Insights on Thickness-Dependent Charge Transfer Efficiency Modulated by Ultrasonic Treatment in Hematite Photoanodes
Insights on Thickness-Dependent Charge Transfer Efficiency Modulated by Ultrasonic Treatment in Hematite Photoanodes
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DOI：
10.1021/acs.jpcc.0c11397
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发表时间：
2021-04-29
影响因子：
3.7
通讯作者：
Li, Yat
中科院分区：
文献类型：
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作者：
Freitas, Andre L. M.;Tofanello, Aryane;Li, Yat
对与赤铁矿的不良电荷载流子动力学相关的固-液界面的理解阻碍了其作为光电化学电池中的光阳极的商业应用。科学界仍在寻求制定一种低成本和可扩展的战略来克服这些缺点。在这里，一个简单的表面改性的赤铁矿光阳极设计与不同的厚度进行了采用超声处理（UST）过程。UST基于固-液能量学产生不均匀的缺陷分布。较厚的光阳极（H-4 h）表明，机械过程可以有助于去除不稳定层，产生有利于氧析出的位点，而不损害固-固界面。H-2 h的UST方法促进了表面态的钉扎，并可能增加了赤铁矿和FTO之间的应力。对较薄的光阳极（H-2 h）的影响可以显著地产生增强表面捕获状态的极化状态，从而减少光生电荷寿命。结果发现，表面羟基化可能是非常依赖于电极厚度。这项研究表明，UST方法是一种有效的工具，以提高更厚的光阳极的性能，如实际应用所需。因此，对于较薄的层，在赤铁矿-FTO界面处引起的应力可以通过克服在固液界面处的有益效果的机械处理而加剧。事实上，通过超声处理过程进行的羟基化是高度推荐的设计较厚的膜。
The comprehension of the solid-liquid interface associated with the poor charge carrier dynamic of hematite has prevented its commercial application as a photoanode in a photoelectrochemical cell. The development of a low-cost and scalable strategy to overcome such drawbacks is still being pursued by the scientific community. Here, a simple surface modification of hematite photoanode designed with different thicknesses was carried out by employing an ultrasonic treatment (UST) process. UST creates an inhomogeneous defect distribution based on the solid-liquid energetics. The thicker photoanodes (H-4h) showed that the mechanical process can contribute to removing unstable layers, creating favorable sites for oxygen evolution without compromise the solid-solid interface. The UST approach for H-2h has promoted surface states pinning and possibly increased the stress between hematite and FTO. The effects on thinner photoanodes (H-2h) can drastically create polarized states that enhance surface trapping states, reducing the photogenerated charge lifetime. The outcome findings reveal that the surface hydroxylation might be extremely dependent on the electrode thickness. This study indicates that the UST approach is an efficient tool to boost the performance of thicker photoanodes, as desired for practical applications. Thus, for thinner layers, the stress induced at the hematite-FTO interface can be aggravated by mechanical treatment overcoming the beneficial effects at the solid-liquid interface. In fact, hydroxylation conducted via the sonication process is highly recommended for designing thicker films.