Indoor air pollution is increasing, becoming a great threat to public health. The three major forms of indoor air pollutants are VOCs (volatile organic compounds), particulate matter, and bioaerosols. To remove these pollutants, complex air purification systems are being used, primarily relying on incineration, adsorption, filtration, and catalytic oxidation. Aerogels and cryogels are novel new materials that appear to have great potential for use in air purification systems. Thus, the work of this dissertation was to develop multi-functional graphene aerogels and composites capable of capturing and transforming airborne pollutants.

In this work, three-dimensional graphene aerogels and composites were prepared by crosslinking two-dimensional graphene oxide nanosheets with functional na...[ Read more ]

Indoor air pollution is increasing, becoming a great threat to public health. The three major forms of indoor air pollutants are VOCs (volatile organic compounds), particulate matter, and bioaerosols. To remove these pollutants, complex air purification systems are being used, primarily relying on incineration, adsorption, filtration, and catalytic oxidation. Aerogels and cryogels are novel new materials that appear to have great potential for use in air purification systems. Thus, the work of this dissertation was to develop multi-functional graphene aerogels and composites capable of capturing and transforming airborne pollutants.

In this work, three-dimensional graphene aerogels and composites were prepared by crosslinking two-dimensional graphene oxide nanosheets with functional nanomaterials. The factors influencing the preparation of graphene-based aerogels were investigated including the initial concentration of graphene oxide suspension, cross-linking agents, and the drying method. The graphene aerogel prepared from ethanol supercritical drying exhibited large surface area (>500 m²/g) and extremely low thermal conductivity (<0.035 W∙m^-1∙K^-1), and the electrically conductive graphene aerogel with excellent thermal insulation properties can be heated up to 207 ºC within 10 min by a localized induction heater (2.8 kW) after deposition on Ni foam.

Nanomaterials, such as metal-organic frameworks and active catalysts, were incorporated into the matrix of the gas-permeable graphene aerogels for the adsorption and catalytic oxidation of toluene. The adsorption capacity of toluene over ZIF-8/graphene aerogel composite was increased by 55.9% compared to that of pure graphene aerogel. Au/V₂O₅/TiO₂/graphene composite aerogel was used for the catalytic removal of toluene, and it achieved 98.5% conversion for 55 mL/min of 300 ppm toluene at 250 ºC (85% for pure Au/V₂O₅/TiO₂). Nano-sized CeO₂ particles were also grown in-situ in the graphene aerogel, and the composite aerogels were able to remove 300 ppm toluene (55 mL/min) catalytically, with conversion reaching 95.7% at 250 ºC. Moreover, the CeO₂-graphene composite aerogel effectively captured airborne particulates (PM 0.3, PM 1.0, PM 2.5, PM 10) with more than 95% removal efficiency. The CeO₂-graphene composite aerogel also showed antibacterial properties, as it killed 99% of E. coli (10⁴-10⁵ CFU/mL) within 4 h.