MXenes for Energy Harvesting and Storage Applications

The demand for new energy resources is increasing daily due to modernization and population growth. The traditional fossil fuel reservoirs are diminishing due to overutilization, which creates unavoidable issues of global warming. To overcome these issues, energy generation from natural and renewable energy sources is explored. The present chapter emphasizes on hydrogen fuel produced from water as a green source of fuel and the development of energy storage devices (supercapacitors and batteries). Developing a suitable non-noble electrocatalyst is highly required to scale up hydrogen production and lower the cost of the water electrolyzers. Concurrently, highly efficient and stable electrode materials are needed to improve the energy charge capacity of supercapacitors and batteries. A new class of 2D materials, ‘MXenes,’ attained special interest as both electrocatalysts and electrode materials due to their exceptional chemical and physical features. The layered structure (higher layer spacing) and the presence of the functional groups on the surface enhance their electrochemical properties. The role of the synthesis procedures modifying the surface characteristics of MXenes to improve the electrochemical water-splitting ability is highlighted. Moreover, the modulation of the spacing between the MXene layers and attached functional groups influences the intercalation/de-intercalation process for improved charge storage performance in supercapacitors and batteries. Different MXene species developed so far are compared regarding the water-splitting performance and energy storage (supercapacitors and batteries) abilities, respectively. The developed materials show a promising potential to replace the costly noble metals in energy production and storage for sustainable development.