Glucose-Assisted Surface Modification to Improve the Catalytic Efficiency of Hydrothermally Synthesized Manganese Oxide Nanoparticles in Hydrogen Peroxide Decomposition

In this study, a hydrothermal synthesis strategy was employed to fabricate a heterogeneous manganese oxide-based nano-catalysts. Potassium permanganate (KMnO₄) served as the manganese precursor, while D-glucose functioned dually as a reducing agent and structural directing agent. The resulting catalyst features a manganese oxide core composed of multiple crystalline phases, encapsulated by a shell enriched with diverse functional moieties, including C=C, –OH, and –COOH groups. Systematic modulation of synthesis parameters—such as pH of the aqueous solution, D-glucose concentration, hydrothermal temperature and duration, as well as subsequent calcination conditions—enabled precise control over the catalyst’s structural evolution. The effects of these synthetic variables on the catalyst’s morphology, surface chemistry, and its catalytic activity for hydrogen peroxide (H₂O₂) decomposition were thoroughly investigated. Under optimal conditions (pH 13, 0.5765 g D-glucose corresponding to 0.04 M, hydrothermal treatment at 100 °C for 6 h, followed by calcination at 550 °C for 3 h), the synthesized catalyst demonstrated the highest catalytic efficiency for H₂O₂ decomposition. The mass activity (M.A.) of the resulting material was found to be 14.96 times greater than that of commercial MnO₂ (SHIMAKYU MnO₂). Characterization by X-ray powder diffraction (XRD), high-resolution field-emission scanning transmission electron microscopy (HR-FESTEM), and Brunauer–Emmett–Teller (BET) surface area analysis confirmed that this synthetic route results in reduced crystallite size, enhanced dispersion, and improved size uniformity prior to calcination. These features contributed to a significantly increased surface area and promoted the formation of a uniform and distinct amorphous carbon protective layer. Fourier-transform infrared spectroscopy (FTIR) further verified the spontaneous redox transformation of glucose under strong alkaline conditions, as well as the calcination-induced oxygen uptake by the catalyst framework. These processes facilitate the enrichment of surface-active functional groups (–OH, –COOH) and stabilization of the carbon-rich (C=C) outer layer, both of which are critical for enhanced catalytic performance. This cost-effective, scalable, and environmentally benign approach to synthesizing manganese-based heterogeneous nano-catalysts presents considerable promise for applications in H₂O₂ decomposition, particularly within green propulsion and environmentally friendly power systems.