Thermal Activation Conditions Research Articles

Тионирование 4-((4-оксо-4H-хромен-3-ил) метилен)-2-фенилоксазол-5(4H)-она с применением реагента LAWESSON’S

Analysis of periodicals has showed that there is no information on the behavior of hybrid heterocyclic systems containing several pharmacophore fragments based on oxazol-5(4H)-ones and chromen-4(4H)-ones in reactions with thionizing reagents under various conditions. The interaction of 4-((4-oxo-4H-chromen-3-yl)methylene)-2-phenyloxazol-5(4H)-one with Lawesson’s reagent (LR) (2,4-bis-[pmethoxyphenyl]) has been studied for the first time – 1,3- dithiaphosphetane-2,4-disulfide) under conditions of thermal activation of the reaction mixture and the use of a closed reactor in the environment of non-polar solvents. Lawesson’s reagent is used as a mild thioniation agent. The scheme of the interaction has been discussed. Initially, it is assumed that the Lawesson reagent (LR) molecule dissociates into the particles of ylide structure, then the interaction with the carbonyl group of the chromen-4-one fragment of the initial substrate takes place, resulting in the formation of a spirocyclic intermediate, the subsequent decomposition of which produces the final product. It has been established that the use of a closed reactor makes it possible to reduce the transformation time and achieve an increase in the yield of the target product compared to the conventional type of activation of the reaction mixture. It has been shown that under the chosen conditions the transformation proceeds with the preservation of the oxazol-5(4H)-one ring. The composition and structure of the resulting compound have been established on the basis of complex data from elemental analysis, IR and NMR spectroscopy.

Carbene-Mediated Polymer Modification Using Diazo Compounds under Photo or Thermal Activation Conditions.

Based on the characteristics of commodity polymers in large quantities and low costs, modification of existing commodity polymers emerges as the most effective approach for exploring novel materials. Nevertheless, conventional modification methods typically involve high-energy processes (e.g., high temperature, high-energy radiation), which may lead to irreversible detrimental effects on the polymers, contradicting the desired performance enhancement through modification. In this work, we propose a carbene-mediated postpolymerization modification (PPM) strategy utilizing diazo compounds. Under photochemical or thermal activation conditions, insertion of the C-H bond can be achieved without compromising the performance of polymers. These diazo compounds can be easily synthesized in just two steps and applied to all C-H-containing polymers. This practical and effective modification strategy offers new opportunities and possibilities for enhancing the value and expanding the applications of polymers.

Activation of 2D/3D zeolitic-imidazole frameworks affecting crystal properties and adsorption performance

The zeolitic-imidazole frameworks (ZIFs) have become popular due to their uniformly structured cavities and portals of framework dimensions, which make them suitable for numerous applications. In order to access pores and functional surfaces, thermal activation is significantly post-treatment on the synthesis of ZIFs for their applications. This study explores the impact of different thermal activation conditions on two- to three-dimensional ZIFs, which significantly affect their structure, morphology, and properties. Their transform structure is evidenced by integrated X-ray diffraction technique, Thermogravimetric analysis, Scanning electron microscope, and Fourier transform infrared spectroscopy. Moreover, the performance of greenhouse gas adsorption (CO2 and CH4) applications is affected by the transformation through the thermal activation of materials. Therefore, understanding the activated conditions that impact material synthesis is crucial to maximizing the potential applications of ZIFs in various fields. The 2D ZIF-L has more exposed external surfaces and open structures, which makes it more reactive towards adsorptive reactants, unlike the 3D ZIFs. The 3D ZIFs have a robust structure and a higher porosity framework that can withstand challenging application conditions. Thus, it's essential to ensure appropriate activation conditions to maintain the functional properties of ZIFs, which are crucial for their optimal performance in various applications.

A study of activated phosphorus distribution within silicon substrate for polysilicon passivating contacts based on an in-line PVD system

