Solar driven cogeneration of freshwater and electricity based on Al2O3 nanoparticles decorated graphene aerogel

The combination of solar water evaporation and hydrovoltaic effect (HVE) provides an effective way to solve the crisis of water shortage and fossil fuel pollution. However, they are still facing challenges of the low output power, slow water evaporation, and high salt accumulation. Here, we design a three-dimensional (3D) Al2O3-decorated graphene aerogel (AGA) that can effectively collect fresh water and electricity simultaneously. The AGA prepared by freeze-drying method has vertical channels, a loose porous structure, and strong hydrophilicity. Moreover, the hydrated ions introduced by Al2O3 lead to strong zeta potential in the channel, thereby resulting in excellent electricity generation capacity. In seawater, the water evaporation performance reaches 3.03 kg m−2 h−1, meanwhile the maximum output voltage is about 0.76 V with output electrical power density reaching 38 mW·m−2.