The Influence of Light‐Generated Radicals for Highly Efficient Solar‐Thermal Conversion in an Ultra‐Stable 2D Metal‐Organic Assembly

Abstract Solar‐thermal water evaporation is a promising strategy for clean water production, which needs the development of solar‐thermal conversion materials with both high efficiency and high stability. Herein, we reported an ultra‐stable cobalt(II)‐organic assembly NKU‐123 with light‐generated radicals, exhibiting superior photothermal conversion efficiency and high stability. Under the irradiation of 808 nm light, the temperature of NKU‐123 rapidly increases from 25.5 to 215.1 °C in 6 seconds. The solar water evaporator based on NKU‐123 achieves a high solar‐thermal water evaporation rate of 1.442 and 1.299 kg m −2 h −1 under 1‐sun irradiation with a water evaporation efficiency of 97.8 and 87.9 % for pure water and seawater, respectively. A detailed mechanism study revealed that the formation of light‐generated radicals leads to an increase of spin density of NKU‐123 for enhancing the photothermal effect, which provides insights into the design of highly efficient photothermal materials.