Pub Date : 2019-02-13DOI: 10.5772/INTECHOPEN.80620
Ziyauddin S. Qureshi, E. Jaseer
Even though gold is inert in its bulk practice, greatly disseminated gold nanoparticles (Au NPs) with dimensions less than 5 nm have been found to be active for a number of oxygen transfer reactions, particularly for low-temperature CO oxidation. The catalytic activity not only be subject to the particle size of Au but also on the nature of the support and the synthesis method of the catalyst. These factors are frequently inter-related such that their separate contributions cannot be easily unrav-eled. Also, the activity of a supported Au catalyst is ruled by a complex combination of contributions of the particle morphology, metal dispersion, and electronic properties of the gold. Higher catalytic activity is being observed for Au NPs supported on reducible metal oxides such as TiO 2 , Co 3 O 4 , CeO 2 , and Fe 2 O 3 . However, silica is an inert, inexpensive, and convenient support that can be shaped into a host of attractive and varied morphologies. In this chapter, the study of CO oxidation catalyzed by mono- and bimetallic Au NPs over various silica supports is discussed in detail.
{"title":"Silica-Supported Gold Nanocatalyst for CO Oxidation","authors":"Ziyauddin S. Qureshi, E. Jaseer","doi":"10.5772/INTECHOPEN.80620","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.80620","url":null,"abstract":"Even though gold is inert in its bulk practice, greatly disseminated gold nanoparticles (Au NPs) with dimensions less than 5 nm have been found to be active for a number of oxygen transfer reactions, particularly for low-temperature CO oxidation. The catalytic activity not only be subject to the particle size of Au but also on the nature of the support and the synthesis method of the catalyst. These factors are frequently inter-related such that their separate contributions cannot be easily unrav-eled. Also, the activity of a supported Au catalyst is ruled by a complex combination of contributions of the particle morphology, metal dispersion, and electronic properties of the gold. Higher catalytic activity is being observed for Au NPs supported on reducible metal oxides such as TiO 2 , Co 3 O 4 , CeO 2 , and Fe 2 O 3 . However, silica is an inert, inexpensive, and convenient support that can be shaped into a host of attractive and varied morphologies. In this chapter, the study of CO oxidation catalyzed by mono- and bimetallic Au NPs over various silica supports is discussed in detail.","PeriodicalId":12764,"journal":{"name":"Gold Nanoparticles - Reaching New Heights","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77561452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-14DOI: 10.5772/INTECHOPEN.80467
Sivakumar Thiripuranthagan, Valentine Rupa
Textile industries produce large quantities of waste water which is notoriously known to contain strong colour, suspended solids and COD. Although several treatment processes, such as filtration, coagulation, oxidation, ozonation, reverse osmosis, etc., have been practiced for many decades, they all have inherent limita-tions. They transfer the harmful pollutants from one phase to another and do not address detoxification. Semiconductor photocatalysis is a promising technique for photodegradation of hazardous chemicals found in waste waters. Among various semiconductors, TiO 2 has been studied widely. However, the main drawbacks associated with TiO 2 are (i) large band gap (Eg > 3.2 eV) (only UV active) and (ii) recombination of excitons. Dye sensitisation, coupling of semiconductors, and transitional metal doping are some of the methods reported to shift its optical response to visible region. Herein, nanoparticles of different noble metals such as Ag, Au and Pt were deposited on synthesised TiO 2 , characterized by XRD, TEM, FT-IR, BET, UV-Vis and AAS and were subjected to the degradation of some textile dyes namely Tartrazine (TAZ), Reactive Yellow-17 (RY-17) and Reactive Black-5 (RB-5) under both UV and visible irradiations. The reaction conditions such as catalyst concentration, dye concentration, pH, irradiation time, light intensity, and additives were optimized for complete decolourisation and discussed.
