Artículos (Instituto de Ciencia de Materiales de Sevilla (ICMS) – CIC Cartuja)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/10964

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In situ XRD and operando XRD-XANES study of the regeneration of LaCo0.8Cu0.2O3 perovskite for preferential oxidation of CO
(Elsevier, 2024-09) Pereñíguez Rodríguez, Rosa María; Ferri, Davide; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España; Swiss National Science Foundation (SNFS)
Combinations of perovskite-type oxides with transition and precious metals exhibit remarkable regenerating properties that can be exploited for catalytic applications. The objective of the present work was to study the structural changes experienced by LaCo0.8Cu0.2O3 under reducing/oxidizing atmosphere (redox) and Preferential Oxidation of CO (PrOx, with high H2 concentration) conditions and their reversibility. LaCo0.8Cu0.2O3 was prepared by ultrasonic spray combustion and was characterized by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). Structural changes were followed by operando XRD and XAS. Metallic Co and Cu were segregated under both sets of reducing conditions and re-dissolved into the perovskite upon oxidation at 500 °C. Simultaneously, the perovskite-type oxide disappeared under reducing conditions and formed again upon high-temperature oxidation. The effects of this reversible reduction/dissolution of B-site metals on catalyst structure and activity were studied concerning the catalytic process of PrOx. The active phases of cobalt and copper oxides suffer a reduction during the PrOx reaction due to the high H2 concentration; thus, the application of an intermediate oxidation treatment can regenerate the catalytic system and the perovskite can be used for several cycles of reaction and regeneration. In contrast, when this intermediate oxidation treatment is not applied, the catalytic performance decreases in successive activity cycles.
Electrochemical Deposition of Manganese Oxide on Paper-Based Laser-Induced Graphene for the Fabrication of Sustainable High-Energy-Density Supercapacitors
(John Wiley & Sons, 2024-07-24) Klem, Maykel dos Santos; Abreu, Rodrigo; Pinheiro, Tomás; Coelho, João; Alves, Neri; Martins, Rodrigo; Universidad de Sevilla. Departamento de Física de la Materia Condensada; São Paulo Research Foundation (FAPESP); Fundação para a Ciên-cia e a Tecnologia; European Union (UE); Junta de Andalucía
Laser-induced graphene (LIG) is widely used to fabricate microsupercapacitors (MSCs) on various sustainable substrates, such as wood, cork, and lignin. However, the fabrication of MSCs, especially high energy density devices on paper, has rarely been reported. In this work, LIG electrodes are fabricated on wax-coated paper, followed by electrochemical deposition of manganese oxide (MnO2). The obtained LIG/MnO2 supercapacitors exhibit a maximum areal capacitance of 86.9 mF cm−2, while a device with pristine LIG electrodes exhibit a capacitance of 9.1 mF cm−2, both measured at a current density of 0.1 mA cm−2. In addition, the supercapacitor exhibits good cycling stability, retaining 80% of its initial capacitance after 1000 charge/discharge cycles at a current density of 1 mA cm−2. Notably, the LIG/MnO2 supercapacitor exhibits an exceptionally high energy density of 7.3 µWh cm−2 at a power density of 38.8 µW cm−2. In summary, a simple, fast, scalable, reproducible, and energy-efficient fabrication method is represented using electrochemical deposition of manganese oxide on paper-based laser-induced graphene, which are natural, abundant, and sustainable materials, paving the way for large-scale production of environmentally friendly supercapacitors.
Expanding the scope of multiphase-flash sintering: Multi-dogbone configurations and reactive processes
(Elsevier, 2024-07-15) Manchón Gordón, Alejandro F.; Molina Molina, Sandra; Perejón Pazo, Antonio; Alcalde Conejo, A.; Sánchez Jiménez, Pedro Enrique; Pérez Maqueda, Luis Allan; Universidad de Sevilla. Departamento de Química Inorgánica; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España
In this work, we have expanded the possibilities of the multiphase-flash sintering (MPFS) technique by investigating several configurations that involve multiple dogbone specimens (ranging from 1 to 3) and multiple phases (also ranging from 1 to 3). Unlike the traditional MPFS approach using complex 3D or cylindrical samples, this new method allows for a direct comparison with the established conventional flash sintering technique. Our experimental results with dense 8-mol% Yttria-stabilized zirconia demonstrate a significant reduction in the onset temperature as the number of phases and dogbones increases. Building on these findings, we achieved the preparation of pure bulk specimens of SrFe12O19 for the first time through reactive multiphase-flash sintering.
