应用光电化学响应法和Mott-Schottky曲线法, 研究了Ni201在500 ℃空气中生成的氧化膜和在pH值为8.4的中性缓冲溶液中阳极氧化生成钝化膜的半导体性质, 分析了Ni201表面钝化膜的结构和组成. Mott-Schottky曲线表明, Ni201在该中性溶液中生成钝化膜的平带电位约为0.40 V, 其在500 ℃空气中生成的氧化膜的平带电位约为0.15 V, 前者的载流子浓度约是后者的34倍. 在中性缓冲溶液中生成钝化膜的光电流谱表明, Ni201的结构由内层NiO和外层Ni(OH)2构成, 其带隙宽度分别为2.8和1.6 eV. 其中, 具有晶体结构的内层NiO的带隙宽度与Ni201在500 ℃空气中生成的氧化膜的带隙宽度2.4 eV相似. 通过光电化学法和Mott-Schottky曲线建立 Ni201表面钝化膜的电子能带结构模型, 解释了其内层NiO和外层Ni(OH)$_{2}$同是p型半导体组成的钝化膜的半导体性质.
The semiconductor properties of the passive film on Ni201 formed by anodic passivation in pH=8.4 buffer solution and the oxide film on Ni201 formed by thermally grown in air at 500 ℃ were investigated by photoelectrochemical response and Mott–Schottky response analysis. The Mott–Schottky plots for both the passive film and the thermal oxide film on Ni201 demonstrated that the two films exhibited p–type semiconductors with different values of flat band potential: 0.40 V for the passive film and 0.15 V for the thermally grown NiO. The photocurrent spectra of the passive film on Ni201 were derived into two peaks for inner NiO and outer Ni(OH)2 layers, respectively. The band gap energy Eg for the inner NiO was 2.8 eV and the Eg for outer Ni(OH)2 was 1.6 eV, respectively. The Eg of the inner NiO of the passive film on Ni201 (2.8 eV) was closed to that of the thermally grown oxide of Ni201 (2.4 eV), indicating that the inner NiO in the passive film is crystalline structure. An electronic energy band model of both p–type semiconductors of inner NiO and outer Ni(OH)2 layers was proposed to explain the photocurrent and Mott–Schottky plots for the passive film on Ni201.
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