Coaxially wet-spun MXene@alginate core-shell fibers with high conductivity for solar/electrothermal conversion and triboelectric sensing

Flexible fiber electrodes have attracted considerable attention for wearable electronics and biological tissue engineering. However, simultaneously achieving high electrical conductivity, mechanical robustness, and multifunctionality remains a significant challenge because conductive materials generally exhibit limited stretchability, while most functional nanomaterials are intrinsically brittle. Here, we construct coaxial wet-spun core-shell composite fibers (MXene@sodium alginate/cellulose nanocrystal/glycerol [MX@SCG]) with a sodium alginate/cellulose nanocrystal/glycerol supporting core and a conductive outer MXene sheath. The flexible sodium alginate matrix offers mechanical protection for fragile MXene nanosheets, endowing fibers with a conductivity of 1,852 S/cm and tensile strength of up to 149 MPa. Such fibers deliver electrothermal conversion performance and visible thermochromic color switching and can be woven into single-electrode triboelectric nanogenerators.