Recently, the flexoelectric effect has triggered considerable interest in energy-related applications, such as flexo-actuation, flexo-photovoltaic, and flexo-catalysis, because of its ubiquitous feature allowing the creation of electric polarity, i.e., the flexoelectric polarization (Pflexo), in non-polar materials by strain gradient. Here, we show a flexoelectric strategy in electrocatalytic water splitting. Remarkably enhanced oxygen evolution reaction (OER) properties are achieved in strain-gradient LaFeO3 (LFO) thin-film heterostructures owing to the promotion of kinetic processes by Pflexo. The improved OER is demonstrated by increased current density of ∼300% in linear sweep voltammetry and lowered charge transfer resistance by two orders of magnitude in electrochemical impedance spectroscopy. These are ascribed to the flexoelectric-induced downward bending of the LFO band, as revealed by density functional theory calculations and band structure measurements. With Pflexo in the thin-film heterostructure catalysts, the adsorption of hydroxyl ions is strengthened on the polar LFO surface, and the transfer of electrons is accelerated from the reactants/key intermediates to the catalyst across the band-tilted LFO layer. These findings indicate the significance of flexoelectric effect in OER kinetics and open a new perspective for exploiting catalytic mechanisms and performances in water splitting.

中文翻译：

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增强柔性薄膜异质结构中的析氧反应


最近，挠曲电效应引发了人们对能源相关应用的极大兴趣，例如柔曲驱动、柔曲光伏和柔曲催化，因为它无处不在的特性允许通过应变梯度在非极性材料中产生电极，即挠曲电极化 （Pflexo）。在这里，我们展示了电催化分解水中的挠曲电策略。由于 Pflexo 促进动力学过程，在应变梯度 LaFeO3 （LFO） 薄膜异质结构中实现了显著增强的析氧反应 （OER） 性能。线性扫描伏安法的电流密度增加了 ∼300%，电化学阻抗谱的电荷转移电阻降低了两个数量级，证明了 OER 的改进。这些归因于 LFO 频段的挠曲电感应向下弯曲，密度泛函理论计算和能带结构测量揭示了这一点。在薄膜异质结构催化剂中使用 Pflexo，羟基离子在极性 LFO 表面上的吸附得到加强，电子通过带倾斜 LFO 层加速从反应物/关键中间体转移到催化剂。这些发现表明了挠曲电效应在 OER 动力学中的重要性，并为开发分解水中的催化机制和性能开辟了新的视角。