赤铁矿
耗尽区
带材弯曲
图层(电子)
密度泛函理论
兴奋剂
纳米技术
材料科学
空间电荷
凝聚态物理
化学物理
电荷密度
化学
光电子学
计算化学
物理
电子
量子力学
冶金
作者
Paola Delcompare-Rodriguez,Nicola Seriani
摘要
The space charge layer in hematite photoelectrodes has been analyzed by means of Poisson–Boltzmann equations, the Stern model, and density functional theory, in view of its application for photoelectrochemical water oxidation. The width of the space charge layer can be smaller than ∼10 Å under experimental conditions. In this regime, a substantial part of the potential drop takes place in the Helmholtz layer, leading to important corrections to the Mott–Schottky behavior of the space charge layer capacitance. These results shed light on an unexpected regime of high photoelectrocatalytic efficiency, different from the classical picture of the electrochemical interface of a semiconducting photocatalyst, which is also amenable to direct study by quantum-mechanical atomistic simulations. Density functional theory has been used to calculate the band bending (BB) in the space charge layer in atomistic models of pristine stoichiometric and hydroxylated surfaces. These surface terminations display BBs of 0.14 and 0.49 eV, respectively, with an increasing width of the space charge layer, however still in the sub-nanometer regime. This work shows that, at high doping, the width of the space charge layer of a hematite photoelectrode can become comparable with interatomic distances.
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