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).