Controllable preparation of faceted Co3O4 nanocrystals@MnO2 nanowires shish-kebab structures with enhanced triethylamine sensing performance

Novel one-dimensional shish-kebab structures composed of active (110)-faceted alpha-MnO2 nanowires as backbones and (111)-faceted Co3O4 nanocrystals as shells were prepared by a hydrothermal method followed by an in-situ epitaxial attachment growth strategy. A series of characterization revealed the formation of Co3O4@ MnO2 heterostructures with closely integrated hetero-interfaces. The growth mechanism study suggested that the multiple functions of hexamethylenetetramine were crucial for the the successful growth of the Co3O4@ MnO2 heterostructures. The gas sensing performance of the Co3O4@MnO2 heterostructures was studied for the first time. It was shown that the Co3O4@MnO2 heterostructures exhibited obvious enhanced triethylamine sensing performance compared with bare MnO2 nanowires and Co3O4 nanocrystals, suggesting a strong synergistic effect. The unique one-dimensional shish-kebab structures, increased surface active oxygen species and closely-attached hetero-interface were the key factors to improve the triethylamine sensing performance. The work not only provide an in-situ strategy for the synthesis of one-dimensional heterostructures, but also provide an effective way to improve the inherently low gas response of alpha MnO2 through comprehensive design of morphology, crystal facet and hetero-interface. Moreover, thanks to the unique morphology, surface and interface characteristics of the Co3O4@MnO2 heterostructures, they are expected to be used in more fields, such as batteries, supercapacitor and catalysis.