A high-performance and salt-resistant 3D solar evaporator based on recycled carbon fiber with a synergistic CuO/rGO photothermal layer

Solar-driven interfacial evaporation (SDIE) holds immense potential for sustainable desalination, yet current solar evaporators remain severely obstructed by the limited evaporation efficiency, inherent mechanical fragility and the complex fabrication of robust photothermal layers. Herein, we propose a “waste-to-wealth” structural engineering and in situ interfacial coupling strategy to develop a highly robust, 3D evaporator (CuO/rGO/PVA/SA-CF). By utilizing recycled waste carbon fiber needle-punched felt as a rigid skeletal constraint for a hydrogel-derived porous matrix, the device achieves an exceptional loading stress of 54.61 MPa at 3% strain, fundamentally resolving the issue of structural deterioration under demanding operational conditions. Furthermore, a highly efficient, single-step vacuum-assisted thermal process was designed to drive a synchronous transformation: the in-situ oxidation of copper alongside the reduction of graphene oxide (GO). This simultaneous oxidation-reduction mechanism yields a highly coupled photothermal architecture, delivering broadband solar absorbance of 95% and effectively reducing the equivalent evaporation enthalpy to 1587.02 kJ kg −1 . Under 1 sun illumination (1 kW m −2 ), the evaporator exhibits a high evaporation rate of 2.142 kg m −2  h −1 with a photothermal conversion efficiency of 91.8%. Furthermore, the device maintains a stable evaporation rate of 1.753 kg m −2  h −1 even in high-salinity brine (20 wt%), demonstrating outstanding salt-rejection performance. This work establishes a scalable, mechanically durable, and eco-friendly paradigm for next-generation solar desalination systems.