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This study explores the synthesis of cyclopenta‐fused polyaromatic hydrocarbons (CP‐PAHs) via Pt‐catalyzed cyclization in water, focusing on the formation of fused pentagonal rings within heavily fused PAH frameworks. Utilizing platinum catalysts at lower temperatures (200‐260 °C) in water, led to the successful synthesis of singly cyclized CP‐PAHs. The reaction conditions facilitated the mono‐cyclization of substrates such as dibenzo[g,p]chrysene and its isomers, yielding the desired products while suppressing the formation of bis‐cyclized compounds. The use of Fe2O3 as an additive in conjunction with PtO2 was effective to suppress hydrogenation of the substrates and products. The products exhibited a redshift in UV‐visible absorption and photoluminescence bands due to a decrease in the HOMO−LUMO energy gap. These findings highlight the potential of Pt‐catalyzed cyclization for the controlled synthesis of CP‐PAHs, with implications for various applications in materials science. [ABSTRACT FROM AUTHOR]

UV-activated catalytic hydrosilation is a low-temperature crosslinking process that has attracted attention for its high efficiency and lower energy demand relative to thermal curing. In this study, formulations comprising industrially relevant model silanes and Pt photocatalysts trimethyl(methylcyclopentadienyl)platinum(IV) and trimethyl(pentamethylcyclopentadienyl)platinum(IV) (MeCpPtMe3 and Cp*PtMe3, respectively) were prepared with and without a photosensitizer (PS) and assessed for catalytic performance by a novel strategy. Photopolymerizations were initiated using different wavelengths from LEDs and monitored in real-time using an Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) "well" strategy to track the degree of cure in ultra-thin films by consumption of hydride via the disappearance of the Si-H bending absorption band at 915 cm−1. Irradiation of formulations with 365 nm excitation showed higher conversions relative to 400 nm light and improvements to calculated initial reaction rates by incorporation of a PS suggested increased sensitization to 365 nm irradiation. To the best of our knowledge, this is the first study to report catalytic performance, electronic absorption spectroscopic data, and the crystal structure of Cp*PtMe3. [ABSTRACT FROM AUTHOR]

Proton-exchange membrane fuel cells are one of the most promising energy conversion technologies for both automotive and stationary applications. Scientists are testing a number of solutions to increase the durability of cells, especially catalysts, which are the most expensive component. These solutions include, among others, the modification of the composition and morphology of supported nanoparticles, the platinum–support interface, and the support itself. A detailed understanding of the mechanism of platinum degradation and the subsequent improvement of the durability of the entire cell requires the development of methods for effectively monitoring the behavior of catalytic nanoparticles under various cell operating conditions. The Identical-Location Transmission Electron Microscopy (IL-TEM) method makes it possible to visually track structural and morphological changes in the catalyst directly. Because the tests are performed with a liquid electrolyte imitating a membrane, they provide better control of the degradation conditions and, consequently, facilitate the understanding of nanoparticle degradation processes in various operating conditions. This review is primarily intended to disseminate knowledge about this technique to scientists using electron microscopy in the study of energy materials and to draw attention to issues related to the characterization of the structure of carbon supports. [ABSTRACT FROM AUTHOR]

A method for producing a composite sorbent with a honeycomb structure (a system of parallel directed permeable pores) for capturing platinum aerosols in high-temperature catalytic processes is proposed. The composite sorbent is prepared from cordierite ceramics with the addition of active calcium oxide. The calcium oxide precursor is introduced into the molding mass as calcium carbonate powder or by impregnating the matrix material with a solution of calcium nitrate. The mechanism of synthesis of the composite sorbent is investigated. Its physicochemical properties are given. Pilot tests of composite sorbents in an industrial reactor have shown its resistance to technological conditions of ammonia conversion and the ability to capture platinum catalyst aerosols. [ABSTRACT FROM AUTHOR]

Biomass is a renewable source of energy obtained from biological materials. Gasification technology is commonly used to produce hydrogen (H 2) from biomass. This method is based on the partial oxidation of the input materials and their conversion into synthetic gas. After gasification, the biomass is converted into a gas consisting of H 2 , carbon monoxide (CO), carbon dioxide (CO 2), and other compounds. This research investigates the number of H 2 molecules (n(H 2)) and CO molecules (n(CO)) in the basic structure at a temperature and pressure of 1 bar and 1800 K. Additionally, the effect of initial pressure (IP) changes on the n(H 2) and n(CO) produced with a 10 % volume fraction of platinum (Pt) catalyst was evaluated using molecular dynamics (MD) simulation. The results demonstrate that the produced n(H 2) and n(CO) increase from 559 to 146 to 586 and 165, increasing the Pt nanocatalyst ratio from 1 % to 10 %. Furthermore, the n(H 2) and n(CO) increase from 586 to 165 to 598 and 175, respectively, by increasing the IP from 1 to 5 bar. Also, the results reveal that the combustion efficiency (CE) increases from 62 % to 66 % with increasing IP from 1 to 5 bar. The application of this research is to study the production of hydrogen and carbon monoxide from biomass using gasification technology. This information can be useful for improving the efficiency of biomass gasification for hydrogen production. [Display omitted] • Hydrogen production by biomass gasification by MD simulation. • Using EAM, Lennard-Jones and Coulomb's potential functions to simulate biomass structure. • Investigation the basic structure of biomass at P=1 bar and T=1800 K in the absence of Pt catalyst. • Investigation the effects of different pressures on hydrogen and CO production in the presence of nanocatalyst. [ABSTRACT FROM AUTHOR]

This article reports on a study that investigated the use of blended sulfonated polymer membranes for fuel cell applications. The researchers blended a sulfonated poly(arylene ether) polymer material with an amine-based crosslinking agent in 1%–5% varying weight percentages. By replacing the sulfonates' hydrogen bonds with the amine groups in the crosslinking agent, the researchers were able to enhance the structure of the polymer material. This, in turn, can help resolve the issue of inadequate dimensional stability of SA8, thereby prolonging the lifespan of fuel cells. The resulting membranes showed improved dimensional stability, oxidative stability, and cell component efficiency, with the 5% crosslinking agent blend ratio demonstrating decrease 30.8 times in swelling ratio and a 4.9% increase in oxidative stability. Additionally, the fuel cell efficiency of the 1% crosslinking agent blend ratio membrane was 20.4% higher than that of the commercial membrane, with a power density of 1.21 W/cm2. The SA8+1P blend ratio had the highest ion exchange capacity and water uptake, resulting in increased proton conductivity and power density. Furthermore, the dimensional stability of the membranes improved with the blend ratio, with the SA8+5P membrane outperforming the commercial Nafion 211 membrane. The SA8+1P and SA8+5P membranes have been proven to demonstrate exceptional performance in terms of ion exchange capacity, conductivity, and dimensional stability. Furthermore, these membranes also show high efficiency in fuel cell efficiency. Overall, the results suggest that blending sulfonated polymer membranes with an amine-based crosslinking agent has the potential to improve the performance of fuel cell components. • SA8 exhibits outstanding membrane-forming properties and remarkable proton conductivity in fuel cells. • Amine-based Sulfonated poly(arylene ether) can increase the dimensional and cell component efficiency stability. • Membranes demonstrate excellent performance with SA8 blending ratios of 1% and 5% crosslinking. [ABSTRACT FROM AUTHOR]

