Mo-Driven Photo-Fenton Catalysis: Synergistic Role of Cu and Fe in Ternary Oxide Nanoparticles for Wastewater Remediation

Abstract

In this study, Mo-based transition metal oxide nanoparticles MoO₃ (MO), CuMoO₄ (CMO), FeMoO₄ (FMO), and Cu_1.815Fe_1.815Mo₃O₁₂ (CFMO) were synthesized via a sol-gel technique. Further, evaluated for their photo-Fenton dye degradation performance against Methylene Blue dye under visible light irradiation using H₂O₂ as an oxidant. Structural, optical, morphological, and surface analyses confirmed the formation of pure-phase nanoparticles with flake-like morphology and tunable band gaps. Optical band gap values decreased from 2.93 eV (MoO₃) to 1.68-1.80 eV for ternary Cu_1.815Fe_1.815Mo₃O₁₂, enhancing visible light absorption. Among all, the ternary oxide with 0.1 M Mo exhibited the highest degradation efficiency of 97.6% within 60 minutes, outperforming the binary (CMO₄: 97.1%, FMO₄: 94.1%) and primary (MoO₃: 98.1% in 180 min) systems. Kinetic studies confirmed first-order degradation behavior with the highest rate constant of 5.9 × 10^-2 min^-1 and shortest half-life of 11.7 minutes for the optimal ternary catalyst. Scavenger experiments further revealed that hydroxyl radicals (•OH) are the dominant reactive species, with moderate contributions from superoxide radicals (•O₂^-) and photogenerated holes (h⁺). The CFMO nanoparticles also retained their catalytic activity after five consecutive cycles, indicating excellent reusability. These findings demonstrate the promising potential of Mo-incorporated ternary oxide nanoparticles as efficient, cost-effective, and recyclable photo-Fenton catalysts for environmental wastewater remediation.