[article-cris] Kemian tekniikan korkeakoulu / CHEM

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  • Syngas Conversion to Higher Alcohols via Wood-Framed Cu/Co-Carbon Catalyst
    (2025-01-27) Yan, Guihua; Pršlja, Paulina; Chen, Gaofeng; Kang, Jiahui; Liu, Yongde; Caro, Miguel A.; Chen, Xi; Zeng, Xianhai; Peng, Bo
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Syngas conversion into higher alcohols represents a promising avenue for transforming coal or biomass into liquid fuels. However, the commercialization of this process has been hindered by the high cost, low activity, and inadequate C2+OH selectivity of the catalysts. Herein, we have developed Cu/Co carbon wood catalysts, offering a cost-effective and stable alternative with superior selectivity for catalytic conversion. The formation of Cu/Co nanoparticles was found, influenced by water-1,2-propylene glycol ratios in the solution, resulting in bidisperse nanoparticles. The Cu/Co-CW-W1P1 catalyst (the ratio between water and 1,2-propanediol is 0.5:0.5) exhibited a remarkable CO conversion rate of 74.8% and a selectivity of 58.7% for C2+OH, primarily comprising linear primary alcohols. This catalyst demonstrated enduring stability and selectivity under industrial conditions, maintaining its efficacy for up to 350 h of operation. We also employed density functional theory (DFT) to analyze selectivity, particularly focusing on the binding strength of CO, a crucial intermediate for subsequent reactions leading to the formation of alcohols. DFT identified the pathway of CHx and CO coupling, ultimately yielding C2H5OH. This computational understanding, coupled with the high performance of the Cu/Co-carbon wood catalyst, paves the way to develop catalytically selective materials tailored for higher alcohol production from a nature-based source.
  • Lignin Nanofiber Flexible Carbon Aerogels for Self-Standing Supercapacitors
    (2025-02-01) Cho, Mi Jung; Yiu, Justine; Lin, Li Ting; Hua, Qi; Karaaslan, Muzaffer A.; Renneckar, Scott
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Renewable feedstocks are sought for clean technology applications, including energy storage applications. In this study, LignoForce™ lignin, a biobased aromatic polymer commercially isolated from wood, was fractioned into two parts using acetone, and the resulting lignin fractions had distinct thermo-rheological behavior. These two fractionated lignins were combined in various ratios and transformed into nanofibers by electrospinning. Subsequently, electrospun fiber materials were disrupted by agitating the mats in water, and the materials were transformed into ultralight 3D aerogels through lyophilization and post-process controlled heating. Using only this combination of two fractions, the morphology of lignin nanofibers was tailored by heat treatment, resulting in lignin aerogels with high flexibility and significant shape recovery properties. Various microscale structures of lignin fibers impacted the resulting physical properties of the elastic aerogel materials, such as resilience, compressive strength, and electrical conductivity for the corresponding carbonized samples. By exploiting lignin's sensitivity to heat and tailoring the thermal properties of the lignin through fractionation, the work provided an interesting path to form robust lignin-derived functional materials without any toxic chemical additives and significant ability to serve as free-standing electrodes with specific capacitance values better than some graphene-based supercapacitors.
  • Impact of powder and electrode ALD coatings on the performance of intercalation cathodes for lithium-ion batteries
    (2025-01-03) Llanos, Princess Stephanie; Bogdanova, Alisa R.; Obrezkov, Filipp; Farrahi, Nastaran; Kallio, Tanja
    A2 Katsausartikkeli tieteellisessä aikakauslehdessä
    The desire to obtain higher energy densities in lithium-ion batteries (LIBs) to meet the growing demands of emerging technologies is faced with challenges related to poor capacity retention during cycling caused by structural and interfacial instability of the battery materials. Since the electrode-electrolyte interface plays a decisive role in achieving remarkable electrochemical performance, it must be suitably engineered to address the aforementioned issues. The development of coatings, particularly on the surface of cathode materials, has been proven to be effective in resolving interfacial issues in LIBs. The use of atomic layer deposition (ALD) over other surface coating techniques is advantageous in terms of coating uniformity, conformity, and thickness control. This review article provides a summary of the impact of various ALD-engineered surface coatings to the cycling performance of different intercalation cathode materials in LIBs. Since ALD allows coating development on complex substrates, this article provides a comprehensive discussion of coatings formed directly on a powder active material and composite electrode. Additionally, a perspective regarding the fundamental deposition parameters and electrochemical testing data to be reported in future research is provided.