UV-activated catalytic hydrosilation is a low-temperature crosslinking process that has attracted attention for its high efficiency and lower energy demand relative to thermal curing. In this study, formulations comprising industrially relevant model silanes and Pt photocatalysts trimethyl(methylcyclopentadienyl)platinum(IV) and trimethyl(pentamethylcyclopentadienyl)platinum(IV) (MeCpPtMe3 and Cp*PtMe3, respectively) were prepared with and without a photosensitizer (PS) and assessed for catalytic performance by a novel strategy. Photopolymerizations were initiated using different wavelengths from LEDs and monitored in real-time using an Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) “well” strategy to track the degree of cure in ultra-thin films by consumption of hydride via the disappearance of the Si-H bending absorption band at 915 cm−1. Irradiation of formulations with 365 nm excitation showed higher conversions relative to 400 nm light and improvements to calculated initial reaction rates by incorporation of a PS suggested increased sensitization to 365 nm irradiation. To the best of our knowledge, this is the first study to report catalytic performance, electronic absorption spectroscopic data, and the crystal structure of Cp*PtMe3.

Polymer electrolyte membrane fuel cells (PEMFCs) have reached the commercialization phase, representing a promising approach to curbing carbon emissions. However, greater durability of PEMFCs is of paramount importance to ensure their long-term viability and effectiveness, and catalyst development has become a focal point of research. Pt nanoparticles supported on carbon materials (Pt/C) are the primary catalysts used in PEMFCs. Accomplishing both a high dispersion of uniform metal particles on the carbon support and robust adhesion between the metal particles and the carbon support is imperative for superior stability, and will thereby, advance the practical applications of PEMFCs in sustainable energy solutions. Ultrasound-assisted polyol synthesis (UPS) has emerged as a suitable method for synthesizing catalysts with a well-defined metal-support structure, characterized by the high dispersion and uniformity of metal nanoparticles. In this study, we focused on the effect of ultrasound on the synthesis of Pt/C via UPS and the resulting enhanced stability of Pt/C catalysts. Therefore, we compared Pt/C synthesized using a conventional polyol synthesis (Pt/C_P) and Pt/C synthesized via UPS (Pt/C_U) under similar synthesis conditions. The two catalysts had a similar Pt content and the average particle size of the Pt nanoparticles was similar; however, the uniformity and dispersion of Pt nanoparticles in Pt/C_U were better than those of Pt/C_P. Moreover, ex/in-situ analyses performed in a high-temperature environment, in which nanoparticles tend to agglomerate, have revealed that Pt/C_U exhibited a notable improvement in the adhesion of Pt particles to the carbon support compared with that of Pt/C_P. The enhanced adhesion is crucial for maintaining the stability of the catalyst, ultimately contributing to a better durability in practical applications. Ultrasound was applied to the carbon support without the Pt precursor under the same UPS conditions used to synthesize Pt/C_U to identify the reason for the increased adhesion between the Pt particles and the carbon support in Pt/C_U, and we discovered that oxygen functional groups (C-O, C = O, and O-C = O) for anchoring site of Pt particles were generated in the carbon support. Pt/C_U displayed an increase in stability in an electrochemical accelerated stress test (AST) in an acidic electrolyte. The physical and chemical effects of ultrasound on the synthesis of Pt/C via UPS were identified, and we concluded that UPS is suitable for synthesizing carbon supported electrocatalysts with high stability.

We propose to use the platinum(II) C,N‐cyclometalated complex (PCC) to catalyze the hydrosilylation and dehydrocoupling reactions of high molecular weight polysiloxanes at elevated temperatures (above 100°C). PCC was prepared via a three‐step procedure consisting of the 2‐hydrazinopyridine synthesis, its treatment with 3‐methoxy‐4‐(prop‐2‐yn‐1‐yloxy)benzaldehyde, and coupling of the obtained product with cis‐[PtCl2(CNXyl)2]. This complex exhibits thermal stability up to 150°C even at heating in air. PCC allows carrying out the cross‐linking of vinyl‐terminated polydimethylsiloxane (V‐PDMS) and polymethylhydrosiloxane (PMHS) by hydrosilylation, as well as PMHS dehydrocoupling cross‐linking at 150 and 120°C, respectively. The coupling (cross‐linking) patterns were successfully confirmed by 1H, 13C, and 29Si solid‐state NMR spectroscopy. The thermal and swelling characteristics and the transparency of the obtained silicone materials indicate the absence of aggregation of platinum particles. [ABSTRACT FROM AUTHOR]

The study is presented on the influence of the composition of a ceria-zirconia support on the structure and the activity in water-gas shift reaction of platinum catalysts (Pt/Ce0.75Zr0.25O2 and Pt/Ce0.4Zr0.5Y0.05La0.05O2). The structure diagnostics of the samples were performed using high-resolution transmission electron microscopy, powder X-ray diffraction, CO chemisorption and X-ray atomic pair distribution function method. It was shown that the catalysts contain highly dispersed platinum particles not exceeding 2 nm in size. Platinum particles supported on Ce0.75Zr0.25O2 are smaller due to the higher specific surface area of the support. The catalysts Pt/Ce0.75Zr0.25O2 and Pt/Ce0.4Zr0.5Y0.05La0.05O2 proved to have similar efficiency while having the same platinum content. It was assumed that the catalysts supported on Ce0.4Zr0.5Y0.05La0.05O2 demonstrate a slightly higher turnover frequency per platinum surface atom, but it is likely compensated by the difference in the supported metal particle size. [ABSTRACT FROM AUTHOR]

A series of methane oxidation catalysts were prepared by doping Santa Barbara Amorphous-15 (SBA-15), a highly mesoporous silica sieve, with varying amounts of Zr (5, 10, and 15 wt%) and loading with 2 wt% Pd and 4 wt% Pt. The catalysts were characterized using various techniques, including BET, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and H2-temperature programmed reduction (H2-TPR). Fresh and aged catalysts were evaluated for methane oxidation. Aging was performed using a simulated lean burn natural gas (NG) engine exhaust containing water vapor (10% vol) and sulfur (10 ppm). It was found that the catalyst with 15 wt% zirconia was the most active and stable of the series, exhibiting the lowest T50 of 481 °C after 40 h of aging. The Pd–Pt catalyst loaded on pure SBA-15 had a T50 of 583 °C after aging, which was 102 °C higher than that of the Pd–Pt catalyst with 15 wt% Zr. The results suggest that the increased performance was due to the higher amount of reducible PtOx species in the proximity of ZrO2 and the sulfur scavenging effect of zirconia, which protected the active metals from forming inactive sulfur complexes. Overall, the Pd–Pt catalyst with 15 wt% Zr loaded on SBA-15 demonstrated excellent methane oxidation activity, hydrothermal stability, and sulfur resistance and can be considered a viable candidate for reducing the methane slip from a lean burn NG engine exhaust. [ABSTRACT FROM AUTHOR]

