Porous Sand Disc: A Sustainable Approach for High-Efficiency Solar-Driven Evaporation

The scarcity of freshwater resources represents a significant challenge to the advancement of humanity and society. While solar-driven interfacial evaporation technology offers distinctive advantages, the acquisition and preparation of photothermal materials have significantly hindered its further development. Herein, we introduce a novel approach employing porous sand disc (PSD) as a photothermal material, showcasing exceptional evaporation performance. The natural sand is transformed into a micron-sized superhydrophilic PSD, which is then used to design a one-dimensional and self-water-supplied T-shaped evaporator (T-PSD), that is similar in function to plant transpiration. The T-PSD demonstrates a remarkable evaporation rate of 1.428 kg/(m²·h) with low surface temperature (36.5 °C) under 1 sun, resulting in an impressive evaporation efficiency of 86.1%. The T-PSD maintains a high evaporation performance even when evaporating salt water, attributed to the PSD crystallizing preferentially at the edge. The edge-preferential crystallization significantly enhances the evaporator’s continuous operational capability. Leveraging abundant and cost-effective natural sand as a photothermal material offers a sustainable development approach for advancing interfacial evaporation technology.