Nature-inspired 3D hierarchical carbon nanotube matrices enable extraordinary solar steam generation

Interfacial solar evaporation, which captures solar energy and localizes the absorbed heat for water evaporation, is considered a promising technology for seawater desalination and solar energy conversion. However, it is currently limited by its low photothermal conversion efficiency, salt accumulation, and poor reliability. Herein, inspired by human intestinal villi structure, we design and fabricate a novel intestinal villi-like nitrogen-doped carbon nanotubes solar steam generator (N-CNTs SSG) consisting of three-dimensional (3D) hierarchical carbon nanotube matrices for ultrahigh solar evaporation efficiency. The 3D matrices with radial direction nitrogen-doped carbon nanotube clusters achieve ultrahigh surface area, photothermal efficiency, and hydrophilicity, which significantly intensifies the whole interfacial solar evaporation process. The new solar evaporation efficiency reaches as high as 96.8%. Furthermore, our ab initio molecular dynamics simulation reveals that N-doped carbon nanotubes exhibit a greater number of electronic states in close proximity to the Fermi level when compared to pristine carbon nanotubes. The outstanding absorptivity in the full solar spectrum and high solar altitude angles of the 3D hierarchical carbon nanotube matrices offer great potential to enable ultrahigh photothermal conversion under all-day and all-season circumstances.