As a renewable energy source, wave energy exploitation reduces fossil energy pollution and aids carbon neutrality. Traditional electromagnetic generators (EMGs) have low low-frequency conversion efficiency, limiting large-scale application. Triboelectric nanogenerators (TENGs), invented in 2012, offer a new way for wave energy harvesting with advantages of wide material selection, low-frequency adaptability, light weight and low cost, but are restricted by marine corrosion and inefficient low-frequency capture. This work designed an arch-structured TENG (Arch-TENG) that captures wave energy via bending. Compared with CS-TENG, its charge transfer increases by over 450%, with a charge output density of 12.7 nC cm2 at 0.5 Hz and stable performance after 26 h tests. The array-integrated device capable of large-scale wave energy harvesting is designed based on the Arch-TENG. It was verified that this device can not only stably power low-power electronic devices but also be used for cathodic protection tests of carbon steel Q235 in seawater, which will provide more practical applications of TENG in marine environments.