In recent years, new types of materials have been discovered with unique properties, in particular two-dimensional (2D) materials. Working with 2D materials is difficult as in their purest form they consist of only a sheet of atoms, one layer thick. This makes analysis a delicate matter, with the use of low energy techniques necessary to prevent degradation and damage. When analyzing 2D materials, the most important considerations are the chemistry, assessment of surface contamination, and the confirmation of the structure. 2D materials, such as hexagonal boron nitrides, transition metal dichalcogenides (TMDs), metal oxides, and hydroxides, have attracted much renewed attention. A new, potentially large category of early transition metal carbides and/or carbonitrides called ¿MXenes¿ has recently been added to the constellation of 2D materials. MXene sheets are a type of material made up of MAX phases, which have the general formula M(n+1)AX(n), where `M¿ is an early transition metal, `A¿ is an A-group element, and `X¿ is either carbon or nitrogen. MXene nanosheets structure will be made by etching the `A¿ group element out of MAX phase.
Our goal is to achieve a 2D MXene multilayer nanosheet structure by synthesizing 2D bulk MAX phases using chemical etching techniques and other useful processes. In order to tailor their properties, we will dope MXene by low cost & easy synthesizing methods. We will introduce Rare Earth elements as dopants so to study the effect of doping on bandgap, optical, electrical, chemical, and magnetic properties. We will study their electronic surface structure, stoichiometry and chemical bonding via X-ray photoelectron spectroscopy. Our ultimate focus will be to utilize our synthesized materials as electrodes or electrolytes in energy storage applications such as batteries. The need of the era is to develop materials that can be utilized in energy storage devices, and nanomaterials are increasing significantly in this field's development.
Over the last few years, research into next-generation battery technology (beyond Li-ion batteries, or LIBs) has increased. A key challenge for these emerging batteries has been the lack of suitable electrode materials, which severely limits their further developments. MXenes, a new class of 2D transition metal carbides, carbonitrides, and nitrides [1] are proposed as electrode materials for these emerging batteries due to several desirable attributes [2, 3]. LIBs have been widely used in the field of portable electric devices due to their high energy density and good cycling performance. To further improve the performance of LIBs, it is of great importance to develop new electrode materials. [3, 7, 8]. MXenes are attractive not just as electrode materials but also as other components in developing battery cells due to their vast and tunable interlayer gaps, outstanding hydrophilicity, remarkable conductivity, compositional diversity, and numerous surface chemistries. The synthesis processes and characteristics of MXenes that enable MXenes to perform a multiple role in these future batteries, including electrodes, metal anode protection layers, sulfur hosts, separator modification layers, and conductive additives, will be explored. Furthermore, a view of possible future research approaches on MXenes and MXene-based materials will be discussed, ranging from material design and processing to fundamental understanding of reaction mechanisms and device performance optimization methodologies. Nevertheless, the investigations on MXenes for other technologies beyond LIBs are rapidly developing and great progress has been achieved very recently [4-6].
This project aims at developing new synthesis routes for growing high-quality 2D MXenes and to dope them, as also to use a variety of advanced techniques available at Sapienza, to determine their structural and electronic properties. Through the proposed investigation, we will develop national and international collaborations so that students can benefit from state-of-the-art laboratories across the world and benefit from the experience of interacting with world-renowned researchers. This project will not only embellishment the skills of students by providing training and hands-on-experience in state-of-the-art equipment but will also help in exploring new smart materials as an alternative to conventional battery electrodes.
References:
1. Naguib, M., et al., Two-dimensional transition metal carbides. ACS nano, 2012. 6(2): p. 1322-1331.
2. Naguib, M., et al., MXene: a promising transition metal carbide anode for lithium-ion batteries. Electrochemistry Communications, 2012. 16(1): p. 61-64.
3. Tang, H., et al., MXene¿2D layered electrode materials for energy storage. Progress in Natural Science: Materials International, 2018. 28(2): p. 133-147.
4. Ming, F., et al., MXenes for Rechargeable Batteries Beyond the Lithium¿Ion. Advanced Materials, 2021. 33(1): p. 2004039.
5. Das, P. and Z.-S. Wu, MXene for energy storage: present status and future perspectives. Journal of Physics: Energy, 2020. 2(3): p. 032004.
6. Wang, Z. A Review on MXene: Synthesis, Properties and Applications on Alkali Metal Ion Batteries. in IOP Conference Series: Earth and Environmental Science. 2021. IOP Publishing.
7. Lei, J.-C., X. Zhang, and Z. Zhou, Recent advances in MXene: Preparation, properties, and applications. Frontiers of Physics, 2015. 10(3): p. 276-286.
8. Naguib, M., et al., New two-dimensional niobium and vanadium carbides as promising materials for Li-ion batteries. Journal of the American Chemical Society, 2013. 135(43): p. 15966-15969.