  • Enhancing Electrical Conductivity in Cellulosic Fabric: A Study of Bio-Based Coating Formulations
    (2025-02-05) Abdi, Babak; Baniasadi, Hossein; Tarhini, Ali; Tehrani-Bagha, Ali
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This study explores the development of electrically conductive bio-based textiles by investigating the fabrication and structural characterization of multi-walled carbon nanotubes (MWCNT) and graphene nanoplatelets (GNP) coatings on viscose fabric (VF) using two bio-based binders. The research employs various analytical techniques, including Fourier transform infrared (FTIR) analysis, water contact angle (WCA) measurements, optical microscopy, air permeability tests, field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), mechanical property evaluations, and electrical conductivity tests. Optimization of the coating process revealed that a binder concentration of 20 g L−1 combined with six dip-dry cycles offered the optimal balance of conductivity, water contact angle (WCA), and coating uniformity. The study found distinct correlations between binder type and properties such as WCA, air permeability, surface coverage, and thermal stability. The incorporation of carbon-based materials significantly enhanced the electrical conductivity of the samples, with MWCNT-coated fabrics demonstrating higher conductivity compared to those coated with GNP. Furthermore, the inclusion of a hot-pressing step further improved the electrical conductivity. MWCNT-coated fabrics exhibited excellent electrical heating properties, generating temperatures up to 130 °C with a 10 V DC voltage. These findings advance the field of e-textiles, presenting straightforward, bio-based methods for creating highly conductive textiles with good mechanical properties and thermal stability.
  • Effects of Hydroxyapatite Additions on Alginate Gelation Kinetics During Cross-Linking
    (2025-01-19) Dimic-Misic, Katarina; Imani, Monir; Gasik, Michael
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Alginate hydrogels have gathered significant attention in biomedical engineering due to their remarkable biocompatibility, biodegradability, and ability to encapsulate cells and bioactive molecules, but much less has been reported on the kinetics of gelation. Scarce experimental data are available on cross-linked alginates (AL) with bioactive components. The present study addressed a novel method for defining the crosslinking mechanism using rheological measurements for aqueous mixtures of AL and calcium chloride (CaCl2) with the presence of hydroxyapatite (HAp) as filler particles. The time-dependent crosslinking behaviour of these mixtures was exploited using a plate–plate rheometer, when crosslinking occurs due to calcium ions (Ca2+) binding to the guluronic acid blocks within the AL polymer, forming a stable “egg-box” structure. To reveal the influence of HAp particles as filler on crosslinked sample morphology, after rheological measurement and crosslinking, crosslinked samples were freeze-dried and their morphology was assessed using an optical microscope and SEM. It was found that the addition of HAp particles, which are known to enhance the mechanical properties and biocompatibility of crosslinked AL gels, significantly decreased (usually rapidly) the interaction between the Ca2+ and AL chains. In this research, the physical “shielding” effect of HAp particles on the crosslinking of AL with Ca2+ ions has been observed for the first time, and its crosslinking behaviour was defined using rheological methods. After crosslinking and rheometer measurements, the samples were further evaluated for morphological properties and the observations were correlated with their dewatering properties. While the presence of HAp particles led to a slower crosslinking process and a more uniform development of the rheological parameters, it also led to a more uniform porosity and improved dewatering properties. The observed effects allow for a better understanding of the crosslinking process kinetics, which directly affects the physical and chemical properties of the AL gels. The shielding behaviour (retardation) of filler particles occurs when they physically or chemically block certain components in a mixture, delaying their interaction with other reactants. In hydrogel formulations, filler particles like hydroxyapatite (HAp) can act as barriers, adsorbing onto reactive components or creating physical separation, which slows the reaction rate and allows for controlled gelation or delayed crosslinking. This delayed reactivity is beneficial for precise control over the reaction timing, enabling the better manipulation of material properties such as crosslinking distribution, pore structure, and mechanical stability. In this research, the physical shielding effect of HAp particles was observed through changes in rheological properties during crosslinking and was dependent on the HAp concentration. The addition of HAp also enabled more uniform porosity and improved dewatering properties. The observed effects allow for a better understanding of the crosslinking process kinetics, which directly affects the physical and chemical properties of the AL gels.
