| 1. |
- Chang, Jian, 1990-, et al.
(författare)
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MXene/Cellulose Composite Cloth for Integrated Functions (if-Cloth) in Personal Heating and Steam Generation
- 2024
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Ingår i: Advanced fiber materials. - 2524-7921. ; 6:1, s. 252-263
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Tidskriftsartikel (refereegranskat)abstract
- Given the abundant solar light available on our planet, it is promising to develop an advanced fabric capable of simultaneously providing personal thermal management and facilitating clean water production in an energy-efficient manner. In this study, we present the fabrication of a photothermally active, biodegradable composite cloth composed of titanium carbide MXene and cellulose, achieved through an electrospinning method. This composite cloth exhibits favorable attributes, including chemical stability, mechanical performance, structural flexibility, and wettability. Notably, our 0.1-mm-thick composite cloth (RC/MXene IV) raises the temperature of simulated skin by 5.6 degrees C when compared to a commercially available cotton cloth, which is five times thicker under identical ambient conditions. Remarkably, the composite cloth (RC/MXene V) demonstrates heightened solar light capture efficiency (87.7%) when in a wet state instead of a dry state. Consequently, this cloth functions exceptionally well as a high-performance steam generator, boasting a superior water evaporation rate of 1.34 kg m(-2) h(-1) under one-sun irradiation (equivalent to 1000 W m(-2)). Moreover, it maintains its performance excellence in solar desalination processes. The multifunctionality of these cloths opens doors to a diverse array of outdoor applications, including solar-driven water evaporation and personal heating, thereby enriching the scope of integrated functionalities for textiles.
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| 2. |
- Héraly, Frédéric, 1995-, et al.
(författare)
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Capacitive CO2 sensor made of aminated cellulose nanofibrils : development and optimization
- 2024
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Ingår i: New Journal of Chemistry. - 1144-0546 .- 1369-9261. ; 48:14, s. 6064-6070
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Tidskriftsartikel (refereegranskat)abstract
- CO2 sensors are very important; however, their performance is limited by stability and selectivity. This study unveils a capacitive CO2 sensor with a dielectric layer comprised of amine-functionalized cellulose nanofibril (CNF) foam, significantly enhanced by the addition of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). The core innovation of this research lies in the strategic use of CNF-based foam, which leads to a substantial increase in sensor capacitance, setting a new standard in CO2 monitoring technologies. The sensor showcases exceptional performance under ambient conditions, with marked improvements in sensitivity towards CO2. The advancements are attributed to the chemisorption properties of the aminated CNFs combined with the DBU enhancement, facilitating more effective CO2 capture. By integrating these materials, we present a sensor that opens new avenues for environmental monitoring, healthcare diagnostics, and industrial safety, establishing a new benchmark for capacitive CO2 sensors in efficiency and environmental sustainability.
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| 3. |
- Héraly, Frédéric, 1995-
(författare)
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Stimuli-Responsive Materials Derived from Cellulose Nanofibrils : Synthesis, characterization, and performance evaluation
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a comprehensive study on stimuli-responsive materials derived from cellulose nanofibrils (CNFs), focusing on their synthesis, characterization, and performance evaluation in various applications. Renowned for their biodegradability, renewability, and robust mechanical properties, CNFs are explored in three primary contexts: moisture-responsive actuators, voltage-responsive actuators, and CO2-responsive sensors.The unique properties of CNFs, such as high tensile strength and surface area, are leveraged to achieve effective motion in response to moisture exposure. Specifically, CNFs are utilized to create bilayer, torsional, and tensile actuators. These actuators exhibit controllable and dynamic responses, making them suitable for applications in soft robotics and wearable technology.In the realm of voltage-responsive actuators, this study investigates the impact of various electrolytes and counteranions on positively charged CNFs. It uncovers the critical role of electrolyte choice, ion migration and the plasticization effect within the CNFs matrix, resulting in volumetric expansion, which is pivotal to the actuation mechanism. These insights pave the way for CNFs applications requiring precise control of motion and flexibility in shape, such as in soft robotics.The third area of application involves the development of a capacitive CO2 sensor using CNFs-based foams functionalized with primary amines to enhance CO2 capture through chemisorption. This functionalization turns the CNFs-based foam into an efficient dielectric layer (DE) for sensor applications. The addition of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to the DE further expands the scope of sensor's capacitance change in response to CO2 exposure, underscoring its potential in environmental monitoring and CO2 detection.Overall, this thesis emphasizes the versatility and adaptability of CNFs as a sustainable biomaterial for developing stimuli-responsive devices. The insights gained from studying CNFs in these varied applications contribute significantly to materials science and open new avenues for research in sustainable, bio-based materials.
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| 4. |
- Lin, Xiang, et al.
