Fine-tuning of redox-ability, optical, and electrical properties of Bi₂MoO₆ ceramics via lanthanide doping and rGO integration for photo-degradation of Methylene Blue and Ciprofloxacin

Herein, lanthanide ion (Gd⁺³) doped Bismuth Molybdate (Bi₂MoO₆) integrated on the rGO sheets has been prepared as a novel photocatalyst (Gd@Bi₂MoO₆/rGO) for the photocatalytic treatment of toxic pollutants. Different physiochemical, optical, electrical, thermal, and electrochemical properties of Gd@Bi₂MoO₆/rGO, along with its counterparts (Bi₂MoO₆ and _Gd@Bi2MoO6) were studied through XRD, SEM/TEM, FT-IR, UV/Vis, I-V, TGA, Mott-Schottky, and EIS measurements. Photocatalytic experiments revealed that Gd@Bi₂MoO₆/rGO exhibited significantly enhanced photocatalytic activity, achieving 96.2 % photo-degradation of Methylene Blue with 120 min of irradiation, which is 6.5 and 3.1 times higher compared to Bi₂MoO₆ (40.9 %) and Gd@Bi₂MoO₆ (64.8 %), respectively. Moreover, Gd@Bi₂MoO₆/rGO demonstrated a notable photocatalytic efficiency of 81.7 % towards Ciprofloxacin, significant as per the existing literature benchmark. The enhanced photocatalytic activity is ascribed to the in-built Gd⁺³ redox centers, high electrical conductivity (7.35 × 10⁻³ S/m), favorable flat band potential (-0.81 V), and low semiconductor impedance (R_ct = 51.71 Ω and R_s = 0.90 Ω). Additionally, the electron-capturing ability of lanthanide dopant ions and S-C heterojunction of Gd@Bi₂MoO₆/rGO facilitates the separation of photo-generated e^-/h⁺ pairs and favors high concentrations of ROS. The results obtained highlight the potential of Gd@Bi₂MoO₆/rGO for applications in photocatalysis and wastewater treatment.