Elephant‐Skin‐Inspired Porous Cementitious Tiles with Programmable Crack Networks for Passive Cooling

Abstract

ABSTRACT Passive evaporation of water reduces a building's cooling energy demand. However, water is often wasted due to rebound, uneven spreading, and rapid drainage. Here, we present an elephant‐skin‐inspired crack network architecture in porous diatomaceous earth (DE)‐cement composites to capture, route, and store water with minimal runoff. DE's micro/nanoporosity enables ultrafast (sub‐50 ms) water imbibition, while crack networks act as capillary conduits that redistribute water across and up inclined surfaces. Substrate‐guided stress concentration converts drying‐induced stochastic fractures into deterministic crack lattices that route and retain water on inclined surfaces, enabling geometry‐tunable, water‐efficient evaporative cooling. Tiles of hexagonal lattices with intermediate crack density maximize lateral redistribution and delay drainage. Infrared imaging reveals edge‐dominated evaporation, sustaining prolonged cooling. In a mockup home model covered with DE‐cement tiles, under repeated water dosing and IR heating, the temperature beneath the DE‐cement tiles is maintained at ∼32°C vs ∼42°C and ∼52°C for cracked and non‐cracked commercial stucco, respectively. The study offers a simple, scalable route for passive cooling.