Premixed combustion of hydrogen/air over a platinum (Pt) catalyst is numerically investigated in a planar channel burner with the aim of stabilising the flame at lean to ultra-lean conditions. A steady laminar species transport model is examined in conjunction with elementary heterogeneous and homogeneous chemical reaction schemes and validated against experimental results. A stability map is obtained in a non-catalytic burner for the equivalence ratios (φ) of 0.15–0.20, which serves as the basis for the catalytic flame analysis. Over the Reynolds numbers (Re) investigated in the non-catalytic burner, no flame is observed for φ ≤ 0.16, and flame extinction occurs at Re < 571 and Re < 381 for φ = 0.18 and 0.20, respectively. Moreover, a significant amount of unburned H 2 exits the burner in all cases. With the Pt catalyst coated on the walls, complete H 2 combustion is attained for 0.10 ≤ φ ≤ 0.20 where the contribution of gas phase (homogeneous) reaction increases with Re. Furthermore, radiation on the wall and at the inlet affects the combustion kinetics and flame temperature. Finally, NO x emission is investigated under the same conditions and found to increase with equivalence ratio but has a negligible effect with the inflow Reynolds number. [Display omitted] • Premixed hydrogen/air combustion at lean to ultra-lean conditions. • A stability map is presented for non-catalytic combustion. • Catalyst enhances flame stability and provides complete hydrogen combustion. • Radiation significantly affects combustion kinetics and flame temperature. • NO x emission at lean to ultra-lean conditions investigated. [ABSTRACT FROM AUTHOR]

The chemoselective hydrogenation of α,β-unsaturated aldehydes is a key strategy for the synthesis of fine chemicals. Herein, we developed an efficient method of depositing Pt particles on FeOx/SBA-15. This strategy is dependent on using a platinum-divinyltetramethyldisiloxane complex (Pt0-DVTMS) as the precursor, which we demonstrate can be removed through a H2-treatment under mild conditions. This, in turn, allowed for the synthesis of catalysts with well dispersed Pt particles. The presence of FeOx species also aided Pt dispersion; when coated onto SBA-15, FeOx strongly interacted with dissociated Pt species, inhibiting both Pt aggregation and metal leaching. Using cinnamaldehyde as a model α,β-unsaturated aldehyde, it was demonstrated that this catalyst was highly selective towards the unsaturated alcohol and no obvious loss in activity was observed over five recycles. This catalyst was determined to be significantly more effective than an analogous catalyst prepared using chloroplatinic acid as a precursor, evidencing the importance of using the Pt0-DVTMS precursor. We corroborate the excellent catalytic performance to highly dispersed Pt-species, whereby Pt0 and Pt2+ play a critical role in activating H2 and the C=O bond. This research demonstrates that the Pt precursor can have a significant impact on the physicochemical properties and thus, the performance of the final catalyst. It also evidences how metal support interactions can dramatically influence selectivity in such hydrogenation reactions. This novel catalyst preparation protocol, using a DVTMS ligand for Pt impregnation, offers a facile approach to the design of multi-component heterogeneous catalysts. [ABSTRACT FROM AUTHOR]

The data on the performance in water gas shift reaction of a powder 5 wt% Pt/Ce 0.75 Zr 0.25 O 2 and a structured 0.33 wt% Pt/Ce 0.75 Zr 0.25 O 2 /θ-Al 2 O 3 /FeCrAl catalysts are reported in this work. For the powder one the lowest outlet CO concentrations were shown to be 0.5, 0.9 and 1.5 vol% corresponding to the initial ones of 5, 10 and 15 vol%, respectively; the temperature required to reach these values did not exceed 310 °C. The quasi in situ XPS data have shown that doping CeO 2 with Zr enhances the reducibility of the oxide allowing Ce3+ formation without any treatment. Additionally, it was found that there are 20–30% of nonmetallic Pt atoms on the surface even after a treatment in CO at 300 °C. For the structured catalyst the downward temperature gradient along the monolith was observed with a dispersion of 50–60 °C. The lowest CO concentrations were observed at the temperatures at the catalyst's back point of 280 °C–3.9 and 4.3 vol% CO in the dry gas for 15,700 and 31,400 cm3·g cat −1·h−1, respectively, for 10 vol% CO in the feed gas. • The powder and structured catalysts 5 wt% Pt/Ce 0.75 Zr 0.25 O 2 for water gas shift reaction. • The catalysts show a good performance below 350 °C in reformate-simulating mixtures. • Doping CeO 2 with Zr allows Ce3+ on the oxide surface without any treatment. • 20–30% of surface Pt atoms are in nonmetallic state even in a reductive atmosphere. [ABSTRACT FROM AUTHOR]

While fuel cells have the potential to be among the key players in clean energy production, they are challenged by the sluggish electrochemical reactions that require an expensive and scarce platinum (Pt) catalyst. Commercial Pt-based catalysts used for facilitating the hydrogen oxidation reaction and oxygen reduction reaction (ORR) in fuel cells are commonly supported by petroleum-sourced carbon materials such as Vulcan XC-72. Thus, the replacement of such support materials with sustainable alternatives while enhancing the catalyst activity is highly desirable. For the first time, a Pt catalyst supported with a sustainably manufactured nanoscale CO2-derived carbon (Pt/CO2-C) was synthesized in this work. Physical and electrochemical characterization of the catalyst revealed the superior activity of Pt/CO2-C toward the ORR in comparison to commercial Pt/C with higher onset potential, mass activity, and specific activity values. Via further improvement, the prepared catalyst material is deemed to be a promising candidate for cheaper and more sustainable fuel cells. [ABSTRACT FROM AUTHOR]

Catalytic dehydrogenation of propane to propylene and by‐product hydrogen is an atom‐economical and environmentally friendly route. PtSn/Al2O3 catalysts have been industrialized in this process, but still suffer from platinum sintering and coke deposition under reaction conditions. Herein, we design a calcium‐modified PtSn/Al2O3 catalyst showing a superior propane dehydrogenation performance. The presence of calcium combined with unsaturated aluminum and tin could consist of a new local microenvironment that promotes the dispersion of the platinum species and increases the electron density of the platinum species, which improves the catalytic activity, facilitates propylene desorption and inhibits coke formation. As a result, the achieved PtSnCa/Al2O3 catalyst exhibits a higher propylene formation rate and a lower coke‐accumulation rate compared to the catalyst without Ca addition. Moreover, the size of active phase clusters (∼1 nm) remained almost unchanged after the catalytic test, indicating a superior sintering resistance. [ABSTRACT FROM AUTHOR]

