Superwetting and photothermal Cu-tetracyanoquinodimethane@stainless steel mesh composite membrane for efficient freshwater generation from oily wastewater emulsions and seawater

Efficient generation of freshwater product from both oily wastewater emulsions and seawater is highly required to alleviate the existing freshwater scarcity, but a challenge unsolved. Herein, we report an effective route to address this challenge by modifying Cu-7,7,8,8-tetracyanoquinodimethane (Cu-TCNQ) microrods on stainless steel mesh (Cu-TCNQ@SSM). Given the superwettability and firm chemical stability, our membrane exhibits highly efficient separation efficiency (SE: 99.7 %) against diverse surfactant-stabilized oily wastewater emulsions under harsh conditions (1 M HCl, 1 M NaOH, or 10 wt% NaCl). Driven by the firm photothermal conversion, superwettability, and robust salt tolerance, our membrane also displays high and durable solar-assisted interface evaporation towards both seawater and oily polluted seawater. The durable evaporation rate for seawater maintains at 2.71 kg m⁻² h⁻¹ under one solar irradiation for 6 h. As for oil-polluted seawater, the evaporation rate can still reach 2.30 kg m⁻² h⁻¹ under one sun irradiation with the oil rejection rate higher than 99.9 % for 6 h. Our results provide an effective avenue to alleviate the existing freshwater shortage.