Download or read book Carbon Supported Transition Metal Nanoparticles for Catalytic and Electromagnetic Applications written by and published by . This book was released on 2018 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently, there has been growing interest in using transition metals (TM) for catalytic and electromagnetic applications, due to the ability of TMs to form stable compounds in multiple oxidation states. In this research, the focus has been on the synthesis and characterization of carbon-supported TM nanoparticles (NPs), specifically palladium (Pd) and gold (Au) NPs, for catalytic applications, and transition metal oxides (TMO) NPs, specifically Fe3O4 NPs for electromagnetic applications. Carbon supports have several advantages, such as enabling even distribution of particles, offering large specific surface area with excellent electron conductivity, and relative chemical inertness. In this dissertation, for catalytic applications, emphasis was on removal of trichloroethylene (TCE) from groundwater. For this application, carbon-supported Pd/Au NP catalysts were developed. Pd was chosen because it is more active, stable and selective for desired end-products, and Au has shown to be a good promotor of Pd's catalytic activity. Often, commercially available Pd-based catalysts are made using harsh chemicals, which can be harmful to the environment. Here, an environmentally friendly process with aspects of green chemistry was developed to produce carbon-supported Pd/Au NP catalysts. This process uses a combination of sonochemistry and solvothermal syntheses. The carefully designed carbon-supported Pd/Au NP catalyst material was systematically characterized, tested against TCE, and optimized for increased rate of removal of TCE. Electron microscopy and spectroscopy techniques were used to study the material including structure, configuration and oxidative state. The Pd/Au NPs were found mainly to form clusters with an aggregate-PdShellAuCore structure. Using state-of-the-art direct detection with electron energy loss spectroscopy, the Pd NPs were found to have an oxidative state of zero (0). The formation of the catalyst material was studied in detail by varying several synthesis parameters including type of solvent, sonication time, synthesis temperature etc. The most optimized catalyst was found remove TCE at double the rate of corresponding commercial Pd-based catalysts in a hydrogen headspace. This material was found to catalyze the removal of TCE via traditional hydrodehalogenation and shows promise for the removal of other contaminants such as trichloropropane (TCP), carbon tetrachloride (CT). The focus of this dissertation was on the development of a methodology for carbon-supported TM and TMO NPs for specific applications. It is envisioned that this approach and strategy will contribute towards the future optimization of similar material systems for a multitude of applications.

Download or read book Nanoparticles in Catalysis written by Karine Philippot and published by John Wiley & Sons. This book was released on 2021-06-28 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoparticles in Catalysis Discover an essential overview of recent advances and trends in nanoparticle catalysis Catalysis in the presence of metal nanoparticles is an important and rapidly developing research field at the frontier of homogeneous and heterogeneous catalysis. In Nanoparticles in Catalysis, accomplished chemists and authors Karine Philippot and Alain Roucoux deliver a comprehensive guide to the key aspects of nanoparticle catalysis, ranging from synthesis, activation methodology, characterization, and theoretical modeling, to application in important catalytic reactions, like hydrogen production and biomass conversion. The book offers readers a review of modern and efficient tools for the synthesis of nanoparticles in solution or onto supports. It emphasizes the application of metal nanoparticles in important catalytic reactions and includes chapters on activation methodology and supported nanoclusters. Written by an international team of leading voices in the field, Nanoparticles in Catalysis is an indispensable resource for researchers and professionals in academia and industry alike. Readers will also benefit from the inclusion of: A thorough introduction to New Trends in the Design of Metal Nanoparticles and Derived Nanomaterials for Catalysis An exploration of Dynamic Catalysis and the Interface Between Molecular and Heterogeneous Catalysts A practical discussion of Metal Nanoparticles in Water: A Relevant Toolbox for Green Catalysis Organometallic Metal Nanoparticles for Catalysis A concise treatment of the opportunities and challenges of CO2 Hydrogenation to Oxygenated Chemicals Over Supported Nanoparticle Catalysts Perfect for catalytic, organic, inorganic, and physical chemists, Nanoparticles in Catalysis will also earn a place in the libraries of chemists working with organometallics and materials scientists seeking a one-stop resource with expert knowledge on the synthesis and characterization of nanoparticle catalysis.

