3D Hollow-Assembled Porous Activated Carbon-Based Interfacial Solar Evaporator for Efficient Seawater Desalination

Interfacial solar desalination is a sustainable and emerging desalination strategy that can address freshwater scarcity. However, many current applications of interfacial evaporators are mainly limited by complicated preparation processes, low evaporation rates, and poor structural stability. Herein, a three-dimensional (3D) macroporous hollow-assembled activated carbon evaporator (MHAC-T) was constructed using an ultrahigh-molecular-weight polyethylene (UHMWPE) matrix embedded with coconut-shell-sourced activated carbon, along with auxiliary components including cotton rods and polystyrene foam for structural reinforcement. The macroporous structure on the top surface of the evaporator, constructed via NaCl-assisted pore formation, markedly enhances both light absorption and water evaporation. Compared with the 2D structure, the 3D evaporator enlarges the effective evaporation area and captures environmental energy, thereby enabling superior evaporation rates and efficiencies. Additionally, the optimal evaporation performance of MHAC-1.5 is obtained by varying the protruding height T (T is taken as 1.0, 1.5, and 2.0 cm) of the cotton rod to adjust the equilibrium between water transport and heat conduction, delivering an evaporation rate of 2.189 kg m⁻² h⁻¹ and 108.9% efficiency under 1 sun. Moreover, the outdoor evaporation setup demonstrated a freshwater yield of 14.0 kg m⁻² day⁻¹. The desalinated water has an ion removal rate of over 99%, complying with the World Health Organization's standard for potable water. Consequently, this low-cost, easy-to-assemble, high-performance MHAC-T evaporator has considerable potential for application in interfacial solar desalination.