Two types of novel municipal sewage sludge (SS) combined TiO ₂ photocatalysts (ST ₁ and ST ₂ ) were synthesized through calcination treatment under different atmospheres (air and N ₂ ). The morphology, structure, and chemical states of photocatalysts were characterized by SEM, XRD, EDS, FT-IR, Raman UV–Vis, BET, and TG-IR. The results showed that ST ₂ consisted of a mesoporous graphene-like structure (20.02 nm) displayed exhibited better visible light photocatalytic performances and the highest BET surface area and pore volume (92.97 m ² g ⁻¹ and 0.46 cm ³ /g). The doping of Carbon and transition metals (Al, Mg) in TiO ₂ strengthened visible-light response by lowering the band gap. The photocatalytic ability is evaluated in the degradation of tetracycline, which is a typical antibiotic in the aquatic environment. The ST ₂ photocatalytic efficiency under visible light than that of ST ₁ and TiO ₂ . The enhancement is formed together by porous surface and lower band gap of ST ₂ , which could offer more active sites and facilitate faster electron-hole pair separation. In addition, the sludge-TiO ₂ calcination in N ₂ (ST ₂ ) has the potential to reduce CO ₂ emission while recovering more energy from the sludge, which turned out to be a more cost-effective way to reutilization of sewage sludge compared with that of calcination in air. ... Read more