Ti3C2Tx-polypyrrole composite hydrogel with hierarchical mass transfer channels for efficient salt-tolerant solar evaporation

Oxidative polymerization strengthens PPy hydrogels and optimizes evaporation enthalpy. • Ti 3 C 2 T x -PPy multilevel channels guide salt crystallization to evaporator edges. • Ti 3 C 2 T x -PPy evaporator delivers 4.63 kg m −2  h −1 , 35% higher than PPy. Solar-driven interfacial evaporation, which relies on localized photothermal conversion at the gas-liquid interface, represents an effective strategy for seawater desalination. However, continuous salt crystallization and deposition at the evaporation interface remain a critical bottleneck that limits long-term operational stability. Herein, we develop a Ti 3 C 2 T x -PPy composite hydrogel evaporator with multilevel mass-transport channels for solar seawater desalination and spatial regulation of salt crystallization. The incorporation of Ti 3 C 2 T x optimizes the internal pore network of the polypyrrole hydrogel, establishing hierarchical mass-transport pathways that promote the preferential migration of salts towards the evaporator edges, where crystallization subsequently occurs. Meanwhile, Ti 3 C 2 T x enhances the photothermal conversion capability of the system and modulates the hydrogen-bonding structure of water molecules, thereby effectively lowering the evaporation energy barrier. Under 1 sun illumination, the Ti 3 C 2 T x -PPy evaporator achieves an evaporation rate of 4.63 kg m −2  h −1 , while maintaining a clean surface and undiminished performance after 50 h of continuous operation. The evaporator also exhibits purification efficiencies exceeding 99% in hypersaline solutions, dye-contaminated wastewater and real seawater, and delivers an average daily water yield of over 25 L m −2 under natural sunlight. This work provides a promising strategy for the design of hydrogel-based solar desalination systems with high efficiency, excellent salt resistance and long-term operational stability. Download: Download high-res image (150KB) Download: Download full-size image