Topological anionic confinement enables synthesis of 2D high-entropy molybdates under mild conditions

Abstract

Two-dimensional high-entropy materials offer vast opportunities, yet their low-temperature synthesis with compositional homogeneity and anisotropic morphology remains challenging, due to thermodynamic competition between entropy-driven mixing and strain-induced phase segregation. Here we report a topological anionic confinement strategy that uses MoO42− tetrahedra as spatially defined scaffolds to suppress cation segregation. This strategy enables the single-step, template-free synthesis of a series of two-dimensional high-entropy molybdate assemblies (M3(MoO4)4·4H2O, M = Mn, Fe, Co, Ni, Cu or Zn) at 120 °C. In situ liquid-phase transmission electron microscopy unveils a non-classical crystallization pathway, where metastable clusters undergo a dissolution–regrowth process for compositional homogenization before coalescing via oriented attachment into well-defined nanoplates, a process critically modulated by interfacial energy. This work not only provides a solution to a long-standing synthetic bottleneck but also establishes topological anionic confinement as a versatile method for entropy-stabilized anisotropic nanomaterial design under mild conditions, opening new avenues for diverse functional applications. Two-dimensional high-entropy materials are of interest for diverse applications, but low-temperature synthesis remains challenging. Now a topological anionic confinement strategy is reported in which MoO42⁻ tetrahedral scaffolds template two-dimensional high-entropy molybdates at 120 °C. Metastable clusters homogenize via a dissolution–regrowth process and then coalesce into well-defined nanoplates.