Activation of Photoelectrochemical Reaction for High Temperature Oxidation Film by Non-stoichiometry Control

研究了氧化物的非化学计量控制对金属高温氧化形成的氧化膜光电化学特性的影响。通过氢还原处理和金属高温氧化制备氧化膜时的氧压控制氧化膜的非化学计量。对于钛高温氧化形成的金红石- tio_2 （n型导电）薄膜，通过氢还原处理和降低氧分压，在氧化膜中引入了氧化离子空位。光阳极电流随还原温度的升高和制备膜所需氧气压力的降低而增大。这表明光阳极反应是通过在氧化膜中引入氧化离子空位而激活的。对于钽高温氧化形成的β - ta_2o_5薄膜（n型导电），氢还原的光阳极电流随着温度的升高而增大。从这些结果中发现，具有n型导电的氧化物半导体的光阳极反应是通过在氧化物中引入氧化物离子空位而激活的。对于铜高温氧化形成的Cu_2O膜（p型导电），在低温下氢还原激活光阴极反应，引起氧化离子空位。因此，在氧化膜中引入氧化离子空位可以激活氧化半导体电极的光电化学反应，而不依赖于导电类型。

The effect of non-stoichiometry control of oxide on photoelectrochemical characteristics of oxide films formed by high temperature oxidation of metals was investigated. The non-stoichiometry of the oxide films was controlled by a hydrogen reduction treatment and a control of oxygen pressure for preparation of oxide films by the high temperature oxidation of metals. For rutile-TiO_2 film (n-type conduction) formed by the high temperature oxidation of titanium, oxide ion vacancies in the oxide film were introduced by the hydrogen reduction treatment and a lowering of oxygen pressure for the preparation of the films. Photo-anodic current was increased with an increase in the reduction temperature and with the lowering of oxygen pressure for the preparation of film. This suggests that the photo-anodic reaction is activated by the introduction of oxide ion vacancies into the oxide film. For beta-Ta_2O_5 film (n-type conduction) formed by high temperature oxidation of tantalum, the photoanodic current increased with increasing temperature for the hydrogen reduction. It was found from these results that the photo-anodic reaction for oxide semiconductor having n-type conduction was activated by the introduction of oxide ion vacancies into the oxide. For Cu_2O film (p-type conduction) formed by high temperature oxidation of copper, photo-cathodic reaction was activated by a hydrogen reduction at low temperature, by which oxide ion vacancies were induced.Consequently, it has become apparent that the introduction of oxide ion vacancy into oxide film activated the photoelectrochemical reaction for oxide semiconductor electrode without depending on the conduction type.