Browsing by Author "Nemani, Kartik"

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    Elucidating the Chemical Order and Disorder in High-Entropy MXenes: A High-Throughput Survey of the Atomic Configurations in TiVNbMoC3 and TiVCrMoC3
    (American Chemical Society, 2022) Leong, Zhidong; Jin, Hongmei; Wong, Zicong Marvin; Nemani, Kartik; Anasori, Babak; Tan, Teck Leong; Mechanical and Energy Engineering, Purdue School of Engineering and Technology
    Expanding the MXene design space from ordered and random double-transition-metal (DTM) MXenes to include high-entropy (HE) MXenes with four or more principal elements enables a powerful approach for enhancing MXene properties. While many DTM MXenes possess unique structures that strongly influence material properties, HE MXenes are largely unknown because they are only recently synthesized. Since certain combinations of transition metals (TMs), e.g., Mo-Ti and Cr-Ti, lead to ordered DTM MXene phases, where Mo/Cr atoms occupy the outer TM layers and Ti atoms occupy the inner layers, it is critical to investigate any possibilities of TM segregation in the atomic layers of HE MXenes. Therefore, we present a high-throughput first-principles study of the atomic configurations of two recently synthesized HE M4C3 MXenes: TiVNbMoC3 and TiVCrMoC3. Combining density functional theory, cluster expansion, and Monte Carlo simulations, we predict a unique preferential occupancy of the TM atoms in the four layers within the single-phase HE MXenes, even at temperatures as high as 2900 K. Across a wide compositional range, the outer (inner) layers are predominantly occupied by two of the four TM elements, with Cr most preferentially occupying the outer layers, followed by Mo, V, Nb, and Ti. The strong compositional dependence of the interlayer segregation highlights the HE MXenes’ tunability. Within each TM layer, the atoms largely form a solid solution, with a tendency for Nb-V separation at lower temperatures. Our results elucidate the chemical order and disorder in HE MXenes, guiding experiments in designing MXenes with enhanced properties within the huge compositional space.
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    Ti3C2Tx MXene Polymer Composites for Anticorrosion: An Overview and Perspective
    (American Chemical Society, 2022) Amin, Ihsan; van den Brekel, Hidde; Nemani, Kartik; Batyrev, Erdni; de Vooys, Arnoud; van der Weijde, Hans; Anasori, Babak; Shiju, N. Raveendran; Mechanical and Energy Engineering, School of Engineering and Technology
    As the most studied two-dimensional (2D) material from the MXene family, Ti3C2Tx has constantly gained interest from academia and industry. Ti3C2Tx 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 Ti3C2Tx MXene make it a promising material for anticorrosion coatings. While there are many reviews on Ti3C2Tx 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 Ti3C2Tx polymer composites for anticorrosion. We also provide an outlook and discussion on possible ways to improve the exploitation of Ti3C2Tx polymer composites as anticorrosive materials. Finally, we provide a perspective beyond Ti3C2Tx MXene composition for the development of future anticorrosion coatings.