Construction of Zeolite‐Type Metal Sulfide “Ion Sieve” Into Electrospun Membranes for Ultrafast and Selective 137 Cs + Sequestration

Abstract Selective 137 Cs + sequestration is challenging due to its high solubility, environmental mobility, and the influence of excessive competitive ions. Herein, we demonstrate an effective strategy for Cs + separation by constructing zeolite‐type metal sulfide as “cesium ion sieve” (CIS), obtaining GaGeS‐1 with “ion‐sieving effect”. Its structure features a zeolite‐type metal sulfide framework with sodalite (SOD) topology based on supertetrahedral T2 clusters. GaGeS‐1 with radiation resistance possesses a maximum Cs + adsorption capacity of 332.52 mg/g and ultrafast adsorption kinetics with removal rate ( R Cs ) of 97.06% within 1.5 min. It achieves highly selective Cs + capture under excessive competing ions, even for actual industrial 137 Cs⁺‐liquid‐waste ( R Cs > 90%). Single crystal structure analysis and density functional theory calculation reveal that “ion‐sieving” originates from strong Cs + ···S 2− interaction, flexible‐robust framework, and optimal Cs + coordination in SOD cage. Furthermore, GaGeS‐1 is integrated with gelatin to fabricate GaGeS‐1/Gel nanofibrous electrospun membranes for a multi‐stage filtration system, enabling efficient, continuous, and recyclable treatment of mixed Na/Cs wastewater (3.58 L/m 2 , R Cs = 99.39%) and Cs + ‐contaminated river water (2.63 L/m 2 , R Cs = 99.23%). This study pioneers an efficient “CIS” by developing zeolite‐type metal sulfide, and provides a universal assembly method toward practical application, opening new insight into radiocesium remediation and advanced nuclear waste management.