This study presents synthesis results of catalysts made of perovskite-like oxide La2-xSrxCuO4 (x=0.0, 0.5, 1.0) using the citrate method and crystallisation at 800°C. The structure of the catalysts was characterised by X-ray diffraction (XRD). The perovskite- like oxide catalyst activity was enhanced with gold (Au) and platinum (Pt). Au was mounted on the perovskite-like oxide catalysts by the sol-gel method. The activity of the perovskite-like oxide La2-xSrxCuO4 (x=0.0, 0.5, 1.0) and the perovskite catalyst LaMnO3/ LaCuO3 was evaluated by complete oxidation of volatile hydrocarbons (HCs) in a mixture of toluene and methyl ethyl ketone (MEK) and carbon monoxide (CO) in a microflow analysis system combined with gas chromatography. The results showed that the light-off temperature (the 50% conversion temperature of the catalysts) of the Pt, Au/perovskite catalyst samples decreased significantly. The light-off temperature of the Au/LaSrCuO4 Au nanoparticle catalysts in the complete CO oxidation reaction reached a temperature of 150°C, lower than the Pt/LaSrCuO4 catalyst (170°C), allowing replacement of previous Pt catalysts with Au nanoparticle catalysts. The LaSrCuO4 catalyst had better oxidising activities than the La2CuO4 catalyst, indicating that the addition of strontium (Sr) has increased the catalyst activity, and demonstrates the potential for application in catalytic converters in motorcycles.

Photocatalytic hydrogen (H2) production is a promising route for alternative energetics. Understanding structure–activity relationships is a crucial step towards the rational design of photocatalysts, which requires the application of operando spectroscopy under relevant working conditions. We performed an operando investigation on a catalytic system during the photodeposition of Pt on TiO2 and photostimulated H2 production, using simultaneous laboratory X-ray absorption spectroscopy (XAS), UV–Vis spectroscopy, and mass spectrometry. XAS showed a progressive increase in Pt fluorescence for Pt deposited on TiO2 for over an hour, which is correlated with the signal of the produced H2. The final Pt/TiO2 catalyst contained Pt(0) particles. The electronic features corresponding to the Pt4+ species in the UV–Vis spectrum of the solution disappear as soon as UV radiation is applied in the presence of formic acid, which acts as a hole scavenger, resulting in the presence of Pt(0) particles in solution. [ABSTRACT FROM AUTHOR]

Catalysts for the oxygen reduction reaction (ORR) in PEM fuel cells are commonly constituted of Pt-based nanoparticles and a carbon support originating from fossil resources. In order to employ a more sustainable carbon support, activated sawdust was chosen in this study. This was firstly steam-activated at 750 °C and then thermally treated at elevated temperatures up to 2800 °C and reducing conditions at 1100 °C. Various physical characterization methods were applied to systematically relate treatment parameters to surface and structural properties of the carbon material. Deposition of small Pt nanoparticles on the biochar-based supports yielded in ORR active catalysts which were analyzed by thin-film rotating disc electrode measurements. The activity and stability towards the ORR of these novel catalysts was compared to a commercial raw oil-based Pt/C and the influence of support modification on the ORR performance was discussed. [ABSTRACT FROM AUTHOR]

A high‐rate oxygen reduction reaction (ORR) is necessary for polymer electrolyte membrane fuel cells (PEMFC). In this work, by using a solution plasma technique, Pt catalytic particles coated with N‐doped graphene (Pt‐NG) were effectively produced at 25°C. According to transmission electron microscope images, the average diameter of Pt particles was 4 nm, while the graphene layer thickness was less than 1 nm. A catalytic layer of Pt‐NG supported on single‐walled carbon nanotubes (Pt‐NG/SWCNT) was synthesized. Cyclic voltammetry was used to assess the ORR characteristics of Pt‐NG/SWCNT catalytic layers. Only at a density of SWCNT to solvent ratio of 0.75 mg ml−1 were the ORR peaks clearly visible. Because of the high resistivity of SWCNT layers, the ORR peaks in other ranges, 0.4 mg ml−1 to 2.0 mg ml−1, were not clearly observed. The effect of SWCNT concentration on conductivity was proven to follow the basic concept of the percolation threshold. [ABSTRACT FROM AUTHOR]

The effect of the support nature and the mass of platinum on the stability, electrochemical characteristics of monoplatinum catalysts, and the reaction path of electrochemical oxygen reduction in alkaline electrolyte is studied. Catalysts with the Pt mass content of 10, 20, 40, 60 wt % are synthesized by the polyol method on carbon nanotubes functionalized in NaOH and doped with nitrogen. The activity, the percentage of hydrogen peroxide formed, and the number of electrons participating in the oxygen reduction reaction are determined from the data obtained by the rotating ring-disk electrode method. For catalysts synthesized on the nitrogen-doped carbon nanotubes, the highest selectivity in the reaction of oxygen reduction to water is observed; the higher Pt surface area at the electrode, the greater is the selectivity, because the contribution of the support surface to the total oxygen reduction reaction decreased. Both the presence of hydrogen peroxide and a decrease in stability result from the decrease in the platinum content in the catalyst. [ABSTRACT FROM AUTHOR]

Chiral surfactants can provide asymmetric environments in water that can enhance the stereoselectivity of chiral metal catalysts. Due to the high dynamic nature of micelles, this specific field of research has been seldom investigated. The design of the surfactant and its interaction with the catalyst is crucial to improve stereoselectivity. We report a series of chiral surfactants bearing rigid aromatic hydrophobic units based on the BINOL scaffold decorated with hydrophilic side chains. In particular, the use of anionic side chains provide better interaction with chiral Pt(II) catalysts due to ion pairing leading to improvements in the enantioselectivity of the sulfoxidation reaction of thioethers with hydrogen peroxide. This proof of concept contribution opens the way to the design of new classes of chiral designer surfactants that could be applied to move to water many classes of stereoselective reactions traditionally carried out in organic media. [Display omitted] [ABSTRACT FROM AUTHOR]

• The synergistic effect of DHPEI and Pt is investigated by ReaxFF MD simulation. • The DHPEI-Pt composite additive shows the highest enhancement in heat sink. • The mechanism of synergistic effect between DHPEI and Pt is revealed. The initiated/catalytic cracking of endothermic hydrocarbon fuels (EHFs) is a viable strategy for improving the thermal management capabilities of regenerative cooling. Either noble metal nanoparticles (NPs) or hyperbranched polymers (HPs) has been confirmed to promote the pyrolysis of EHFs but their synergistic catalytic mechanism remains unclear. Aiming to address such issues, the cooling performance of n-dodecane in the presence of platinum (Pt), decanoic anhydride modified hyperbranched polyethyleneimine (DHPEI), and their composite (DHPEI-Pt) was investigated using ReaxFF MD simulations, respectively. The results indicate that all three additives significantly reduce the initial pyrolysis temperature of n-dodecane, ultimately leading to an increase in heat sink through enhanced conversion and gas yield. The composite DHPEI-Pt demonstrates better cooling performance compared to single additive alone, with a 28 % increase in heat sink (5.89 MJ/kg at 2800 K) and a 20 % reduction in activation energy of n-dodecane compared to pure pyrolysis. This is attributed to the synergistic mechanism between the chain initiation reaction promoted by DHPEI self-cracking and the dehydrogenation reaction catalyzed by Pt. This work bridges the current gap in the microscopic understanding of the synergistic catalytic mechanism between metals and HPs, and provides reliable guidance for the development of EHFs catalytic cracking technology. [ABSTRACT FROM AUTHOR]

