Two-Dimensional Materials for Electrochemical Energy Storage, Thermal Energy Storage and Management, and Hydrogen Production and Storage

Two-dimensional (2D) materials combine atomic-scale thickness, open interfaces, and tunable electronic structures, but their practical value depends on whether nanoscale advantages survive processing, assembly, and operation. This review establishes a structure-interface-transport-stability (SITS) framework to compare 2D materials across electrochemical energy storage, thermal energy storage and management, and hydrogen production and storage. This review mainly covers advances since 2021, while retaining selected foundational references needed to establish key concepts, benchmark properties, and mechanistic context. Rather than cataloging materials by application, the analysis examines how common strategies—including thinning, defect engineering, interlayer expansion, functionalization, and heterostructure construction—alter the transport of electrons, ions, phonons, H*, molecular H2, and atomic hydrogen in hydrides. Cross-field comparison reveals a recurring trade-off: strategies that improve site accessibility or local transport often reduce density, increase interfacial resistance, or compromise stability. The central bottleneck is therefore the translation of favorable material-level metrics into reproducible device- and system-level performance. The review identifies 2D materials as most effective when they regulate critical interfaces, sustain continuous transport networks, or integrate complementary functions, and outlines priorities in scalable synthesis, operando validation, multiphysics modeling, and sustainable manufacturing.