Integrating spacers (0D, 1D, 2D, 3D) into 2D MXenes for enhanced energy storage and conversion applications

The phenomenon of two-dimensional (2D) MXene layered nanosheets exhibiting a propensity to restack or aggregate can be attributed to the significant influence of strong Van der Waals forces in conjunction with hydrogen bonding interactions. Notably, 2D MXenes exhibit adjustable compositions, adaptable structural configurations, and varied surface chemistries that can be seamlessly integrated with supplementary spacer components to eliminate the dead volume by enlarging the stacked 2D layers. Promoting the development of spacer elements and incorporating them into 2D MXenes smartly, starting from 0 to 1 to 2 to 3 dimensions, may effectively tackle the previously mentioned challenges. It is crucial and timely to summarize the recent contributions made on the spacers (0D-like carbon dots (CDs), quantum dots (QDs), etc., 1D-like nanotubes, nanowires, etc., 2D graphene/dichalcogenides-related materials, etc., 3D cube, nanoflower-shaped, large metal-organic frameworks (MOFs), etc.) integrations in a review article to the various 2D MXene families, working mechanisms, microstructure, and electrochemical performances for energy conversion and storage-related applications. In addition, we provided comprehensive recommendations and prospects for future research directions, encompassing both computational and experimental findings on 0-3D spacer nanomaterials for versatile 2D MXene layer engineering and their multifunctional applications.