An in-line PVD system consisting of plasma oxidation chamber and phosphorus-doped amorphous silicon deposition chamber was used to fabricate highly-doped polysilicon passivating contact structure for commercial TOPCon solar cells, which can help to achieve simple fabrication process and excellent electrical properties. In this paper, we studied how the doping profiles of ionized phosphorus atoms in the passivating contact formed by this method varies with the deposition conditions, especially the in-diffusion profile in the silicon substrate. Increasing the RF power of plasma oxidation can prevent phosphorus from penetrating through SiOx to form a shallow profile, and reducing the power is conducive to the formation of more pinholes on SiOx, resulting in a wide profile following the shallow profile. The shallow profile effectively inhibits the surface recombination rate and thus achieve good passivation quality, while the emergence of the following wide profile helps to reduce the contact resistivity by providing more majority carrier transport channels. The 100 W condition constructed a shallow and gradually widening doping profile, exhibiting a low recombination current density of 16.5 fA/cm2 and a low contact resistivity of 1.87 mΩ·cm2. However, the SiOx thickness and density obtained at 80 W are insufficient for achieving a shallow-first-then-widen doping profile, even with adjustments to thermal activation conditions. Additionally, we found the engineering of surface microstructure on silicon wafers also has an impact on the doping profile.

Photothermal Catalytic Reduction of CO2 by Cobalt Silicate Heterojunction Constructed from Clay Minerals

The coupled utilization of solar and thermal energy is considered an efficient way to improve the efficiency of CO2 reduction. Herein, palygorskite (Pal) clay is as a silicon source, while Co2+ is introduced to prepare two-dimensional Co2SiO4 nanosheets, and the excess of Co2+ leads to the growth of Co3O4 on the surface of Co2SiO4 to obtain an S-scheme Co2SiO4/Co3O4−x heterojunction, which facilitates the charge transfer and maintains higher redox potentials. Benefiting from black color and a narrow band gap, the cobalt oxide on the surface can increase the light absorption and produce a local photothermal effect. Under proper thermal activation conditions, the photoelectrons captured by the abundant oxygen vacancies can obtain a secondary leap to the semiconductor conduction band (CB), suppressing the recombination of electron-hole pairs, thus favoring the electron transfer on Co2SiO4/Co3O4−x. The composites not only have abundant oxygen vacancies, but also have a large specific surface area for the adsorption and activation of CO2. The yields of CH3OH on Co2SiO4/Co3O4−5% reach as high as 48.9 μmol·g−1·h−1 under simulated sunlight irradiation. In situ DRIFTS is used to explore the photocatalytic reduction CO2 mechanism. It is found that the thermal effect facilitates the generation of the key intermediate COOH* species. This work provides a new strategy for photothermal catalytic CO2 reduction by taking advantage of natural clay and solar energy.

High-strength geopolymer concrete based on coal washing waste

In recent years, geopolymers have gained significant attention as an environmental-friendly alternative to Ordinary Portland Cement (OPC). Geo-Polymer Concrete (GPC) can be made using different aluminosilicate sources but using waste aluminosilicate sources not only helps to reduce environmental pollution, also leads to efficient waste management. Coal Washing Waste (CWW) refers to the waste that remains after coal washing process in the purification plants. CWW (if properly activated) can be used as a high potential aluminosilicate source to produce GPC or a supplementary cementitious material in the production of Blended Cement (BC). Hence, this study aims to investigate the use of CWW as a waste aluminosilicate source for manufacturing GPC. In this regard, CWW subjected to various methods of thermal activation and the obtained ash was used to produce GPC specimens. Thereafter, the mechanical and physical properties of CWW based-GPC were studied and also compared with conventional concrete. Furthermore, CWW ash was used as an OPC partial replacement (15 %) for BC production. The obtained results indicated that thermal activation conditions of CWW have a significant effect on the properties of the obtained CWW ash. Rapid and abrupt cooling of ash after heat treatment resulted in higher pozzolanic reactivity and thus higher compressive strength. Moreover, CWW ash-based GPC offers higher mechanical strengths, as well as excellent resistance to acidic conditions and low water absorption capacity. Furthermore, CWW ash-based GPC provides proper resistance to evaluated temperatures so that it is almost stable up to 800 °C.

Thermal activation and structural transformation mechanism of kaolinitic coal gangue from Jungar coalfield, Inner Mongolia, China

The benefits of industrial solid waste as a supplementary cementitious material in the manufacture of eco-efficient cement are evident in the context of sustainable and green development. Coal gangue from the Jungar coalfield, Inner Mongolia, China, was characterized and activated thermally at 500 °C–1000 °C. This study investigated the effects of thermal activation conditions on the phase and structural changes of the minerals in coal gangue. The pozzolanic activity of the thermally activated coal gangue was evaluated using both direct and indirect methods. The experimental results show that the coal gangue had a silicoaluminous nature mainly comprising of kaolinite. The pozzolanic activity of coal gangue depends on the phase and structural transformation of kaolinite during calcination. Highest pozzolanic activity is reached when calcined at 800 °C for 2 h, with lime consumption and strength activity index up to 1039 mg g−1 and 1.1, respectively. The high pozzolanic activity of metakaolinite was attributed mainly to the formation of a five-coordinated Al sheet and the less polymerized Si sheet after dehydroxylation under calcination.

