Publications by authors named "Raul Arenal"
The burgeoning field of 2D heterostructures targets the combination of 2D materials with 3D, 1D, or 0D nanomaterials. Among the most popular 2D materials, the 2H polytype of molybdenum disulfide (MoS) features a well-defined bandgap that becomes direct at the monolayer level, which can be exploited for photodetection. A notable limitation of 2H-MoS is its curtailed absorbance beyond the visible range.
View Article and Find Full Text PDFWe explore the possibility to perform an in-situ transmission electron microscopy (TEM) thermoelectric characterization of materials. A differential heating element on a custom in-situ TEM microchip allows to generate a temperature gradient across the studied materials, which are simultaneously measured electrically. A thermovoltage was induced in all studied devices, whose sign corresponds to the sign of the Seebeck coefficient of the tested materials.
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- 2D materials, such as transition metal-dichalcogenides like MoS, have gained significant attention for their unique layered structures, which lead to distinct physicochemical properties when isolated as single layers compared to their bulk forms.
- The ability to stack and twist these layers creates new phenomena, such as Moiré patterns, while misfit layer compounds (MLCs) introduce unconventional lattice structures that allow for the formation of nanotubes.
- The stability and behavior of these nanostructures, particularly under elevated temperatures, are important aspects that remain underexplored, prompting studies using advanced techniques like electron microscopy and synchrotron-based X-ray methods to understand their decomposition and recrystallization processes.
The MXene family has rapidly expanded since its discovery in 2011 to include nearly 50 unique MXenes, not accounting for solid solutions and diverse surface terminations. However, a question raised since their discovery has been: What is the effect of ? In other words, how does the number of layers affect the MXene properties? To date, no direct study of the impact of has been conducted due to the lack of isoelemental MXene compositions spanning more than two values. Herein, we report on a system of three MXenes with identical M-site chemistries, (MoV)CT ( = 1, 2, and 3), allowing for the study of MXene structure-property relationships across , for the first time.
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- - Simple and fast methods to detect antibiotics in food and drinks are needed due to their widespread use in livestock, leading to drug residues in products.
- - The study introduces gold nanoclusters (AuNCs) modified with -acetyl-l-cysteine, which can detect tetracyclines by showing a decrease in fluorescence at 700 nm as antibiotic concentration increases, with a detection limit of 0.8 ppm.
- - This sensing method demonstrates high selectivity for tetracyclines over other substances like anions and metal ions, with fluorescence quenching explained through both dynamic and static mechanisms, primarily driven by photoinduced electron transfer (PET).
Article Synopsis
- Understanding the behavior and limits of nanostructures during high-temperature reactions is essential for controlling their shape and properties.
- Lanthanide-based misfit-layered compounds (MLCs) nanotubes have various structures and disorders that can significantly affect their functionalities, but limited knowledge on their thermodynamic and kinetic stability hinders their production and use.
- This study investigates the growth and stability of specific MLC nanotubes through detailed imaging and diffraction techniques, providing valuable insights for further research on their physical and chemical properties, especially concerning their high-temperature stability.
Article Synopsis
- In situ transmission electron microscopy (TEM) is important for studying nanomaterials, but sample preparation difficulties have hindered research on their electrical properties.
- This study introduces a support-based transfer method that improves the reproducibility of moving individual 1D and 2D materials for electrical investigation using in situ TEM.
- The method allows for detailed studies on the structural and electrical characteristics of nanomaterials, and it can also be adapted for other types of experiments or applications in electrical, optoelectronic, and sensing devices.
Ultra-Low-Loaded Platinum Bonded Hexagonal Boron Nitride as Stable Electrocatalyst for Hydrogen Generation.
ACS Appl Mater Interfaces
February 2024
Article Synopsis
- The study develops a highly efficient hydrogen evolution reaction (HER) catalyst using ultrathin hexagonal boron nitride (hBN) layers enhanced with low amounts of platinum (Pt), crucially maintaining Pt's active state through nitrogen bonding.* -
- A novel catalyst, hBN_Au_Pt, is created by decorating hBN sheets with gold (Au) nanoparticles and then anchoring Pt, resulting in a high turnover frequency for HER and excellent durability through rigorous testing.* -
- The findings are supported by density functional theory calculations, which clarify the electronic modifications and catalytic performance of the hBN_Au_Pt system, highlighting its advantages over traditional catalysts, including resistance to carbon corrosion and Pt leaching.*
Article Synopsis
- * The study focused on a new type of nanocarrier made from carbon nano-onions (CNOs), which successfully targeted cancer cells that have a specific receptor (CD44), while sparing non-targeted cells.
