquids:+ordered+mesoporous+silicas+containing+covalently+linked+ionic+species.">Supported ionic liquids: ordered mesoporous silicas containing covalently linked ionic species.</a> Chemical Communications. 15, 1768-1769 (2004).</li><li>Yang, J. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+preparation+variables+in+the+synthesis+of+Au/Al2O3+using+EXAFS+and+electron+microscopy.">Understanding preparation variables in the synthesis of Au/Al2O3 using EXAFS and electron microscopy.</a> Applied Catalysis A: General. 291 (1-2), 73-84 (2005).</li><li>Chen, L. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intercalation+of+aggregation-free+and+well-dispersed+gold+nanoparticles+into+the+walls+of+mesoporous+silica+as+a+robust+&#8216;green&#8217;+catalyst+for+n-alkane+oxidation.">Intercalation of aggregation-free and well-dispersed gold nanoparticles into the walls of mesoporous silica as a robust &#8216;green&#8217; catalyst for n-alkane oxidation.</a> Journal of the American Chemical Society. 131, 914-915 (2009).</li><li>Wang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoscale+gold+intercalated+into+mesoporous+silica+as+a+highly+active+and+robust+catalyst.">Nanoscale gold intercalated into mesoporous silica as a highly active and robust catalyst.</a> Nanotechnology. 23, 294010-294018 (2012).</li><li>Chen, L. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlled+synthesis+of+nanoscale+icosahedral+gold+particles+at+room+temperature.">Controlled synthesis of nanoscale icosahedral gold particles at room temperature.</a> Chemcatchem. 4, 1662-1667 (2012).</li></ol>

The authors have nothing to disclose.

Dentro do protocolo de síntese, a atenção a concentração de agente tensioactivo, pH da solução e a temperatura de reacção é crítica para o sucesso da formação de GMS. Os passos críticos são 1.2, 1.3, 1.4 e 1.6. Os parâmetros acima mencionados controlar o parâmetro de embalagem crítico e fase de micelas formadas a partir de surfactante. A fase e a morfologia das micelas determina o estado final de matriz de sílica, que serve como o quadro de GMS. Também importante no processo de formação é a sequê...

Como uma tecnologia emergente que tem um grande potencial em aplicações de catálise, materiais em nanoescala receberam interesse de pesquisa intensiva nas últimas décadas. Entre os catalisadores nanoescala relatado, os catalisadores de metais nobres, tais como Au, Ag, Pd e Pt têm atraído a atenção mundial 1-3. Seleccione reações catalíticas incluem a oxidação de monóxido de carbono pesquisadores em Au, Heck reacção em catalisadores de paládio, e divisão de água com Pt. Apesar do potencial promissor catalítica, ouro escala nano é limitada na sua aplicabilidade devido à desactivação do envenenamento, coque, degradação térmica, e sinterização. Tem sido relatado que o ouro, como um representante para os metais nobres, tem uma selectividade elevada e é menos propenso a lixiviação de metais pesados, a sobre-oxidação e auto-envenenamento 4. No entanto, a performance catalítica de ouro depende fortemente do tamanho da partícula. Haruta et al., Relatou a relação entre o desempenho catalítico e irdiâmetro aglomerado ld, demonstrando a maior atividade de catalisadores de ouro com tamanho de partícula ~ 2,7 nm 5. O tamanho das partículas dos metais nobres pode ser controlada pelo método de preparação 6-9; no entanto, o grande obstáculo para uma aplicação ampla permanece a agregação e perda de actividade. Para resolver o problema de sinterização, é um método comum para imobilizar as partículas em nano-escala sobre um material de suporte. Vários materiais de apoio foram aplicadas incluindo sílica porosa 10-11, óxidos metálicos semicondutores 12-13, polímeros 14, o grafeno e os nanotubos de carbono 15 16. Entre os materiais utilizados, a sílica porosa é de um material atraente como um apoio, porque é apenas levemente ácida, relativamente inerte, termicamente e quimicamente estável, e podem ser preparadas com muito bem definido meso / micro-porosidade. A estrutura porosa oferece um bom suporte para partículas de metal, mas também dá acesso tamanho do substrato seletiva paraos catalisadores de metal. Esta selectividade é particularmente promissora devido à capacidade de afinação relacionado com estes materiais porosos. Muitas vezes, as partículas de ouro são encontrados para ser extremamente móvel em superfícies de sílica e 17-18 formam facilmente muito grandes (50+) nm partículas não reactivos quando exposto a altas temperaturas, tornando assim difícil para preparar nanopartículas de ouro em sílica 19. Mukherjee et ai. Relataram a imobilização de nanopartículas de ouro sobre mesoporosa de sílica monodispersas MCM-41 de 3-aminopropil-trimetoxi-silano e 3-mercaptopropil-trietoxissilano, e as nanopartículas de ouro apoiados foram encontrados como sendo altamente activo para reacções de hidrogenação e não lixiviação de ouro foi encontrado 20 na reacção. Seguindo o relatório de modificação da superfície de sílica mesoporosa, que relataram um método para preparar ouro intercalado na parede de sílica mesoporosa (GMS). Além disso, a abordagem de sílica mesoporosa suportada oferece um ap escaláveldagem para alterar potencialmente o catalisador e independentemente ambiente poroso. Desde processos catalíticos são de vital importância económica, os benefícios poderiam ser de grande alcance. A capacidade de desenvolver catalisadores &quot;verdes&quot; teria um profundo impacto positivo sobre o meio ambiente e melhorar a viabilidade e recurso econômico eficiência dos processos industriais importantes.