纺织工业产生大量的废水，众所周知，这些废水含有强烈的颜色，悬浮物和COD。虽然几个治疗过程,如过滤、凝固、氧化、臭氧化,反渗透,等等,已经实行了几十年的人,他们都有固有的limita-tions。它们将有害污染物从一个阶段转移到另一个阶段，而不解决解毒问题。半导体光催化是一种很有前途的光降解废水中有害化学物质的技术。在各种半导体中，二氧化钛得到了广泛的研究。然而，与tio2相关的主要缺点是:(i)大带隙(Eg > 3.2 eV)(仅UV活性)和(ii)激子的重组。染料敏化、半导体耦合和过渡金属掺杂是将其光学响应转移到可见光区域的一些方法。,不同的贵金属纳米粒子如Ag)、非盟和Pt沉积在合成TiO 2, XRD, TEM, ir、打赌,紫外可见和AAS和受到一些纺织染料的降解即柠檬黄(小胡子)、活性黄17 (RY-17)和活性Black-5 (RB-5)紫外和可见的射线。对催化剂浓度、染料浓度、pH、辐照时间、光照强度、添加剂等条件进行了优化，并进行了讨论。
{"title":"Detoxification of Carcinogenic Dyes by Noble Metal (Ag, Au, Pt) Impregnated Titania Photocatalysts","authors":"Sivakumar Thiripuranthagan, Valentine Rupa","doi":"10.5772/INTECHOPEN.80467","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.80467","url":null,"abstract":"Textile industries produce large quantities of waste water which is notoriously known to contain strong colour, suspended solids and COD. Although several treatment processes, such as filtration, coagulation, oxidation, ozonation, reverse osmosis, etc., have been practiced for many decades, they all have inherent limita-tions. They transfer the harmful pollutants from one phase to another and do not address detoxification. Semiconductor photocatalysis is a promising technique for photodegradation of hazardous chemicals found in waste waters. Among various semiconductors, TiO 2 has been studied widely. However, the main drawbacks associated with TiO 2 are (i) large band gap (Eg > 3.2 eV) (only UV active) and (ii) recombination of excitons. Dye sensitisation, coupling of semiconductors, and transitional metal doping are some of the methods reported to shift its optical response to visible region. Herein, nanoparticles of different noble metals such as Ag, Au and Pt were deposited on synthesised TiO 2 , characterized by XRD, TEM, FT-IR, BET, UV-Vis and AAS and were subjected to the degradation of some textile dyes namely Tartrazine (TAZ), Reactive Yellow-17 (RY-17) and Reactive Black-5 (RB-5) under both UV and visible irradiations. The reaction conditions such as catalyst concentration, dye concentration, pH, irradiation time, light intensity, and additives were optimized for complete decolourisation and discussed.","PeriodicalId":12764,"journal":{"name":"Gold Nanoparticles - Reaching New Heights","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90839918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-12-10DOI: 10.5772/INTECHOPEN.82433
J. Puszkiel
Hydride forming materials, i.e., binary, complex hydrides, and their mixtures, have been extensively investigated owing to their potential hydrogen storage properties. They possess high volumetric hydrogen capacity and relative high gravimetric hydrogen capacity. However, one of the main constraints for their practical application is their slow kinetic behavior. For this reason, enormous effort has been devoted to improve the hydrogenation and dehydrogenation rates. Several strategies have been developed for the enhancement of the kinetic behavior of the most relevant hydride forming materials such as MgH2, MBH4 (M = Li, Ca, Mg, Na, K), MNH2 (M = Li and Mg), MBH4 + ‘MH2 (M = Li, Ca, Mg; ‘M = Li, Mg, Ca), and MNH2 + ‘MH2 (M = Li, Mg; ‘M = Li). Tuning the kinetic behavior of these hydride forming materials involves different approaches and their combinations. The most relevant approaches are: (1) improving the microstructural refinement via mechanical milling, (2) doping with transition metal and transition metal compounds, (3) forming in situ catalyst, and (4) nanoconfining doped hydride forming materials. Herein, basic concepts about the chemical reaction for the hydride compound formation/decomposition, thermodynamics, kinetics, and applied strategies to enhance the kinetic behavior of hydride compounds and systems are comprehensively described and discussed.
{"title":"Tailoring the Kinetic Behavior of Hydride Forming Materials for Hydrogen Storage","authors":"J. Puszkiel","doi":"10.5772/INTECHOPEN.82433","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.82433","url":null,"abstract":"Hydride forming materials, i.e., binary, complex hydrides, and their mixtures, have been extensively investigated owing to their potential hydrogen storage properties. They possess high volumetric hydrogen capacity and relative high gravimetric hydrogen capacity. However, one of the main constraints for their practical application is their slow kinetic behavior. For this reason, enormous effort has been devoted to improve the hydrogenation and dehydrogenation rates. Several strategies have been developed for the enhancement of the kinetic behavior of the most relevant hydride forming materials such as MgH2, MBH4 (M = Li, Ca, Mg, Na, K), MNH2 (M = Li and Mg), MBH4 + ‘MH2 (M = Li, Ca, Mg; ‘M = Li, Mg, Ca), and MNH2 + ‘MH2 (M = Li, Mg; ‘M = Li). Tuning the kinetic behavior of these hydride forming materials involves different approaches and their combinations. The most relevant approaches are: (1) improving the microstructural refinement via mechanical milling, (2) doping with transition metal and transition metal compounds, (3) forming in situ catalyst, and (4) nanoconfining doped hydride forming materials. Herein, basic concepts about the chemical reaction for the hydride compound formation/decomposition, thermodynamics, kinetics, and applied strategies to enhance the kinetic behavior of hydride compounds and systems are comprehensively described and discussed.","PeriodicalId":12764,"journal":{"name":"Gold Nanoparticles - Reaching New Heights","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87131341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-09DOI: 10.5772/INTECHOPEN.81637
Ting Chen, Y. Shon
Selective hydrogenation of olefins is an important process in both chemical and pharmaceutical industries. This chapter reviews intriguing catalytic studies accomplished by employing a variety of catalysts such as metal complexes, supported materials, supported metal complexes, and nanosized materials for polyene hydrogenation. In addition, new research area involving unsupported colloidal nanoparticle catalysts, which exhibit an excellent activity and selectivity toward the polyene hydrogenation is introduced. The high activity of colloidal metal nanoparticle catalysts often allows the reactions to be completed under mild conditions, at atmospheric pressure, and room temperature. These colloidal nanoparticle catalysts also offer an advantage of facile separation and multiple recycling without significant losses in activity and selectivity. This chapter provides important fundamental understandings on the influence of chemical environments (solvents, ligands, dop-ants, etc.) and compositions (metal complex, metals, alloys, etc.) toward the catalytic activity and selectivity of various catalysts in homogeneous, heterogeneous, and semi-heterogeneous conditions. The systematic evaluation discussed in this chapter would pave a way to further develop chemo-, regio-, and stereo-selective catalysts for polyene hydrogenation.
