CNTs modified geopolymer microspheres loaded with Cu-La bimetallic composites and its photocatalytic performance

CNTs-modified geopolymer microspheres (GM _{x wt%CNTs} ) were synthesized by adding carbon nanotubes (CNTs) into the geopolymer precursors. And, the Cu-La supported modified geopolymer photocatalysts (1.0%CuO/7.5%La ₂ O ₃ @GM _{x wt%CNTs} ) were prepared by using GM _{x wt%CNTs} as the carrier. Photocatalytic experiments showed that 1.0%CuO/7.5%La ₂ O ₃ @GM _0.5%CNTs had the highest photocatalytic activity when CNTs were doped at 0.5 wt%, and the degradation rate of 30 mg/L TCH solution reached 89.51% when irradiated with visible light for 100 min, and 1.0%CuO/7.5%La ₂ O ₃ @GM _0.5%CNTs had good salt resistance, recycling stability and universality, and the free radical capture experiments found that h ⁺ was the main active species in this photocatalytic system, with •O ²⁻ was the secondary active species. Characterization analysis showed that by doping CNTs, the conductivity of the material was increased and the resistance of charge transfer at the interface of the material was reduced, which improved the separation efficiency of photogenerated electron-hole pairs, and enabled the catalysts to exhibit a stronger response to visible light. In addition, the CNTs-modified microspheres possessed a more porous structure and larger specific surface area, which provided more active sites for photocatalytic reactions.