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Ferroelectric polarization-enhanced charge separation in quantum dots sensitized semiconductor hybrid for photoelectrochemical hydrogen production
Nano Energy ( IF 17.6 ) Pub Date : 2020-11-23 , DOI: 10.1016/j.nanoen.2020.105626
Min Zhang , Faying Li , Daniele Benetti , Riad Nechache , Qin Wei , Xiwei Qi , Federico Rosei

A major unresolved challenge in photoelectrochemical (PEC) solar fuels production is the efficient separation of charges. Here we successfully synthesized a hybrid ferroelectric-semiconducting TiO2 system as photoanode, sensitized with colloidal quantum dots (QDs) to enhance light absorption. By tuning the amount of barium titanate (BaTiO3, BTO) in the photoanode composition and its polarization state, we could obtain a remarkable enhancement up to + 105% compared to the simple TiO2 photoanode. By using engineered QDs with a gradient interface, the photoanode reached a photocurrent density (Jph) and charge-separation efficiency (ηseparation) of 15.3 mA cm−2 and 22.3% at 0.5 V versus the reversible hydrogen electrode (RHE), respectively. To investigate the general beneficial effect of the addition of BTO, three different kinds of QDs were used. By systematically investigating UV–Visible absorption and band alignment, we were able to attribute the increased Jph to an improved charge separation, which was induced by the ferroelectric depolarization electric field. The results were further confirmed by photoluminescence and electrochemical impedance spectroscopy measurements. Our work provides unique insights to improve the performance of PEC photoelectrodes by combining ferroelectric and semiconducting features with the broad absorption of colloidal QDs.



中文翻译:

量子点敏化半导体杂化物中铁电极化增强的电荷分离,用于光电化学制氢

光电化学(PEC)太阳能燃料生产中的主要未解决挑战是电荷的有效分离。在这里,我们成功地合成了一种混合的铁电半导体TiO 2系统作为光阳极,并用胶体量子点(QDs)进行了敏化以增强光吸收。通过调整光阳极成分中钛酸钡(BaTiO 3,BTO)的数量及其偏振态,与简单的TiO 2光阳极相比,我们可以获得高达+ 105%的显着增强。通过使用带有梯度界面的工程QD,光阳极的光电流密度(J ph)和电荷分离效率(η分离)达到15.3 mA cm -2相对于可逆氢电极(RHE)在0.5 V时为22.3%。为了研究添加BTO的一般有益效果,使用了三种不同的QD。通过系统地研究紫外可见吸收和能带对准,我们能够将增加的J ph归因于电荷分离的改善,这是由铁电去极化电场引起的。通过光致发光和电化学阻抗谱测量进一步证实了该结果。通过将铁电和半导体特性与胶体量子点的广泛吸收相结合,我们的工作提供了独特的见解,以提高PEC光电极的性能。

更新日期:2020-12-14
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