Preparation of three-dimensional Ce-doped Sn^sub 3^O^sub 4^ hierarchical microsphere and its application on formaldehyde gas sensor

3-D hierarchical Sn3O4 and Ce-doped Sn3O4 microspheres assembled by nano-sheets were obtained by a one-step hydrothermal method and their formaldehyde sensing properties were investigated. The experiment results showed that the responses of the sensors based on Ce-Sn3O4 microspheres with different Ce-doping content were improved in different extents. The response of the optimal sensor based on Ce-Sn3O4 microspheres was 2.5 times higher than that of sensor based on Sn3O4 to 100 ppm formaldehyde. In addition, the sensors based on Ce-Sn3O4 microspheres showed good selectivity, repeatability, stability and fast response and recovery rate (about 4 s and 8 s to 200 ppm formaldehyde, respectively). Also, the possible mechanism of the improvement of formaldehyde sensing properties caused by Ce-doping was discussed.