Synthesis and processing of two-dimensional nitride MXenes for electrocatalysis and energy storage

Two-dimensional (2D) transition metal nitride MXenes have been explored as promising alternatives to the widely used titanium carbide MXene for electronic and energy systems because of their unique electrochemical and catalytic properties. However, scalable production of nitride MXenes has been limited by the intrinsically weak transition metal nitride bonding, which significantly deteriorates the quality of crystals and transport pathways, affecting tunable electrochemical properties. This review provides a comprehensive overview of the underlying formation of layered solids and the recent advances in etching techniques to gain key insights into the exfoliation of single- to few-layer nitride MXenes. Subsequently, solution-processable utilization and modifications of 2D flakes for energy conversion and storage fields are introduced, comparing the novel performance related to electronegative nitrogen with that of conventional carbide MXenes. Finally, future research directions for large-scale preparation and stabilization strategies are proposed, along with previously reported synthesis routes of carbide MXenes, to encourage advances in the field of 2D MXenes and expand their boundaries for various stoichiometric compositions and applications.