<table><tbody><tr><td>poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol)</td><td>Aldrich</td><td>435465-250ML</td><td></td></tr><tr><td>tetraethoxysilane</td><td>TCI</td><td>201-083-8</td><td></td></tr><tr><td>bis[3-(triethoxysilyl)propyl]-tetrasulfide</td><td>GELEST</td><td>SIB1825.0-100GM</td><td></td></tr><tr><td>chloroauric acid</td><td>Aldrich</td><td>520918-1G</td><td></td></tr><tr><td>benzyl alcohol</td><td>Sigma-Aldrich</td><td>305197-1L</td><td></td></tr><tr><td>nitrogen physisorption</td><td>Micromeritics</td><td>Tristar II</td><td></td></tr><tr><td>X-ray diffraction</td><td>Philips</td><td>X&#039;Pert Pro</td><td></td></tr><tr><td>transmission electron microscopy</td><td>Philips</td><td>CM200</td><td></td></tr><tr><td>gas chromatography</td><td>Shimadzu</td><td>GC-2010</td><td></td></tr></tbody></table>

synthesis and catalytic performance of gold intercalated in the walls of mesoporous silica

Como um promissor reactor nano cataliticamente activo, intercalados em nanopartículas de ouro mesoporosa de sílica (GMS) foram sintetizados com êxito e propriedades dos materiais foram investigados. Usamos uma abordagem sol-gel um pote de intercalar nano partículas de ouro nas paredes de sílica mesoporosa. Para começar a síntese, P123 foi utilizado como molde para formar micelas. Então TESPTS foi utilizado como um agente de modificação da superfície para se intercalam nano partículas de ouro. Seguindo este processo, TEOS foi adicionado como uma fonte de sílica que foi submetido a um processo de polimerização em meio ácido. Após o processamento hidrotérmico e calcinação, o produto final foi adquirida. Várias técnicas foram utilizadas para caracterizar a porosidade, morfologia e estrutura do intercalada sílica mesoporosa ouro. Os resultados mostraram uma estrutura estável de sílica mesoporosa após intercalação ouro. Através da oxidação de álcool benzílico como um valor de referência de reacção, os materiais de GMS mostraram alta selectividade e reciclagem.

Este método foi utilizado para comparar os níveis de síntese do heme em condições normais (HBEC30KT) vs cancerosas (células de pulmão HCC4017). A Figura 2 mostra um nível mais elevado da síntese de heme em células de cancro (HCC4017) do que as células normais de pulmão (HBEC30KT). O nível de síntese do heme foi medido também em células normais e cancerosas, na presença de cianeto de carbonilo mitocondrial desacoplador 3-clorofenilhidrazona (CCCP). As células foram tratadas com 10 mM de...