Download or read book Synthesis of Supported Metal Nanoparticles on High Surface Area Supports for Application in Energy Conversion and Heterogeneous Catalysis written by Nazgol Norouzi and published by . This book was released on 2020 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precise control of metal nanoparticles' size, composition, and dispersity over high surface area supports are highly desirable to address current challenges in energy storage and conversion as well as catalytic processes involving precious metals. Therefore, developing viable synthetic routes that enable new catalytic systems derived from inexpensive transition metals or limited use of precious metals is vital for clean energy applications such as fuel cells and rechargeable batteries or affordable drugs in the pharmaceuticals arena. In addition to metal components of heterogeneous catalysts, the catalyst support is an integral part of catalyst design as it can impart both physical stability and catalytic enhancement through strong metal-support interactions. In particular, recent studies have shown that the incorporation of heteroatoms like nitrogen and phosphorus in high surface area carbon supports is an effective approach for tailoring the textural and electronic properties of carbon supports. Here we introduce different supported metal nanoparticles on high surface area supports, with their characteristic tuned toward different applications. In the first project, we developed an iron phosphide doped porous carbon system (PFeC) and used it as a cathode catalyst for oxygen reduction reaction (ORR) in fuel cells. The conversion of chemical energy to electrical energy is a sustainable approach for energy production achieved by fuel cells. Currently, the noble metal platinum, in the form of 20 wt% Pd deposited on carbon support (Pt/C) is the commercially available catalyst for the ORR. Sluggish ORR mechanism and lack of long-term stability demand for a more sustainable, inexpensive, and kinetically efficient replacement catalyst. Here iron phosphide nanoparticles (NPs) incorporated in a phosphorus-doped porous carbon, with a high specific area (SABET = 967 m2 g−1) was synthesized using inexpensive reactants, triphenylphosphine and iron chloride by a facile carbonization/chemical activation method via zinc chloride. PFeC selectively reduces O2 via an efficient reaction pathway and exhibits superior long-term stability than Pt/C. The superior electrocatalytic performance is credited to the synergistic effects between the P and Fe which, form well-defined and well-distributed nanoparticles confined in highly porous carbon nanosheets. In the second project, supported palladium-based ultra-small bimetallic NPs deposited on mesoporous fumed silica support (SABET = 350 m2 g−1) were synthesized and used as a catalyst for Suzuki -Miyaura cross-coupling (SCC) reactions. Bimetallic NPs consisting of active metal Pd and base metals (Cu, Ni, and Co) were deposited on the silica support through strong electrostatic (SEA) synthesis method yielding homogeneously alloyed nanoparticles with an average size of 1.3 nm. All bimetallic catalysts were found to be highly active toward SCC surpassing the activity of monometallic Pd/SiO2. In particular, the catalyst consisting of Cu and Pd (CuPd/SiO2), performed the SCC with a remarkable turn over frequency of 248000. The combination of Pd with base metals helps in retaining the Pd0 status by charge donation from base metals to Pd and thus facilitating the SCC, in specific lowering the activation energy of the aryl halide oxidative addition rate-limiting step. In the third and last project, functionalized supports are widely utilized in energy conversion and energy storage applications. High surface area porous carbon materials have been introduced as a highly active cathode material for Lithium-sulfur batteries (LSB). The electrochemical performance of the LSB can be largely improved by the efficient reversible conversion of lithium polysulfides to Li2S during discharge and to elemental sulfur during charge. Nickel NPs deposited on high surface area nitrogen-doped carbon support (Ni/BIDC-900, SABET = 3560 m2 g−1) act as active centers for the adsorption of polysulfides during the discharge process and rapidly convert them to Li2S while catalyzing Li2S oxidation to sulfur in the reverse process. The addition of Ni NPs improves the reaction kinetics and activity retention of the LSB.

