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

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 SnS₄ tetrahedra within Sn₂S₆ dimers into distorted Sn₃S₄ broken-cube clusters, yielding a [Sn₃S₇]_n ^2n- layered geometry. Cerium oxidation states, particularly Ce³⁺ 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.