Watch this Scientific Journal Video about Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica at JoVE.com

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

Síntese e desempenho catalítico de ouro intercalados nas paredes de mesoporosos Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties ...

synthesis-catalytic-performance-gold-intercalated-walls-mesoporous

Research

JoVE Journal

Chemistry

10.0K visualizações.  Colorado School of Mines. Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

Vídeo: Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan &#948; solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials&#39; morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by St&#246;ber&#39;s methods, which have smooth surfaces.

Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle ...

Química

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using conventional synthesis techniques. Coupling soft landing with in situ characterization using secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS) enables analysis of well-defined surfaces under clean vacuum conditions. The capabilities of three soft-landing instruments constructed in our laboratory are illustrated for the representative system of surface-bound organometallics prepared by soft landing of mass-selected ruthenium tris(bipyridine) dications, [Ru(bpy)3]2+ (bpy = bipyridine), onto carboxylic acid terminated self-assembled monolayer surfaces on gold (COOH-SAMs). In situ time-of-flight (TOF)-SIMS provides insight into the reactivity of the soft-landed ions. In addition, the kinetics of charge reduction, neutralization and desorption occurring on the COOH-SAM both during and after ion soft landing are studied using in situ Fourier transform ion cyclotron resonance (FT-ICR)-SIMS measurements. In situ IRRAS experiments provide insight into how the structure of organic ligands surrounding metal centers is perturbed through immobilization of organometallic ions on COOH-SAM surfaces by soft landing. Collectively, the three instruments provide complementary information about the chemical composition, reactivity and structure of well-defined species supported on surfaces.

In Situ SIMS and IR Spectroscopy of Well-defined Surfaces Prepared by Soft Landing of Mass-selected Ions

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of novel materials. Coupled with analysis by in situ secondary ion mass spectrometry (SIMS) and infrared reflection absorption spectroscopy (IRRAS), soft landing provides unprecedented insights into the interactions of well-defined species with surfaces.

In situ SIMS e IR Espectroscopia de Superfícies bem definidos preparados pela Soft Landing de Íons Mass-selecionados

Soft landing of mass-selected ions onto surfaces is a powerful approach for the highly-controlled preparation of materials that are inaccessible using ...

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

Síntese, caracterização e funcionalização de híbrida UA / CDS e Au / ZnS Núcleo / Shell Nanopartículas

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs within the interlayer space of semiconducting layered titania nanosheet (TNS) films was investigated here. Two types of intermediate films (i.e., TNS films containing methyl viologen (TNS/MV2+) and 2-ammoniumethanethiol (TNS/2-AET+)) were prepared. The two intermediate films were soaked in an aqueous tetrachloroauric(III) acid (HAuCl4) solution, whereby considerable amounts of Au(III) species were accommodated within the interlayer spaces of the TNS films. The two types of obtained films were then soaked in an aqueous sodium tetrahydroborate (NaBH4) solution, whereupon the color of the films immediately changed from colorless to purple, suggesting the formation of AuNPs within the TNS interlayer. When only TNS/MV2+ was used as the intermediate film, the color of the film gradually changed from metallic purple to dusty purple within 30 min, suggesting that aggregation of AuNPs had occurred. In contrast, this color change was suppressed by using the TNS/2-AET+ intermediate film, and the AuNPs were stabilized for over 4 months, as evidenced by the characteristic extinction (absorption and scattering) band from the AuNPs.

In Situ Synthesis of Gold Nanoparticles without Aggregation in the Interlayer Space of Layered Titanate Transparent Films

Here, we present a protocol for the in situ synthesis of gold nanoparticles (AuNPs) within the interlayer space of layered titanate films without the aggregation of AuNPs. No spectral change was observed even after 4 months. The synthesized material has expected applications in catalysis, photo-catalysis, and the development of cost-effective plasmonic devices.

In situ Síntese de Nanopartículas de Ouro sem agregação no espaço Interlayer de Layered titanato filmes transparentes

Combinations of metal oxide semiconductors and gold nanoparticles (AuNPs) have been investigated as new types of materials. The in situ synthesis of AuNPs ...

