Bio-Inspired Dual-Gradient Aerogel Enables Sustainable Freshwater Production and Energy Harvesting.

Solar-driven interfacial evaporation and moisture-electricity generation offer promising routes to sustainable freshwater and energy production, yet their integration into a single water and electricity co-production system (WECPS) has remained largely unrealized. Here, we rationally design a dual-gradient aerogel (DGA) with engineered ion and water gradients that enables long-term salt-resistant solar evaporation alongside high-performance moisture-electricity generation. The ion gradient, created through asymmetric ion doping with two surfactants, drives directional ion diffusion to enhance electrical output, while the water gradient, arising from hydrophilicity differences and asymmetric porosity, sustains continuous water and ion transport and induces the Marangoni effect for uninterrupted evaporation. As a result, the DGA-based WECPS delivers power densities up to 324-fold higher than homogeneous aerogels and maintains stable solar evaporation for seven days in saline environments. An outdoor DGA-array WECPS further demonstrates simultaneous freshwater production and energy harvesting under real conditions. These findings establish a practical pathway toward efficient, self-sustaining water-energy co-production technologies.