Download or read book Carbon Based Nanomaterials for Energy Conversion and Storage written by Jia-Nan Zhang and published by Springer Nature. This book was released on 2022-08-26 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book systematically summarizes the advanced development of carbon-based nanomaterials for electrochemical catalysis, and it is comprised of four sections. The first section discusses about the fundamental synthesis, characterization techniques, and catalytic effects on the energy conversion and storage mechanism. The second section elaborately reviews various types of electrocatalytic reactions on carbon-based materials and their performance. The third section focuses on batteries about carbon-based materials with different storage mechanism. And the last one, the following enlightenment in terms of theoretical development and experimental research is provided to the general readers: 1) Precise design and construction of local atomic and electronic structures at the interface of catalysts; 2) Selective activation and directed conversion of carbon-based energy-carrying molecules at the interface; 3) Interaction mechanism and regulation of catalyst solid surface interface properties under environment and external field. This book will be useful for researchers and students who are interested in carbon-based nanomaterials, electrochemical catalysts and energy storage.

Download or read book Nanotechnology in Catalysis written by Bert Sels and published by John Wiley & Sons. This book was released on 2017-06-20 with total page 1500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reflecting the R&D efforts in the field that have resulted in a plethora of novel applications over the past decade, this handbook gives a comprehensive overview of the tangible benefits of nanotechnology in catalysis. By bridging fundamental research and industrial development, it provides a unique perspective on this scientifically and economically important field. While the first three parts are devoted to preparation and characterization of nanocatalysts, the final three provide in-depth insights into their applications in the fine chemicals industry, the energy industry, and for environmental protection, with expert authors reporting on real-life applications that are on the brink of commercialization. Timely reading for catalytic chemists, materials scientists, chemists in industry, and process engineers.

Download or read book Metal Nanoparticles for Catalysis written by Franklin (Feng) Tao and published by Royal Society of Chemistry. This book was released on 2014-06-30 with total page 285 pages. Available in PDF, EPUB and Kindle. Book excerpt: An introduction to the synthesis and applications of different nanocatalysts.

Download or read book Carbon And Tmds Nanostructures For Energy Applications written by Ashish Kumar Mishra and published by World Scientific. This book was released on 2024-01-22 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: The world's increasing demand for energy is mainly being fulfilled by non-renewable fossil fuels. Its long-run usage is unsustainable due to depleting resources and adverse effects on the environment. To resolve these issues, researchers are transitioning toward high-performance renewable and sustainable energy sources and storage systems like electrochemical cells for hydrogen production, supercapacitors, batteries, and so forth. Currently, the main challenges to developing these systems require efficient electrode materials with properties like good electrical conductivity, high surface area, good catalytic activity, and so on. Carbon nanostructures (such as graphene and carbon nanotubes) and inorganic transition metal dichalcogenides (such as MoS2, WS2, MoSe2, etc.) are promising candidates for such energy applications owing to their unique properties and exceptional performance. This book summarizes the synthesis of carbon and TMDs to their applications in energy generation and storage. The aim of this book is to benefit the readers with recent aspects and future perspectives of carbon and TMDs-based nanomaterials dedicated to the field of energy generation and storage technologies. Also, professionals might find it useful in fabricating or characterizing these materials for targeted applications.