A supervised multiclass framework for mineral classification of Iberian beads
(Public Library of Science, 2024-07-10) Sánchez Gómez, Daniel; Odriozola Lloret, Carlos Patricio; Sousa, Ana Catarina; Garrido Cordero, José Ángel; Romero García, Galo; Martínez Blanes, José María; Edo I. Benaiges, Manel; Villalobos García, Rodrigo; Gonçalves, Victor S.; Universidad de Sevilla. Departamento de Prehistoria y Arqueología; Universidad de Sevilla. Departamento de Química Inorgánica; Fundação para a Ciência e a Tecnologia. Portugal; Ministerio de Ciencia y Tecnología (MCYT). España
Research on personal adornments depends on the reliable characterisation of materials to trace provenance and model complex social networks. However, many analytical techniques require the transfer of materials from the museum to the laboratory, involving high insurance costs and limiting the number of items that can be analysed, making the process of empirical data collection a complicated, expensive and time-consuming routine. In this study, we compiled the largest geochemical dataset of Iberian personal adornments (n = 1243 samples) by coupling X-ray fluorescence compositional data with their respective X-ray diffraction mineral labels. This allowed us to develop a machine learning-based framework for the prediction of bead-forming minerals by training and benchmarking 13 of the most widely used supervised algorithms. As a proof of concept, we developed a multiclass model and evaluated its performance on two assemblages from different Portuguese sites with current mineralogical characterisation: Cova das Lapas (n = 15 samples) and Gruta da Marmota (n = 10 samples). Our results showed that decisión-tres based classifiers outperformed other classification logics given the discriminative importance of some chemical elements in determining the mineral phase, which fits particularly well with the decision-making process of this type of model. The comparison of results between the different validation sets and the proof-of-concept has highlighted the risk of using synthetic data to handle imbalance and the main limitation of the framework: its restrictive class system. We conclude that the presented approach can successfully assist in the mineral classification workflow when specific analyses are not available, saving time and allowing a transparent and straightforward assessment of model predictions. Furthermore, we propose a workflow for the interpretation of predictions using the model outputs as compound responses enabling an uncertainty reduction approach currently used by our team. The Python-based framework is packaged in a public repository and includes all the necessary resources for its reusability without the need for any installation.
Materials for 3D Printed Metal and Metal-Ion Batteries
(John Wiley & Sons, 2024) García Rodríguez, Tomás; Medina Santos, Jesus I.; Coelho, João; Pinilla, Sergio; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Comunidad Autónoma de Madrid; Junta de Andalucía; Science Foundation Ireland
The review provides an overview of the latest innovations, trends, and challenges in the field of 3D-printed metal and metal-ion batteries. It focuses on the materials used in the printing of batteries, including electrodes, electrolytes, and other electroactive components. Compared to other high-quality reviews on the topic, this review provides a broader selection of materials that are expected to gain attention in the next few years, such as redox-active polymers and metal-organic frameworks. This work gives an overview and insight into the latest trends in printing techniques as well as a statistical review of their uses and strengths. We have also gathered the latest works done for each of the material types, and we have taken the opportunity to put them in context and use them to exemplify in which direction is the field going. The review concludes with a critical view of the challenges ahead and a discussion of the direction that the field is taking as well as the external factors that might help to define its future.
