Magnesium-Modified Co3O4 Catalyst with Remarkable Performance for Toluene Low Temperature Deep Oxidation

Co3O4, MgCo2O4 and MgO materials have been synthesized using a simple co-precipitation approach and systematically characterized. The total conversion of toluene to CO2 and H2O over spinel MgCo2O4 with wormlike morphology has been investigated. Compared with single metal oxides (Co3O4 and MgO), MgCo2O4 with the highest activity has exhibited almost 100% oxidation of toluene at 255 °C. The obtained results are analogous to typical precious metal supported catalysts. The activation energy of toluene over MgCo2O4 (38.5 kJ/mol) is found to be much lower than that of Co3O4 (68.9 kJ/mol) and MgO ((87.8 kJ/mol)). Compared with the single Co and Mg metal oxide, the as-prepared spinel MgCo2O4 exhibits a larger surface area, highest absorbed oxygen and more oxygen vacancies, thus highest mobility of oxygen species due to its good redox capability. Furthermore, the samples specific surface area, low-temperature reducibility and surface adsorbed oxygenated species ratio decreased as follows: MgCo2O4 > Co3O4 > MgO; which is completely in line with the catalytic performance trends and constitute the reasons for MgCo2O4 high excellent activity towards toluene total oxidation. The overall finding supported by ab initio molecular dynamics simulations of toluene oxidation on the Co3O4 and MgCo2O4 suggest that the catalytic process follows a Mars–van Krevelen mechanism.

Facile preparation of hierarchical MgCo2O4/MgCo2O4 nanochain array composites on Ni foam as advanced electrode materials for supercapacitors

Schematic illustration of the two-step synthesis of MgCo₂O₄/MgCo₂O₄ directly grown on Ni foam.

An urchin-like MgCo2O4@PPy core-shell composite grown on Ni foam for a high-performance all-solid-state asymmetric supercapacitor

In recent years, the electrochemical properties of supercapacitors have been greatly improved due to continuous improvement in their composite materials. In this study, an urchin-like MgCo2O4@PPy/NF (MgCo2O4@polypyrrole/Ni foam) core-shell structure composite material was successfully developed as an electrode for supercapacitors. The MCP-2 composite material, obtained by a hydrothermal method and in situ chemical oxidative polymerization, shows a high specific capacitance of 1079.6 F g-1 at a current density of 1 A g-1, which is much higher than that of MC (783.6 F g-1) under the same conditions. Simultaneously, it has low resistance and an excellent cycling stability of 97.4% after 1000 cycles. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) was assembled using MCP-2 as the positive electrode and activated carbon (AC) as the negative electrode. The MCP-2//AC ASC exhibits high specific capacitance (94 F g-1 at a current density of 0.4 A g-1), high energy density (33.4 W h kg-1 at a power density of 320 W kg-1), high volumetric energy density (17.18 mW h cm-3 at a volumetric power density of 0.16 W cm-3) and excellent cycling stability (retaining 91% of the initial value after 10 000 cycles). Simultaneously, the device has low leakage current and excellent self-discharge characteristics. All these results indicate that the MCP-2//AC ASC is a good energy storage device; it can support the function of two LEDs for 20 minutes. These results indicate that the MCP-2//AC ASC will play an important role in energy structures in the future.