La, Ce co-doped In2O3 hierarchical microstructure with high sensing performance towards n-butanol

Dual rare earth (La/Ce) doped In2O3 hierarchical microstructures are prepared by a hydrothermal method followed by calcination. Various combination amounts of La and Ce are systematically investigated via a climbing method to determine an optimized co-doping sample. Characterization results indicate that doping enables to distort crystal structure, leading to hierarchical morphology with large surface area, abundant surface defects and oxygen vacancy. Gas sensing tests reveal that co-doping into In2O3 significantly improves the sensing performance towards n-butanol. The La1Ce4.5-In2O3 sample has the highest sensing response (143) towards 100 ppm n-butanol at the optimized temperature of 280 degrees C, which is 8.0, 4.3 and 1.4 times higher than that of the pristine In2O3, La1-In2O3 and Ce4.5-In2O3, respectively. To deeply understand the enhanced sensing mechanism, electrochemical experiments are conducted. The high sensing performance of La1Ce4.5-In2O3 can be attributed to: (1) its optimized band structure, (2) large carrier density, (3) low charge transfer resistance, and (4) strong redox activity on the surface of materials.