Antibacterial evaporator based on reduced graphene oxide/polypyrrole aerogel for solar-driven desalination

Solar-driven water evaporation is a sustainable method to purify seawater. Nevertheless, traditional volumetric water-evaporation systems suffer from the poor sunlight absorption and inefficient light-to-thermal conversion. Also, their anti-bacterial and anti-fouling performances are crucial for the practical application. Herein, we introduce reduced graphene oxide (RGO) with broadband absorbance across the entire solar spectrum, and polypyrrole (PPy), an antibacterial polymer with efficient solar absorption and low thermal conductivity, to develop integrated RGO/PPy aerogel as both the solar absorber and evaporator for highly efficient solar-driven steam generation. As a result, the RGO/PPy aerogel shows strong absorption and good photothermal performance, leading to an evaporation rate of 1.44 kg·m⁻²·h⁻¹ and high salt rejection (up to 99.99%) for real seawater, with photothermal conversion efficiency > 90% under one sun irradiation. The result is attributed to the localized heat at the air–water interface by the RGO/PPy and its porous nature with functional groups that facilitates the water evaporation. Moreover, the RGO/PPy demonstrates excellent durability and antibacterial efficiency close to 100% for 12 h, crucial characteristics for long-term application. Our well-designed RGO/PPy aerogel with efficient water desalination performance and antibacterial property provides a straightforward approach to improve the solar-driven evaporation performance by multifunctional materials integration, and offers a viable route towards practical seawater desalination.