Green Fabrication of Stackable Laser-Induced Graphene Micro-Supercapacitors under Ambient Conditions: Toward the Design of Truly Sustainable Technological Platforms
(John Wiley & Sons, 2024) Silvestre, Sara L.; Morais, Maria; Soares, Raquel R. A.; Johnson, Zachary T.; Benson, Eric; Ainsley, Elisabeth; Pham, Veronica; Claussen, Jonathan C.; Gomes, Carmen L.; Martins, Rodrigo; Fortunato, Elvira; Pereira, Luis; Coelho, João; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Fundação para a Ciência e a Tecnologia. Portugal; European Union (UE); Junta de Andalucía; National Science Foundation (NSF)
Extensive research into green technologies is driven by the worldwide push for eco-friendly materials and energy solutions. The focus is on synergies that prioritize sustainability and environmental benefits. This study explores the potential of abundant, non-toxic, and sustainable resources such as paper, lignin-enriched paper, and cork for producing laser-induced graphene (LIG) supercapacitor electrodes with improved capacitance. A single-step methodology using a CO2 laser system is developed for fabricating these electrodes under ambient conditions, providing an environmentally friendly alternative to conventional carbon sources. The resulting green micro-supercapacitors (MSCs) achieve impressive areal capacitance (≈7–10 mF cm−2) and power and energy densities (≈4 μW cm-2 and ≈0.77 µWh cm−2 at 0.01 mA cm−2). Stability tests conducted over 5000 charge–discharge cycles demonstrate a capacitance retention of ≈80–85%, highlighting the device durability. These LIG-based devices offer versatility, allowing voltage output adjustment through stacked and sandwich MSCs configurations (parallel or series), suitable for various large-scale applications. This study demonstrates that it is possible to create high-quality energy storage devices based on biodegradable materials. This development can lead to progress in renewable energy and off-grid technology, as well as a reduction in electronic waste.
Elucidating the Mechanism of Iron-Catalyzed Graphitization: The First Observation of Homogeneous Solid-State Catalysis
(Wiley, 2024) Hunter, Robert D.; Takeguchi, Masaki; Hashimoto, Ayako; Ridings, Kannan M.; Hendy, Shaun C.; Zakharov, Dmitri; Warnken, Nils; Isaacs, Jack; Fernández Muñoz, Sol; Ramírez Rico, Joaquín; Schnepp, Zoe; Universidad de Sevilla. Departamento de Física de la Materia Condensada; University of Birmingham; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Junta de Andalucía; ALBA staff
Carbon is a critical material for existing and emerging energy applications and there is considerable global effort in generating sustainable carbons. A particularly promising area is iron-catalyzed graphitization, which is the conversion of organic matter to graphitic carbon nanostructures by an iron catalyst. In this paper, it is reported that iron-catalyzed graphitization occurs via a new type of mechanism that is called homogeneous solid-state catalysis. Dark field in situ transmission electron microscopy is used to demonstrate that crystalline iron nanoparticles “burrow” through amorphous carbon to generate multiwalled graphitic nanotubes. The process is remarkably fast, particularly given the solid phase of the catalyst, and in situ synchrotron X-ray diffraction is used to demonstrate that graphitization is complete within a few minutes
Al2O3/Y3Al5O12 (YAG)/ZrO2 Composites by Single-step Powder Synthesis and Spark Plasma Sintering
(Elsevier, 2024) Vakhshouri, Maryam; Najafzadehkhoee, Aliasghar; Talimian, Ali; López Pernía, Cristina; Poyato, Rosalía; Gallardo López, Ángela María; Gutiérrez Mora, Felipe; Prnova, Anna; Galusek, Dušan; Universidad de Sevilla. Departamento de Física de la Materia Condensada; European Union (UE); JECS Trust
Alumina-yttrium aluminum garnet (YAG)-zirconia composites are often produced by the melt solidification method. In the present study, we investigated the fabrication of α-Al2O3/Y3Al5O12 (YAG)/ZrO2 composite by Spark Plasma Sintering (SPS) of powders synthesized by Pechini's sol-gel method. The ternary composites with homogenous microstructure and high density were produced by SPS at 1300 °C for 15 min. The addition of ZrO2 promoted the sintering of composites, resulting in a higher density and, in turn, higher hardness. A change in the indentation fracture behavior as the result of ZrO2 addition was observed.