Download or read book Nanostructure of Transition Metal and Metal Oxide for Electrocatalysis written by Yanjuan Gu and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Nanostructure of Transition Metal and Metal Oxide for Electrocatalysis" by Yanjuan, Gu, 谷艳娟, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled NANOSTRUCTURE OF TRANSITION METAL AND METAL OXIDE FOR ELECTROCATALYSIS Submitted by Gu Yan Juan for the degree of Doctor of Philosophy at The University of Hong Kong in August 2006 Pd, Pt, and Ru nanoparticles that were uniformly dispersed on multi-walled carbon nanotubes (MWNTs) were synthesized by vacuum pyrolysis using metal acetylacetonate as metal precursor, and the nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X- ray diffraction (XRD). The size and distribution of the nanoparticles were strongly affected by the reaction time, temperature, and the initial mass ratio of the metal precursors to MWNTs. The higher temperature, the smaller Pd nanoparticles were formed at the range of 250 to 500 C. The average size of the Pd nanoparticles increased with the increase in mass ratio of the metal precursors to MWNTs. The particle size of Pt and Ru showed little change with the change in mass ratio. Pt and Ru nanoparticles had the mean diameters of 3.00.6 and 2.50.4 nm when the mass ratio of Pt(acac) and Ru(acac) to 2 3 MWNTs was both 2:1 at 500 C. The electrocatalytic activity of Pt/MWNTs and PtRu/MWNTs was investigated at room temperature by cyclic voltammetry and chronoamperometry. All of the electrochemical results showed that the PtRu/MWNTs catalyst exhibit high activity for methanol oxidation that resulted from the high surface area of carbon nanotubes and the platinum/ruthenium nanoparticles. Compared with Pt/MWNTs, the onset potential is much lower and the ratio of forward anodic peak current to reverse anodic peak current is much higher for methanol oxidation. Pt Ru /MWNTs displayed the best electrocatalytic 45 55 activities among all carbon nanotubes supported Pt and PtRu catalysts. Hyperbranched RuO nanostructures can be formed through the oxidation of Ru nanoparticles at relatively low temperatures in air, which is a very simple and low cost method. The morphology of the RuO nanostructure is closely associated with the dispersivity of the Ru nanoparticles on the MWNTs. Cu, Pt and Pd nanoparticles are very effective catalysts in the formation of RuO hyperbranched nanostructures. The electrochemical studies of these nanorods demonstrated that they display characteristic properties of RuO (110) surface. The successful attachment of Pt nanoparticles to RuO surface through a simple, two-step chemically controlled procedure is reported. The effect of the single crystal structure of RuO nanorods on the electrocatalytic activity of Pt nanoparticles was investigated, showing that the presence of the RuO nanorods greatly increases the electrochemical activity of electrodes toward methanol oxidation, not only increasing the current density but also shifting the onset potential of methanol electrooxidation to over 200 mV lower than that on the Pt nanoparticle electrode. The results described here also demonstrate the ability of metal oxide nanorods to serve as a conductive support for fuel cell applications. DOI: 10.5353/th_b3777439 Subjects: Electrocatalysis Transition metals Nanoparticles Nanostructured materials Methanol - Oxidation

Download or read book Design Synthesis and Characterization of Transition Metal Oxide Based Functional Materials for Multi phase Catalytic Applications written by and published by . This book was released on 2015 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Metal Metal Oxide Nanoparticles Supported on Nanostructured Carbons for Electrochemical Applications written by 杨纯臻 and published by . This book was released on 2017-01-26 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Metal/metal oxide nanoparticles supported on nanostructured carbons for electrochemical applications" by 杨纯臻, Chunzhen, Yang, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Among various electrochemical devices that have been developed for energy storage and conversion, electric double layer capacitors (EDLCs) and direct methanol fuel cells (DMFC) have received much research attention. Nanostructured carbon materials have been playing an important role in the development of these devices, due to such characteristics as good electrical conductivity, high chemical stability, high surface area and large pore volumes and etc. In an EDLC, nanostructured carbon electrodes, possessing pores of varied length scales, can deliver electric energy at high current loadings. This kind of pore structure also benefits the deposition of metal catalysts and the transport of reactants and products in the methanol oxidation reaction. In order to systematically study the structural effects on the electrochemical capacitance and ionic transport, a series of three-dimensional hierarchical carbons with hollow core-mesoporous shell (HCMS) structure were template-synthesized. Periodically ordered macroscopic hollow cores of 330 nm in diameter were surrounded by a mesoporous shell containing uniform pores of 3.9 nm. The shell thickness was stepwise increased from 0, 25, 50 to 100 nm. The HCMS structure was modeled by a 5-level transmission line model to study the capacitance contribution from the pores at different length scale. Results revealed that the HCMS carbon with thicker mesoporous shells can provide high capacitance, while thinner shells could deliver high power output. A series of HCMS carbon sphere supported Pt nanoparticles were synthesized via the "Carbonization over Protected and Dispersed Metal" (CPDM) method. Contrary to the conventional "polyol" synthetic method, whereas most of Pt nanoparticles were deposited on the external surface of carbon spheres; the Pt nanoparticles synthesized via the CPDM method were found encapsulated in the mesoporous carbon shells and highly dispersed throughout the carbon texture. "Accelerated stress tests‟ (ASTs) were conducted to investigate the nanopores confinement effect toward the electrochemical stability of these Pt catalysts. Results revealed that (1) the nanopores confined Pt nanoparticles on HCMS carbon spheres exhibited a stable electrochemical active surface area (ECSA) and catalytic activity; and (2) thick mesoporous carbon shells could provide better protection over the Pt nanoparticles. This "CPDM" method was further extended to synthesize highly alloyed PtRu nanoparticles supported electrocatalysts. It is expected that this CPDM method can also be applied to synthesize other metal/metal oxide supported catalysts with stable electrochemical performance. WO3 has been demonstrated as a promsing co-catalyst for Pt in the methanol oxidation reaction (MOR). The synthesis of Pt-WO3/C catalyst with well-controlled nanoparticle size (2.5 nm) and composition was achieved via a microwave-assisted water-oil microemulsion reaction. Hydrogen adsorption, CO-stripping and Cu- stripping methods were used to estimate the ECSA of Pt in the Pt-WO3/C catalysts. Among these, Cu-stripping method was relatively more reliable due to the overlapping involvement of the WO3 component in the other methods. The methanol oxidation measurement shows that a 1:1 Pt: W ratio catalyst exhibits the highest Pt-mass current density of 271 mA mg-1-Pt, 1.4 times higher than that of commercial E-TEK catalyst.

