Efficient formaldehyde removal by maximizing adsorption/catalytic sites over graphene-Ce modified TiO 2

Formaldehyde (HCHO) is a critical indoor pollutant that necessitates efficient removal strategies. Achieving efficient adsorption/catalytic and recycling of metal oxides for HCHO removal is challenging due to the limited exposure of active sites. In this study, a series of TiO 2 composites modified with graphene and cerium oxide were synthesized via a sol–gel method to address HCHO removal. Experimental results revealed that the composite labeled 1 %G-Ce 0.2 -TiO 2 achieved the highest adsorption/catalytic performance, with a maximum adsorption capacity of 11.98 mg/g. The co-modification with CeO 2 and graphene enhanced the formation of oxygen vacancies, increased the number of oxygen-containing functional groups, and expanded the specific surface area of the adsorbents. These modifications significantly exposed more adsorption/catalytic sites, thereby boosting the efficiency of HCHO removal. Furthermore, 1 %G-Ce 0.2 -TiO 2 demonstrated robust regeneration capabilities. After a simple heat treatment, the adsorption/catalytic capacity of the regenerated material retained 80 % of the original material’s capacity. The strong correlation of the adsorption data with the kinetic and isotherm models confirms the physicochemical synergy between HCHO and 1 %G-Ce 0.2 -TiO 2. The adsorbed HCHO is converted by reactive oxygen species into dioxymethylene (DOM), which is subsequently transformed by additional reactive oxygen species and hydroxyl groups into formate species, and ultimately into CO 2 and H 2 O.