In Situ Control of Thermal Activation Conditions by Color for Serpentines with a High Iron Content.

Serpentine heat treatment at temperatures of 650–750 °C yields magnesium–silicate reagent with high chemical activity. Precise and express control of roasting conditions in laboratory kilns and industrial aggregates is needed to derive thermally activated serpentines on a large scale. Color change in serpentines with a high iron content during roasting might be used to indicate the changes in chemical activity in the technological process. This study gives a scientific basis for the express control of roasting of such serpentines by comparing the colors of the obtained material and the reference sample. Serpentines with different chemical activity were studied by X-ray diffraction, Mössbauer spectroscopy, and optical spectroscopy. The color parameters were determined using RGB (red, green, blue), CIELAB (International Commission on Illumination 1976 L*a*b), and HSB (hue, brightness, saturation) color models. The color of heat-treated samples was found to be affected by changes in the crystallochemical characteristics of iron included in the structure of the serpentine minerals. The color characteristics given by the CIELAB model were in good coherence with the acid-neutralizing ability and optical spectra of heat-treated serpentines. Thus, in contrast to the long-term analysis by these methods, the control by color palette provides an express assessment of the quality of the resulting product.

COMPREHENSIVE EXAMINATION OF DEHYDROXYLATION OF KAOLINITE, DISORDERED KAOLINITE, AND DICKITE: EXPERIMENTAL STUDIES AND DENSITY FUNCTIONAL THEORY

Kaolins and clays are important raw materials for production of supplementary cementitious materials and geopolymer precursors through thermal activation by calcination beyond dehydroxylation (DHX). Both types of clay contain different polytypes and disordered structures of kaolinite but little is known about the impact of the layer stacking of dioctahedral 1:1 layer silicates on optimum thermal activation conditions and following reactivity with alkaline solutions. The objective of the present study was to improve understanding of the impact of layer stacking in dioctahedral 1:1 layer silicates on the thermal activation by investigating the atomic structure after dehydroxylation. Heating experiments by simultaneous thermal analysis (STA) followed by characterization of the dehydroxylated materials by nuclear magnetic resonance spectroscopy (NMR) and scanning electron microscopy (SEM) together with first-principles calculations were performed. Density functional theory (DFT) was utilized for correlation of geometry-optimized structures to thermodynamic stability. The resulting volumes of unit cells were compared with data from dilatometry studies. The local structure changes were correlated with experimental results of increasing DHX temperature in the following order: disordered kaolinite, kaolinite, and dickite, whereupon dickite showed two dehydroxylation steps. Intermediate structures were found that were thermodynamically stable and partially dehydroxylated to a degree of DHX of 75% for kaolinite, 25% for disordered kaolinite, and 50% for dickite. These thermodynamically stable, partially dehydroxylated intermediates contained AlV while metakaolinite and metadickite contained only AlIV with a strongly distorted coordination shell. These results indicate strongly the necessity for characterization of the structure of dioctahedral 1:1 layer silicates in kaolins and clays as a key parameter to predict optimized calcination conditions and resulting reactivity.

Study on surface modification of attapulgite

In this study, the surface modification of attapulgite was studied. Firstly, the experiment of acid roasting was carried out. The morphology and composition of attapulgite before and after modification were systematically studied by means of SEM, TEM and FTIR. The results showed that the optimal experimental conditions for modification were hydrochloric acid acidification, the concentration was 1 M, the acidification time was 4 h, and the temperature was 75 °C.The thermal activation conditions were determined to be 420 °C roast for 2 h. Attapulgite was successfully modified, and its specific surface area ratio increased greatly, from 144.29 m2g−1 to 187.87 m2g−1. In this study, the attapulgite with high specific surface area prepared is of great significance for the further use of attapulgite with high added value.