Engenharia

Preparation of Functional Silica Using a Bioinspired Method

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally purify the same by acid elution. By combining sodium silicate with a polyfunctional bioinspired additive, silica is rapidly formed at ambient conditions upon neutralization. 
The effect of neutralization rate and biomolecule addition point on silica yield are investigated, and biomolecule immobilization efficiency is reported for varying addition point. In contrast to other porous silica synthesis methods, it is shown that the mild conditions required for bioinspired silica synthesis are fully compatible with the encapsulation of delicate biomolecules. Additionally, mild conditions are used across all synthesis and modification steps, making bioinspired silica a promising target for the scale-up and commercialization as both a bare material and active support medium.
The synthesis is shown to be highly sensitive to conditions, i.e., the neutralization rate and final synthesis pH, however tight control over these parameters is demonstrated through the use of auto titration methods, leading to high reproducibility in reaction progression pathway and yield. 
Therefore, bioinspired silica is an excellent active material support choice, showing versatility towards many current applications, not limited to those demonstrated here, and potency in future applications.

Here, we present a protocol to synthesize bioinspired silica materials and immobilize enzymes therein. Silica is synthesized by combining sodium silicate and an amine &#39;additive&#39;, which neutralize at a controlled rate. Material properties and function can be altered either by in situ enzyme immobilization or post-synthetic acid elution of encapsulated additives.

Preparação de sílica funcional usando um método Bioinspirada

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally ...

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various precursor noble metal ions with reducing agents in a 1:1 (v/v) ratio results in the formation of metal gels within seconds to minutes compared to much longer synthesis times for other techniques such as sol-gel. Conducting the reduction step in a microcentrifuge tube or small volume conical tube facilitates a proposed nucleation, growth, densification, fusion, equilibration model for gel formation, with final gel geometry smaller than the initial reaction volume. This method takes advantage of the vigorous hydrogen gas evolution as a by-product of the reduction step, and as a consequence of reagent concentrations. The solvent accessible specific surface area is determined with both electrochemical impedance spectroscopy and cyclic voltammetry. After rinsing and freeze drying, the resulting aerogel structure is examined with scanning electron microscopy, X-ray diffractometry, and nitrogen gas adsorption. The synthesis method and characterization techniques result in a close correspondence of aerogel ligament sizes. This synthesis method for noble metal aerogels demonstrates that high specific surface area monoliths may be achieved with a rapid and direct reduction approach.

A rapid, direct solution-based reduction synthesis method to obtain Au, Pd, and Pt aerogels is presented.

Um método de síntese rápida para Au, Pd e Pt Aerogels através de redução direta baseada em solução

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) with a 4.6 nm pore size, and ordered silica porous matrix, SBA-15, with a 5.3 nm pore size. This work describes the surface properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the differently ordered porous materials with similar pore sizes. For this purpose, OMC and SBA-15 with highly ordered nanoporous structures are synthesized via impregnation of the silica matrix by applying a carbon precursor and by the sol-gel method, respectively. The porous structure of investigated systems is characterized by an N2 adsorption-desorption analysis at 77 K. To determine the electrochemical character of the surface of synthesized materials, potentiometric titration measurements are conducted; the obtained results for OMC shows a significant pHpzc shift toward the higher values of pH, relative to SBA-15. This suggests that investigated OMC has surface properties related to oxygen-based functional groups. To describe the surface properties of the materials, the contact angles of liquids penetrating the studied porous beds are also determined. The capillary rise method has confirmed the increased wettability of the silica walls relative to the carbon walls and an influence of the pore roughness on the fluid/wall interactions, which is much more pronounced for silica than for carbon mesopores. We have also studied the melting behavior of D2O confined in OMC and SBA-15 by applying the dielectric method. The results show that the depression of the melting temperature of D2O in the pores of OMC is about 15 K higher relative to the depression of the melting temperature in SBA-15 pores with a comparable 5 nm size. This is caused by the influence of adsorbate/adsorbent interactions of the studied matrices.

Here we report the synthesis and characterization of ordered nanoporous carbon (with a 4.6 nm pore size) and SBA-15 (with a 5.3 nm pore size). The work describes the surface and textural properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the materials.

