3D Solar‐Driven Interfacial Evaporator Based on Tailored TiO 2 Nanotube Arrays by Wireless Anodizing for Efficient Desalination

ABSTRACT Solar‐driven interfacial evaporation is an energy‐efficient desalination strategy. However, the existing solar‐driven interfacial evaporators mostly rely on a surface‐localized photothermal layer for heat confinement, which limits evaporation exclusively to the top surface. The internal transfer channels and potential evaporation area remain unexplored, restricting water production rates. Here, a wireless anodization with a composite bipolar electrode has been proposed to prepare completely internal anodized porous Ti with TiO 2 nanotube (TNT) arrays, serving for 3D solar‐driven interfacial evaporation. By regulating the reaction area and intensity, the TiO 2 nanotubes (TNTs) with tailored size (diameter of 120–170 nm, length of 3–10 µm) have successfully anisotropically grown on the porous Ti substrates, constructing internal interconnected channels. The obtained wireless anodized porous Ti (WAPT) possessed an increased surface area of 7.938 m 2 ·g −1 , as well as solar absorbance >80%, superhydrophilicity (totally wetting within 10 s), and low evaporation enthalpy (451.83 kJ·kg −1 ), making efficient water evaporation with larger evaporation area and lower energy consumption possible. Under one‐sun irradiation, the WAPT showed an evaporation rate of 1.68 kg·m −2 ·h −1 with no salt crystallization and could maintain over 30 days. By assembling the WAPTs into a 3D interfacial evaporator, cooperated with wind‐driven cold evaporation, the maximum evaporation rate reached 2.412 kg·m −2 ·h −1 . In outdoor conditions (solar intensity of 0.6 kW·m −2 at 12 pm), the water collection rate reached 1.59 kg·m −2 ·h −1 . This work should make possible the development of a high‐performance solar‐driven interfacial evaporator for various applications.