Download or read book Sustainable Preparation of Metal Nanoparticles written by Rafael Luque and published by Royal Society of Chemistry. This book was released on 2013 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: This timely publication bridges and presents the latest trends and updates in three hot topics of current and future society: nanomaterials, energy and environment. It provides the state-of-the-art as well as current challenges and advances in the sustainable preparation of metal nanoparticles and their applications. The book fills a critical gap in a multidisciplinary area of high economic, social and environmental importance. Currently, there are no books published that deal with these ever increasing important topics, as most books in this area focus on a particular topic (eg. nanomaterials or catalysis or energy or environment). This is the first multidisciplinary edited book covering the very basics to the more advanced, trendy developments, containing a unique blend of nano, green, renewable and bio.

Download or read book PHOTOCATALYSIS ON DIELECTRIC ANTENNA SUPPORTED RHODIUM NANOPARTICLES written by Xinyan Dai and published by . This book was released on 2020 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Light absorption in metal catalyst nanoparticles can excite charge carriers to generate hot electron (and complimentary hot holes) with energy higher than the Fermi level. When hot electrons possess energy high enough, they exhibit a high tendency to inject into antibonding orbitals of adsorbates on the photoexcited metal nanoparticles, weakening the corresponding chemical bonds to promote chemical reactions with accelerated reaction kinetics and improved selectivity. Such hot-carrier chemistry has been reported on plasmonic metal nanoparticles, such as silver and gold, which exhibit strong surface plasmon resonances (SPRs) and strong light absorption. However, these metal nanoparticles are not suitable catalysts because their affinity toward interesting molecules is limited. In contrast, most transition metals, such as platinum-group metals and early transition metals, are industrially essential catalysts, but light absorption power in metal nanoparticles is low due to the absence of SPRs in the visible spectral range. Therefore, it is intriguing to explore the potential of hot-carrier catalytic chemistry on photoexcited non-plasmonic metal nanoparticles. Upon the absorption of the same optical power, metal nanoparticles with a small size usually exhibit a high probability of hot electron production and high efficiency of injecting hot electrons into adsorbates. It is challenging to have strong light absorption power and operation stability of the catalyst metal nanoparticles with small sizes. In this thesis, dielectric light antenna, i.e., spherical silica nanoparticles with strong surface scattering resonances near their surfaces, is introduced to support the metal catalyst nanoparticles, enabling improved light absorption power in the metal nanoparticles and operation stability. This thesis focuses on ultrafine rhodium (Rh) nanoparticles (with sizes ranging from 1.7 nm to 4.2 nm) that are widely used as thermal catalysts in many important industry reactions, especially for oxygen-containing species conversion, an oxyphilic feature of Rh nanoparticles. Firstly, this dissertation conducted a comparative study to investigate the influence of silica geometry, nanospheres, and rodlike nanoparticles on the light absorption of Rh nanoparticles. Both silica substrates enhanced the light absorption of loaded Rh nanoparticles due to elongated light scattering paths (random scattering) and enhanced electromagnetic field intensity (resonant scattering). However, silica nanospheres support both resonant scattering and random light scattering modes, exhibiting a higher Rh absorption than the usage of rodlike silica nanoparticles. The light resonant scattering modes on highly symmetrical silica nanospheres enable producing "hot spots" with a much higher electromagnetic field intensity than incident light intensity. This study then investigated the effect of silica geometries on photocatalytic performance. The CO2 hydrogenation was studied as a model reaction. The Rh/silica nanosphere system exhibited a faster photocatalytic kinetic than the case of rodlike silica nanoparticles. It is possibly due to the enhanced light power density around the silica nanospheres. The results give a promise of expanding Rh nanoparticles from thermo-catalysis to photocatalysis. Secondly, this dissertation moves onto accelerating aerobic oxidation of primary alcohols to aldehydes, which was benefited from activated oxygen molecules by hot electron injection. This study found that photoexcited Rh