Tailored Sr-Bi₄Ti₃O₁₂/Co₃O₄ S-scheme heterojunction for highly efficient solar-light photodegradation of crystal...

The development of efficient photocatalysts for wastewater treatment is crucial for mitigating organic pollution. In this work, a Sr-doped Bi₄Ti₃O₁₂/Co₃O₄ S-scheme heterojunction was synthesized via a facile solid-state and precipitation method and evaluated for the solar-light-driven photodegradation of crystal violet (CV) dye. X-ray diffraction (XRD) confirmed the orthorhombic phase of Bi₄Ti₃O₁₂ with successful Sr incorporation along with spinel Co₃O₄. FTIR spectra displayed characteristic metal oxygen vibrations, validating composite formation. UVDRS analysis revealed extended solar light absorption with a significantly reduced band gap of 1.6 eV compared to pristine Bi₄Ti₃O₁₂ (2.8 eV). Photoluminescence studies showed suppressed charge recombination, indicating efficient charge carrier separation. Under solar -light irradiation, the Sr-doped Bi₄Ti₃O₁₂/Co₃O₄ composite achieved ∼95% degradation of CV within 55 min, following pseudo-first-order kinetics (k = 0.035 min^-1). Furthermore, the photocatalyst exhibited excellent stability and reusability over multiple cycles. These findings highlight the synergistic role of Sr doping and S-scheme heterojunction formation in enhancing photocatalytic performance, offering a promising pathway for the design of advanced materials for wastewater remediation.