Dual mode switchable Janus Nano-ZnO/rGO cellulose fabric with radiative regulation and sweat transport for personal thermal management

Global energy demands and climate change challenges have highlighted the need for sustainable and energy-efficient solutions, driving interest in personal thermal management (PTM) technologies. Traditional PTM systems, however, rely on unidirectional thermal regulation, limiting their adaptability to fluctuating ambient conditions and humidity gradients. To overcome these limitations, we engineered a Janus Nano-ZnO/rGO nonwoven fabric (NZr@NF) that combines dynamic bidirectional thermal regulation with unidirectional sweat transport. The cooling side, featuring in situ grown Nano-ZnO layers, achieved high solar reflectance (88.49 %) and infrared emittance (94.20 %), allowing for net radiative cooling power of up to 100.38 W·m −2 . The heating side, functionalized with PDMS@rGO composites, demonstrated remarkable solar absorptance (94.86 %). Compared with the raw fabric, outdoor measurements demonstrated that it achieved an additional cooling effect of 6.27 °C and an additional heating effect of 17.1 °C. This Janus NZr@NF also excelled in moisture-wicking, achieving a cumulative one-way moisture transport index of 442.1 %, effectively mitigating post-sweat discomfort by facilitating evaporation and heat dissipation. With its ultraviolet (UV) resistance, breathability, and moisture permeability, this multifunctional metamaterial provides an innovative direction for wearable energy-saving PTM fabrics.