Hierarchical solar interface evaporator derived from natural multilevel plant leaves for high-efficiency desalination

Abstract

Solar-driven interfacial evaporation has emerged as a sustainable strategy for seawater desalination. However, achieving both high energy utilization and ultrafast evaporation under standard solar illumination remains challenging. In this work, we present a hierarchical solar interface evaporator derived from carbonized natural plant leaves, which retain intrinsic multilevel architectures including vascular channels, surface micro-textures, and interlayer porosity. These structures facilitate efficient water transport, broad-spectrum light absorption, and rapid vapor escape. More importantly, the hierarchical system enables multistage energy utilization by coupling direct solar absorption with passive environmental energy harvesting and latent heat recycling from upper to lower evaporation stages. As a result, the 9-stage evaporator attains an exceptionally high evaporation rate of 6.12 kg m⁻² h⁻¹ for 1 h under 1-sun (1 kW m⁻²) without external energy input, significantly surpassing the thermodynamic limit of conventional single-stage systems. The system also exhibits excellent long-term stability and salt rejection in continuous desalination tests. This study demonstrates the feasibility of using carbonized natural materials to construct low-cost, high-efficiency evaporators and offers new insights into multistage energy utilization strategies for practical water purification applications.