Novel Cu and Leaf Nanostructure‐Based Photothermal Biomaterial for Efficient Solar Steam Generation

Abstract Solar steam generation (SSG) is promising for clean water production owing to low cost, simple operation, and green technology. This work investigates the fabrication of bioinspired photothermal (BIPT) material by sputtering a copper layer on Phanera purpurea (PP) leaf for application in SSG systems. It is observed that the light absorbance of the BIPT material exceeds 92% in the wavelength region of 300–2500 nm. This is due to the light trapping effect caused by multi‐internal reflection inside the Cu‐coated leaf nanostructure. The BIPT material exhibits a low thermal conductivity and easy cleaning properties as a result of PP leaf surface features. A novel strategy in this work is the design of the BIPT material‐based SSG system to recycle the radiative heat loss for evaporation. The developed SSG system results in a solar steam efficiency of 83.7% and a water evaporation rate of 1.45 kg m⁻² h⁻¹ under 1 sun. It is also applied in seawater desalination and the produced water satisfies the WHO standards for ion concentrations in clean water. Because of the simple procedure and low cost, the sputtering Cu on the PP leaf can be potentially used in the mass production of BIPT material for seawater desalination.