All‐Scale Structural Optimization of Resiliently Crystalline Na–Ce–Sn–S Chalcogel for Efficient Oxygen Evolution Reaction Electrocatalyst

Abstract The metal cation linker in metathesis‐derived chalcogels critically governs structural evolution, porosity, and resultant physicochemical properties. However, most studies have emphasized atomic‐scale functionality of metal linker within chalcogel network, with limited attention to local structural transformation and even long‐range ordering. This work demonstrates the unprecedented role of cerium ions in directing the formation of a sustainable 2D crystalline Ce–Sn–S (CTS) chalcogel. The crystalline framework arises from coordination transformation of SnS 4 tetrahedra within Sn 2 S 6 dimers into distorted Sn 3 S 4 broken‐cube clusters, yielding a [Sn 3 S 7 ] n 2n− layered geometry. Cerium oxidation states, particularly Ce 3+ enrichment, further stabilize the crystalline network via a templating effect and enhance electrocatalytic activity. The optimized CTS‐5 chalcogel exhibits superior oxygen evolution reaction performance, including a low overpotential of 300 mV at 10 mA cm −2 , the lowest Tafel slope of 80 mV dec −1 , and stable operation for 50 h at 10 mA cm −2 . The crystalline CTS chalcogel represents a new class of aerogel materials, where robust 2D crystallinity persists even under high cation loading, enabling functional tunability without compromising network integrity.