Low-frequency blue energy harvesting for sustainable and active anticorrosion

Engineering materials serving in marine surroundings are inevitably corroded. The corrosive marine conditions can also be utilized to harvest kinetic ocean wave energy to solve this problem. Leveraging water–solid triboelectrification to harvest low-frequency wave energy for active anticorrosion is promising. Existing techniques are efficient in harnessing environmental energy with frequencies higher than 3 Hz, whereas the dominated ocean waves with optimal wave spectral density fluctuate from 0.45 to 1.5 Hz. Herein, we proposed a highly efficient and sustainable blue energy-powered cathodic protection (BECP) strategy by fusing water–solid triboelectric nanogenerators and cathodic protection technology. Leveraging the highly efficient triboelectrification between the moving water and hydrophobic fluorinated ethylene propylene tube, we developed the built-in power module, enabling the harvest of ocean wave energy lower than 1.5 Hz. The generated volumetric current density is 28.9 mA·m⁻³, 5–20 times higher than the values of the reported devices. Moreover, the proposed BECP performs comparably to conventional cathodic protection in corrosion inhibition. Significantly, the proposed approach can be easily applied to ships, buoys, and other offshore platforms to simultaneously realize blue energy harvesting and engineering material protection, providing an alternative to traditional active protection technology.