Electrically conductive, transparent polymeric nanocomposites modified by 2D Ti3C2Tx (MXene)

The electrically conductive, transparent, and flexible self-standing thin nanocomposite films based on copolyamide matrix (coPA:Vestamelt X1010) modified with 2D Ti3C2Tx (MXene) nanosheets were prepared by casting and their electrical, mechanical and optical properties and then, were investigated. The percolation threshold of the MXene filler within the coPA matrix was found to be 0.05 vol. %, and the highest determined electrical conductivity was 1.4 x 10(-2) Scm(-1) for the composite filled with 5 wt. % (1.8 vol. %) of MXene. The electrical conductivity of the as-prepared MXene was 9.1 Scm(-1), and the electrical conductivity of the MAX phase (the precursor for MXene preparation) was 172 Scm(-1). The transparency of the prepared composite films exceeded 75%, even for samples containing 5 wt. % of MXene, as confirmed by UV spectroscopy. The dynamic mechanical analysis confirmed the improved mechanical properties, such as the storage modulus, which improved with the increasing MXene content. Moreover, all the composite films were very flexible and did not break under repeated twisting. The combination of the relatively high electrical conductivity of the composites filled with low filler content, an appropriate transparency, and good mechanical properties make these materials promising for applications in flexible electronics.Qatar University Collaborative High Impact Grant [QUHI-CENG-18/19-1

MXene-nanocellulose composite development by hydrothermal method for supercapacitor application

MXenes, as representative of two-dimensional (2D) materials, stand out unique in many applications. Among MXene family, Tin+1CnTx is the most mentioned and used one, which displayed large surface area and high electrical conductivity, even higher than well-known graphene. Owing to these merits, Tin+1CnTx is an excellent candidate as electrode material for energy storage application, such as supercapacitor. However, Tin+1CnTx easily undergoes re-stacking together with poor flexibility and low mechanical strength, which limit its performance and application. Herein, cellulose nanofibers (CNF) were introduced in order to address these issues, which are expected to prevent the re-stacking and increase the strength and flexibility of composite film. Composites were prepared with MXene and different types of CNF by hydrothermal method, supposedly bringing good dispersion. The as-prepared high-charge CNF/MXene composite exhibited relatively low areal capacitance of 12.6 mF/cm2 at applied current density of 1 mA/cm2 while it maintained capacitance retention of higher than 90% after 1000 cycles, displaying good cycling stability. Besides, composite films with different mass ratios of MXene and CNF (10M:90C, 50M:50C, 70M:30C) were fabricated to investigate the optimal amount of MXene used for self-standing film electrode. It turned out that all the films did not show desirable conductivity. Spectroscopic analyses and comparisons of films, prepared by hydrothermal treatment and sonication, implied that the oxidation of Ti atoms within MXene during hydrothermal process might be the reason for low conductivity, whereas sonication worked better for homogeneous dispersion of MXene and CNF, further leading to uniform conductivity of composite film

Robust Bioinspired MXene–Hemicellulose Composite Films with Excellent Electrical Conductivity for Multifunctional Electrode Applications

MXene-based structural materials with high mechanical robustness and excellent electrical conductivity are highly desirable for multifunctional applications. The incorporation of macromolecular polymers has been verified to be beneficial to alleviate the mechanical brittleness of pristine MXene films. However, the intercalation of a large amount of insulating macromolecules inevitably compromises their electrical conductivity. Inspired by wood, short-chained hemicellulose (xylo-oligosaccharide) acts as a molecular binder to bind adjacent MXene nanosheets together; this work shows that this can significantly enhance the mechanical properties without introducing a large number of insulating phases. As a result, MXene–hemicellulose films can integrate a high electrical conductivity (64,300 S m–1) and a high mechanical strength (125 MPa) simultaneously, making them capable of being high-performance electrode materials for supercapacitors and humidity sensors. This work proposes an alternative method to manufacture robust MXene-based structural materials for multifunctional applications

Nanocellulose/zero, one- and two-dimensional inorganic additive based electrodes for advanced supercapacitors

Nowadays, the growing threat of environmental pollution and the energy crisis have accelerated the advancement of sustainable energy sources and highly efficient energy storage technologies. Supercapacitors' outstanding efficiency and accessibility have attracted much interest in portable electronics. However, compared to other energy storage devices, commercially available supercapacitors offer minimal advantages, and it is also very difficult to balance their electrochemical performance, such as cyclability, energy density, and capacitance. Fabricating high-performance supercapacitors with attractive electrical parameters and flexibility depends on the composition of the electrodes. Nanocellulose, which is derived from waste biomass because of its high mechanical strength, strong chemical reactivity, and biodegradability, has been used to integrate 2D, 1D, and zero-dimensional inorganic additive materials to develop a promising material for supercapacitor electrodes. The present review summarises recent advancements in the progress of nanocellulose/2D-, 1D-, and zero-dimensional inorganic material-based composite electrodes for their application in supercapacitors. Different strategies for developing nanocellulose/inorganic additive-based composite electrodes are reviewed, and subsequently, the potential of nanocellulose/multidimensional inorganic additive-based electrodes in supercapacitors is fully elaborated. In the end, current challenges and future directions for the development finally, current challenges and future directions for developing nano cellulose-based nanocomposite electrodes in supercapacitors were also discussed.</p

