Oxidized Ti3C2 MXene nanosheets for dye-sensitized solar cells

Porous TiO2 electrodes were prepared by oxidizing two-dimensional titanium carbide nanosheets (Ti3C2 MXene) and the electrodes were tested in dye-sensitized solar cells. The effects of oxidation temperature and duration time together with various thicknesses on the device performance were investigated. A power conversion efficiency of 2.66% was observed

Ti₃C₂T_<i>x</i>MXene Polymer Composites for Anticorrosion:An Overview and Perspective

[Image: see text] As the most studied two-dimensional (2D) material from the MXene family, Ti(3)C(2)T(x) has constantly gained interest from academia and industry. Ti(3)C(2)T(x) MXene has the highest electrical conductivity (up to 24,000 S cm(–1)) and one of the highest stiffness values with a Young’s modulus of ∼ 334 GPa among water-dispersible conductive 2D materials. The negative surface charge of MXene helps to disperse it well in aqueous and other polar solvents. This solubility across a wide range of solvents, excellent interface interaction, tunable surface functionality, and stability with other organic/polymeric materials combined with the layered structure of Ti(3)C(2)T(x) MXene make it a promising material for anticorrosion coatings. While there are many reviews on Ti(3)C(2)T(x) MXene polymer composites for catalysis, flexible electronics, and energy storage, to our knowledge, no review has been published yet on MXenes’ anticorrosion applications. In this brief report, we summarize the current progress and the development of Ti(3)C(2)T(x) polymer composites for anticorrosion. We also provide an outlook and discussion on possible ways to improve the exploitation of Ti(3)C(2)T(x) polymer composites as anticorrosive materials. Finally, we provide a perspective beyond Ti(3)C(2)T(x) MXene composition for the development of future anticorrosion coatings

Rational Design of Two-Dimensional Transition Metal Carbide/Nitride (MXene) Hybrids and Nanocomposites for Catalytic Energy Storage and Conversion

Electro-, photo-, and photoelectrocatalysis play a critical role toward the realization of a sustainable energy economy. They facilitate numerous redox reactions in energy storage and conversion systems, enabling the production of chemical feedstock and clean fuels from abundant resources like water, carbon dioxide, and nitrogen. One major obstacle for their large-scale implementation is the scarcity of cost-effective, durable, and efficient catalysts. A family of two-dimensional transition metal carbides, nitrides, and carbonitrides (MXenes) has recently emerged as promising earth-abundant candidates for large-area catalytic energy storage and conversion due to their unique properties of hydrophilicity, high metallic conductivity, and ease of production by solution processing. To take full advantage of these desirable properties, MXenes have been combined with other materials to form MXene hybrids with significantly enhanced catalytic performances beyond the sum of their individual components. MXene hybridization tunes the electronic structure toward optimal binding of redox active species to improve intrinsic activity while increasing the density and accessibility of active sites. This review outlines recent strategies in the design of MXene hybrids for industrially relevant electrocatalytic, photocatalytic, and photoelectrocatalytic applications such as water splitting, metal–air/sulfur batteries, carbon dioxide reduction, and nitrogen reduction. By clarifying the roles of individual material components in the MXene hybrids, we provide design strategies to synergistically couple MXenes with associated materials for highly efficient and durable catalytic applications. We conclude by highlighting key gaps in the current understanding of MXene hybrids to guide future MXene hybrid designs in catalytic energy storage and conversion applications

Interface binding and mechanical properties of MXene-epoxy nanocomposites

Thermosetting epoxy polymers exhibit excellent stiffness and strength and are commonly utilized as matrices to make fiber reinforced composites. However, epoxy thermosets are brittle and typically possess a low fracture toughness that restricts their applications. One promising mechanism for improving mechanical properties of epoxy is the integration of micro- and nano-scale fillers. MXenes, a large family of 2D transition-metal carbides, carbonitrides, and nitrides, can be used to produce multifunctional polymer nanocomposites due to their excellent electrical, thermal, and mechanical properties. We employed density functional theory and coarse-grained molecular dynamics simulations to evaluate binding energy and microscopic mechanisms of fracture under uniaxial tension for MXene-epoxy composites. The simulation results were verified by manufacturing Ti3C2Tx MXene-epoxy composites and studying their structure and fracture surfaces. MXene-epoxy binding energies are largely unaffected by MXene type (Ti2CTx or Ti3C2Tx). Binding between Ti3C2Tx and epoxy becomes stronger with less hydrogen coverage of Ti3C2Tx surface due to increase in favorable electrostatic interactions. The Young's modulus of MXene-epoxy composites is greater compared to the neat epoxy which originates from stress transfer between the matrix and the nanofiller, the modulus linearly increases with the filler loading up to 1 vol %. At higher filler contents, the increase of the modulus is reduced due to filler aggregation. Void formation was detected near edges of the particles in MXene-epoxy composites under deformation from both experimental and simulation studies of the fracture surfaces. From these observations, we expect the MXene fillers to improve epoxy toughness and enhance its mechanical performance

