Emergence of Voronoi-Patterned Cellular Membranes via Confinement Transformation of Self-Assembled Metal-Organic Frameworks.

The self-assembly of nanoparticles allows the fabrication of complex, nature-inspired architectures. Among these, Voronoi tessellations─intricate patterns found in many natural systems such as insect wings and plant tissues─have broad implications across materials science, biology, and geography. However, replicating these irregular yet organized features at the nanoscale through nanoparticle self-assembly remains challenging. Here, we introduce a confinement transformation method to generate two-dimensional (2D) Voronoi patterns by converting metal-organic frameworks, specifically zeolitic imidazolate framework-8 (ZIF-8), into layered hydroxides. The process begins with the self-assembly of ZIF-8 particles into densely packed monolayers at the liquid-air interface, driven by the Marangoni effect. Subsequent Ni2+-induced etching converts the floating ZIF-8 monolayer into a freestanding membrane composed of interconnected polygonal cells, closely resembling the geometric characteristics of Voronoi tessellations. We systematically investigate the parameters affecting the transformation of ZIF-8 particles, shedding light on the mechanism governing Voronoi pattern formation. Mechanical testing and simulations demonstrate that the resulting cellular membranes exhibit enhanced stress distribution and crack resistance, attributed to their Voronoi-patterned architecture. These robust, monolithic membranes composed of Ni-based hydroxides, when serving as catalyst support materials, can synergistically enhance the intrinsic activity of Pt catalysts for alkaline hydrogen evolution reaction by facilitating water dissociation. This work presents a promising approach for creating nature-inspired materials with optimal stress management, superior mechanical properties, and potential catalytic applications.