  • Bi-hierarchical porous Pt microspheres grown on Ti wire with TiO2 nanotubes layer for selective alcohol sensing
    (2022) Fedorov, Fedor S.; Goldt, Anastasia E.; Zamansky, Konstantin; Vasilkov, Mikhail Yu; Gaev, Andrey; Lantsberg, Anna V.; Zaytsev, Valeriy; Aslyamov, Timur; Nasibulin, Albert G.
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    This study focuses on the synthesis of bi-hierarchical porous Pt microspheres directly on titania nanotube arrays grown on a Ti wire for their application as a one-electrode selective alcohol sensor. We evaluate the synthesis conditions, morphology, structure of the obtained material using scanning, transmission electron microscopy and electron diffraction. The sensor performance is assessed in a one-electrode configuration, using thermocycling protocols both to heat and acquire a signal that we further process with a machine learning algorithm for selective determination of alcohols. We found that reduction of Pt precursor by formic acid facilitates the appearance of quasi-1D Pt structures without using any surfactant. High excess of formic acid yields the formation of quasi-dendritic Pt structures with the overall morphology of a sphere and channels whose diameter remains one of the TiO2 nanotubes. Our data suggest the growth of Pt spheres to be diffusion controlled with constant or decreasing nucleation rate that should include assembling of Pt nanorods. The fabricated sensors based on the synthesized structures show a chemiresistive response to methanol, ethanol and isopropanol vapors in the mixture with air, which we selectively determine using only one sensor.
  • Enhanced superhydrophobic robustness of black silicon employing nanojungle structures
    (2025-02-07) Meng, Lingju; Awashra, Mohammad; Mirmohammadi, Seyed Mehran; Mousavi, Seyede Maryam; Vapaavuori, Jaana; Jokinen, Ville; Franssila, Sami
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Superhydrophobic surfaces are essential in various industries such as textiles, aviation, electronics and biomedical devices due to their exceptional water-repellent properties. Black silicon (b-Si) would be an ideal candidate for some applications due to its nanoscale topography made with a convenient lithography-free step and Complementary Metal-Oxide-Semiconductor (CMOS) compatible fabrication process. However, its use is hindered by serious issues with mechanical robustness. This study presents ‘nanojungle b-Si,’ characterized by elongated and deep nanostructures and fabricated through photoresist micromasks associating with Bosch etching. These nanojungle structures exhibit enhanced robustness and sustain superhydrophobicity under abrasive conditions, outperforming traditional ‘nanograss b-Si.’ Optical analysis indicates that the nanojungle structures dissipate abrasive impact energy more effectively, preserving surface roughness and hydrophobicity. Notably, nanojungle b-Si maintains its superhydrophobicity even after impinging by 20 g of sand impacting from a height of 40 cm. This advancement in b-Si surfaces holds significant potential for enhancing future technological applications.
  • Dispersion of bacterial cellulose bundles in organic solvents and their assembly as ultra-low grammage coating on woven fabric
    (2025-04-15) Li, Joanne; Cham, Yee Shuen; Kondor, Anett; Kontturi, Eero; Stone, Corinne; Dennis, Mike; Lee, Koon Yang
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Water is commonly considered as the optimal dispersing medium for nanocellulose given its hydrophilic nature. However, studies have also proven otherwise that alternative organic solvents may give better dispersion quality. Herein, a thermodynamic approach is used to estimate the Hansen solubility parameters of bacterial cellulose (BC) and understand the dispersion of BC bundles in selected organic solvents (i.e. ethyl acetate, acetone and ethanol-water mixtures). The correlation between the BC dispersion in different solvents and the aerosol particulate filtration performance of the resultant BC coated woven fabric is also presented. It is discovered that the best dispersion was achieved in a 60 % ethanol-water mixture, resulting in enhanced aerosol particulate filtration performance. At a BC coating grammage of 0.5 g m−2, the filtration efficiency exceeded 80 %, outperforming the BC coating produced from a water dispersion. These findings highlight the potential of understanding nanocellulose dispersion from a solubility parameter approach.
