Engineering in‐plane porosity in <scp>MXenes</scp> for energy storage: Correlating synthesis strategies with pore structure control

Abstract MXenes have attracted significant attention as next‐generation energy storage materials owing to their excellent physicochemical properties. Nevertheless, severe self‐stacking of MXene nanosheets substantially compromises their electrochemical performance and has emerged as a bottleneck issue in energy storage applications. Pore engineering is recognized as an effective approach to address this issue, including out‐of‐plane and in‐plane pores. Contrary to out‐of‐plane pore creation, which commonly employs physical or chemical modulation for pore formation as interlayer gaps or channel structures between adjacent nanosheets, in‐plane pore creation involves constructing nanoscale pore structures directly on MXene nanosheets, enabling simultaneous improvement of ion diffusion without compromising high packing density. However, the physicochemical properties of MXenes vary depending on their synthesis methods, thus requiring tailored in‐plane pore construction strategies. This review emphasizes the relatively underexplored area of in‐plane pore construction, systematically classifying and evaluating various strategies while elucidating the structure‐performance relationships. Furthermore, we identify key challenges in the scalable fabrication of porous MXenes, providing insightful perspectives for future research directions toward practical energy storage applications. image