Chemical engineering of 2D materials for electrochemical energy storage

L'attractivité des supercondensateur réside dans leur complémentarité avec les batteries, en particulier en termes de durée de vie et de puissance. Leur densité d'énergie plus faible reste un inconvénient qui peut être dépassé en travaillant sur les matériaux d'électrode. Au cours e cette thèse, divers matériaux 2D ont permis la formulation d'électrodes présentant de meilleures densités d'énergie. L'intercalation de Cu2+ dans delta-MnO2 par une méthode hydrothermale a conduit à une amélioration fdes performances. Des effets synergiques ont été observés dans des composites à base de MnO2 et Ti3C2-MXene. Ils ont été attribués à l'amélioration de la conductivité électronique apportée par le composant MXene. Pour éviter le ré- empilement des Mxenes exfoliés, des méthodes de templating ont conduit à des matériaux expansés et des mousses. Une couche de MXene à la surface de fibres de carbone modifiée par physisorption de molécules rédox-actives a augmenté fortement la cyclabilité de l'électrode.Supercapacitors attractiveness lies in their complementarity with batteries, especially in terms of expended lifespan and greater power density. Their lower energy density however remains a drawback and the electrode material design and composition play a crucial role to address it. During this thesis work, various 2D materials were used to fabricate electrodes with enhanced energy densities. An hydrothermal method was explored using delta-MnO2 for Cu2+ intercalation leading to performance improvement. Attractive synergistic effects were evidenced in composite materials based on 2D pseudocapacitive MnO2 and Ti3C2-MXene. They have been assigned to electronic conductivity improvement from MXene component. To prevent the restacking of exfoliated MXene, template-assisted syntheses led to expanded MXene and foam. An MXene coating was deposited at the surface of carbon fibers modified by physisorbed redox-active organic salts, promoting efficient charge storage and stabilizing the assemble

Freestanding MXene‐based macroforms for electrochemical energy storage applications

Freestanding MXene-based macroforms have gained significant attention as versatile components in electrochemical energy storage applications owing to their interconnected conductive network, strong mechanical strength, and customizable surface chemistries derived from MXene nanosheets. This comprehensive review article encompasses key aspects related to the synthesis of MXene nanosheets, strategies for structure design and surface medication, surface modification, and the diverse fabrication methods employed to create freestanding MXene-based macroform architectures. The review also delves into the recent advancements in utilizing freestanding MXene macroforms for electrochemical energy storage applications, offering a detailed discussion on the significant progress achieved thus far. Notably, the correlation between the macroform's structural attributes and its performance characteristics is thoroughly explored, shedding light on the critical factors influencing efficiency and durability. Despite the remarkable development, the review also highlights the existing challenges and presents future perspectives for freestanding MXene-based macroforms in the realms of high-performance energy storage devices. By addressing these challenges and leveraging emerging opportunities, the potential of freestanding MXene-based macroforms can be harnessed to enable groundbreaking advancements in the field of energy storage

Interlayered Thin Film Composite (iTFC) Membranes: The Synthesis and Assembly of Active Layer from Conjugated Microporous Polymer

The pursuit of advanced materials with well-defined structures at sub-1 nm size, multi-functionalities, and superior chemical stability is essential for enhanced separation performance but technically challenging. Limitations of conventional TFC membranes for use in Organic Solvent Nanofiltration (OSN) can be addressed by manipulating the pore size and chemical properties of the film with novel materials. Conjugated microporous polymers (CMPs) are promising in a few years because of their highly ordered structure and excellent stability. Porphyrin, one of the basic building blocks, can form a conjugated polymer. Herein, poly(5,10,15,20-tetrakis(4-aminophenyl)porphyrin) or PTAPP, is considerably selected as an active layer from CMPs using an electrochemical approach with various processing parameters such as scan rate, monomer concentration, and cycle number. The assembly of electropolymerized PTAPP membranes with or without an interlayer was studied. The highest separation performance of PTAPP/Nylon membrane using the dense bottom film as the upper layer of the membrane, accounting for 59% of RB-5 dye rejection in methanol and 7.82 L.m-2.h-1.bar-1 methanol permeance. In addition, PTAPP/PE exhibited molecular-sieving selectivity against the mixture of CR and MB dyes and the mixture of CR and MO dyes, with rejection values of 94.48% and 96.16%, respectively. In addition, due to its rigid framework structure of the bottom film, PTAPP/Nylon membrane performed higher NaCl rejection (89%) than the control membrane (53%). Based on SEM characterization, the morphology of poly-TAPP film using MXene as an interlayer revealed the highly porous PTAPP film. However, the pore uniformity, structure, and thickness vary, not strongly correlated with the scan rates. Advisor: Siamak Nejat