Microcrystal Cellulose‐Mediated Interpenetrating Networks toward Synergistic Water Transport and Activation for High‐Efficiency Solar‐Driven Interfacial Evaporation

ABSTRACT Solar‐driven interfacial evaporation (SDIE) represents a promising technology for seawater desalination and water purification, whose core performance is dominantly by water transport and activation. Biomass‐derived hydrogels (BDHs) are attractive candidates owing to their excellent hydrophilicity and tunable networks. However, designing BDHs with simultaneous ultrafast water transport and efficient intermediate water (IW) activation remains challenging. Herein, a “hierarchical support” strategy is developed by employing rigid microcrystalline cellulose (MCC) as a framework to mediated the flexible sodium alginate‐Ca 2+ (SA‐Ca 2+ ) networks, constructing ordered hierarchical porous hydrogels. The hierarchical channel architecture enables low‐resistance water pathways, regulated water states, and optimized interfacial interactions, thus significantly elevating the IW fraction. The optimized RHB@MS‐25 exhibits a high evaporation rate of 3.07 kg m −2 h −1 with 94.8% solar‐to‐vapor efficiency under 1 sun irradiation. Notably, it exhibits outstanding stability and purification efficiency (∼100%) toward seawater, high‐salinity brines, extreme pH wastewater, heavy metal ions solutions (Fe 3+ , Cu 2+ , Cr 6+ , Co 2+ , Ni 2+ ), and organic dyes (Rhodamine B, methyl orange, methylene blue). This study establishes an interpenetrating hierarchical network, deciphers the mechanism underlying enhanced water transport and activation, and realizes high‐value conversion of natural biomass and agricultural wastes. It provides a facile, economical, and sustainable paradigm for advancing multi‐scenario water purification technologies.