Two-Dimensional Mesoporous Materials for Energy Storage and Conversion: Current Status, Chemical Synthesis and Challenging Perspectives

Two-dimensional (2D) mesoporous materials (2DMMs), defined as 2D nanosheets with randomly dispersed or orderly aligned mesopores of 2-50 nm, can synergistically combine the fascinating merits of 2D materials and mesoporous materials, while overcoming their intrinsic shortcomings, e.g., easy self-stacking of 2D materials and long ion transport paths in bulk mesoporous materials. These unique features enable fast ion diffusion, large specific surface area, and enriched adsorption/reaction sites, thus offering a promising solution for designing high-performance electrode/catalyst materials for next-generation energy storage and conversion devices (ESCDs). Herein, we review recent advances of state-of-the-art 2DMMs for high-efficiency ESCDs, focusing on two different configurations of in-plane mesoporous nanosheets and sandwich-like mesoporous heterostructures. Firstly, a brief introduction is given to highlighting the structural advantages (e.g., tailored chemical composition, sheet configuration, and mesopore geometry) and key roles (e.g., active materials and functional additives) of 2DMMs for high-performance ESCDs. Secondly, the chemical synthesis strategies of 2DMMs are summarized, including template-free, 2D-template, mesopore-template, and 2D mesopore dual-template methods. Thirdly, the wide applications of 2DMMs in advanced supercapacitors, rechargeable batteries, and electrocatalysis are discussed, enlightening their intrinsic structure-property relationships. Finally, the future challenges and perspectives of 2DMMs in energy-related fields are presented.