| As an important p-type semiconductor,Cr2O3 and CuO has many outstanding physical and chemical properties It is noteworthy that Cr2O3 and CuO have sensitive of overwhelming majority reduce gas,such as ethanol,ammonia and carbon monoxide.As we know,most of the traditional resistance types of sensors should run at high temperature and high gas concentration,because gas adsorption-desorption carried out very slowly at RT.The surface photovoltage(SPV) method is a well established contactless and nondestructive technique for semiconductor characterization that relies on analyzing illumination-induced changes in the surface voltage.At the same time, nanostructured materials will change its physical and chemical properties.Therefore,it is significative work to study gas-sensitive characters of Cr2O3 and CuO nanostructured by surface photovoltage spectroscopy in this thesis.In Chapter 2,Cr2O3 hollow nanospheres were synthesized via a hydrothermal approach and the room-temperature gas sensing properties were investigated by means of SPV technique.Compared with the traditional bulk materials,the gas-sensing properties of Cr2O3 hollow nanospheres in the same concentration of the alcohol have increase significantly.The reason was that the surface of the Cr2O3 hollow nanospheres exited more defects and adsorption oxygen ions which can react with ethanol molecules to release electron and make electron-hole pairs separate effectively so as to increase the sensitivity for ethanol.Experiment results indicated the method of SPV can realize highly sensitive to detect gas-sensitive characters at room temperature.In Chapter 3,we prepared CuO nanorods arrays,nanoflower and nanoflake by controlling the hydrothermal reaction temperaturewe and studied the gas-sensitive characters of CuO nanorod arrays for the detection of ethanol by SPV spectroscopy. Similarly,the value of SPV of the samples was more than the bulk CuO's.This would validate the results of Chapter 2.
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