THE OPTIMIZATION OF THE METHOD FOR SYNTHESIS OF HYDROTREATING CATALYSTS

Nowadays the standards for sulfur content in different countries provide for a significant reduction of the indicator to 10 ppm for the gasoline- the raw material for catalytic reforming and 0,01% by weight. Restriction of the total content of aromatic hydrocarbon (no more than 20%), replaced by standards of polycyclic aromatic hydrocarbons (no more than 6-10%) and cetane number (45 and higher). This article outlines the development of optimization of the method for synthesis of hydrotreating catalysts. The main purpose of this article is consideration, mainly by the composition of the developed catalyst, of the ways of their modification by additional components, changing the number of active components, modification of the porous structure of the carrier through the synthesis of special types of aluminum oxide with a specified pore distribution by radius or inserting the zeolite component, changes in the conditions of thermal activation of catalysts. One of the main trends in the development of hydrotreating catalysts is their modification by different additives, for example: phosphorus, alkali element, zinc, tin, germanium, copper, uranium, etc. KEYWORDS: activity of industrial catalyst, impregnation by solutions, carrier modification, dispersion of nickel on aluminum oxide.

∞3[Cu2(mand)2(hmt)]–MOF: A Synergetic Effect between Cu(II) and Hexamethylenetetramine in the Henry Reaction

∞3[Cu2(mand)2(hmt)]·H2O (where mand is totally deprotonated mandelic acid (racemic mixture) and hmt is hexamethylenetetramine) proved to be a stable metal–organic framework (MOF) structure under thermal activation and catalytic conditions, as confirmed by both the in situ PXRD (Powder X-ray diffraction) and ATR–FTIR (Attenuated total reflection-Fourier-transform infrared spectroscopy) haracterization. The non-activated MOF was completely inert as catalyst for the Henry reaction, as the accessibility of the substrates to the channels was completely blocked by H-bonded water to the mand entities and CO2 adsorbed on the Lewis basic sites of the hmt. Heating at 140 °C removed these molecules. Only an insignificant change in the relative ratios of the XRD facets due to the capillary forces associated to the removal of the guest molecules from the network has been observed. This treatment afforded the accessibility of nitromethane and various aldehydes (4-bromobenzaldehyde, 4-nitrobenzaldehyde, and p-tolualdehyde) to the active catalytic sites, leading to conversions up to 48% and selectivities up to 98% for the desired nitroaldol products. The behavior of the catalyst is solvent-sensitive. Protic solvents completely inhibited the reaction due to the above-mentioned strong H-bonds. Accordingly, very good results were obtained only with aprotic solvents such as acetonitrile and 1,4-dioxane. The synthesized MOF is completely recyclable as demonstrated for five successive cycles.

Activation Conditions of Kutahya-Unye Bentonite for Removal of Nickel from Waste Water

Any impurities above a certain concentration in water are harmful to the living spaces of living things. Therefore, the removal of pollutants in the water is very important in terms of maintaining the lives of living things. Nickel has an important place in metal coating due to its hardness, corrosion resistance and brilliance. Significant quantities of nickel are present in industrial and urban wastewater, particularly in steel enterprises and the electroplating industry waste waters. This study aims to investigate the effects of thermal and chemical activation conditions of Kutahya-Unye bentonite for removing nickel from wastewater. The bentonite samples were activated by two different methods: (i) thermal activation, (ii) acid activation. The operating range of the thermal activation studies was determined as 100, 300, 500, 700 0C. In the acid activation studies, the samples which were thermally activated, were entreated with 0.5 and 1 M HCl solutions. And, also acid activation was studied at different times to investigate the activation time on bentonite properties. The effects of temperature and acid treatment on calcium based-bentonite samples were investigated by Fourier Transform Infrared (FT-IR) between the region of 4000-400 cm−1. It was observed that increasing the activation temperature has increased the nickel amount at the waste water. The optimal activation time for nickel removal from wastewater was determined to be 120 minutes, which resulted in the use of activation temperature 700 0C and 0.5 M HCl acid. It was concluded that if we can increase the adsorption capacity and applicability, Ca-bentonite may be a promising clay for the removal of nickel in the wastewater stream.

Catalytic and Enantioselective Diels‐Alder Reaction of Siloxydienes

AbstractDiels‐Alder reaction is one of the most well‐known named reactions in organic chemistry. It involves a diene substrate and a dienophile substrate. Among dienes, siloxydiene is a reactive substrate that is often used in Diels‐Alder reaction. In general, Diels‐Alder reaction is promoted by an acidic reagent. In many cases, the stereoselectivity of the reaction is also controlled by acids. However, siloxydienes are labile under acidic conditions. Thus, it should be difficult to develop a reaction using siloxydiene as a substrate. Nevertheless, siloxydienes are still used in synthetic organic chemistry, and most reactions are performed under thermal activation conditions. In this minireview, we summarize the reported examples of catalytic and enantioselective Diels‐Alder reactions of siloxydienes based on the structure of the diene. We present the activation methods used, the existing problems, and a clue for the further development of this annulation chemistry.

