Sustainable methanol production from CO2 using waste mask-derived activated carbon and Cu–C/TiO2 photocatalyst

This study aimed to develop a low-cost, circular route for sustainable methanol production by coupling capture of CO₂ from waste polypropylene surgical masks with solar-driven conversion. Used masks were upcycled into activated carbon that adsorbed CO₂ at 2.711 mmol g⁻¹ . The captured CO₂ was reduced to methanol using a copper–carbon co-doped titanium dioxide (Cu–C/TiO₂) photocatalyst operated under ultraviolet (UV) light and natural sunlight in a compact integrated CO₂-to-methanol photoreactor. Relative to commercial TiO₂, the co-doped catalyst increased methanol productivity by about sixfold. After 5 h, methanol concentrations reached 3.79 g L⁻¹ under UV irradiation and 3.39 g L⁻¹ under sunlight. Using seawater as the reaction medium provided the highest yield, though it posed regeneration challenges, while the catalyst maintained 98.6 % of its activity after regeneration. A laboratory-scale carbon balance indicated near carbon-neutral performance for the conversion step, and analysis suggests a path to carbon-negative operation at scale by combining avoided mask incineration with sustained CO₂ capture. These results demonstrate that upcycling mask waste into an efficient CO₂ sorbent and pairing it with a regenerable photocatalyst can produce methanol under mild conditions using low-cost hardware, offering a practical carbon capture and utilization pathway that simultaneously mitigates plastic waste and greenhouse-gas emissions. • Integrated C 2 M Reactor: Mask based AC for carbon capture + Cu–C/TiO 2 for photocatalytic methanol formation. • Mask-derived activated carbon adsorbed 2.710 mmol g⁻¹ of CO 2 . • Cu–C/TiO 2 outperformed TiO 2 baseline by ∼6 × in methanol yield. • Seawater gave highest yield (3.79 g L⁻¹) but adds fouling/purification hurdles. • Carbon balance indicates low footprint, viable route to sustainable fuel.