  • Coupled Modeling of Computational Fluid Dynamics and Granular Mechanics of Sand Production in Multiple Fluid Flow
    (2024-12) Khamitov, Furkhat; Shabdirova, Ainash; Kozhagulova, Ashirgul; Nguyen, Hop Minh; Zhao, Yong
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Sand production is a significant issue in oil and gas fields with poorly consolidated formations, often involving the multiphase flow of reservoir fluids and solid particles. The multiscale mechanisms of sand production, particularly fluid flow and particle movement, remain poorly understood. This study investigates these mechanisms using a coupled computational fluid dynamics and discrete element method (CFD-DEM) modeling approach. Single and multiple fluid flows of water and heavy oil were simulated with increasing fluid injection velocities, leading to different sand production patterns. The simulation results were compared with experimental results from a large cylindrical specimen of weak artificial sandstone under similar loading conditions. The multiphase conditions created various localized flow and deformation patterns that influenced both fluid and solid production, resulting in shorter transient sand production periods. Microstructures and phenomena such as fingering and water coning were observed, associated with a critical flow rate below which oil displacement was uniform and no water breakthrough occurred. Higher fluid injection velocities and fluid viscosities resulted in greater drag forces, leading to progressive damage zones and explaining the occurrence of single or multiple staged sand production events. The evolution of the microscopic granular structure was visualized under the effect of transient sand production.
  • Stable Air Plastron Prolongs Biofluid Repellency of Submerged Superhydrophobic Surfaces
    (2025-01-28) Awashra, Mohammad; Mirmohammadi, Seyed Mehran; Meng, Lingju; Franssila, Sami; Jokinen, Ville
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Superhydrophobic surfaces find applications in numerous biomedical scenarios, requiring the repellence of biofluids and biomolecules. Plastron, the trapped air between a superhydrophobic surface and a wetting liquid, plays a pivotal role in biofluid repellency. A key challenge, however, is the often short-lived plastron stability in biofluids and the lack of knowledge surrounding it. Plastron stability refers to the duration for which a surface remains in the Cassie state before transitioning to the fully wetting Wenzel state. Here, a submersion test with real-time optical monitoring is used to determine the plastron lifetime of different superhydrophobic surfaces upon immersion in various biofluids. We find that biofluids of all types exhibit shorter plastron lifetimes compared to pure water, which is attributed to their lower surface tension and biomolecular adsorption through hydrophobic–hydrophobic interactions. Proteins and glucose are identified as the major contributors to plastron dissipation in fetal bovine serum-based biofluids. Plastron minimizes the solid–liquid interface, reducing biomolecular adsorption, making its stability crucial for biofluid repellence. Thus, the effects of surface texture, feature size, Cassie solid fraction, Wenzel dimensionless roughness, and surface chemistry on plastron stability are investigated. Our key findings indicate that prolonged plastron stability and thus enhanced biofluid repellency are achieved through a combination of larger plastron volumes, increased Wenzel roughness degrees, greater Cassie solid fractions, and smaller feature sizes. We demonstrate that with optimized parameters, our surface design can maintain plastron stability and sustain a consistent solid–liquid area fraction for over 120 h in complex biofluids containing high levels of protein and glucose, underscoring a robust design for long-term use in biomedical and antifouling applications. This research is essential for advancing the design of superhydrophobic surfaces that effectively resist biofouling in diverse medical and engineering settings.
  • Towards More Sustainable Interactive Textiles: A Literature Review on The Use of Biomaterials for eTextiles.
    (2024-05-11) Guridi Sotomayor, Sofia; Iannacchero, Matteo; Pouta, Emmi
    A4 Artikkeli konferenssijulkaisussa
    The development of functional fibres, active materials, and flexible electrical components has introduced new ways of embedding interactive capabilities within textiles. However, this seamless integration poses challenges in terms of materials, disassembly, and disposal, revealing an urgent need to address the issue of sustainability when creating new electronic textiles. Authors have proposed eco-design guidelines that emphasise the use of renewable and biodegradable materials. Despite these recommendations, the potential of biomaterials in eTextiles remains largely unexplored. This integrative literature review showcases how biomaterials emerged as catalysts for expanding possibilities within eTextiles and HCI, not only through their environmental sustainability but also through their dynamic and transformative nature, fostering a realm of novel interactive experiences. We suggest the potential of developing fully bio-based eTextile systems, the need for broader sustainability and aesthetic studies, the relevance of DIY methods, and the urgency of textile knowledge integration.