Copassivation of polycrystalline CdTe absorber by CuCl thin films for CdTe solar cells

Copper has been introduced in CdTe solar cell manufacturing for a long time and is critical for achieving high performance devices. In this work, CuCl thin films were prepared by vacuum thermal deposition and then used as a buffer layer with a thermal annealing treatment for activation in the CdTe solar cells. The results indicate that Cu and Cl diffused into the CdTe absorber which was beneficial for doping and copassivation. The carrier density for CdTe solar cells in the vicinity of the pn junction was significantly improved from 6.1 × 1013 to 4.3 × 1014 cm−3, and Voc was increased by >70 mV. The cell with the CuCl thin films was more uniform and revealed higher photocurrent response than the reference cell. The results also indicate that the formation of ohmic back contacts to CdTe solar cells due to the presence of the CuxTe (Cu7Te4) thin films. An optimal device with open circuit voltage of ~820 mV, and fill factor of ~72% and efficiency reaching 16.69% was obtained by the control of the copper concentration and the thermal activation conditions of the CuCl buffer layer.

The Thermal Activation of Nsu Clay for Enhanced Alumina Leaching Response

The thermal activation conditions for enhancing the leaching of alumina from Nsu clay from south-eastern Nigeria was investigated. The clay assayed 28.9% and 50.59% , comprising mainly kaolinite mineral (82.6%) and quartz (12.5%). Thermal activation rendered the alumina in the clay acid-soluble by transforming the clay from its crystalline nature to an amorphous phase or metakaolinite. The clay samples were heated at calcination temperatures of 500, 600, 700, 800, and 900 °C at holding times of 30, 60, and 90 minutes. Uncalcined clay samples and samples calcined at 1000 °C (holding for 60 minutes) were used in the control experiments. Leaching of alumina from the resulting clay calcines passing 300 μm sieve (-50 mesh) was done in 1M hydrochloric acid solution at room temperature using a solid/liquid ratio of 0.02g/ml and shaking speed of 100 rpm. The solubility data given by the fraction of Al ion taken into leach solution showed that the clay calcined at 700 °C (holding for 60 minutes) responded most to leaching. In general, it was observed that samples calcined for 60 minutes responded better than those held for 30 or 90 minutes. The activation energies for leaching the clay calcines were 29.50, 32.92, 26.71, 30.18, 29.18, and 33.24 kJ/mol for samples calcined for 60 minutes at 500, 600, 700, 800, 900, and 1000 °C, respectively. The activation energy of leaching for the uncalcined sample was 35.07 kJ/mol. Thus, calcines produced at 700 °C (holding for 60 minutes) had the highest leaching response for alumina and the lowest leaching activation energy of 26.71 kJ/mol. It is concluded therefore that Nsu kaolinite clay should be best calcined for alumina yield by heating up to 700 °C and holding for 60 minutes at that temperature. The clay deposit can be used as alternative resource for alumina production.

The Thermal Activation of Nsu Clay for Enhanced Alumina Leaching Response

The thermal activation conditions for enhancing the leaching of alumina from Nsu clay from south-eastern Nigeria was investigated. The clay assayed 28.9% and 50.59% , comprising mainly kaolinite mineral (82.6%) and quartz (12.5%). Thermal activation rendered the alumina in the clay acid-soluble by transforming the clay from its crystalline nature to an amorphous phase or metakaolinite. The clay samples were heated at calcination temperatures of 500, 600, 700, 800, and 900 °C at holding times of 30, 60, and 90 minutes. Uncalcined clay samples and samples calcined at 1000 °C (holding for 60 minutes) were used in the control experiments. Leaching of alumina from the resulting clay calcines passing 300 μm sieve (-50 mesh) was done in 1M hydrochloric acid solution at room temperature using a solid/liquid ratio of 0.02g/ml and shaking speed of 100 rpm. The solubility data given by the fraction of Al ion taken into leach solution showed that the clay calcined at 700 °C (holding for 60 minutes) responded most to leaching. In general, it was observed that samples calcined for 60 minutes responded better than those held for 30 or 90 minutes. The activation energies for leaching the clay calcines were 29.50, 32.92, 26.71, 30.18, 29.18, and 33.24 kJ/mol for samples calcined for 60 minutes at 500, 600, 700, 800, 900, and 1000 °C, respectively. The activation energy of leaching for the uncalcined sample was 35.07 kJ/mol. Thus, calcines produced at 700 °C (holding for 60 minutes) had the highest leaching response for alumina and the lowest leaching activation energy of 26.71 kJ/mol. It is concluded therefore that Nsu kaolinite clay should be best calcined for alumina yield by heating up to 700 °C and holding for 60 minutes at that temperature. The clay deposit can be used as alternative resource for alumina production.