Au and Pt Remain Unoxidized on a CeO2-Based Catalyst during the Water-Gas Shift Reaction
(American Chemical Society, 2022-01-12) Ramírez Reina, Tomás; González Castaño, Míriam; López Flores, Víctor; Martínez Tejada, Leidy Marcela; Zitolo, Andrea; Ivanova, Svetlana; Xu, Wenquian; Centeno Gallego, Miguel Ángel; Rodriguez, Jose A.; Odriozola Gordón, José Antonio; Universidad de Sevilla. Departamento de Química Inorgánica; Department of Energy. United States; Ministerio de Ciencia e Innovación (MICIN). España
The active forms of Au and Pt in CeO2-based catalysts for the water-gas shift (WGS) reaction are an issue that remains unclear, although it has been widely studied. On one hand, ionic species might be responsible for weakening the Ce-O bonds, thus increasing the oxygen mobility and WGS activity. On the other hand, the close contact of Au or Pt atoms with CeO2 oxygen vacancies at the metal-CeO2 interface might provide the active sites for an efficient reaction. In this work, using in situ X-ray absorption spectroscopy, we demonstrate that both Au and Pt remain unoxidized during the reaction. Remarkable differences involving the dynamics established by both species under WGS atmospheres were recognized. For the prereduced Pt catalyst, the increase of the conversion coincided with a restructuration of the Pt atoms into cuboctahedrical metallic particles without significant variations on the overall particle size. Contrary to the relatively static behavior of Pt0, Au0 nanoparticles exhibited a sequence of particle splitting and agglomeration while maintaining a zero oxidation state despite not being located in a metallic environment during the process. High WGS activity was obtained when Au atoms were surrounded by oxygen. The fact that Au preserves its unoxidized state indicates that the chemical interaction between Au and oxygen must be necessarily electrostatic and that such an electrostatic interaction is fundamental for a top performance in the WGS process
Manganese Dioxide Supported on Porous Biomorphic Carbons as Hybrid Materials for Energy Storage Devices
(American Chemical Society, 2016-10) Gutiérrez Pardo, Antonio Anselmo; Lacroix, Bertrand; Martínez Fernández, Julián; Ramírez Rico, Joaquín; Universidad de Sevilla. Departamento de Física de la Materia Condensada; Junta de Andalucía; Ministerio de Economía y Competitividad (MINECO). España
A facile and low-cost method has been employed to fabricate MnO2/C hybrid materials for use as binder-free electrodes for supercapacitor applications. Biocarbon monoliths were obtained through pyrolysis of beech wood, replicating the microstructure of the cellulosic precursor, and serve as 3D porous and conductive scaffolds for the direct growth of MnO2 nanosheets by a solution method. Evaluation of the experimental results indicates that a homogeneous and uniform composite material made of a carbon matrix exhibiting ordered hierarchical porosity and MnO2 nanosheets with a layered nanocrystalline structure is obtained. The tuning of the MnO2 content and crystallite size via the concentration of KMnO4 used as impregnation solution allows to obtain composites that exhibit enhanced electrochemical behavior, achieving a capacitance of 592 F g–1 in electrodes containing 3 wt % MnO2 with an excellent cyclic stability. The electrode materials were characterized before and after electrochemical testing.
Nitrogen Nanobubbles in a-SiOxNy Coatings: Evaluation of Its Physical Properties and Chemical Bonding State by Spatially Resolved Electron Energy-Loss Spectroscopy
(American Chemical Society, 2016) Lacroix, Bertrand; Fortio Godinho, Vanda Cristina; Fernández Camacho, Asunción; European Union (UE); Ministerio de Economía y Competitividad (MINECO). España; Consejo Superior de Investigaciones Científicas (CSIC); Junta de Andalucía
Nanoporous silicon-based materials with closed porosity filled with the sputtering gas have been recently developed by magnetron sputtering. In this work the physical properties (density and pressure) of molecular nitrogen inside closed pores in a SiOxNy coating are investigated for the first time using spatially resolved electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope. The paper offers a detailed methodology to record and process multiple EELS spectrum images (SIs) acquired at different energy ranges and with different dwell times. An adequate extraction and quantification of the N–K edge contribution due to the molecular nitrogen inside nanopores is demonstrated. Core-loss intensity and N chemical bond state were evaluated to retrieve 2D maps revealing the stable high density of molecular nitrogen (from 40 to 70 at./nm3) in nanopores of different size (20–11 nm). This work provides new insights into the quantification of molecular N2 trapped in porous nitride matrices that could also be applied to other systems.
