N-Doped Carbon-Confined Metal Sulfide Heterojunctions for Solar Water Evaporation and Adsorption-Assisted Photocatalytic Antibiotic Removal

Abstract Solar-driven interfacial evaporation offers a promising route for freshwater production, yet organic micropollutants such as tetracycline (TC) in feedwater may become enriched during evaporation, jeopardizing water quality. Herein, we design a dual-functional Co8FeS8/Co9S8-based aerogel (denoted as CFS/CS@NC-H) via H2/Ar etching, which simultaneously achieves high-rate evaporation and in situ TC degradation. The introduced sulfur vacancies and the bimetallic sulfide heterostructure broaden light absorption, suppress radiative electron–hole recombination, and promote nonradiative relaxation, giving rise to a synergistic photothermal–photocatalytic effect. Raman spectroscopy and differential scanning calorimetry (DSC) analyses further reveal that the Co8FeS8/Co9S8-based material effectively activates water molecules and substantially reduces the evaporation enthalpy. Consequently, under 1 sun illumination, the CFS/CS@NC-H aerogel delivers an evaporation rate of 2.31 kg m–2h–1 in pure water, and comparable rates are sustained in lake water, seawater, heavy metal-containing wastewater, and TC solution, demonstrating excellent salt resistance and practical adaptability. During evaporation, the aerogel efficiently degrades TC, thereby mitigating the risk of pollutant accumulation. The detoxification efficacy was further validated via pea sprout germination bioassays; the degraded TC solution achieved a germination rate of 84%, closely approaching that of pure water (90%) and far surpassing that of the untreated TC solution (56%), unequivocally confirming the drastic reduction in biological toxicity resulting from the catalytic degradation. This work highlights H2/Ar etching as an effective strategy to engineer transition metal sulfide-based materials for integrated solar evaporation and pollutant degradation, holding significant promise for sustainable water purification in complex aquatic environments.