Antireflective copper surfaces fabricated by low-cost nanosecond lasers for efficient photothermal conversion and desalination

Surfaces with efficient photothermal conversion have great value in both science and industry. In this study, large-area hierarchical microstructures and nanostructures with high light absorptance over a wide spectrum range from ultraviolet to the near-infrared region were fabricated on copper surfaces by a low-cost green nanosecond laser system. By optimizing the morphology of laser-induced surface structures, the average light absorptance in the wavelength range of 220–800 nm and 220–2500 nm can be as high as 98.9% and 91.9%, respectively. Moreover, the laser-processed surfaces demonstrated a photothermal conversion efficiency of more than 52% under 15 sun illuminations. The authors also showed that the desalination efficiency was greatly improved when the prepared surfaces were used as the solar energy harvesting surfaces in the solar energy driven desalination system.