Template-free synthesis of mesoporous ZnCo2O4 nanosheets and quasi-cubes via a simple solvothermal route

Abstract

Porous ZnCo2O4 nanosheets (NSs) were synthesized via a solvothermal method in ethylene glycol (EG) and water combined solvent, and followed by calcination in air at 400 °C for 2 h. No surfactant or template was employed during the entire synthetic process. The ZnCo2O4 NSs have a thickness of about 100–150 nm, and possess a BET surface area and pore size of 54.4 m2 g−1 and 7.8 nm, respectively. Such porous NSs would gradually stack into quasi-cube-like microstructures with reaction time prolonging. Quasi-cubes with edge length ranging from 10 to 30 μm were produced, and NSs almost disappeared after 15 h of solvothermal treatment. It was found that the volume ratio of EG to water played important role for the final shapes of ZnCo2O4. Some irregular and broken NSs were formed if less amount of EG was used, while quasi-microcubes stacked by NSs were dominant in the product as the ratio of EG to water increased to 4:1. The current approach is simple and low cost, and can be extended for preparation of other transition metal oxides in nanoscaled size and porous structure.