Janus cellulose nanofiber foam-based flexible triboelectric nanogenerator for wearables

Triboelectric nanogenerators (TENGs) are widely applied in wearable electronics due to their self-powered sensing capability for real-time monitoring of human physiological and motion states. However, reconciling superior mechanical properties with high-efficiency triboelectric output remains a key challenge. Herein, a Janus-structured cellulose nanofiber (CNF) positive triboelectric foam is fabricated via a dual-layer integration strategy. Its Janus asymmetric structure simultaneously integrates exceptional electrical output performance and remarkable mechanical properties. Owing to huge surface potential difference caused by Janus asymmetric structure, yields a strong built-in electric field within the foam, boosting charge transfer, achieving enhanced TENG output performance with open-circuit voltage (V_OC) of 108 V and short-circuit current (I_SC) of 1.35 μA. Compared with original CNF foam-based TENG, the Janus CNF foam-based TENG exhibits 309% and 650% enhancement in V_OC and I_SC, respectively. Benefiting from the asymmetric pore distribution, the material effectively provides abundant stress transfer pathways, resulting in an improved tensile strength of 1.38 MPa, which shows a 1050% enhancement compared with that of the pure CNF foam. Furthermore, TENG integrated by such flexible Janus foam material provides a promising reference for the construction of high-performance, stable energy harvesting and conversion devices.