Scalable and high throughput photothermal water disinfection with negligible CO2 footprint utilizing nanostructured carbon coatings

Water heating and disinfection with reduced energy and CO2 footprint demands new and efficient materials for solar-thermal conversion technologies. Here, we demonstrate nanostructured porous hard-carbon florets (NCF) as effective solar absorber coating achieving excellent photon thermalization efficiency (87%). Functional NCF coating on three-dimensionally tapered helical solar receivers generate high surface temperatures (up to 95 °C). Such ‘green-heat’ is channeled to heat water up to 82 °C that simultaneously results in water disinfection through thermal shock. Untreated lake-water with high turbidity (5 NTU), high bacterial load (106 CFU mL−1) and pathogenic fungi is effectively disinfected in a continuous flow process. Translating this, a fully automated SWAP prototype (solar water antimicrobial purifier), delivers bacteria free hot water at an output capacity of 42 L m−2 day−1 with the lowest CO2 footprint (5 kg L−1) in comparison to all other existing approaches (>40 kg L−1).