  • Atom’s Dynamics and Crystal Structure: An Ordinal Pattern Method
    (2025-01-30) Abram, Rafał; Nowak, Roman; Chrobak, Dariusz
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The ubiquitous nature of thermal fluctuations poses a limitation on the identification of crystal structures. However, the trajectory of an atom carries a fingerprint of its surroundings. This rationalizes the search for a method that can determine the local atomic configuration via the analysis of the movement of an individual atom. Here, we report, while using molecular modeling, how a statistical analysis of a single-atom speed trajectory, represented by ordinal patterns, distinguishes between actual crystal structures. Using the Shannon entropy of ordinal patterns enabled discernment of the studied high-pressure silicon phases. Identification of the atoms occupying the 2(c) and 6(f) Wyckoff positions of the r8 crystal revealed an increase in the developed method’s accuracy with trajectory length. The proposed concept of studying the structure of crystals offers new opportunities in solid-solid phase transformation studies.
  • Rheology of pumpable slurry of enzymatic hydrolysis lignin in fuel compatible solvent with high solid loading
    (2025-02-01) Zhang, Yuxing; Li, Xiang; Sang, Yushuai; Chen, Hong; Li, Yongdan
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Enzymatic hydrolysis lignin (EHL) is the main solid waste from the growing second-generation (2G) bioethanol production industry. The industrial valorization of EHL with large scale requires a highly efficient transportation method. Slurries composed of solid and liquid phases have been widely employed in the pipeline transportation of solid feedstocks. In this work, two types of EHL samples, i.e., corn cob EHL (CC EHL) and pine wood EHL (PW EHL), were utilized to prepare EHL-alkane and EHL-alcohol slurries. Among the slurries examined, the CC EHL-alkane slurry exhibits the highest flowable solid concentration, achieving 70 wt%. The CC EHL-alcohol slurry shows dilatant characteristics, while CC EHL-alkane, PW EHL-alcohol, and PW EHL-alkane slurries present pseudoplasticity. The increase of particle size results in the decrease of the viscosity of the CC EHL-heptane slurry. The CC EHL-alkane slurries and all PW EHL slurries with highest solid concentration display pumpability and possibility of pipeline transportation. The dispersants, i.e., Span 80 and oleic acid, significantly improve the stability of EHL-heptane slurry.
  • Experimental and Cubic Plus Association Equation of State modelling study of phase equilibria of 1-Ethyl-3-methylimidazolium methanesulfonate + methanol + dimethyl carbonate + water binary and quaternary mixtures: The role of ionic liquids vapor pressure in modelling
    (2025-03-15) Laakso, Juho-Pekka; Asadzadeh, Behnaz; Uusi-Kyyny, Petri; Liang, Xiaodong; Kontogeorgis, Georgios M.; Alopaeus, Ville
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Understanding the phase equilibria of ionic liquids (ILs) in mixtures related to dimethyl carbonate (DMC) synthesis is important for enhancing the yield of DMC by absorbing the water produced during the reaction. 1-Ethyl-3-methylimidazolium methanesulfonate ([Emim][MeSO3]) shows promise as a water absorbent for this application. This study investigates the phase equilibria of binary and quaternary mixtures containing [Emim][MeSO3], water, methanol, and DMC at 102 kPa. Vapor-liquid equilibrium (VLE) and liquid-liquid equilibrium (LLE) were measured using the circulation still and cloud point method. The Cubic Plus Association (CPA) equation of state (EOS) was used for modelling, using two parameterization strategies for [Emim][MeSO3]. The first strategy used density and vapor pressure (CPAρP), whereas the second strategy used density and isobaric heat capacity (CPAρC). The CPAρP parameter set demonstrated generally higher accuracy in modelling binary and quaternary mixtures. It slightly improved VLE modelling of the H2O + [Emim][MeSO3] mixture and enhanced LLE modelling of DMC + [Emim][MeSO3] mixture over the CPAρC parameter set, with AAD values of 0.01 and 0.12 for the mole fraction of [Emim][MeSO3]. For the quaternary mixture, the CPAρP parameter set outperformed the CPAρC parameter set in modelling the relative volatility of methanol with AAD values of 0.11 and 0.17. The results provide insights into phase equilibria modelling for mixtures involving [Emim][MeSO3], water, methanol, and DMC. Including the vapor pressure of [Emim][MeSO3] in the parameter regression improved the accuracy of the CPA model enhancing its ability to realistically simulate phase equilibria, which is essential for designing water absorbent for DMC synthesis.