Due to stringent environmental regulations and the limited resources of fossil-based fuels, there is an urgent demand for clean and eco-friendly energy conversion devices. These criteria appear to be met by hydrogen proton exchange membrane fuel cells (PEMFCs). PEMFCs have attracted tremendous attention on account of their excellent performance with tunable operability and good portability. Nonetheless, their practical applications are hugely influenced by the scarcity and high cost of platinum (Pt) used as electrocatalysts at both cathode and anode. Pt is also susceptible to easy catalyst poisoning. Herein, this paper reviews the progress of the research regarding the development of electrocatalysts practically used in hydrogen PEMFCs, where the corner-stone reactions are cathodic oxygen reduction reaction (ORR) and anodic hydrogen oxidation reaction (HOR). To reduce the costs of PEMFCs, lessening or eliminating the use of Pt is of prime importance. For current and forthcoming laboratory/large-scale PEMFCs, there is much interest in developing substitute catalysts based on cheaper materials. As such are non-platinum (non-Pt), non-platinum group metals (non-PGMs), metal oxides, and non-metal electrocatalysts. Hence, high-performance, state-of-the-art, and novel structured electrocatalysts as replacements for Pt are needed. • Current progress and enhancement of ORR and HOR catalysts for hydrogen PEMFCs. • Practical aspects of ORR and HOR electrocatalysts used in hydrogen PEMFCs. • Perspective on the remaining challenges and research directions of hydrogen PEMFCs. [ABSTRACT FROM AUTHOR]

Results of studying the sorption-enhanced water gas shift reaction over a mechanical mixture of grains of 5 wt % Pt/Ce0.75Zr0.25O2 catalyst and 10 wt % NaNO3/MgO sorbent are presented. It is shown that pure magnesium oxide sorbs virtually no СО2 under model conditions, while its promotion with NaNO3 substantially improves the dynamic sorption capacity in the 300–350°C range of temperatures with a maximum at 320°C. The catalyst shows high activity and selectivity in the water gas shift reaction for a model mixture (CO, 11.6; H2, 61; H2O, 27.4 vol %). The concentration of CO at the outlet from the reactor is less than 1 vol % in the 220–400°C range of temperatures (the minimum is 0.3 vol % at 240°C) with СН4 at the temperatures below 320°C (0.61 vol % at this point). Using this sorbent in mixtures with a catalyst in the sorption-enhanced water gas shift reaction at 320°C substantially reduces its sorption capacity, due probably to the full conversion of NaNO3 into Na2CO3 that is not completely decomposed at the stage of regeneration. This nevertheless allows the outlet СО and СН4 concentrations to be halved, relative to values observed at this temperature in experiments with no sorbent: 6.1 × 10−4 and 8.2 × 10−2 vol % per dry gas basis at the middle of the first adsorption cycle. Prospects for using this approach in the sorption-enhanced water gas shift reaction and the need for further studies on improving the capacity and stability of the presented sorbents are described. [ABSTRACT FROM AUTHOR]

The monitoring of environmental contamination is an important issue to protect human health and the atmospheric environment. In this study, the optical imaging of mesh structures not coated and coated with platinum was performed to analyze the optical characteristics of the lattices. A nickel monolith catalyst was manufactured via additive manufacturing and coated with platinum, and it was presented to characterize the catalyst properties. The analysis focused on the process of coating using hydrazine bath as a reducing agent. The results showed an increase in the thickness of the coating with baths with durations of 1.5 h, 2.0 h and 2.5 h. The coating thickness was strongly dependent on time duration. The SEM images and EDX were used to confirm the process of coating and analyze the presence of platinum on the catalyst. Coating layers were very thin, and others were not homogeneous over the surface. When the catalyst was exposed to platinum for 2.5 h, the catalyst showed an efficiency of 0.06% for NOx, 0.10%, for CO and 0.09% for HC reduction. [ABSTRACT FROM AUTHOR]

Cu-based materials can produce hydrocarbons in CO 2 electroreduction (CO 2 RR), but their stability still needs to be enhanced particularly in acidic media. Metallic Pt is highly stable in both acidic and alkaline media, yet rarely utilized in CO 2 RR, due to the competitive activity in hydrogen evolution reaction (HER). In this research, abundant thionine (Th) molecules are stably confined within Pt nanocrystals via a molecular doping strategy. The Pt surface is successfully modulated by these Th molecules, and thereby the dominant HER activity is converted to CO 2 RR activity. CO 2 could be electroreduced to CH 4 using organic molecule-modified Pt-based catalysts for the first time. Specifically, this composite catalyst maintains more than 100-hour stability in strong acid conditions (pH 1), even comparable to those state-of-the-art CO 2 RR catalysts. In-situ spectroscopic analysis and theoretical calculations reveal that the molecular modification can decrease the energy barrier for *COOH formation, and guarantee the sufficient local *H near Pt surface. Additionally, the *H derived from H 2 O dissociation is favorable for the *CO hydrogenation pathway towards *CHO, eventually leading to the formation of CH 4 . This strategy might be easily applied to microenvironment and interface regulation in other electrocatalytic reactions., (© The Author(s) 2024. Published by Oxford University Press on behalf of China Science Publishing & Media Ltd.)

Ordered mesoporous carbon (OMC) has attracted a great deal of attention as catalyst support due to their tunable morphological and textural properties. In this study, the characteristics and catalytic properties of OMC-supported Pt catalysts prepared by one-step modified soft-template self-assembly method (Pt/OMC-one-pot) were compared to the Pt impregnated on OMC, activated carbon (AC), and nonuniform meso/macroporous carbon (MC) in the selective hydrogenation of furfural to furfuryl alcohol (FA) under mild conditions (50℃, 2 MPa H2). Larger Pt particle size (~4 nm) was obtained on the Pt/OMC-onepot comparing to all the impregnated ones, in which the Pt particle sizes were in the range 0.5 - 2 nm. Reduction step was not necessary on the Pt/OMC-one-pot and among the catalysts studied, the Pt/OMCone-pot exhibited the highest furfural conversion and FA selectivity under aqueous conditions. The use of methanol as the solvent resulted in the formation of solvent product (2-furaldehyde dimethyl acetal) instead. The amount of Pt being deposited, location of Pt particles, and metal-support interaction strongly affected recyclability of the catalysts because some larger size Pt particles with weak metal-support interaction could be leached out during the liquid-phase reaction, rendering similar catalytic performances of the various porous carbon supported catalysts after the 3rd cycle of run. [ABSTRACT FROM AUTHOR]

