Operando X射线吸收光谱法（XAS）观察赤铁矿（α-Fe2O3）光电阳极上FeNi（Oxy）氢氧化物覆盖层中的光诱导氧化，用于太阳能水分解。,Langmuir

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Operando X射线吸收光谱法（XAS）观察赤铁矿（α-Fe2O3）光电阳极上FeNi（Oxy）氢氧化物覆盖层中的光诱导氧化，用于太阳能水分解。
Langmuir ( IF 3.7 ) Pub Date : 2020-09-08 , DOI: 10.1021/acs.langmuir.0c02065
Anton Tsyganok ₁ , Paolo Ghigna ₂ , Alessandro Minguzzi ₃ , Alberto Naldoni ₄ , Vadim Murzin _{5,

6} , Wolfgang Caliebe ₅ , Avner Rothschild ₁ , David S Ellis ₁

Affiliation

的铁-镍合金（氧）氢氧化物助催化剂覆盖层是光电化学沉积在薄膜的赤铁矿（α-的Fe ₂ ö ₃）光电阳极，导致光电流起始电位的阴极位移约为100 mV。Fe和Ni K边缘的Operando X射线吸收光谱（XAS）用于研究在黑暗和光照条件下，电势变化的覆盖层的变化。电位或照度对Fe的氧化态影响很小，这表明Fe原子在整个电位范围内不会累积大量电荷。相反，Ni K-边缘光谱显示出在黑暗和光照下对电势的明显依赖性。由于产生的光电压，照明的作用是转移Ni氧化的开始，并暗示在赤铁矿中光生的空穴主要转移到表层中的Ni原子上。Ni的氧化态的增加在与Ni的氧化还原波相对应的电势下进行，Ni的氧化还原波在氧释放反应（OER）开始之前立即发生。对获得的光谱进行线性组合拟合分析表明，覆盖层不必完全氧化即可促进氧气的释放。阴极放电测量表明，光生电荷几乎全部存储在覆盖层体积内的Ni原子中。

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Operando X-ray Absorption Spectroscopy (XAS) Observation of Photoinduced Oxidation in FeNi (Oxy)hydroxide Overlayers on Hematite (α-Fe2O3) Photoanodes for Solar Water Splitting.

An FeNi (oxy)hydroxide cocatalyst overlayer was photoelectrochemically deposited on a thin-film hematite (α-Fe₂O₃) photoanode, leading to a cathodic shift of ∼100 mV in the photocurrent onset potential. Operando X-ray absorption spectroscopy (XAS) at the Fe and Ni K-edges was used to study the changes in the overlayer with potential in the dark and under illumination conditions. Potential or illumination only had a minor effect on the Fe oxidation state, suggesting that Fe atoms do not accumulate significant amount of charge over the whole potential range. In contrast, the Ni K-edge spectra showed pronounced dependence on potential in the dark and under illumination. The effect of illumination is to shift the onset for the Ni oxidation because of the generated photovoltage and suggests that holes that are photogenerated in hematite are transferred mainly to the Ni atoms in the overlayer. The increase in the oxidation state of Ni proceeds at potentials corresponding to the redox wave of Ni, which occurs immediately prior to the onset of the oxygen evolution reaction (OER). Linear combination fitting analysis of the obtained spectra suggests that the overlayer does not have to be fully oxidized to promote oxygen evolution. Cathodic discharge measurements show that the photogenerated charge is stored almost exclusively in the Ni atoms within the volume of the overlayer.

更新日期：2020-10-06

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