  • Influence of tundish flux on reoxidation behavior of Al-killed Ti-containing stainless steel
    (2025-03-01) Jun, Yeongjin; Chung, Yongsug; Park, Sungjin; Kang, Suchang; Paek, Min-Kyu; Park, Joo Hyun
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The cleanliness of Ti-containing ferritic stainless steel (Ti-FSS) has been improved via vacuum-oxygen-decarburization (VOD) and ladle treatment (LT) processes. However, the reoxidation phenomena inevitably occur during melt transfer from ladle to continuous casting tundish, resulting in a loss of titanium yield in conjunction with the formation of reoxidative inclusions. Hence, the present work aims to systematically investigate the combinational effect of different tundish fluxes on the reoxidation behavior of Al-killed Ti-FSS melt. Rice husk ash (RHA) and MgO (M) insulation powders, and calcium aluminate, CaO–Al2O3 (CA) based flux were used for the experiments. When the molten steel was covered by M + CA fluxes, the average size of inclusions decreased. On the other hand, when the RHA + CA fluxes were added, the average size of inclusion decreased, whereas total number of inclusions significantly increased due to a reoxidation reaction by SiO2 in RHA. When the M + RHA + CA combinative fluxes were added, the size of inclusion decreased, and the number of inclusions exhibited a value between the M + CA and RHA + CA conditions. Consequently, a decrease in total oxygen content in Ti-FSS was most effective in the M + CA flux combination.
  • Guided Heterostructure Growth of CoFe LDH on Ti3C2Tx MXene for Durably High Oxygen Evolution Activity
    (2025-01-22) Sheng, Jiali; Kang, Jiahui; Jiang, Pan; Meinander, Kristoffer; Hong, Xiaodan; Jiang, Hua; Nonappa; Ikkala, Olli; Komsa, Hannu Pekka; Peng, Bo; Lv, Zhong Peng
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Heterostructures of layered double hydroxides (LDHs) and MXenes have shown great promise for oxygen evolution reaction (OER) catalysts, owing to their complementary physical properties. Coupling LDHs with MXenes can potentially enhance their conductivity, stability, and OER activity. In this work, a scalable and straightforward in situ guided growth of CoFeLDH on Ti3C2Tx is introduced, where the surface chemistry of Ti3C2Tx dominates the resulting heterostructures, allowing tunable crystal domain sizes of LDHs. Combined simulation results of Monte Carlo and density functional theory (DFT) validate this guided growth mechanism. Through this way, the optimized heterostructures allow the highest OER activity of the overpotential = 301 mV and Tafel slope = 43 mV dec−1 at 10 mA cm−2, and a considerably durable stability of 0.1% decay over 200 h use, remarkably outperforming all reported LDHs-MXenes materials. DFT calculations indicate that the charge transfer in heterostructures can decrease the rate-limiting energy barrier for OER, facilitating OER activity. The combined experimental and theoretical efforts identify the participation role of MXene in heterostructures for OER reactions, providing insights into designing advanced heterostructures for robust OER electrocatalysis.
  • Nanostructured single-atom catalysts derived from natural building blocks
    (2024-03-01) Zhang, Yajing; Yang, Guobin; Wang, Jin; Zhao, Bin; He, Yunxiang; Guo, Junling
    A2 Katsausartikkeli tieteellisessä aikakauslehdessä
    Single-atom catalysts (SACs) exhibit maximized atomic utilization with individual metal atoms anchored on supporting materials, where the pursuit of high performance and low cost presents challenges. In this case, carbon provides structural versatility and customizable properties as a supporting material, which has been extensively studied. Biomass materials have emerged as promising precursors for the preparation of carbon-based SACs due to their renewable nature for sustainability, abundance for low cost, and high carbon content for advanced performance. In this review, representative synthesis strategies and advanced characterization techniques for biomass-derived CS-SACs are summarized, which facilitate the establishment of guidelines for the rational design and fabrication of biomass-derived SACs. In addition, we provide a timely and comprehensive discussion on the use of a broad range of natural biomass for SACs, with insights into the specific carbon nature of biomass resources, including their carbon structures, metal-carbon coordination environment, and center metal species. Furthermore, the application areas of biomass-derived CS-SACs in various catalytic processes are reviewed. Overall, the challenges and future perspectives of using biomass as precursors for SACs are outlined. We hope that this review can offer a valuable overview of the current knowledge, recent progress, and directions of biomass-derived SACs.