Сравнительный анализ методов оценки конкурентоспособности организации

Материалы XIV Междунар. науч. конф. студентов, магистрантов, аспирантов и молодых ученых, Гомель, 13–14 мая 2021 г

High capacity silicon anodes enabled by MXene viscous aqueous ink

The ever-increasing demands for advanced lithium-ion batteries have greatly stimulated the quest for robust electrodes with a high areal capacity. Producing thick electrodes from a high-performance active material would maximize this parameter. However, above a critical thickness, solution-processed films typically encounter electrical/mechanical problems, limiting the achievable areal capacity and rate performance as a result. Herein, we show that two-dimensional titanium carbide or carbonitride nanosheets, known as MXenes, can be used as a conductive binder for silicon electrodes produced by a simple and scalable slurry-casting technique without the need of any other additives. The nanosheets form a continuous metallic network, enable fast charge transport and provide good mechanical reinforcement for the thick electrode (up to 450 µm). Consequently, very high areal capacity anodes (up to 23.3 mAh cm−2) have been demonstrated

Enhancement of Ti3C2 MXene Pseudocapacitance after Urea Intercalation Studied by Soft X ray Absorption Spectroscopy

MXenes have shown outstanding properties due to their highly active hydrophilic surfaces coupled with high metallic conductivity. Many applications rely on the intercalation between Ti3C2Tx Tx describes the OH, F and O surface terminations flakes by ions or molecules, which in turn might alter the Ti3C2Tx surface chemistry and electrochemical properties. In this work, we show that the capacitance, rate capability, and charge carrier kinetics in Ti3C2Tx MXene electrodes are remarkably enhanced after urea intercalation u Ti3C2Tx . In particular, the areal capacitance increased to 1100 mF cm2, which is 56 higher than that of pristine Ti3C2Tx electrodes. We attribute this dramatic improvement to changes in the Ti3C2Tx surface chemistry upon urea intercalation. The oxidation state and the oxygen bonding of individual Ti3C2Tx flakes before and after urea intercalation are probed by soft X ray absorption spectroscopy XAS at the Ti L and O K edges with 30 nm spatial resolution in vacuum. After urea intercalation, a higher Ti oxidation state is observed across the entire flake compared to pristine Ti3C2Tx. Additionally, in situ XAS of u Ti3C2Tx aqueous dispersions reveal a higher Ti oxidation similar to dry samples, while for pristine Ti3C2Tx the Ti atoms are significantly reduced in water compared to dry sample

Distinguishing electronic contributions of surface and sub-surface transition metal atoms in Ti-based MXenes

MXenes are a rapidly-expanding family of 2D transition metal carbides and nitrides that have attracted attention due to their excellent performance in applications ranging from energy storage to electromagnetic interference shielding. Numerous other electronic and magnetic properties have been computationally predicted, but not yet realized due to the experimental difficulty in obtaining uniform surface terminations (Tx), necessitating new design approaches for MXenes that are independent of surface terminations. In this study, we distinguished the contributions of surface and sub-surface Ti atoms to the electronic structure of four Ti-containing MXenes (Ti2CTx, Ti3C2Tx, Cr2TiC2Tx, and Mo2TiC2Tx) using soft x-ray absorption spectroscopy. For MXenes with no Ti atoms on the surface transition metal layers, such as Mo2TiC2Tx and Cr2TiC2Tx, our results show minimal changes in the spectral features between the parent MAX phase and its MXene. In contrast, for MXenes with surface Ti atoms, here Ti3C2Tx and Ti2CTx, the Ti L-edge spectra are significantly modified compared to their parent MAX phase compounds. First principles calculations provide similar trends in the partial density of states derived from surface and sub-surface Ti atoms, corroborating the spectroscopic measurements. These results reveal that electronic states derived from sub-surface M-site layers are largely unperturbed by the surface terminations, indicating a relatively short length scale over which the Tx terminations alter the nominal electron count associated with Ti atoms and suggesting that desired band features should be hosted by sub-surface M-sites that are electronically more robust than their surface M-site counterparts

Expanding frontiers in materials chemistry and physics with multiple anions

During the last century, inorganic oxide compounds laid foundations for materials synthesis, characterization, and technology translation by adding new functions into devices previously dominated by main-group element semiconductor compounds. Today, compounds with multiple anions beyond the single-oxide ion, such as oxyhalides and oxyhydrides, offer a new materials platform from which superior functionality may arise. Here we review the recent progress, status, and future prospects and challenges facing the development and deployment of mixed-anion compounds, focusing mainly on oxide-derived materials. We devote attention to the crucial roles that multiple anions play during synthesis, characterization, and in the physical properties of these materials. We discuss the opportunities enabled by recent advances in synthetic approaches for design of both local and overall structure, state-of-the-art characterization techniques to distinguish unique structural and chemical states, and chemical/physical properties emerging from the synergy of multiple anions for catalysis, energy conversion, and electronic materials