In the present work, Pt/γ‐Al2O3 catalysts with high metal dispersion were prepared and characterized using chloroplatinic acid and platinum acetylacetonate as metal precursors. The activity and selectivity of the catalysts were evaluated in the hydrogenation of sunflower oil. A comprehensive analysis of the effects of key operational parameters on catalytic performance was carried out. The experimental variables were hydrogen pressure (275.8–551.6 kPa), temperature (160–200°C), and catalyst loading (0.005–0.015 kg Ptexp/m3oil). Platinum catalysts were active, with a double bond conversion of 28% at 2 h. The metal precursor affected catalyst selectivity. The catalyst prepared with chloroplatinic acid exhibited a lower formation of trans‐isomers compared with Pt acetylacetonate. The γ‐Al2O3 supported platinum catalyst with a metal loading of 0.51 wt.% and a metal dispersion of 98% maintained its initial catalyst activity and selectivity after 10 consecutive uses (1200 min accumulate operation time), without changes in its catalytic properties. The obtained results suggested that Pt catalysts are an attractive alternative to conventional nickel catalysts for the hydrogenation of vegetable oil. [ABSTRACT FROM AUTHOR]

Designing and fabricating active and thermally stable bifunctional catalysts with minimal noble metal loadings are crucial for reversible solid oxide cells (rSOCs). This study employed Pt nanoparticles fabricated via plasma-enhanced atomic layer deposition (PEALD) to a nickel-yttria stabilized zirconia (Ni-YSZ) electrode to serve as effective catalysts in fuel cell and electrolysis modes. Despite the minimal Pt catalyst loading (<1 μg cm–2), the PEALD Pt@Ni-YSZ catalytic electrode exhibited superior electrochemical performance, (20 % higher than the bare cell), both in the fuel cell and electrolysis modes. Remarkably, this performance is sustained without any degradation over a 50 h duration at 700 °C. Dissimilar stabilization behaviors of the Pt catalysts occurred as distributed fine particles on Ni and anchored coarsened particles at the grain boundaries on YSZ surfaces. Furthermore, the mechanism of the enhanced hydrogen evolution/oxidation reactions with the PEALD Pt@Ni-YSZ electrode was verified using density functional theory simulations. [Display omitted] • Bi-functional PEALD Pt@Ni-YSZ fuel electrodes for rSOCs with extremely low Pt loading (0.2 µg cm−2) are reported. • SOCs with PEALD Pt@Ni-YSZ show even higher performance both in fuel cell and electrolysis modes at 700 °C. • PEALD Pt is finely distributed on Ni, while agglomerates into larger particles on YSZ upon rSOC operation. • DFT calculations unveil the mechanism of HER and HOR activation in PEALD Pt@Ni-YSZ. [ABSTRACT FROM AUTHOR]

[Display omitted] • LES modelling of turbulent catalytic hydrogen/air combustion. • Intensification of the turbulent catalytic process in non-planar reactor. • Enhanced catalytic activity with staggered cylinders in a non-planar reactor. • Convective mass and heat transfer influence catalytic activity. • Achieved 62.5 % catalyst saving with non-planar reactor design. Catalytic-aided combustion has been proven effective for premixed hydrogen/air mixtures, particularly under lean to ultra-lean conditions. However, minimising the required catalyst sets a significant challenge because noble metals with high catalytic activity are rare and expensive. Therefore, this study aims to intensify the catalytic combustion process by investigating a non-planar reactor comprising an array of platinum-coated half- and full-cylinders through large eddy simulation. A premixed mixture with a fuel-lean equivalence ratio of 0.15 and an incoming Reynolds number of 3500 based on hydraulic diameter is used. For comparison, a planar reactor without cylinders is also studied under the same operating conditions and with the same amount of platinum-coated surface area. The simulation employs the turbulent kinetic energy sub-grid model and the eddy dissipation concept to model the turbulent catalytic reacting flow. The discrete ordinate model is used to account for radiation heat transfer in the catalytic process. Numerical simulations are validated against experimental results prior to analysis. The findings indicate that the placement of cylinders along the reactor length enhances convective mass transfer and intensifies catalytic combustion, resulting in effective combustion over a smaller catalytic surface. Compared to planar models, non-planar reactors demonstrate a much better H 2 conversion efficiency throughout the reactor length, saving nearly 62.5 % of the catalyst. [ABSTRACT FROM AUTHOR]

• We propose here the synthesis of dihydroxybenenzes by isomerization over Pt/ZSM-5. • Catalyst converts catechol and hydroquinone to each other with selectivity up to 74 %. • Isomerization proceeds via coke formed by quinone condensation and hydrogenolysis. Dihydroxybenzenes, including catechol, resorcinol and hydroquinone, have significant commercial value for a variety of applications such as adhesives, resins, pharmaceuticals, coatings etc. However, selective production of required isomers by phenol hydroxylation represents a considerable challenge. Here, we report a new approach for the synthesis of dihydroxybenzenes by their isomerization using a bifunctional Pt/ZSM-5 catalyst. The catalyst successfully facilitates the transformation of catechol and hydroquinone to each other with a selectivity of up to 74 % and yields up to 50 %. The investigation of the mechanism suggests that isomerization proceeds via a carbonaceous deposit (coke) formed by intermediate quinone condensation with subsequent hydrogenolysis to isomers. The proposed mechanism shows the way for the design of the efficient process for isomerization of dihydroxybenzenes. [ABSTRACT FROM AUTHOR]

The kinetics of the platinum‐catalyzed dehydrocondensation reaction for five different mono‐alcohols and water is studied in order to identify the ones with the highest effectiveness in releasing gaseous H2 from the SiH groups of poly(methylhydrosiloxane) (PMHS). Our results show that the most common logic rules of alcohol reactivity do not apply in such reactions and that a set of aspects need to be considered together to understand or predict the outcome and the possible applications. In dehydrocondensation of PMHS, the use of Lamoreaux' catalyst may be considered to be a cost‐effective alternative, a novel approach in characterizing catalyzed reaction kinetics under mild conditions. To the best of our knowledge, it is the first article describing the use of Lamoreaux' in this approach. [ABSTRACT FROM AUTHOR]

The solvent effect in the catalytic depolymerization of the three-dimensional network of lignin is discussed based on recent reports in this field. Also, the results of an experimental study on the depolymerization of kraft lignin are presented. The cleavage of ether bonds within the lignin network was promoted using ruthenium and platinum on activated carbon (Ru/C and Pt/C), two common hydrogenolysis catalysts. Methanol was identified as a suitable solvent. Noteworthy, under the chosen reaction conditions, the catalysts showed significant resilience to the sulfur present in kraft lignin. The conversion of kraft lignin to lignin oil was strongly affected by the reaction conditions. Although the Ru/C catalyst provided the highest yield at supercritical conditions, a maximum yield was obtained for the Pt/C catalyst at near-critical conditions. The formation of guaiacol, 4-alkylguaiacols, isoeugenol, and 4-ethyl-2,6-dimethoxyphenol is attributed to the solubility of oligomeric lignin fragments in the solvent and the relative propensity of specific groups to adsorb on the catalyst surface. [ABSTRACT FROM AUTHOR]