{"title":"Selective Mono-Hydrogenation of Polyunsaturated Hydrocarbons: Traditional and Nanoscale Catalysis","authors":"Ting Chen, Y. Shon","doi":"10.5772/INTECHOPEN.81637","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.81637","url":null,"abstract":"Selective hydrogenation of olefins is an important process in both chemical and pharmaceutical industries. This chapter reviews intriguing catalytic studies accomplished by employing a variety of catalysts such as metal complexes, supported materials, supported metal complexes, and nanosized materials for polyene hydrogenation. In addition, new research area involving unsupported colloidal nanoparticle catalysts, which exhibit an excellent activity and selectivity toward the polyene hydrogenation is introduced. The high activity of colloidal metal nanoparticle catalysts often allows the reactions to be completed under mild conditions, at atmospheric pressure, and room temperature. These colloidal nanoparticle catalysts also offer an advantage of facile separation and multiple recycling without significant losses in activity and selectivity. This chapter provides important fundamental understandings on the influence of chemical environments (solvents, ligands, dop-ants, etc.) and compositions (metal complex, metals, alloys, etc.) toward the catalytic activity and selectivity of various catalysts in homogeneous, heterogeneous, and semi-heterogeneous conditions. The systematic evaluation discussed in this chapter would pave a way to further develop chemo-, regio-, and stereo-selective catalysts for polyene hydrogenation.","PeriodicalId":12764,"journal":{"name":"Gold Nanoparticles - Reaching New Heights","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85627836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-11-05DOI: 10.5772/INTECHOPEN.80052
Pablo Gaviña, M. Parra, S. Gil, A. Costero
Gold nanoparticles (AuNPs) have been extensively used for the design of colorimetric sensors and probes due to their interesting photophysical properties. In particular, their surface plasmon resonance (SPR) is influenced not only by the size but also by the shape or the properties of the matrix surrounding the nanoparticles. This SPR band is sensitive to the proximity of other nanoparticles, and thus, analyte-triggered aggregation of AuNPs results in an important bathochromic shift of the SPR band and a change in the color of the solution from red to blue due to interparticle surface plasmon coupling. The selectivity of the AuNPs-based sensors toward the different analytes will depend on the recognition properties of the molecules attached to the surface of the nanoparticles. In this chapter, a selection of biologically active molecules has been considered as analytes: neurotransmitters, nerve agents, pesticides, and carboxylates of biological interest.
{"title":"Red or Blue? Gold Nanoparticles in Colorimetric Sensing","authors":"Pablo Gaviña, M. Parra, S. Gil, A. Costero","doi":"10.5772/INTECHOPEN.80052","DOIUrl":"https://doi.org/10.5772/INTECHOPEN.80052","url":null,"abstract":"Gold nanoparticles (AuNPs) have been extensively used for the design of colorimetric sensors and probes due to their interesting photophysical properties. In particular, their surface plasmon resonance (SPR) is influenced not only by the size but also by the shape or the properties of the matrix surrounding the nanoparticles. This SPR band is sensitive to the proximity of other nanoparticles, and thus, analyte-triggered aggregation of AuNPs results in an important bathochromic shift of the SPR band and a change in the color of the solution from red to blue due to interparticle surface plasmon coupling. The selectivity of the AuNPs-based sensors toward the different analytes will depend on the recognition properties of the molecules attached to the surface of the nanoparticles. In this chapter, a selection of biologically active molecules has been considered as analytes: neurotransmitters, nerve agents, pesticides, and carboxylates of biological interest.","PeriodicalId":12764,"journal":{"name":"Gold Nanoparticles - Reaching New Heights","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2018-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72940283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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