  • Specific Protein Quantification by Radioimmuno-Dot-Blot Assay for Complex Mixture Samples Utilizing Strep-Tag and Tritium-Labeled Strep-Tactin
    (2025-01-21) Malkamäki, Maaria; Gandier, Julie-Anne; Meinander, Kristoffer; Linder, Markus
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Accurately quantifying specific proteins from complex mixtures like cell lysates, for example, during in vivo studies, is difficult, especially for aggregation-prone proteins. Herein, we describe the development of a specific protein quantification method that combines a solid-state dot blot approach with radiolabel detection via liquid scintillation counting. The specific detection with high sensitivity is achieved by using the Twin-Strep protein affinity tag and tritium-labeled 3HStrep-TactinXT probe. While the assay was developed with the recombinant silk protein CBM-AQ12-CBM as a target, the method can be adapted to other recombinant proteins. Variations of the protein tag and Strep-Tactin probe were tested, and it was found that only the combination of Strep-TactinXT and Twin-Strep-tag performed adequately: with this combination, a precision of 95% and an accuracy of 86% were achieved with a linear region from 19 to 400 ng and a limit of quantification at 0.4 pmol. To achieve this, critical optimization steps were preventing nonspecific adsorption and promoting surface adhesion of the target protein to the solid nitrocellulose membrane. The often-overlooked challenges of sample preparation and protein immobilization in quantification assays are discussed and insights into overcoming such issues are provided.
  • Size effect on the structural and magnetic phase transformations of iron nanoparticles
    (2024-11-21) Front, Alexis; Förster, Georg Daniel; Fu, Chu Chun; Barreteau, Cyrille; Amara, Hakim
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Iron nanoparticles are among the most promising low-dimensional materials in terms of applications. This particularity is attributable to the magnetic properties of these nanoparticles, which exhibit different allotropes as a function of temperature. In this work, we sought to characterise at the atomic scale how their structural and magnetic transformations can be affected by the size. To achieve this objective, we developed a tight-binding model incorporating a magnetic contribution via a Stoner term implemented in a Monte Carlo code to relax the structure and the magnetic state. Using our approach, we show that magnetism is strongly reinforced by the surface, which leads to an increase in the Curie temperature as the size of the particle decreases contrary to the solid-solid transition temperature. Our work thus provides a deep understanding at the atomic scale of the key factors that determine the structural and magnetic properties of Fe nanoparticles, shedding more light on their unique character, which is crucial for further applications.
  • Utilizing waste lithium-ion batteries for the production of graphite-carbon nanotube composites as oxygen electrocatalysts in zinc–air batteries
    (2025-01-01) Praats, Reio; Sainio, Jani; Vikberg, Milla; Klemettinen, Lassi; Wilson, Benjamin P.; Lundström, Mari; Kruusenberg, Ivar; Liivand, Kerli
    A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The increasing global demand for energy has led to a rise in the usage of lithium-ion batteries (LIBs), which ultimately has resulted in an ever-increasing volume of related end-of-life batteries. Consequently, recycling has become indispensable to salvage the valuable resources contained within these energy storage devices. While various methods have been developed for the recovery of valuable cathode metals from spent LIBs, the anode's active material, graphite, is mostly lost from circulation. This study introduces an innovative method to valorize black mass leach residue, a waste product from industrial hydrometallurgical LIB recycling processes. Predominantly composed of graphite and minor metal residues, this material can be converted into a valuable bifunctional oxygen electrocatalyst. This transformation is achieved by doping the leach residue with nitrogen and through the incorporation of carbon nanotubes into the modified matrix, to enhance the surface area and conductivity of the produced electrocatalyst. These novel catalyst materials can enhance the oxygen reduction reaction and oxygen evolution reaction in zinc–air batteries (ZAB). The best catalyst material exhibited a commendable power density of 97 mW cm−2 in ZAB, demonstrating stable performance over 70 hours of continuous charge–discharge cycling. This research represents a significant advancement in the shrewd utilization of LIB recycling waste, which further enhances the goal of closed-loop materials circularity.