Micron flower-like CuO light trapping grown on the copper foam skeleton combined with PVDF membrane for solar-driven vacuum membrane distillation

• Photothermal composite membrane with a photothermal active-layer and a microporous hydrophobic separation layer. • Interfacial anchoring avoided detachment of the photothermal material from the membrane surface. • Micron flower-like CuO light trapping improved the photothermal performance. Solar-driven photothermal conversion vacuum membrane distillation (SVMD) becomes an energy-efficient water treatment thanks to the thermal localization of photothermal membranes. Membrane photothermal activity and distillation performance are essential for creating photothermal composite membranes. Herein, a CuO/CF-PVDF photothermal composite membrane has been designed with flower-like copper oxide (CuO/CF) photothermal active-layer and polyvinylidene fluoride (PVDF) microporous hydrophobic separation layer. Firstly, the flower-like CuO/CF layer with the light trapping was obtained by in-situ surface oxidation on the copper foam (CF) surface. Then, by the NIPS method, PVDF microporous hydrophobic layer was scraped on one side of the CuO/CF photothermal active-layer and firmly fixed on the porous surface of CuO/CF layer by anchoring effect. The light trap consisted of CuO micron flowers and Cu(OH) 2 nanowires. The gaps among the petals increased the light refractive rate and absorption area, thus enhancing the photothermal performance of the CuO/CF. Under 1 kW‧m −2 solar irradiation, the absorption rate reached up to 95 %, and the photothermal conversion efficiency achieved 94 %. For the SVMD process, compared to current research, the CuO/CF-PVDF achieved the permeate flux of 3.34 kg‧m −2 ‧h −1 and energy efficiency of 88 % under average feed temperature. Overall, the CuO/CF-PVDF membrane has promising potential for desalination by fully using sustainable energy.