Until quite recently, Arctic diesel fuel was produced in accordance with GOST R 55475 with a cold filter plugging point down to –52°C using a depressant-dispersing additive. However, in the Arctic, the temperature drops to –60°C and below, and the use of depressant-dispersing additives provokes product stratification with a sharp deterioration in the properties of the lower layer. This limited the application of Arctic diesel fuel in the Arctic. For such conditions, the Ministry of Defense of the Russian Federation developed its own standards for Arctic diesel fuel without the use of depressant-dispersing additives, and suggesting values not higher than –65°C for the cloud point, pour point and cold filter plugging point. An obstacle for obtaining a product with such properties is the difficulty of simultaneously providing the required cetane number and the low temperature properties. This paper presents a method for obtaining Arctic diesel fuel with the desired properties based on deeply isomerized diesel fractions. To implement the project, the existing units at Slavneft-YANOS PJSC were analyzed, and a chain of units was assembled for primary oil refining, hydrotreating 80 atm and isodewaxing. In the course of a number of experiments new causes of the onset of cold filter plugging point were discovered, which were explained by an increase in the diesel fuel viscosity at extremely low temperatures. To reduce the viscosity of the product, hydrocracked kerosene was added to the formula. In May 2020, permits were received from the Ministry of Defense of the Russian Federation, and in October 2021, for the first time in the Russian Federation and in the world, the first industrial batch of 3,000 tons was successfully produced. [ABSTRACT FROM AUTHOR]

In this study, a mesoporous SBA-15 silica catalyst was prepared and modified with encased 1% platinum (Pt) metal nanoparticles for the hydrocracking and hydroisomerization of n-heptane in a heterogeneous reaction. The textural and structural characteristics of the nanostructured silica, including both encased and non-encased nanoparticles, were measured using small-angle X-ray diffraction (XRD), nitrogen adsorption-desorption porosimetry, Brunauer–Emmett–Teller (BET) surface area analysis, Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Catalytic testing was carried out in a plug-flow reactor under highly controlled operating conditions involving the reactant flow rate, pressure, and temperature. Gas chromatography was used to analyze the species as they left the reactor. The results demonstrated that 1% Pt/SBA-15 has a high n-heptane conversion activity (approximately 85%). Based on the results of this experimental work, there is no selectivity in the SBA-15 catalysts for isomerization products because they are inactive at the relatively low temperature that is essential for hydroisomerization. On the other hand, the SBA-15 catalysts have a considerable selectivity for products that have cracks, owing to their ability to withstand extremely high temperatures (300–400 ​°C) as well as the availability of Lewis acid sites within the catalyst structure.

Pt has been used as a cocatalyst for semiconductor photocatalysis because of its high catalytic activity. Although Pt catalysts are highly active for both oxidation and reduction reactions, photocatalysts have exploited the activity of Pt almost exclusively for reduction reactions. In the case of Au nanoparticles combined with a semiconductor, oxidation reactions take place at the Au surface due to plasmon-induced charge separation (PICS). If Au nanoparticles are replaced with Pt nanoparticles, oxidation reactions may occur at the Pt surface. However, Pt is much less plasmonic in comparison with Au, in the visible wavelength range. In order to make Pt nanoparticles resonant with visible light, here we coupled small Pt nanospheres (PtNSs) with large Au nanocubes (AuNCs) electromagnetically on TiO2, so that a coupling resonance mode arose at ~600 nm. The bimetallic coupling allowed the PtNS and the AuNC to serve as a charge separation and catalytic reaction unit and a light-harvesting antenna unit, respectively. Light collected by the AuNC is transferred to the PtNS, where hot electron-hole pairs are generated. The electrons are injected into TiO2, and the holes drive the oxidation reactions at the Pt surface. We performed oxidation of water at the PtNSs. As a result of coupling, the external quantum efficiency of PICS was enhanced by a factor of 28 because of the amplified interparticle electric field and intensified light absorption in the PtNS. [ABSTRACT FROM AUTHOR]

Products of the reaction of water with technical aluminum alloys activated with Ga–In eutectic were obtained. The major impurities in the aluminum hydroxide formed are Ga (5 wt %), In, and Cu (0.6–0.7 wt %); Fe, Zn, Ca, Mg, and Mn were also detected in amounts less than 0.1 wt %. A procedure was suggested for purification of the contaminated Ga–In eutectic used for the Al activation with the aim of subsequent reuse of the eutectic. The oxide phase obtained from the synthesized product is γ-Al2O3 modified with Ga and In. It is characterized by the developed surface (surface area ~300 m2 g–1) and mesoporous structure; it can be used as an adsorbent and support for dehydrogenation catalysts. Platinum catalyst on the oxide support obtained is comparable in propane dehydrogenation performance to model systems based on А0 aluminum alloy. [ABSTRACT FROM AUTHOR]

Understanding the interaction between metal and the support is crucial in searching of efficient and recyclable noble metal heterogeneous catalysts. Herein, we report a core‐shell structured support for Pt catalyst with a magnetic Fe3O4 core and a porous silica shell bearing amino groups. The prepared catalyst Fe3O4@mSiO2‐APTES‐Pt showed a high loading of Pt (7.93 wt%) as well as a high fraction of active Pt0 species, which both contributed to the high activity toward a model hydrosilylation reaction between 1‐octene and 1, 1, 1, 3, 5, 5, 5‐heptamethyltrisiloxane (HMTS). X‐ray photoelectron spectra (XPS) analysis revealed that the amino ligands played a dominant role in Pt loading and Fe2+ probably facilitated the formation of low valence Pt0. Under the combined effect of magnetic nature of the support and proper support‐metal interactions, the catalyst exhibited excellent recyclability with a recovery of 99.7% and a yield of over 90% even after eight runs of recycling. This catalyst may provide a new option in designing and preparing heterogeneous catalysts that are highly recoverable, reusable, and recyclable. [ABSTRACT FROM AUTHOR]

Dry (CO 2) reforming of methane (DRM) is of great interest in scientific, environmental, and industrial applications. The high-energy stationary path DRM provides gigatons of CO 2 utilization to produce syngas (CO and H 2), which is used to form a wide range of valuable chemicals and products through Fischer-Tropsch process. Numerous fences remain in the DRM including the absence of durable, effective, and economically viable catalysts that maintain outstanding catalytic performance along with deactivation resulting from carbon deposition. Pt-based catalyst is highly auspicious for DRM with a substantial resistance to carbon deposition and subsequent deactivation compared to Ni or another transition-metal catalyst. However, its high cost can be stay as an obstacle for the industrial application unless it is introduced with other cheap transition metals. This review emphasizes some salient features of the rational designs and fundamentals for engineering of Pt shape/composition to understand the elementary steps involved in DRM and to exploit the effect of Pt with other noble and earth-abundant-metals to form highly active and stable bi- and tri-metallic catalysts in the context of promoting DRM and their related mechanism, and deactivation regimes supported with several paradigms for rich-hydrogen production. The current critical scientific issues of methane reforming and their challenges, besides the potential prospects, are finally highlighted. [Display omitted] • Engineering of Pt-based catalysts for Dry (CO 2) Reforming of Methane (DRM). • Discussion of DRM mechanism, thermodynamics, and operation parameters. • Highlighting various shapes and compositions Pt-based catalysts fabrication for DRM. • Effect of the support, promoter, and reaction conditions on the DRM activity of Pt. • Factors affecting syngas (CO/H 2) production and coking mechanism during DRM on Pt. [ABSTRACT FROM AUTHOR]

