Comparative life cycle assessment of the fabrication of visible-light-driven photocatalytic TiO2 – Carbon dots nanocomposites for wastewater treatment

TiO₂ nanoparticles are promising photocatalysts due to their oxidizing strength and inertness. However, their inability to efficiently absorb visible light limits industrial applications that could use sunlight. The addition of carbon dots to TiO₂ has been recently shown to have the potential to address this issue by enhancing the visible-light-driven photocatalytic efficiency of the resulting nanocomposites. However, concrete data on their sustainable development and fabrication is lacking. Herein, we performed a life cycle assessment (LCA) study to understand the environmental impacts of different TiO₂‑carbon dots nanocomposites with enhanced visible-light-driven photocatalytic activity. It was found that the nanocomposites with the highest photocatalytic activity were the ones whose synthesis was associated with lower environmental impacts. Furthermore, the carbon dots generally have little to moderate contributions to most impact categories, except for marine eutrophication. Finally, the most critical parameter was found to be the source of TiO₂ for the nanocomposites.