Janus Dual Self‐Strengthening Structure of Bi2O3/Gd2O3 Nanofibrous Membranes for Superior X‐Ray Shielding

Abstract Bi 2 O 3 /rare earth oxide biphasic absorbers are attractive for high‐efficiency X‐ray shielding due to the complementary X‐ray absorption effects. However, its application is severely hindered by poor interphasic contact. Here, a new Janus interface engineering strategy is reported for the construction of continuous and flexible Bi 2 O 3 /Gd 2 O 3 crystal nanofibrous membranes (FJNMs) with micro/nano dual self‐strengthening interphasic adhesion. This strategy facilitates online micro‐interlocking between Bi 2 O 3 /Gd 2 O 3 nanofibers and in situ nano‐grain fusion between Bi 2 O 3 /Gd 2 O 3 crystals, significantly enhancing the adhesive strength at the Bi 2 O 3 /Gd 2 O 3 interface. Additionally, the synergistic shielding effect from Bi 2 O 3 /Gd 2 O 3 absorption and multiple reflections in Bi 2 O 3 and Gd 2 O 3 crystal lattices make the nanofibrous membranes a superior X‐ray radiation barrier. The FJNMs demonstrate integrated features of exceptional X‐ray shielding efficiency (91%–100%), robust interfacial adhesion (lap‐shear strength >3.8 MPa), prominent flexibility, lightweight, and outstanding breathability. The design concepts of fibrosing biphasic absorber assemblies pave the way for asymmetrically assembling biphasic materials, setting the stage for a fundamental shift in next‐generation radiation shielding materials.