[Display omitted] • Small and uniform CeO 2 nanoparticles were prepared on Al 2 O 3 (CA-T) using a two-step incipient wetness impregnation method. • Pt single sites anchored to step sites of small CeO 2 entities within CA-T were more stable than those anchored to crystal surface of large CeO 2 particles on regular ceria-alumina. • The reactivity of CO adsorbed on Pt sites decreased by Pt cluster step sites ≈ Pt cluster terrace sites > Pt cluster corner sites ≫ Pt single sites on CeO 2. • Abundant Pt cluster step and terrace sites as well as rich Pt-CeO 2 interfaces facilitated the activated Pt/CA-T catalyst for efficient CO oxidation at low temperatures. In heterogeneous catalysis, the promotion of low temperature activity and enhancement of thermal stability simultaneously especially for precious metal catalysts is always highly demanded but very challenging. Herein we report a novel Pt catalyst on ceria-alumina (CeO 2 /Al 2 O 3) support (Pt/CA-T) engineered by a two-step ceria deposition strategy, exhibiting superior thermal stability and low-temperature carbon monoxide (CO) oxidation activity after activation. Pt single sites anchored to engineered CeO 2 edge sites are much more stable than that to CeO 2 (111) surface, and such stable single sites can be transformed into highly active Pt clusters for efficient low-temperature CO oxidation. Active site identification indicates that the CO oxidation activity of different Pt sites follows such sequence: Pt cluster step sites ≈ Pt cluster terrace sites > Pt cluster corner sites ≫ Pt single sites on CeO 2. The excellent low temperature activity of activated Pt/CA-T catalyst for CO oxidation is associated with its abundant Pt cluster step and terrace sites as well as rich Pt-CeO 2 interfaces, which facilitate the adsorption of active CO species and superior oxygen activation/transfer ability. The present study provides new insights into the structure–activity relationship of Pt-CeO 2 -Al 2 O 3 catalyst, which can also guide the preparation of other highly robust supported catalysts for important industrial applications. [ABSTRACT FROM AUTHOR]

A density functional theory (DFT) computation on oxygen species adsorbed on platinum (Pt) catalyst surfaces has been carried out to elucidate oxygen isotope fractionation observed at the cathode of a polymer electrolyte membrane fuel cell (PEMFC). The Pt(111) catalyst surface was modelled by a Pt19 cluster, and O, OH, OHH, OO, OOH, OHOH and HOHOH were assumed to be the oxygen species adsorbed on the Pt(111) surface. The oxygen isotope reduced partition function ratios (RPFRs) of the adsorbed species were calculated using the vibrational frequencies obtained by normal mode analyses performed on the optimized structures. Various oxygen isotope exchange equilibria among the adsorbed oxygen species and oxygen and water molecules in the gas phase were examined using their RPFRs. Experimental observation that the lighter 16O is enriched in water molecules exhausted from the cathode is explainable in a satisfactory manner by assuming oxygen isotope exchange equilibria of O2 molecule with O, OH, OO and OOH adsorbed on the Pt(111) surface that appear in the first half of the conversion reaction from O2 to H2O and those of H2O molecule with the adsorbed oxygen species, OHH, OHOH and HOHOH, formed in the latter half of the conversion reaction. [ABSTRACT FROM AUTHOR]

Highly dispersed 1.9 wt % Pt/Ce0.75Zr0.25O2 –x and 5 wt % Pt/Ce0.75Zr0.25O2– x catalysts with an average particle size of 0.9 nm were prepared by sorption-hydrolytic precipitation. It was shown that the catalysts are active in the water gas shift reaction in a mixture simulating synthesis gas produced by steam reforming of natural gas. At an initial CO concentration of 10 vol % and a flow rate of 30000 ncm3 h–1, outlet CO and CH4 concentrations reach 2.5 and 0.01 vol %, respectively, over 1.9 wt % Pt/Ce0.75Zr0.25O2– x at 325°C and 1.5 and 0.075 vol %, respectively, over 5 wt % Pt/Ce0.75Zr0.25O2– x at 300°С. The observed reaction orders for CO and H2O over 5 wt % Pt/Ce0.75Zr0.25O2– x were found to be close to zero, and the apparent activation energy for both catalysts was 86 kJ/mol. Transmission electron microscopy of the catalysts showed that the narrow size distribution and high dispersion of the supported particles are retained during the reaction. However, some coarsening of Pt particles occurs, the average size increases to 1.4 and 1.6 nm for 1.9 wt % Pt/Ce0.75Zr0.25O2– x and 5 wt % Pt/Ce0.75Zr0.25O2– x, respectively. For the catalysts after the reaction, the metallic Pt surface area values, measured by CO chemisorption and transmission electron microscopy, differ significantly. Most likely, it is caused by the presence of some of the surface Pt atoms in the oxidized state. It was shown that the temperature dependences of the turnover frequency in the water gas shift reaction per the length unit of the metal-support interface, coincide for catalysts 1.9 wt % Pt/Ce0.75Zr0.25O2– x and 5 wt % Pt/Ce0.75Zr0.25O2– x. Based on this, an assumption was made about the leading role of the Pt–Ce0.75Zr0.25O2– x boundary in the catalysis of the water gas shift reaction. [ABSTRACT FROM AUTHOR]

The monitoring of environmental contamination is an important issue to protect human health and the atmospheric environment. In this study, the optical imaging of mesh structures not coated and coated with platinum was performed to analyze the optical characteristics of the lattices. A nickel monolith catalyst was manufactured via additive manufacturing and coated with platinum, and it was presented to characterize the catalyst properties. The analysis focused on the process of coating using hydrazine bath as a reducing agent. The results showed an increase in the thickness of the coating with baths with durations of 1.5 h, 2.0 h and 2.5 h. The coating thickness was strongly dependent on time duration. The SEM images and EDX were used to confirm the process of coating and analyze the presence of platinum on the catalyst. Coating layers were very thin, and others were not homogeneous over the surface. When the catalyst was exposed to platinum for 2.5 h, the catalyst showed an efficiency of 0.06% for NOx, 0.10%, for CO and 0.09% for HC reduction.

A series of model NOx storage-reduction (NSR) catalysts with different Rh/Pt weight ratios were prepared independently by wet impregnation and then mechanically mixed to investigate the effect of the Rh/Pt weight ratio on the overall NOx removal efficiency and nitrogen yield. XRD, EDS and H2-TPR studies indicated the coexistence of BaCO3, MnOx and BaMnO3 phases in the catalysts. Increasing Rh/Pt weight ratio enhanced NOx reduction under the rich phase, and improved overall N2-yield in the kinetic regime of NO conversion, but shows a negative effect in the equilibrium-limited regime above 400 °C.