Gradient-Maintaining Water-Water Interfaces Generate Ordered Mineral Architectures with Nanofluidic Functions

Understanding how ordered structures emerge in chemically complex environments remains a central challenge in chemistry. Although chemical gradients impose directionality in aqueous systems, it remains unclear whether such gradients can drive self-organization in compositionally diverse seawater. Here we show that gradientmaintaining water-water interfaces, designed to reproduce seawater-hydrothermal fluid interactions, convert chemical gradients into ordered mineral architectures through diffusiophoresis. Using a microfluidic platform, we demonstrate that sustained ionic gradients align brucite nanocrystals into vent-like structures with unidirectional, periodic, and radial patterns. These mineral architectures function as nanofluidic systems and enable osmotic energy conversion. Increasing the NaCl gradient further enhances structural alignment and diffusion potentials, directly linking chemical gradients to structural order and function. These results identify the gradient-driven electric fields established at water-water interfaces as essential for translating chemical gradients into structural order and function, redefining seawater not merely as a solvent but as a source of self-organization.