All‐Weather Adaptable Non‐Woven Janus Graphene Fibers with Asymmetric Wettability, Reliable Flame Retardancy and Synergistic Evaporative Cooling‐Ultrafast Joule Heating

ABSTRACT Against the backdrop of drastic global climatic change, personal thermal management (PTM) textiles have emerged as a critical safeguard for human comfort and safety. However, the inherent trade‐off between moisture management and active heating functionality significantly impedes their widespread application. Herein, a flexible Janus graphene fiber fabric (J‐GFF) was fabricated via wet spinning, selective filtration, Ca ²⁺ ‐induced fiber fusion, and floating polymer modification strategies. By tailoring the interfacial fusion degree and surface treatment, J‐GFF exhibited an excellent water vapor transmission (WVT) rate of 233.5 g m ⁻² h ⁻¹ and superior evaporative cooling performance, benefiting from the formed hierarchical structures and adjusted wetting behavior. Thus, when the J‐GFF was used as artificial wearable textiles, the temperature of the human skin surface decreased by 4.5°C under normal conditions, and even up to 14°C under heavy perspiration. Moreover, the produced fabric demonstrated extraordinary heating efficiency and flame retardancy, where fabrics could be heated to 175°C at a high heating rate of 690°C s ⁻¹ to withstand ∼500°C firing for over 15 s. Thus, this work offers a novel avenue for developing next‐generation all‐weather and multifunctional PTM textiles with evaporative cooling, breathability, mechanical durability, and Joule heating and safety.