Zirconium retention for minimizing environmental risk: Role of counterion and clay mineral
(Elsevier, 2021-03) Montes Montañez, Laura; Pavón González, Esperanza; Cota Reguero, Agustín; Alba Carranza, María Dolores; Universidad de Sevilla. Departamento de Física de la Materia Condensada
Zr(IV) together with U(IV) are the major components of high-level radionuclide waste (HLRW) and spent nuclear fuel (SNF) from nuclear power plants. Thus, their retention in the waste disposal is of great importance for the environmental risk control. Here, the influence of clay minerals on the retention of Zr(IV), as component of the nuclear waste and as chemical analogues of U(IV), has been evaluated. Three clay minerals, two bentonites and one saponite, were hydrothermally treated with three zirconium salts. A structural study at long-range order by X-ray diffraction and short-range order by NMR was performed to evaluate the generation of new zirconium phases and degradation of the clay minerals. Three immobilization mechanisms were observed: i) cation exchange of ZrO2+ or Zr4+ by clay minerals, ii) the precipitation/crystallization of ZrO2, and, iii) the chemical interaction of zirconium with the clay minerals, with the formation of zirconium silicates.
On the Adsorption Properties and Applications of Mixed-linker MOFs Based on HKUST-1
(Elsevier, 2022) Puerto Rodríguez, Macarena; López Cartes, Carlos; Ayala Espinar, Regla; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Economía y Competitividad (MINECO). España; Junta de Andalucía
Different mixed-linker MOFs based on HKUST-1 have been successfully synthesized using BtTC (1,2,4,5-benzenetetracarboxylate) and BDC (1,4-benzenedicarboxylate) as modulator ligands. These MOFs maintain the HKUST-1 structure up to 25% and 50% of trimesic acid replacing with BtTC and BDC ligands, respectively. A low percentage of modulator ligand provokes an increasing of the MOF surface area keeping its microporosity whereas a higher content of BtTC induces mesoposority in the samples. The adsorption of moisture ambient or vapour iodine reveals that there is a relation between the surface area and the capacity of adsorption of the samples. However, this relation is not found in the experiments of Congo Red removal from aqueous and ethanol solutions. The pH of the solutions has a significant effect on the adsorption capacity of the samples.
Design of Full-Temperature-Range RWGS Catalysts: Impact of Alkali Promoters on Ni/CeO 2
(American Chemical Society, 2022) Gandara Loe, Jesús; Zhang, Qi; Villora Picó, Juan José; Sepúlveda Escribano, Antonio; Pastor Pérez, Laura; Ramírez Reina, Tomás; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla
Reverse water gas shift (RWGS) competes with methanation as a direct pathway in the CO2 recycling route, with methanation being a dominant process in the low-temperature window and RWGS at higher temperatures. This work showcases the design of multi-component catalysts for a full-temperature-range RWGS behavior by suppressing the methanation reaction at low temperatures. The addition of alkali promoters (Na, K, and Cs) to the reference Ni/CeO2 catalyst allows identifying a clear trend in RWGS activation promotion in both low- and high-temperature ranges. Our characterization data evidence changes in the electronic, structural, and textural properties of the reference catalyst when promoted with selected dopants. Such modifications are crucial to displaying an advanced RWGS performance. Among the studied promoters, Cs leads to a more substantial impact on the catalytic activity. Beyond the improved CO selectivity, our best performing catalyst maintains high conversion levels for long-term runs in cyclable temperature ranges, showcasing the versatility of this catalyst for different operating conditions. All in all, this work provides an illustrative example of the impact of promoters on fine-tuning the selectivity of a CO2 conversion process, opening new opportunities for CO2 utilization strategies enabled by multi-component catalysts.