(författare)
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Ionic Conjugated Microporous Polymers for Cycloaddition of Carbon Dioxide to Epoxides
- 2024
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Ingår i: Macromolecular materials and engineering. - 1438-7492 .- 1439-2054. ; 309:2
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Tidskriftsartikel (refereegranskat)abstract
- Along the development of ionic porous organic polymers, simple and efficient synthetic methods are actively pursued. Herein, the Debus–Radziszewski reaction is applied to synthesize ionic conjugated microporous polymers (iCMPs) in one step. A series of imidazolium-linked iCMP-X (X = 1, 2, 3) are developed for CO2 sorption and in situ conversion with epoxide into cyclic carbonates. The as-synthesized iCMPs are characterized in detail by scanning electron microscope, solid-state nuclear magnetic resonance, X-ray photoelectron spectroscopy, X-ray diffraction analysis, N2/CO2 sorption, and more. Among all synthesized iCMPs, iCMP-1 possesses the highest specific surface area and in turn the strongest CO2 sorption capacity. Moreover, through a simple anion ion exchange reaction with halide, iCMP-1 is transformed to iCMP-1@Cl that embodies significant catalytic capability for converting CO2 into cyclic carbonates.
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| 5. |
- Pang, Kanglei, 1993-, et al.
(författare)
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Redirecting configuration of atomically dispersed selenium catalytic sites for efficient hydrazine oxidation
- 2024
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Ingår i: Matter. - 2590-2393 .- 2590-2385. ; 7:2, s. 655-667
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the reconstruction of surface sites is crucial for gaining insights into the true active sites and catalytic mechanisms. While extensive research has been conducted on reconstruction behaviors of atomically dispersed metallic catalytic sites, limited attention has been paid to non-metallic ones despite their potential catalytic activity comparable or even superior to their noble-metal counterpart. Herein, we report a carbonaceous, atomically dispersed non-metallic selenium catalyst that displayed exceptional catalytic activity in the hydrazine oxidation reaction (HzOR) in alkaline media, outperforming the noble-metal Pt catalysts. In situ X-ray absorption spectroscopy (XAS) and Fourier transform infrared spectroscopy revealed that the pristine SeC4 site pre-adsorbs an ∗OH ligand, followed by HzOR occurring on the other side of the OH–SeC4. Theoretical calculations proposed that the pre-adsorbed ∗OH group pulls electrons from the Se site, resulting in a more positively charged Se and a higher polarity of Se–C bonds, thereby enhancing surface reactivity toward HzO/R.
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| 6. |
- Saeedi Garakani, Sadaf, 1993-
(författare)
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Heteroatom-doped porous carbon materials derived from poly(ionic liquid)s and their composites for battery and catalytic applications
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the past decade, there has been significant interest in heteroatom-doped porous carbons, driven by the distinctive and adjustable physical and chemical properties that they exhibit across scales, from the atomic to the macroscopic level. Particularly, attributes such as conductivity, electron density, high specific surface area, hierarchical pore structure, and oxidation resistance offer a wide range of characteristics for diverse applications. The development of multimodal, hierarchical pore sizes, ranging from micropores to macropores, ensures balanced diffusion resistance and a high surface area for active site accommodation. However, their synthesis usually involves multiple steps or complicated processing to incorporate both hierarchically porous structures and heteroatoms in carbon materials.This PhD thesis explores poly(ionic liquid)s (PILs) for preparation of heteroatom-doped porous carbon materials, driven by the growing demand for functional carbons in industry and academia. The aim of this thesis is to develop straightforward synthetic approaches to introduce various heteroatoms and different pore sizes in the carbonous structure and study their diverse functions. Here, we propose and explore fabrication methods based on two precursors. First, PILs were examined as both the carbon and heteroatom source, serving as a sacrificial template for porous carbons. Second, the delicate structure of wood was employed as a carbon source to generate macropores, while being coated with PILs to introduce heteroatoms or iron-based nanoparticles and create additional micropores. Moreover, the application of these carbonaceous materials was studied in two areas, i.e., batteries and artificial enzymes. This research is likely to contribute to a deeper understanding of synthetic methodologies of heteroatom-doped porous carbon materials and their physiochemical properties for various applications.
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| 7. |
- Saeedi Garakani, Sadaf, 1993-, et al.
(författare)
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Poly(ionic liquid)-derived metal-free heteroatom co-doped porous carbons with peroxidase-like activity
- 2024
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Ingår i: Applied Materials Today. - 2352-9407. ; 37
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Tidskriftsartikel (refereegranskat)abstract
- Development of affordable, efficient and metal-free heterogeneous catalytic systems has been a persistent challenge in academia and industry. Heteroatom-doped metal-free carbon materials are increasingly recognized as valuable heterogeneous catalysts, and if well-designed, can present comparable performance to, or even surpass transition metal-containing catalysts. Their physicochemical properties and structural characteristics are tunable in a wide range, plus being free of leakage problems of transition metal species into the environment. Herein, three types of hierarchically porous N/X co-doped carbon materials (X denotes B, P or S) were synthesized via using poly(ionic liquid)s (PILs) as carbon precursors and source of heteroatom dopants. The incorporation of sacrificial pore-inducing templating agents which created abundant edge defects, in combination with a heteroatom co-doping strategy, enhanced the number of active sites and their peroxidase-like catalytic activities. Comparison with only nitrogen single-doped porous carbons as reference demonstrated that co-doping with nitrogen and another heteroatom exhibits higher peroxidase-like activity and affinity towards substrates. Among the three types of heteroatom co-doped porous carbonaceous artificial enzymes, the N/B co-doped carbonaceous catalyst displayed the highest specific activities and Vmax values. These observations suggest a synergistic effect of the co-dopants, here N and B in the enzyme that holds a promising potential to further enhance peroxidase-like activity.
