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Semi-conducting metal oxides possess a broad range of electrical,chemical and physical properties that are often highly sensitive to changes in the chemical environment.[1] Thus various metal oxides are employed in chemical sensors with different performances.[2] Traditional sensing materials are nanoparticles,[3,4] and the common routes for their sensing enhancements are decreasing their diameters or adding doping metals.[5] However,these struggles often fail due to the aggregation growth among the un-ordered nanoparticles.[6] Recently,interest in one-dimensional (1D) nanostructures has been greatly stimulated since their sensing properties can be improved in this way.[7-11] The high surface-to-volume ratio of 1D nanostructures (a higher surface area provides more sites for analyte molecule adsorption) make them much more sensitive than nanoparticles.[12,13]Many high performance sensors have been obtained based on 1D nanomaterials.However,the investigation on the combination of 1D and porous nanostructures is quite rare.[14-17] As is known,porous structures can improve the adsorption and desorption of the gases on chemical sensors effectively,thus many have been used for enhancing sensing.