Engineering interfacial thermal energy management via grooved B4C-polyurethane architectures for high-efficiency solar-thermal desalination

Solar-driven interfacial evaporation represents a sustainable pathway to mitigate global water scarcity; however, its practical implementation is often constrained by the trade-off between high efficiency, structural complexity, and susceptibility to salt fouling. Herein, we developed a scalable, cost-effective solar evaporator fabricated from boron carbide (B 4 C) nanoparticles, which is anchored on a groove-engineered polyurethane (PU) foam within a polyvinyl alcohol (PVA) matrix, bridging the gap between efficiency and scalability. This cavity-inspired grooved structure couples efficient photothermal conversion, local heat confinement without any solar concentrator, and fast water transport with effective hydrophilicity (zero contact angle). The effective heat localization realized in these grooved structures (42.16 °C) than plain structure (39.06 °C), as simulated through COMSOL heat transfer simulations. Under one-sun irradiation, the optimized evaporator achieves an evaporation rate of 1.55 kg m −2  h −1 , a value increased by 28 % compared with plain structure systems (1.21 kg m −2  h −1 ) while maintaining stable performance across diverse aqueous environments, including seawater, river water, and industrial effluents (MO, MB, RhB) with varying salinity and pH. The system also exhibits exceptional antifouling characteristics, with >99 % salt rejection and > 98 % removal of heavy metal ions (Pb 2+ , Cd 2+ ). This work combines material innovation with structure design and pushes the development of robust, high-throughput solar evaporators for the real world for desalination and wastewater treatment. The B 4 C@PU system thereby provides a green route for alleviating water scarcity by simultaneously solving the critical bottlenecks of density, cost, and salt fouling.