Biomimetic 3D Membranes with MXene Heterostructures for Superior Solar Steam Generation, Water Treatment, and Electricity Generation

2D MXene materials have shown great potential in photothermal conversion, especially for solar steam generation. However, the obvious light losses at the liquid−solid interfaces still limit its broad applications, thereby resulting in a poor light absorption ability. To this end, a facile and general approach is designed for the construction of nanoflower MXene@MoS2 with excellent photothermal conversion ability via one‐step hydrothermal process. Thanks to the multireflective and synergestic effects between MXene and MoS2, the hierarchical MXene@MoS2 heterostructure exhibits broadband light absorption and improved photothermal conversion capacity (69 °C after 10 min solar illumination). Furthermore, inspired by the water vapor process in multiple channels of trees, an ultrathin MXene@MoS2‐based nanofibrous membrane is assembled via directional electrospinning technology. Compared with traditional irregular channels, the controllable and tree‐inspired 3D structure shows competitive advantages in solar absorption and water transport. Thus, the as‐prepared self‐floating membrane presents durable hydrophobicity (contact angle [CA] = 125°) and a high evaporation rate of 1.39 kg/(m2h) (91% efficiency) under 1 sun, which is higher than reported. This 3D MXene‐based device also shows promising electrical generation, solar‐driven sewage, and desalination treatments (99% desalination efficiency). Such high‐performance self‐floating photothermal membranes with multifunctionalities might provide an effective strategy for solving the global problems of freshwater shortage.