Propriedades de superfície de carbono de Nanoporous sintetizado e matrizes de sílica

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) ...

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

Síntese e caracterização de nanopartículas de ouro Anfífilos

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared according to the methodology developed by surface organometallic chemistry (SOMC). In this framework, catalytic cycles can be determined by isolating crucial intermediates. All air-sensitive materials are handled under inert atmosphere (using gloveboxes or a Schlenk line) or high vacuum lines (HVLs, &#60;10-5 mbar). The preparation of SiO2-700 (silica dehydroxylated at 700 &#176;C) and subsequent applications (the grafting of complexes and catalytic runs) requires the use of HVLs and double-Schlenk techniques. Several well-known characterization methods are used, such as Fourier-transform infrared spectroscopy (FTIR), elemental microanalysis, solid-state nuclear magnetic resonance spectroscopy (SSNMR), and state-of-the-art dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS). FTIR and elemental microanalysis permit scientists to establish the grafting and its stoichiometry. 1H and 13C SSNMR allows the structural determination of the hydrocarbon ligands coordination sphere. DNP SENS is an emerging powerful technique in solid characterization for the detection of poorly sensitive nuclei (15N, in our case). SiO2-700 is treated with about one equivalent of the metal precursor compared to the amount of surface silanol (0.30 mmol&#183;g-1) in pentane at room temperature. Then, volatiles are removed, and the powder samples are dried under dynamic high vacuum to afford the desired materials [(&#8801;Si-O-)Hf(&#951;2&#960;-MeNCH2)(&#951;1-NMe2)(&#951;1-HNMe2)]. After a thermal treatment under high vacuum, the grafted complex is converted into metal imido silica complex [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)]. [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] effectively promotes the metathesis of imines, using the combination of two imine substrates, N-(4-phenylbenzylidene)benzylamine, or N-(4-fluorobenzylidene)-4-fluoroaniline, with N-benzylidenetert-butylamine as substrates. A significantly lower conversion is observed with the blank runs; thus, the presence of the imido group in [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is correlated to the catalytic performance.

A new group IV metal catalyst for imine metathesis is prepared by grafting amine metal complex onto dehydroxylated silica. Surface metal fragments are characterized using FT-IR, elemental microanalysis, and solid-state NMR spectroscopy. Further dynamic nuclear polarization surface enhanced NMR spectroscopy experiments complement the determination of the coordination sphere.

Metathesis de imine por catalisadores sílica-apoiados usando a metodologia da química organometálica de superfície

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared ...

A Salt-Templated Synthesis Method for Porous Platinum-based Macrobeams and Macrotubes

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed by rinsing and supercritical drying steps, often resulting in mechanically fragile materials. Here, a method to synthesize nanostructured porous platinum-based macrotubes and macrobeams with a square cross section from insoluble salt needle templates is presented. The combination of oppositely charged platinum, palladium, and copper square planar ions results in the rapid formation of insoluble salt needles. Depending on the stoichiometric ratio of metal ions present in the salt-template and the choice of chemical reducing agent, either macrotubes or macrobeams form with a porous nanostructure comprised of either fused nanoparticles or nanofibrils. Elemental composition of the macrotubes and macrobeams, determined with x-ray diffractometry and x-ray photoelectron spectroscopy, is controlled by the stoichiometric ratio of metal ions present in the salt-template. Macrotubes and macrobeams may be pressed into free standing films, and the electrochemically active surface area is determined with electrochemical impedance spectroscopy and cyclic voltammetry. This synthesis method demonstrates a simple, relatively fast approach to achieve high-surface area platinum-based macrotubes and macrobeams with tunable nanostructure and elemental composition that may be pressed into free-standing films with no required binding materials.

A synthesis method to obtain porous platinum-based macrotubes and macrobeams with a square cross section through chemical reduction of insoluble salt-needle templates is presented.

Um método de síntese com modelo de sal para macrobeams e macrotubos baseados em platina porosos

The synthesis of high surface area porous noble metal nanomaterials generally relies on time consuming coalescence of pre-formed nanoparticles, followed ...