Acetic acid gas sensors based on Ni^(2+) doped ZnO nanorods prepared by using the solvothermal method

Ni^（2＋）-doped ZnO nanorods with different doping concentrations are prepared via the solvothermal method.The doped ZnO nanorods are characterized by X-ray diffraction（XRD） and scanning electron microscopy （SEM）,respectively.The amount of Ni^（2＋） ions that enter the lattice of ZnO increases with increasing the Ni^（2＋）/Zn^（2＋） molar ratio when the molar ratio of Ni^（2＋）/Zn^（2＋） in the starting solution is lower than 3%and does not change obviously if the mole ratio of Ni^（2＋）/Zn^（2＋） in the starting solution is in the range of 3-10 mol%.The effect of Ni^（2＋） doping on the gas-sensing properties is investigated.The results reveal that the amount of Ni^（2＋） has a great influence on the response（R_a/R_g） and the gas-sensing selectivity.The sensor based on 1 mol%Ni^（2＋） doped ZnO nanorods （120℃,10 h） exhibits a high response to acetic acid vapor,in particular,the responses to 0.001 ppm and 0.01 ppm acetic acid vapor reach 1.6 and 2,respectively.The response time and the recovery time for 0.001 ppm acetic acid are only 4 s and 27 s,respectively.