nanoparticles enabled accelerating the alcohol oxidation kinetics by four times at a light power intensity of 0.4 W cm-2, accompanied by a reduced activation energy of 21 kJ mol-1. The derived Langmuir-Hinshelwood rate equation was used to fit the oxygen partial pressure results. Photo-illumination promotes the cleavage of associatively adsorbed oxygen molecules into adsorbed oxygen atoms, reducing the energy barrier. Besides, the silica-supported Rh nanoparticles exhibited a higher photocatalytic performance because of the good colloidal stability and enhanced light absorption of small-sized Rh particles. This part of the dissertation shows the possibility of hot-electron mediated reaction pathways towards a desirable kinetic of alcohol oxidation. Thirdly, it will be meaningful to use the abstracted protons from cheap alcohol sources to reduce other organic molecules rather than dangerous hydrogen gas. This dissertation then investigated the possibility of using an isopropanol solvent as a hydrogen source to reduce nitrobenzene and the feasibility of enhancing the selectivity of the reaction with the light illumination. The results showed that the isopropanol was spontaneously oxidized, producing acetone. Light illumination onto Rh particles selectively enhanced the coupling of reduced nitrobenzene intermediates to produce azoxybenzene. The selectivity of nitrobenzene and production rates gradually increased with a higher number of light photons. Photo-illumination promotes both aniline and azoxybenzene production rates. Hot electrons on Rh particles possibly enabled activating nitrobenzene molecules and increasing concentrations of reduced nitrobenzene intermediates. It resulted in a higher possibility of condensation product and azoxybenzene selectivity, which could not be obtained by elevating temperature without light illumination. This part of the work demonstrated the feasibility of hot electrons from Rh nanoparticles to tune the reaction selectivity in a liquid phase. Lastly, it is challenging to modulate the selectivity of CH4 from CO2 hydrogenation because of the competitive CO production. This dissertation moves towards enhancing both kinetic rates and selectivity of CH4 for gaseous CO2 hydrogenation by photoexcited Rh nanoparticles. Light illumination onto Rh/silica nanosphere particles resulted in the selectivity of CH4 over 99% in contrast to ~70% under dark conditions at 330 oC and with an absorbed light power intensity of 1.5 W cm-2. The activation energy of CH4 production and CO2 consumption gradually decreased with higher light power intensity because of the transient injection of hot electrons into adsorbates to activate intermediates. Increasing operating temperature and light power intensity synergistically enhanced the reaction kinetics. Besides, a middle-sized Rh nanoparticle showed a better photocatalytic performance than that of the largest-sized Rh nanoparticles because of the balance in hot-electron production efficiency and intrinsic catalytic performance. Partial pressure dependence and in situ infrared characterizations showed that the critical stable intermediates for CH4 production should be hydrogenated CO2 species (HCOO* COOH*) and hydrogenated CO* species (carbonyl hydride or HxCO*). The light illumination exclusively enhanced the dissociation of CO2 and CO* without apparent influence on CO* desorption. Under high reaction temperature, light illumination preferred a faster CO* conversion than CO2 dissociation, leading to high CH4 selectivity. This result was also supported by higher methanation rates of CO gas under light illumination. The infrared result showed a reduced stretching frequency of CO*, which supported the possibility of the electron from Rh back-donating into antibonding orbitals of strongly adsorbed CO* species. However, hot electrons from silver nanoparticles with a weak COOH* or CO* adsorption could not efficiently activate carbon-species and could not promote CO2 hydrogenation kinetics. This dissertation offers an avenue of enhancing light absorption of small-sized Rh nanoparticles and expanding its usage from thermal catalysis to photocatalysis for driving oxidation and reduction reactions. The reactants share a common feature containing oxygen elements, a strong affinity with rhodium metal for efficient hot electron injection. We studied the light power intensity and temperature-dependence, showing the accelerated reaction kinetics by hot electron-driven pathways. Photo-excited rhodium nanoparticles were believed to promote the cleavage of chemical bonds O-O, N-O, and C-O to drive chemical transformations. The findings offer insights into developing the scope of non-plasmonic metal nanoparticles in photocatalytic reactions for industrial applications.

