Hierarchical structured Cu@carbon/carbon cloth film with high levels of light absorption for efficient solar thermal desalination

Abstract

Interfacial solar steam generation (ISSG) has attracted widespread attention as a zero-carbon emission, highly efficient thermal utilization and low-energy desalination technique. In this work, a novel hierarchical structured Cu@carbon/carbon cloth (Cu@C/CC) film is developed for improved light absorption for highly efficient ISSG. The Cu@C with an urchin-like structure, has the benefit of trapping light and resisting oxidation, which can prolong the regeneration of the film. Moreover, the CC serves as an efficient water transpiration base as well as solar absorber. The acid-treated CC with a large number of hydrophilic groups reduces the vaporization enthalpy of water. As a result, the Cu@C/CC demonstrates the highest light absorption of 92% when the wavelength varies from 200 to 2500 nm, whereas it is 80% for pure CC film. Interestingly, the Cu@C/CC film demonstrates Janus behavior due to the different wetting behavior on both sides, which enhances durability and thus ensures a high, water delivery rate. The evaporation rate of the Cu@C/CC film reaches 2.31 kg m⁻² h⁻¹. After 10 cycles, the evaporation rate remains at 2.17 kg m⁻² h⁻¹. In simulated seawater, the concentrations of K⁺, Ca²⁺, Na⁺ and Mg²⁺ decrease from 415.9, 411.2, 10976.0 and 1282.5 mg L⁻¹ to 9.2, 1.5, 23.5 and 0.4 mg L⁻¹, respectively. Beyond that, the removal rates of methyl orange and methylene blue by the Cu@C/CC film are 99.6% and 98.6%, respectively, suggesting excellent removal performance when treating organic pollutants and during sterilization.