Hierarchically porous cobalt oxyhydroxide derived from Morpho-butterfly wings: Preparation, characterization, and carbon monoxide detection at low temperatures



Hierarchical porous cobalt oxyhydroxide (CoOOH) has been successfully synthesized using a Morpho-butterfly wing as template via a sol–gel dip-coating process followed by a hydrothermal approach. The precursor concentrations and dip-coating cycles have a large effect on the morphologies and porous structures of wings-templated CoOOH according to field emission scanning electron microscopy (FE-SEM), mercury porosimetry, and Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption investigations. Cross-sensitivity of the wings-templated and non-templated CoOOH sensors to various gases coexisting with the environments was investigated. It is revealed that wings-templated CoOOH has excellent sensitivity and selectivity to carbon monoxide (CO) due to inheritance of the wing's hierarchical porous structure. The sensing response (S) to CO of wings-templated CoOOH is about 1.48 times higher than that of non-templated CoOOH. The optimum working temperature of the wings-templated CoOOH and wings-templated Zn-doped CoOOH for CO detection was roughly 70 °C. The wings-templated Zn-doped CoOOH also exhibited high sensitivity (5.68) and selectivity for CO relative to H2 (equation image = 4.37). The selective sensing mechanism has been discussed in terms of gas–solid reactions, grain size, and hierarchical porous microstructures.