FePc-rGO/PAN Heterostructured 2D Photothermal Membranes with Multi-Scale Synergistic Effects: High-Efficiency Solar Desalination via Electrospun Hierarchical Design

Abstract

Solar-driven desalination faces critical challenges in achieving full-spectrum solar utilization and anti-salts capacity during photothermal conversion. Although the reduced graphene oxide (rGO) exhibits broadband solar spectral absorption, its limited visible-light harvesting and salt resistance ability constrain practical performance. Herein, a 2D FePc-rGO/PAN photothermal membrane via electrospinning is reported. In which, Polyacrylonitrile (PAN) is designed as a fibrous substrate to effectively stabilize the heterostructured porous FePc/rGO, achieving a hierarchical architecture from micron-sized cross-linked fiber networks, nanoscale surface porosity, to molecular arrangements. This composite membrane shows a high solar conversion efficiency of 93.45% compared to that of the prepared 1.5%GO-PAN (74.89%). Under one sun illumination, FePc-rGO/PAN with the hierarchical structure exhibits a maximum evaporation rate of 5.79 kg m⁻² over 2 h irradiation. The enhanced desalination performance of the rGO/FePc-PAN is partially attributed to the light absorption enhancement by FePc in the visible spectrum (400–700 nm), the near-infrared region (1500–2400 nm) and the interactions between FePc and rGO. Additionally, the low surface activity of FePc molecules contributes to the anti-salt deposition capability of the rGO/FePc-PAN, while maintaining a stable membrane structure after repeated water washing cycles.