MXene/N‐Doped Carbon Nanotube Photothermal Layer‐Vertical Channel Aerogel Solar Steam Generator with Excellent Salt Resistance and High Efficiency Stability

ABSTRACT Enhancing photothermal conversion efficiency and modulating sodium ion transport are crucial for constructing high‐performance solar evaporators. Based on the layer‑pillar‑layer structural design, this study prepared a modular photothermal aerogel evaporator (PM/SFA) composed of MXene/TiO 2 /nitrogen‑doped carbon nanotube photothermal film (PVDF/MTNC) and sodium alginate/fiber aerogel (SFA). The top photothermal film forms a three‑dimensional layer‑pillar‑layer heterostructure via in‑situ growth of nitrogen‑doped carbon nanotube micropillars between MXene nanosheets, which widens the interlayer spacing and prolongs the optical path to improve light‑harvesting efficiency. The bottom layer uses sodium alginate as the aerogel matrix, with fiber reinforcement to enhance its mechanical properties, ensuring structural and channel integrity under 90 kPa compressive stress. Vertical microchannels are fabricated via directional freezing to reduce water transport tortuosity, and capillary force enables self‐dilution of brine for efficient salt inhibition and continuous desalination. Under one‐sun irradiation, the evaporator delivers an evaporation rate of 3.42 kg·m −2 ·h −1 and an outdoor freshwater yield of 18.42 kg·m −2 within 8 h, exhibiting outstanding desalination performance. This work provides a novel strategy for developing high‐performance, salt‐resistant MXene‐based solar evaporators through structural innovations of sodium alginate fiber aerogel and layered photothermal materials.