Biopolymer-Assisted Hydrothermal Synthesis of Manganese Cobalt Spinel Oxide (MnCo2O4) Using Cellulose and Chitosan for Enhanced Catalytic Performance

This study reports the synthesis and photocatalytic performance of MnCo₂O₄ nanospinels fabricated with biodegradable stabilizers-chitosan (CHT) and biomass-cellulose (BC)-for the degradation of methylene blue (MB) under UV-rich solar irradiation. Structural and optical analyses (FTIR, XRD, XPS, PL, TGA, UV-Vis, and BET) revealed that the stabilizers significantly improved crystallinity, porosity, and charge-carrier separation while suppressing electron-hole recombination. Among the catalysts, MnCo₂O₄-CHT exhibited the best performance, achieving 96% MB degradation within 120 min, with the highest apparent rate constant (k_app = 0.0203 min^-1) and shortest half-life (t₁/₂ = 34.2 min). In comparison, MnCo₂O₄-BC and MnCo₂O₄-Neat achieved 65% and 45% degradation, respectively. The enhanced activity of MnCo₂O₄-CHT is attributed to the chelation and electron-donating ability of chitosan's -NH₂ and -OH groups, which facilitate efficient charge transfer and reactive oxygen species (ROS) generation. These findings demonstrate the effectiveness of stabilizer-assisted synthesis in tuning the physicochemical properties of spinel oxides, offering a sustainable and high-performance photocatalyst for environmental remediation and wastewater treatment applications.