Commercial black dye without plasmonic effect: A low-cost viable candidate as a solar absorber for photo-thermal interfacial evaporation and desalination?

Despite the full-spectrum absorption of solar incident, plasmonic metal-based materials and carbon-based materials still suffer from the drawbacks of risk for leakage to bulk water, fragility and high-cost preparation processes in long-term desalination. However, without the characterizations of strong conductivity and plasmonic effect, the black dye with clour of black is unable to achieve broadband absorption over the full-wave spectrum. For this reason, nearlly all of the effort has been continually devoting to seek conductive materials, neglecting the black dye which is colour of black but nonconducting. In this context, commercial low-cost black dye, which is conventionally used to dye fabric with durable black colour, was employed conclusively as an absorber to examine its viability in the field of photo-thermal interfacial evaporation for the first time. By choosing commercial artificial suede as the dying subject, a black-coloured photothermal film (BCPF) fabricated by a fairly low-cost black colorant and very facile staining method features superior wettability, stability (treated by ultrasonic agitation for at least 15 h without any fading) and performance in photo-thermal conversion. Evaporation tests show that the evaporation rate of BCPF-based evaporators can reach as high as 1.85 kg m−2 h−1. Furthermore, a strategy of laying under BCPF a layer of CAS film can greatly improve the salt-rejection ability of the evaporation device, not only causing dramatic degradation of the evaporation performance hardly but also contributing to environmental sustainability. In summarry, this study demonstrates the black dye as solar absorber for promising sustainable desalination, and also paving a way for the future exploration of practical new type photothrmal materials for interfacial evaporation. Schematic fabrication process of the black dye-based evaporation device for water evaporation and desalination. [Display omitted] •Commercial low-cost black dye as an absorber employed conclusively.•Commercial artificial suede is choose as the suitble dying subject to fabricate photo-thermal film.•Evaporation rate of the prepared evaporators can reach as high as 1.85 kg m−2 h−1.•A strategy of addition a layer of CAS film can greatly improve the salt-rejection ability.