Biomass-derived calcium carbonate-loaded CuS-doped full-spectrum responsive TiO₂ composite for formaldehyde removal

Formaldehyde is a highly toxic volatile organic pollutant that poses severe threats to human health and the ecological environment. This study utilizes oyster shells and eggshells as raw materials to construct a biomass-derived porous CaCO 3 matrix, and then CuS nanoparticles were in-situ loaded onto the CaCO 3 surface by low-temperature degreasing and hydrothermal treatment, followed by the integrating of full-spectrum responsive TiO 2 to achieve defect complementarity. The resulting ternary composite integrates adsorption and photocatalytic functionalities via multi-mechanism synergy. CuS extends TiO₂'s light absorption range into the visible and near-infrared regions; the porosity of biomass CaCO 3 synergistically enhances specific surface area and active site density with CuS. Under simulated sunlight irradiation, this composite achieved 85.38% formaldehyde adsorption efficiency and 98.31% degradation rate through efficient photogenerated charge separation and reactive oxygen species generation. This work demonstrates broad application prospects in formaldehyde removal and offers new insights into solid waste resource utilization.