- * The CNO-based carrier was able to deliver a new kind of chemotherapeutic drug, showing enhanced effectiveness against resistant pancreatic cancer cells, highlighting the potential for carbon nanoparticles in cancer therapy.
Article Synopsis
- Imogolite nanotubes (INTs) have unique characteristics due to their large band gaps, which limit their use as photocatalysts for processes like hydrogen production.
- Researchers modified these nanotubes by incorporating titanium into their structure, adjusting the titanium concentration to optimize performance.
- The best results were found at a titanium ratio of 0.4, leading to significant hydrogen production—1500 µmol/g in 5 hours—indicating the potential for using modified INTs in energy applications as effective photocatalysts.
Article Synopsis
- * This study focuses on creating robust and reusable SERS microfluidic chips to help first responders identify neurotoxic gases accurately and quickly, emphasizing important features like detection limits, response time, and reusability.
- * The research includes developing a special 3D structure using mesoporous silica and gold nanoparticles which enhances gas detection performance, specifically evaluating its effectiveness with DMMP, a neurotoxic simulant, under various conditions.
Article Synopsis
- - The study challenges the traditional view of phyllosilicate minerals, like mica and chlorite, by demonstrating that exfoliated nanosheets from these materials can display electronic activity, rather than being simply inactive and inert.
- - Through advanced techniques like electron diffraction and spectroscopy, researchers observed a unique spectral fingerprint that varies with the size and number of layers of the nanosheets, revealing significant changes in their electronic properties.
- - The findings indicate that as the surface area of these nanosheets increases, their bandgap decreases due to a quantum confinement effect, which suggests they can behave like semiconductors and exhibit enhanced catalytic activity for hydrogen production.
Article Synopsis
- Photo-rechargeable batteries can charge conventional metal-ion batteries using solar energy instead of electricity and do not cause unwanted side reactions.
- The design features a two-electrode setup with TiS-TiO hybrid sheets that enhance light absorption and facilitate lithium ion movement, leading to better battery performance.
- Experiments show that these solar solid-state batteries can efficiently charge lithium-ion cells without negative interactions at battery interfaces, indicating a promising future for renewable energy technologies.
Article Synopsis
- * The study introduces a new method to create a P3HT-GO nanohybrid using a technique called miniemulsion synthesis, which helps maintain beneficial structural changes in the polymer chains that enhance performance.
- * The combination of P3HT and GO results in improved charge transfer efficiency in films, although it reduces certain charge transport processes, indicating a shift in how these materials can be used in future electronic devices.
Asymmetrical Plasmon Distribution in Hybrid AuAg Hollow/Solid Coded Nanotubes.
Nanomaterials (Basel)
March 2023
Article Synopsis
- The study focuses on the engineering of plasmon resonances in 1D hollow AuAg nanotubes to create nanostructures with specific optical properties.
- Using electron energy loss spectroscopy (EELS), researchers observed distinct plasmon modes, confirming their findings with simulations that showed strong plasmon activity within the nanotubes due to hybridization effects.
- Two key features of the hybrid nanotubes are highlighted: they generate unique localized surface plasmon resonances from both hollow and solid segments, and the interaction between these segments leads to asymmetrical plasmon distributions that can be manipulated for advanced applications.
Article Synopsis
- Conventional epitaxy is essential in semiconductor technology, allowing precise atomic-scale control over thin films and nanostructures for applications in nanoelectronics and sensors.
- "Van der Waals" (vdW) and "quasi-vdW (Q-vdW)" epitaxy describe the weaker interactions during the growth of 2D materials on various substrates, with intense research focused on layer growth of transition metal dichalcogenides (TMDCs) on sapphire.