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| 8. |
- Sikdar, Anirban, 1991-, et al.
(författare)
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Hierarchically Porous 3D Freestanding Holey-MXene Framework via Mild Oxidation of Self-Assembled MXene Hydrogel for Ultrafast Pseudocapacitive Energy Storage
- 2024
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Ingår i: ACS Nano. - 1936-0851 .- 1936-086X. ; 18:4, s. 3707-3719
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Tidskriftsartikel (refereegranskat)abstract
- The true promise of MXene as a practical supercapacitor electrode hinges on the simultaneous advancement of its three-dimensional (3D) assembly and the engineering of its nanoscopic architecture, two critical factors for facilitating mass transport and enhancing an electrode’s charge-storage performance. Herein, we present a straightforward strategy to engineer robust 3D freestanding MXene (Ti3C2Tx) hydrogels with hierarchically porous structures. The tetraamminezinc(II) complex cation ([Zn(NH3)4]2+) is selected to electrostatically assemble colloidal MXene nanosheets into a 3D interconnected hydrogel framework, followed by a mild oxidative acid-etching process to create nanoholes on the MXene surface. These hierarchically porous, conductive holey-MXene frameworks facilitate 3D transport of both electrons and electrolyte ions to deliver an excellent specific capacitance of 359.2 F g–1 at 10 mV s–1 and superb capacitance retention of 79% at 5000 mV s–1, representing a 42.2% and 15.3% improvement over pristine MXene hydrogel, respectively. Even at a commercial-standard mass loading of 10.1 mg cm–2, it maintains an impressive capacitance retention of 52% at 1000 mV s–1. This rational design of an electrode by engineering nanoholes on MXene nanosheets within a 3D porous framework dictates a significant step forward toward the practical use of MXene and other 2D materials in electrochemical energy storage systems.
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| 9. |
- Yang, Chen, 1993-, et al.
(författare)
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Nanofibrous Porous Organic Polymers and Their Derivatives : From Synthesis to Applications
- 2024
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Ingår i: Advanced Science. - 2198-3844.
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Forskningsöversikt (refereegranskat)abstract
- Engineering porous organic polymers (POPs) into 1D morphology holds significant promise for diverse applications due to their exceptional processability and increased surface contact for enhanced interactions with guest molecules. This article reviews the latest developments in nanofibrous POPs and their derivatives, encompassing porous organic polymer nanofibers, their composites, and POPs-derived carbon nanofibers. The review delves into the design and fabrication strategies, elucidates the formation mechanisms, explores their functional attributes, and highlights promising applications. The first section systematically outlines two primary fabrication approaches of nanofibrous POPs, i.e., direct bulk synthesis and electrospinning technology. Both routes are discussed and compared in terms of template utilization and post-treatments. Next, performance of nanofibrous POPs and their derivatives are reviewed for applications including water treatment, water/oil separation, gas adsorption, energy storage, heterogeneous catalysis, microwave absorption, and biomedical systems. Finally, highlighting existent challenges and offering future prospects of nanofibrous POPs and their derivatives are concluded.
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| 10. |
- Yang, Song, et al.
(författare)
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Regulating the Tautomerization in Covalent Organic Frameworks for Efficient Sacrificial Agent-Free Photocatalytic H2O2 Production
- 2024
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Ingår i: Macromolecules. - 0024-9297 .- 1520-5835. ; 57:5, s. 2039-2047
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of photocatalytic production of H2O2 is constrained by the low selectivity toward oxygen reduction, and the active sites are still under debate. Herein, analogous covalent organic framework photocatalysts were synthesized from triformylphloroglucinol (Tp) and predesigned diamines, in which a molecular engineering strategy was employed to manipulate the energy barrier for the targeted proton transfers. The tautomerization of enol-imine to keto-enamine introduced abundant alkene bonds (C═C), which serve as the primary adsorption sites and have a lower energy barrier for the reduction of the O2 reduction. DHAA-Tp COF displayed a remarkable photocatalytic H2O2 production rate of 219.5 μmol h–1 g–1 without any sacrificial reagent, which stands out among the structure-related materials. A switch from a concerted one-step 2e– to a two-step single e– process in O2 reduction was observed in TCNAQ-Tp COF, which is presumably ascribed to the suppressed tautomerization mediated by the strong electron-withdrawing cyano groups. The results demonstrate a novel concept for the photocatalytic production of H2O2 using an efficient, stable, and recyclable metal-free photocatalytic system.
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