Preparation of In2O3-CuO and its room temperature gas-sensitive properties for formaldehyde under photoactivation
In2O3-CuO composites were prepared from hydrothermal reaction of InCl3·4H2O and Cu(NO3)2·3H2O with urea as precipitant,characterized by XRD,SEM,TEM,UV-Vis absorption spectrum,XPS and EIS,and further evaluated for their gas-sensitive properties and sensing mechanism in UV excitation.The results showed that In2O3-CuO composites exhibited a sensitivity of 298 for formaldehyde gas with a mass concentration of 50 mg/L at room temperature(25℃)under 375 nm UV light irradiation,123 times more sensitive than pure In2O3(2.4).The significant improvement in gas sensitivity was attributed to p-n heterojunction formed by In2O3 and CuO,while the photogenerated electrons-hole,generated at the heterojunction interface under the synergistic photoactivation conditions,and the oxygen species(O2 and O2-)established a photoactivated adsorption-desorption cycle of oxygen,resulting in the enhancement of gas adsorption-desorption process and surface reaction of the material at room temperature.
In2O3-CuOUV-photoactivationroom temperature gas sensitivityp-n heterojunctionformaldehydefunctional materials
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