- This study investigates the growth of WS using a metal-seeding step in a metal-organic chemical vapor deposition (MOCVD) system, revealing how an interfacial layer affects the epitaxial growth of semiconductor layers, which may inform the design of
Article Synopsis
- The study focuses on covalently modifying tungsten disulfide (WS) with nickel-porphyrin (NiP) to create a new hybrid material (WS-NiP) for enhanced catalytic performance in the oxygen evolution reaction.
- The characterization of WS-NiP utilizes various advanced techniques including spectroscopy and electrochemical methods to analyze its effectiveness under both dark and illuminated conditions.
- The findings reveal that the material exhibits improved electrocatalytic activity due to the coordination of nickel centers with photoreceptive porphyrin chains, highlighting its potential for developing cost-effective alternatives to noble metal catalysts in water oxidation.
Article Synopsis
- * The resulting hybrid materials showed improved performance in hydrogen evolution reactions, achieving lower overpotential and better stability compared to the original forms of MoSe and WSe.
- * This easy modification approach could be applied to other transition metal dichalcogenides, creating potential for new functional nanomaterials in electrocatalysis.
Size effect of CoS cocatalyst on photocatalytic hydrogen evolution performance of g-CN.
J Colloid Interface Sci
April 2023
Article Synopsis
- Researchers are focused on developing inexpensive cocatalysts to enhance the photocatalytic efficiency of catalysts.
- CoS/g-CN composite photocatalysts were created by depositing CoS onto the surface of g-CN, allowing control over the size of CoS from single atoms to nanometers, which impacted photocatalytic performance.
- The 5CoS/CN setup showed the highest efficiency in hydrogen production under visible light, significantly outperforming pure g-CN and nearly matching the performance of Platinum-based catalysts, with theoretical insights suggesting that the size of CoS plays a crucial role in electron accumulation and separation.
Article Synopsis
- Researchers developed new types of probes made from all-graphenic carbon morphologies attached to individual carbon nanotubes, which may enhance scanning probe microscopy (SPM) techniques.
- They tested three methods for mounting these probes, two involving focused ion/electron beams and one using an optical microscope, highlighting the pros and cons of each method.
- Analysis showed the carbon cone structures were highly sensitive to ion and electron irradiation, likely due to many free graphene edges, suggesting that these carbon cones could outperform traditional probes like silicon or diamond in SPM applications.
Article Synopsis
- Explosive percolation is a phenomenon where a network becomes highly conductive with the sudden formation of new pathways, making it an important area of study in materials science.
- In this research, graphene oxide and synthetic polymer latex are combined to create low percolation threshold composites, enhancing electrical conductivity through the formation of organized conductive pathways.
- The process of reducing graphene oxide at lower temperatures not only modifies the polymer but also creates crosslinking agents, resulting in composites that outperform traditional dense networks in terms of conductivity.
Article Synopsis
- A key challenge in single-atom (SA) catalysis is creating fully inorganic sites that can achieve the high reaction selectivity typically seen in organometallic catalysts used in homogeneous catalysis.
- Researchers have found that isolated rhodium (Rh) atoms on oxygen-defective SnO can achieve high turnover frequency (TOF) and excellent selectivity for gas-phase hydroformylation of ethylene while preventing unwanted olefin hydrogenation.
- The study demonstrates that a significant reduction of lattice oxygen in the SnO surface allows for greater flexibility in the coordination of Rh atoms, resulting in exceptional catalytic performance comparable to liquid-phase molecular catalysts.
Article Synopsis
- * The study investigates how the surrounding chemical environment of cobalt, particularly the type of axial ligation (pyridine vs. imidazole), influences catalytic performance in acidic conditions.
- * Results show that pyridine results in significantly better electrocatalytic performance, while imidazole offers impressive long-term stability.
High aspect-ratio gold nanostructures sustain Fabry-Perot-like surface plasmon responses from infrared to visible light energies. We show that some resonances can be tuned by means of laser irradiation, where low energy modes stay unperturbed. After laser irradiation, gold nanowires' tips are transformed into nanoparticles of various sizes joint to gold nanowires, producing high aspect-ratio half-dumbbells and dumbbells structures.
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