An iron oxide photoanode with hierarchical nanostructure for efficient water oxidation
An iron oxide photoanode with hierarchical nanostructure for efficient water oxidation
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DOI：
10.1039/c3ta13830e
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发表时间：
2014-01
影响因子：
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通讯作者：
Tae-Youl Yang;Ho‐Young Kang;K. Jin;Sangbaek Park;Jihoon Lee;U. Sim;Hui-Yun Jeong;Young‐Chang Joo;K. Nam
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文献类型：
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作者：
Tae-Youl Yang;Ho‐Young Kang;K. Jin;Sangbaek Park;Jihoon Lee;U. Sim;Hui-Yun Jeong;Young‐Chang Joo;K. Nam
赤铁矿（α-Fe 2 O3）由于其可见光光子吸收能力和较高的化学稳定性，在光电化学水氧化领域受到广泛关注，但其空穴扩散长度短、过电位大等问题仍有待克服。在这里，为了解决这些挑战，我们开发了一种由铁氧化物组成的分级纳米结构光阳极;掺杂钛的赤铁矿纳米棒用未掺杂的赤铁矿底层和β-FeOOH纳米分支装饰。通过水热合成法制备了掺钛赤铁矿纳米棒阵列，这种纳米结构提供了增强的光生电荷分离。衬层不仅增加了光电流密度，而且提高了起始电位。在赤铁矿表面外延生长的β-FeOOH纳米枝进一步增加了光电流，但由于平带电位的增加，β-FeOOH使起始电位正移。光电流瞬态和电化学阻抗谱的分析表明，β-FeOOH通过降低阳极/电解质的电荷转移电阻来提高光电流。这项研究证明了一种新的可能性，提高效率的赤铁矿光阳极与其他铁氧化物的界面。
Hematite (α-Fe2O3) has been attracting attention for photoelectrochemical water oxidation due to its visible light photon absorption capacity and high chemical stability, but the short-diffusion length of holes and the large overpotential are still challenging to overcome. Here, in an effort to address these challenges, we develop a hierarchically nanostructured photoanode composed of iron-oxides; Ti-doped hematite nanorods are decorated with an undoped hematite underlayer and β-FeOOH nano-branches. The Ti-doped hematite nanorod array is prepared by hydrothermal synthesis, and this nanostructure offers enhanced separation of photogenerated charges. The underlayer not only increases the photocurrent density but also improves the onset potential. The photocurrent further increases by the epitaxially grown β-FeOOH nano-branches on the hematite, but the onset potential is positively shifted by the β-FeOOH due to increasing flat-band potential. The analyses of the photocurrent transients and electrochemical impedance spectra reveal that β-FeOOH improves the photocurrent by decreasing the resistance to charge transfer through the anode/electrolyte. This study demonstrates a new possibility for improving the efficiency of a hematite photoanode with the interface of other iron-oxides.