Tortuosity regulation of two-dimensional nanofluidic films for water evaporation-induced electricity generation

Water evaporation-induced electricity generation is a promising technology for renewable energy harvesting. However, the output power of some reported two-dimensional (2D) nanofluidic films is still restricted by the relatively weak water–solid interactions within the tortuous nanochannels. To further enhance the comprehension and utilization of water–solid interactions, it is of utmost importance to conduct an in-depth investigation and propose a regulatory concept encompassing ion transport. Herein, we propose tortuosity regulation of 2D nanofluidic titanium oxide (Ti_0.87O₂) films to optimize the ion transport within the interlayer nanochannel for enhanced efficiency in water evaporation-induced electricity generation for the first time. The significance of tortuosity in ion transport is elucidated by designing three 2D nanofluidic films with different tortuosity. Tortuosity analysis and in situ Raman measurement demonstrate that low tortuosity can facilitate the formation of efficient pathways for hydrated proton transport and promote water–solid interactions. Consequently, devices fabricated with the optimized 2D nanofluidic films exhibited a significantly enhanced output power density of approximately 204.01 µW·cm⁻², far exceeding those prepared by the high-tortuosity 2D nanofluidic films. This work highlights the significance of the construction of low tortuosity channels for 2D nanofluidic films with excellent performance.