Plant-leaf-inspired MXene-silk composite for intelligent solar steam generation combined with mechanical actuation

Solar steam generators based on photothermal materials are important in producing fresh water. However, conventional solar steam generators are difficult to self-adapt to the complex external environment as organisms. Herein, inspired by the plant leaf, we propose a photothermal composite based on MXene and silk to add more functionality. On one hand, the composite achieves an evaporation rate of 1.51 kg·m⁻²·h⁻¹ and a conversion efficiency of 86.9% under a solar intensity of 1 kW·m⁻², mimicking the water transpiration of plant leaf. On the other hand, the MXene-silk-based actuator shows a maximum bending curvature of 0.91 cm⁻¹ under a solar intensity of 5 kW·m⁻². Furthermore, an intelligent solar system is constructed utilizing the synergy of solar steam generator and actuator, which advances the research from the material level to the system level. Mimicking the behavior of plant leaf, the system can automatically open during the day to generate steam and fresh water. And at night or in bad weather, it will automatically close to prevent external pollution such as dust, achieving intelligent anti-fouling. This research will have good application prospects in less developed areas. Meanwhile, it also provides a certain reference value for exploring multi-functional photothermal devices in the future.