Sol-gel synthesis, characterization and catalytic activity of manganese-doped calcium cobalt oxide

This study investigates manganese-doped calcium cobalt oxide (MCCO - Ca₃Co 2-x MnₓO₆, x = 0–0.3) as a catalyst for the environmentally significant reduction of 4-nitrophenol (4-NP). While cobalt oxides are known catalysts, this work provides the first systematic evaluation of Mn-doping effects in Ca₃Co₂O₆ for this application. MCCO materials were synthesized via sol-gel, with FTIR confirming phase formation after 10 h of calcination 1000°C and XRD revealing lattice parameter shifts consistent with Mn incorporation. SEM and BET analyses showed that Mn doping significantly altered particle morphology and textural properties, including non-monotonic changes in specific surface area. Catalytic evaluation using NaBH 4 showed optimal performance for the MCCO sample with x = 0.1, achieving the highest apparent rate constant (kₐₚₚ = 0.412 min⁻¹) and 98.77 % 4-NP reduction efficiency within 10 min at pH 8. This composition also demonstrated good reusability, retaining 94.76 % efficiency after eight cycles. These findings highlight the critical role of Mn doping level in tuning the structural properties and catalytic performance of Ca₃Co₂O₆, identifying MCCO-0.1 as a highly efficient and reusable catalyst for 4-NP reduction. • Novel Mn-doped Ca₃Co₂O₆ catalyst for 4-NP reduction. • Optimal MCCO synthesis: 1000°C calcination for 10 h. • Mn doping level significantly tunes MCCO catalysis. • MCCO-0.1 catalyst shows good reusability over 8 cycles