Download or read book Synthesis Characterization and Applications of Metal Nanoparticles Supported on Porous Carbon written by Charitha Jayaruk Thambiliyagodage and published by . This book was released on 2017 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: Porous carbon incorporating metal nanoparticles has been synthesized by nanocasting. The main two methods of synthesis were used: the formation of nanoparticles during the carbonization of carbon, and the formation of nanoparticles by metal precursor infiltration and reduction on porous carbon. The catalytic activity of nickel nanoparticles incorporated onto hierarchically porous carbon monoliths for the reduction of p-nitrophenol was studied. p-Quinoimine was identified as the stable intermediate. Catalytic graphitization of monolithic hierarchically porous carbon by iron, cobalt and nickel nanoparticles was investigated. The catalytic graphitization of amorphous carbon increased with increasing pyrolysis temperature. Iron was capable of graphitizing carbon more effectively than cobalt and nickel, with cobalt being higher in activity than nickel. Oxygen and nitrogen rich mesoporous carbon were used to support gold nanoparticles and their catalytic activity was investigated for oxidation of benzyl alcohol in water. The catalysts showed significant catalytic activity, but loss of activity were found, resulting in decreasing conversion of benzyl alcohol on subsequent cycles.

Download or read book Surface Modified Nanomaterials for Applications in Catalysis written by Manoj B. Gawande and published by Elsevier. This book was released on 2022-05-22 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface Modified Nanomaterials for Applications in Catalysis: Fundamentals, Methods and Applications provides an overview of the different state-of-the-art surface modification methods of nanomaterials and their commercial applications. The main objective of this book is to comprehensively cover the modification of nanomaterial and their fabrication, including different techniques and discussions of present and emerging commercial applications. The book addresses fundamental chemistry concepts as applied to the modification of nanomaterials for applications in energy, catalysis, water remediation, sensors, and more. Characterization and fabrication methodologies are reviewed, along with the challenges of up-scaling of processes for commercial applications. This book is suitable for academics and practitioners working in materials science, engineering, nanotechnology, green chemistry and chemical engineering. Provides an overview of the basic principles of surface modification of nanomaterials Reviews useful fabrication and characterization methodologies for key applications Addresses surface modified nanomaterials for applications in catalysis, energy, sensor, environment, and more

Download or read book Immobilization and Application of Catalysts on Magnetic Carbon Coated Metal Nanoparticles written by Sebastian Wittmann and published by . This book was released on 2012 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Synthesis of Ferromagnetic Nanoparticles Formic Acid Oxidation Catalyst Nanocomposites and Late transition Metal boride Intermellatics by Unique Synthetic Methods and Single source Precursors written by Matthew S. Wellons and published by . This book was released on 2008 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multifunctional Inorganic Nanomaterials for Energy Applications written by H.P. Nagaswarupa and published by CRC Press. This book was released on 2024-06-19 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multifunctional Inorganic Nanomaterials for Energy Applications provides deep insight into the role of multifunctional nanomaterials in the field of energy and power generation applications. It mainly focuses on the synthesis, fabrication, design, development, and optimization of novel functional inorganic nanomaterials for energy storage and saving devices. It also covers studies of inorganic electrode materials for supercapacitors, membranes for batteries and fuel cells, and materials for display systems and energy generation. Features: Explores computational and experimental methods of preparing inorganic nanomaterials and their multifunctional applications Includes synthesis and performance analysis of various functional nanomaterials for energy storage and saving applications Reviews current research directions and latest developments in the field of energy materials Discusses importance of computational techniques in designing novel nanomaterials Highlights importance of multifunctional applications of nanomaterials in the energy sector This book is aimed at graduate students and researchers in materials science, electrical engineering, and nanomaterials.