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

An ultra-stable two-dimensional cobalt(II)-organic assembly NKU-123 for efficient photothermal conversion is reported. Under 808 nm light, the temperature of NKU-123 rapidly increases from 25.5 to 215.1 °C in 6 seconds. NKU-123 exhibits a 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. The role of light-generated radicals to the photothermal conversion was revealed.

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.

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