A facile coordination compound precursor route to controlled synthesis of Co3O4 nanostructures and their room-temperature gas sensing properties

We report a simple and novel coordination compound precursor route to synthesize shape-controlled Co3O4 nanostructures. The resultant morphologies of the nanostructures can be tailored by controlling the reaction temperature and the sodium hydroxide concentrations during the growth process. Temperature was found to play an important role in the formation of CoOOH nanosheets and Co3O4 nanooctahedra. A too low temperature (< 100 degrees C) is disadvantageous for the formation of regular hexagonal CoOOH nanosheets and a too high temperature (> 200 degrees C) is unfavourable for the formation of Co3O4 nanooctahedra. At a certain temperature, sodium hydroxide concentration is also crucial for the formation of different shapes of Co3O4 nanostructures. A possible growth mechanism governing the formation of such nanostructures is discussed. The gas sensing properties of the as-synthesized nanostructures are investigated in detail, which reveals that the as-prepared Co3O4 nanostructures exhibit superior sensitivity to CO and CH4 relative to bulk Co3O4 at room temperature, as well as good reproducibility and short response/recovery times. The as-prepared Co3O4 nanostructures could have potential applications in nanosensors.