Embracing the sustainable horizons through bioenergy innovations: a path to a sustainable energy future
(Frontiers Media, 2024-07-30) Blay Roger, José Rubén; Saif, Maria; Bobadilla Baladrón, Luis Francisco; Ramírez Reina, Tomás; Nawaz, Muhammad Asif; Odriozola Gordón, José Antonio; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Union (UE)
The urgent need for mitigating climate change necessitates a transformative shift in energy production and consumption paradigms. Amidst this challenge, bioenergy emerges as a pivotal contributor to the global energy transition, offering a diverse array of solid, liquid, and gaseous fuels derived from biomass. This mini review delves into the unique potential of bioenergy innovations, particularly renewable diesel, bio jet fuel, and ethanol, to reduce greenhouse gas emissions and transform various industries. The article highlights critical technological advancements, supportive policies, and cross-sector collaboration essential for a sustainable energy transition. Specific challenges such as ensuring a consistent biomass feedstock supply, decentralizing processing units, and navigating complex regulatory frameworks are examined. Innovative solutions like decentralized biomass processing and enhanced biomass logistics are discussed as pathways to overcome these barriers. The review provides specific recommendations for near-term policies and strategies to support decentralized facilities, showcasing bioenergy’s role in achieving a sustainable future.
Formic Acid as Renewable Reagent and Product in Biomass Upgrading
(Elsevier, 2023) Achour, Mahdi; Álvarez Hernández, Débora; Ruiz López, Estela; Megías Sayago, Cristina; Ammari, Fatima; Ivanova, Svetlana; Centeno, Miguel Ángel; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía
The problems associated with the use of molecular hydrogen (transportation, storage and high cost) have pushed scientists to the pursuit of efficient hydrogen donors, able to reduce chemical bonds in the presence of catalysts through catalytic transfer hydrogenation (CTH) reactions. In this sense, formic acid stands up as one of the most important and safest chemical molecules for H2 generation under mild conditions. It can be obtained from biomass through different catalytic transformations and used as well to upgrade biomass to platform chemicals. This review summarizes the recently published studies dealing with formic acid production from biomass (using glucose as representing molecule) along with its use in hydrogen involved reactions of different groups of platform chemicals upgrading.
Controlling Copper Location on Exchanged MOR-Type Aluminosilicate Zeolites for Methanol Carbonylation: In Situ/Operando IR Spectroscopic Studies
(Elsevier, 2024-10) Luque Álvarez, Ligia Amelia; Torres Sempere, Guillermo; Romero Sarria, Francisca; Bobadilla Baladrón, Luis Francisco; Ramírez Reina, Tomás; Odriozola Gordón, José Antonio; Universidad de Sevilla. Departamento de Química Inorgánica; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Sevilla
Replacing homogeneous catalytic processes by heterogeneous routes based on the utilization of solid catalysts is of great interest from an environmental point of view. Owing to their genuine pore structure, zeolites such as mordenites (MOR) have emerged as game-changing materials to enable the heterogenization of catalytic processes including methanol carbonylation. Cu-exchange zeolites take the edge over pristine zeolites, leading to enhanced catalytic performance in terms of greater activity, selectivity, and stability. Herein, the overall catalytic activity and stability can be modulated upon controlling the environment and location of copper active sites in zeolites. In this study, Cu-exchanged mordenites were strategically synthesized to investigate the role of Cu location inside of MOR cavities under working conditions by means of in situ/operando infrared (IR) spectroscopic studies. The results obtained revealed that a major proportion of Cu in the MR-8 cavities notably enhances the activity and stability of the catalyst. This study provides crucial insights for fine-tuning zeolite catalysts to achieve the heterogenization of homogeneous carbonylation processes.
Iron-catalyzed Graphitization for the Synthesis of Nanostructured Graphitic Carbons
(Royal Society of Chemistry, 2022) Hunter, R. D.; Ramírez Rico, Joaquín; Schnepp, Z.; Universidad de Sevilla. Departamento de Física de la Materia Condensada; University of Birmingham
Carbons are versatile and diverse materials that have numerous applications across energy and environmental sciences. Carbons with a graphitic structure are particularly appealing due to their high chemical stability, large surface areas and high thermal and electronic conductivity. Numerous methods exist to produce nanostructured graphitic carbons but some of these can be energy-intensive and/or have problems with scalability. One option that is being increasingly explored is the process of iron-catalyzed graphitization. This simply involves the pyrolysis of carbon-rich precursors in the presence of an iron catalyst and has been used to produce carbons with a wide range of structures and properties. This review will examine the current field of iron-catalyzed graphitization, with a focus on molecular organic or biomass precursors. Bio-derived precursors are particularly attractive as a potential option for sustainable production of graphitic carbons. We start with a brief introduction to some key carbon structures, the current applications in which they are employed and some of the key methods that have been developed to produce nanostructured graphitic carbons. We will then review the history of catalytic graphitization before evaluating the wide range of conditions and precursors that have been employed in catalytic graphitization. Finally, this review will investigate the current challenges facing iron-catalyzed graphitization, looking particularly at the limitations of the current understanding of the mechanistic aspects of graphitization, with a view to outlining where research in this field might progress.
