Synthesis of Sb2S3:Eu thin films as a catalyst for the efficient photocatalytic degradation of rhodamine B (RhB) dye under visible light

Abstract

Eu was successfully incorporated into Sb₂S₃ thin films for proficient photocatalytic degradation of rhodamine B (RhB) dye under visible light. In this work, we reported the effect of incorporating Eu ions into Sb₂S₃ thin films at different doping levels to tailor their structural, optical, electrical, and photocatalytic properties. Grazing incidence X-ray diffraction (GIXRD) analysis revealed that the fabricated films exhibited an orthorhombic crystalline structure. Additionally, the GIXRD peaks shifted towards lower angles as the doping level increased. The Williamson–Hall method was used to estimate the effective crystallite size considering the strain components. The field emission scanning electron microscope (FESEM) characterisation demonstrated that the grain size decreased and a denser microstructure was observed as the Eu degree increased. The estimated optical band gap (E_g) value increases from 1.67 eV to 1.72 eV as the level of Eu doping rises from 0 to 8 at%, making the films suitable for photocatalytic applications. The photocatalytic activities of the pristine and Eu-doped Sb₂S₃ thin films were evaluated by the degradation of highly toxic Rhodamine B (RhB) dye under dark and various light conditions for 120 min. A remarkable photodegradation rate was achieved with the optimal doping level of 4 at% of Eu, demonstrating a 90.99% degradation of RhB. Electrochemical impedance spectroscopy (EIS) measurements show that the lifespan of photoinduced electrons for 4 at% Eu³⁺ samples is approximately 10 fold higher than that of the pristine sample. In terms of chemical kinetics, the degradation of RhB by the Sb₂S₃:Eu (4 at% of Eu) photocatalyst was found to follow pseudo-first-order kinetics with a rate constant of 0.049 min⁻¹ under visible light irradiation. A conceivable molecular mechanism for photocatalytic degradation of the RhB dye by Sb₂S₃:Eu photocatalysts is also provided. These results highlight the potential of Eu-doped Sb₂S₃ thin films for advanced photocatalytic applications. Specifically, Sb₂S₃:Eu 4 at% exhibits favourable properties. Thus, it was concluded that these photocatalysts are highly suitable for the remediation of dye-contaminated wastewater.