Graphitic Carbon Nitride‐Based Composites for Advanced Thermal Management: From Passive Fillers to Active Multifunctional Platforms

Advanced thermal management increasingly requires materials capable of not only dissipating heat but also regulating, converting, and storing thermal energy. Graphitic carbon nitride (g‐C 3 N 4 ), a two‐dimensional polymeric semiconductor, has emerged as a promising platform for next‐generation thermal management materials (TMMs), owing to its moderate intrinsic thermal conductivity, high thermal stability, facile functionalization, and low cost. Crucially, g‐C 3 N 4 nanosheets act as an active regulator of phonon transport and interfacial coupling, rather than serving as simple passive fillers. Despite these attributes, a comprehensive and up‐to‐date assessment of this field remains lacking. Herein, this review outlines the synthetic strategies from different dimensionalities and then establishes a design paradigm for g‐C 3 N 4 ‐based composites that integrates structure, interface, and function. By coupling dimensional and pathway engineering with interfacial regulation, g‐C 3 N 4 enables the construction of efficient phonon transport networks while simultaneously minimizing interfacial thermal resistance. More importantly, these same structural and electronic characteristics form multifunctional capabilities, including electromagnetic interference shielding, thermoelectric conversion, flame retardancy, and photothermal energy harvesting and storage, thereby extending thermal management from passive heat dissipation to active energy regulation. Overall, this review presentsg‐C 3 N 4 as a versatile and active enabler for designing next‐generation multifunctional TMMs.