PHOTOELECTROCHEMISTRY OF NICKEL-HYDROXIDE THIN-FILMS
PHOTOELECTROCHEMISTRY OF NICKEL-HYDROXIDE THIN-FILMS
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DOI：
10.1149/1.2096777
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发表时间：
1989-04-01
影响因子：
3.9
通讯作者：
CORRIGAN, DA
中科院分区：
文献类型：
--
作者：
CARPENTER, MK;CORRIGAN, DA
报道了电致变色氢氧化镍薄膜在1 M KOH溶液中的光电化学行为。阴极光电流是从还原膜，其表现为p型半导体。还原相的有效带隙估计为3.6-3.9 eV，尽管光学吸光度和光作用数据表明进入带隙的状态的显著拖尾。从氧化膜的阳极光电流，表现为n型半导体，可以产生的能量低至1.5 eV的可见光。阴极和阳极光电流的瞬态行为和效率的报告。在氢氧化镍氧化还原反应发生的电位区域，发现了一种不寻常的瞬态光电流响应。光照产生一个阴极电流尖峰，随后是一个小的稳态阳极光电流，而光的中断引起阳极电流尖峰。阴极光响应，发现只有在电位氧化和还原形式的膜存在。对瞬态的可能解释包括双电层效应、表面氧化还原反应的加速和中间带隙态的激发。氢氧化镍的结构和电化学由于其作为镍电池系统中的活性材料的重要性而被广泛研究（1-2）。氢氧化镍也是一种有前途的电致变色材料，在”智能”窗户中具有潜在的应用（3-5）。这种窗户具有可变的透光特性，并且可用于隐私应用以及用于减少汽车和建筑物中的太阳热负荷。氢氧化镍的电致变色反应是一个可逆的氧化还原反应，其中还原态几乎是透明的，而氧化态是深棕色。光学性质的这种显著变化是由于氢氧化镍的电子性质在氧化/还原时发生的变化。此外，电子性质也可能强烈影响氢氧化镍电极的动力学行为，从而影响电致变色膜中的着色/漂白过程（5）。显然，氧化相和还原相的电子性质的知识是重要的系统的完整理解。氢氧化镍在碱性溶液中的氧化通常写为
The photoelectrochemical behavior of electrochromic nickel hydroxide films in 1M KOH is reported. Cathodic photocurrent was obtained from reduced films which behave as p-type semiconductors. The effective bandgap of the reduced phase is estimated to be 3.6-3.9 eV, although optical absorbance and photoaction data indicate a significant tailing of states into the bandgap. Anodic photocurrent from oxidized films which behave as n-type semiconductors can be generated by visible light of energies as low as 1.5 eV. Transient behaviors and efficiencies of both the cathodic and anodic photocurrents are reported. An unusual transient photocurrent response was found in the potential region in which the nickel hydroxide redox reaction occurs. Illumination produced a cathodic current spike followed by a small, steady-state anodic photocurrent, while interruption of the light caused an anodic current~ pike. The cathodic photoresponse was found only at potentials where both oxidized and reduced forms of the film were present. Possible explanations for the transients include double-layer effects, acceleration of surface redox reactions, and the excitation of midgap states.The structure and electrochemistry of nickel hydroxide has been studied extensively due to its importance as the active material in nickel battery systems (1-2). Nickel hydroxide is also a promising electrochromic material with potential application in" smart" windows (3-5). Such windows have variable light transmission characteristics and may be useful both for privacy applications and for the reduction of solar heat load in automobiles and buildings. The electrochromic reaction of nickel l~ ydroxide is a reversible redox reaction in which the reduced form is nearly transparent while the oxidized material is a dark brown. This dramatic change in optical properties is due to changes in the electronic properties of nickel hydroxide which occur upon oxidation/reduction. In addition, electronic properties are also likely to strongly affect the kinetic behavior of nickel hydroxide electrodes and thus affect the coloration/bleaching processes in electrochromic films (5). Clearly, knowledge of the electronic properties of both the oxidized and reduced phases is important for a complete understanding of the system. The oxidation of nickel hydroxide in basic solutions is typically written as