Ultra-thin atomic layer deposited aluminium oxide tunnel layer passivated hole-selective contacts for silicon solar cells

In this work, we use ultra-thin thickness-controllable spatial atomic layer deposited (ALD) aluminium oxide (AlOx) tunnel layers, which contain high negative fixed charges (Qf), capped by highly boron-doped polysilicon layers to form tunnel layer passivated contacts. The high Qf of the tunnel layers is expected to enhance the carrier selectivity of these passivated hole-extracting contacts. The dependence of the ALD AlOx tunnel layer contact passivation performance on its thickness is investigated. Furthermore, two different thermal charge activation conditions, i.e., fast firing using a belt furnace at 700 and 800 °C are compared. The best measured recombination current density J0 and implied open-circuit voltage iVoc of the developed AlOx/polysilicon passivated contacts with a symmetrical AlOx/SiNx stack passivation are 6.6 fA/cm2 and 723 mV, respectively. Based on the measured J0 and on the measured total contact resistivity of the passivated contact, the practical efficiency limit of a rear-side full area passivated contact solar cell with a conventionally diffused front side is calculated to be as high as 23.2%. Additionally, three rear-side metallization schemes: (1) thermally evaporated full-area silver contacts; (2) screen-printed non-firing-through aluminium contacts and (3) screen-printed firing-through silver-aluminium contacts, are compared. Finally, rear-emitter solar cells, using a rear-side hole-selective AlOx tunnel layer passivated contact, are fabricated, which shows an efficiency of up to 20.5%. While the proposed hole-selective passivated contact scheme appears to be promising based on the simulation prediction, the efficiency of the fabricated cells is largely limited by the non-optimized front-side reflectance and recombination losses as well as the use of non-optimized rear-side metallization schemes.

Evidence for Redox Mechanisms in Organometallic Chemisorption and Reactivity on Sulfated Metal Oxides.

The chemical and electronic interactions of organometallic species with metal oxide support materials are of fundamental importance for the development of new classes of catalytic materials. Chemisorption of Cp*(PMe3)IrMe2 on sulfated alumina (SA) and sulfated zirconia (SZ) led to an unexpected redox mechanism for deuteration of the ancillary Cp* ligand. Evidence for this oxidative mechanism was provided by studying the analogous homogeneous reactivity of the organometallic precursors toward trityl cation ([Ph3C]+), a Lewis acid known to effect formal hydride abstraction by one-electron oxidation followed by hydrogen abstraction. Organometallic deuterium incorporation was found to be correlated with surface sulfate concentration as well as the extent of dehydration under thermal activation conditions of SA and SZ supports. Surface sulfate concentration dependence, in conjunction with a computational study of surface electron affinity, indicates an electron-deficient pyrosulfate species as the redox-active moiety. These results provide further evidence for the ability of sulfated metal oxides to participate in redox chemistry not only toward organometallic complexes but also in the larger context of their application as catalysts for the transformation of light alkanes.

Transformation of a Pt–CeO2 Mechanical Mixture of Pulsed‐Laser‐Ablated Nanoparticles to a Highly Active Catalyst for Carbon Monoxide Oxidation

AbstractThe pulsed laser ablation (PLA) in alcohol and water media was employed to prepare Pt and CeO2 PLA‐nanoparticles of different sizes and degrees of defectiveness. Interactions of metallic platinum and ceria particles were studied using the thermal activation of Pt–CeO2 mechanical mixtures in the CO+O2 reaction medium or O2 atmosphere. The thermal activation resulted in oxidized Pt2+/Pt4+ states of platinum in the surface solid solutions PtCeOx and/or PtOx clusters. Catalysts formed after calcination of the PLA‐ablated Pt–CeO2 mixtures in oxygen at 450–600 °C revealed CO conversion at very low temperatures up to 70 % depending on the conditions of PLA particles preparation and thermal activation of Pt–CeO2 mechanical mixture.