Understanding Ice and Water Film Formation on Soil Particles by Combining Density Functional Theory and Casimir-Lifshitz Forces
(American Physical Society, 2023) Boström, M.; Kuthe, S.; Carretero Palacios, S.; Esteso Carrizo, Victoria; Li, Y.; Brevik, I.; Gopidi, H. R.; Malyi, O. I.; Glaser, B.; Persson, C.; Universidad de Sevilla. Departamento de Física de la Materia Condensada; ENSEMBLE3 (Centre of Excellence for nanophotonics, advanced materials and novel crystal growth-based technologies). Polonia; European Union (UE). H2020; Norway Research Council
Thin films of ice and water on soil particles play crucial roles in environmental and technological processes. Understanding the fundamental physical mechanisms underlying their formation is essential for advancing scientific knowledge and engineering practices. Herein, we focus on the role of the Casimir-Lifshitz force, also referred to as dispersion force, in the formation and behavior of thin films of ice and water on soil particles at 273.16 K, arising from quantum fluctuations of the electromagnetic field and depending on the dielectric properties of interacting materials. We employ the first-principles density functional theory (DFT) to compute the dielectric functions for two model materials, CaCO3 and Al2O3, essential constituents in various soils. These dielectric functions are used with the Kramers-Kronig relationship and different extrapolations to calculate the frequency-dependent quantities required for determining forces and free energies. Moreover, we assess the accuracy of the optical data based on the DFT to model dispersion forces effectively, such as those between soil particles. Our findings reveal that moisture can accumulate into almost micron-sized water layers on the surface of calcite (soil) particles, significantly impacting the average dielectric properties of soil particles. This research highlights the relevance of DFT-based data for understanding thin film formation in soil particles and offers valuable insights for environmental and engineering applications.
The Role of Protective Surface Coatings on the Thermal Stability of Delithiated Ni-Rich Layered Oxide Cathode Materials
(Multidisciplinary Digital Publishing Institute (MDPI), 2023) Reissig, Friederike; Ramírez Rico, Joaquín; Placke, Tobias Johannes; Winter, Martin; Schmuch, Richard; Gómez Martín, Aurora; Universidad de Sevilla. Departamento de Física de la Materia Condensada; European Union (UE). H2020; Junta de Andalucía; Ministerio de Ciencia e Innovación (MICIN). España
To achieve a broader public acceptance for electric vehicles based on lithium-ion battery (LIB) technology, long driving ranges, low cost, and high safety are needed. A promising pathway to address these key parameters lies in the further improvement of Ni-rich cathode materials for LIB cells. Despite the higher achieved capacities and thus energy densities, there are major drawbacks in terms of capacity retention and thermal stability (of the charged cathode) which are crucial for customer acceptance and can be mitigated by protecting cathode particles. We studied the impact of surface modifications on cycle life and thermal stability of LiNi0.90Co0.05Mn0.05O2 layered oxide cathodes with WO3 by a simple sol–gel coating process. Several advanced analytical techniques such as low-energy ion scattering, differential scanning calorimetry, and high-temperature synchrotron X-ray powder diffraction of delithiated cathode materials, as well as charge/discharge cycling give significant insights into the impact of surface coverage of the coatings on mitigating degradation mechanisms. The results show that successful surface modifications of WO3 with a surface coverage of only 20% can prolong the cycle life of an LIB cell and play a crucial role in improving the thermal stability and, hence, the safety of LIBs.

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