Recent developments involving MXenes to create robust, flexible, and incredibly effective electrolytic energy storage devices powered by supercapacitors have been discussed in the latest research published in Coordination Chemistry Reviews.
Study: MXene based emerging materials for supercapacitor applications: Recent advances, challenges, and future perspectives. Image Credit: Vektor illustration/Shutterstock.com
Advantages and Progress of 2D Materials
The unique features and huge applicability of two-dimensional (2D) revolutionary material graphene led to the identification of a variety of 2D materials with properties and uses comparable to graphene. Single-layered graphene, for example, demonstrated better conductance at room temperature while transmitting 97.7 percent of light waves, making it the most researched 2D material.
The advanced features and uses of 2D structures are due to their greater effective surface area and enhanced quantum hall effect. These fascinating features and uses prompted the development of additional 2D materials such as covalent organic frameworks (COFs), transition metal dichalcogenides (TMDs), metal-organic frameworks (MOFs), metal oxides, and hydroxides.
The unique electrical framework, substantial effective surface region, high surface to volume ratio, flexibility, structurally thinner layering, and mechanical strain tolerance of 2D materials make them more desirable than bulk materials.
What are MXenes?
The exceptional qualities of 2D materials resulted in the development of another 2D novel material, MXene, ushering in a new era in nanotechnology and materials engineering.
MXenes are a series of stacked transition metal carbides, nitrides, or carbonitrides that have been selectively etched from their respective primary MAX forms. MAX substance phase, the predecessor of MXene, has the molecular formula Mn+1AXn (n = 1 to 4), where M is an initial transition metallic element, A is an element from groups 13-15 of the periodic table, and X is the carbide or the nitride group.
An essential part of its composition is the surface termination functional groups produced due to the electrochemical etching fabrication method. It is also primarily responsible for the hydrophilic nature of the material. The interface termination units also affect MXene's electrical and ion transport characteristics, which affect its conductance.
Utilization of MXene Material
Owing to their unusual integration of metal and ceramic qualities, they have been widely employed in a variety of applications.
MXenes have strong metallic conductance, outstanding thermal permeability, great tensile stability, amazing optical characteristics, exquisite electric and magnetic characteristics, exceptional wettability, and intercalation capabilities due to their excellent surface properties.
MXenes' distinctive properties and ease of fabrication have made them an appropriate choice for a plethora of different applications in different fields such as treating wastewater, biosensing, photocatalysis, modern electronics, and power conversion implementations.
Synthesis Processes of MXene
The fabrication of thin layered MXenes may be divided into two types: top-down and bottom-up approaches. Layers of MXene screens are passivated from their MAX phase/non-MAX phase predecessors in the top-down technique, and diverse materials are mixed to generate MXene nanostructured thin films in the bottom-up method. The key criterion for obtaining a 2D structure from its comparable 3D version is to diminish the 3D structure's interfacial linkages.
Factors Affecting MXene-based Supercapacitor Performance
The fabrication process is the most important factor as it plays a vital role in determining the inherent characteristics.
Processes that allow increased interlayer space allows for greater ion deposition and electrolyte penetration, which can aid in boosting energy density. The electrochemical properties of MXene-based supercapacitors also vary depending on the MXene antecedents utilized for synthesis. Furthermore, the dimensions of the MXene particles are very important.
MXenes with lower lateral sizes decrease the ion diffusion channel, rendering ion electrolytes more approachable to the electrode surface and, as a result, improving electrochemical properties. By changing the electrolytes, the efficiency of supercapacitors may be altered. MXene's interlayer gap is increased by the appropriate electrolyte.
Challenges and Future Perspective
MXenes have various limitations; thus further study is needed to combat these issues and make them more widely usable.
For the transfer of MXene from lab to industrial scale, the accessibility of antecedents, manufacturing costs, efficient production processes, safety, and environmental implications must all be considered. Although much effort has been done to enhance the productivity of MXene-based supercapacitors, further research is needed to develop translucent, versatile, downsized, and low-cost devices with higher electrochemical performance and structural strength.
Additionally, discovering eco-friendly etchants for their synthesis at a cheaper cost and efficiently without compromising performance has piqued the scientific community's attention. In short, much research is needed in areas such as novel electrode design for superconductors to successfully implement this technology on a worldwide scale.
Panda S. et. al. (2022) MXene based emerging materials for supercapacitor applications: Recent advances, challenges, and future perspectives. Coordination Chemistry Reviews. 462(1). 214518. Available at: https://www.sciencedirect.com/science/article/pii/S0010854522001138