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Fast formation of single-unit-cell-thick and defect-rich layered double hydroxide nanosheets with highly enhanced oxygen evolution reaction for water splitting
Nano Research ( IF 9.9 ) Pub Date : 2018-03-19 , DOI: 10.1007/s12274-017-1806-x
Rui Gao , Dongpeng Yan

The development of high-efficiency electrocatalysts for oxygen evolution reactions (OERs) plays an important role in the water-splitting process. Herein, we report a facile way to obtain two-dimensional (2D) single-unit-cell-thick layered double hydroxide (LDH) nanosheets (NSs, ∼1.3 nm) within only 5 min. These nanosheets presented significantly enhanced OER performance compared to bulk LDH systems fabricated using the conventional co-precipitation method. The current strategy further allowed control over the chemical compositions and electrochemical activities of the LDH NSs. For example, CoFe-LDH NSs presented the lowest overpotential of 0.28 V at 10 mA/cm2, and the NiFe-LDHs NSs showed Tafel slopes of 33.4 mV/decade and nearly 100% faradaic efficiency, thus outperforming state-of-the-art IrO2 water electrolysis catalysts. Moreover, positron annihilation lifetime spectroscopy and high-resolution transmission electron microscopy observations confirmed that rich defects and distorted lattices occurred within the 2D LDH NSs, which could supply abundant electrochemically active OER sites. Periodic calculations based on density functional theory (DFT) further showed that the CoFe- and NiFe-LDHs presented very low energy gaps and obvious spin-polarization behavior, which facilitated high electron mobility during the OER process. Therefore, this work presents a combined experimental and theoretical study on 2D single-unit-cell-thick LDH NSs with high OER activities, which have potential application in water splitting for renewable energy.
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中文翻译:

快速形成单细胞厚且缺陷丰富的层状双氢氧化物纳米片,并具有高度增强的析氧反应,可用于水分解

用于氧气析出反应(OER)的高效电催化剂的开发在水分解过程中起着重要作用。在本文中,我们报告了一种简便的方法,可在5分钟内获得二维(2D)单细胞厚的层状双氢氧化物(LDH)纳米片(NSs,〜1.3 nm)。与使用常规共沉淀法制备的大体积LDH系统相比,这些纳米片具有显着增强的OER性能。当前的策略进一步允许控制LDH NS的化学组成和电化学活性。例如,CoFe-LDHs NSs在10 mA / cm 2时呈现出最低的0.28 V过电势,而NiFe-LDHs NSs的Tafel斜率为33.4 mV /十倍,法拉第效率接近100%,因此其表现优于目前的状态。艺术IrO 2水电解催化剂。此外,正电子an没寿命谱和高分辨率透射电子显微镜观察证实,二维LDH NSs内发生了丰富的缺陷和畸变的晶格,可以提供丰富的电化学活性OER位点。基于密度泛函理论(DFT)的定期计算进一步表明,CoFe-和NiFe-LDHs的能隙非常低,自旋极化行为也很明显,这促进了OER过程中的高电子迁移率。因此,这项工作提出了具有较高OER活性的二维单单元厚LDH NSs的组合实验和理论研究,在可再生能源的水分解中具有潜在的应用。
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更新日期:2018-03-19
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