Engineering Ultrafine NiFe-LDH into Self-Supporting Nanosheets: Separation-and-Reunion Strategy to Expose Additional Edge Sites for Oxygen Evolution,Small

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Engineering Ultrafine NiFe-LDH into Self-Supporting Nanosheets: Separation-and-Reunion Strategy to Expose Additional Edge Sites for Oxygen Evolution
Small ( IF 13.0 ) Pub Date : 2021-10-11 , DOI: 10.1002/smll.202103785
Zhihao Zhang _{1,

2} , Chunli Wang _{1,

2,

3} , Xuelu Ma ₃ , Feng Liu _{1,

2} , Hai Xiao ₄ , Jing Zhang _{1,

2} , Zhang Lin ₅ , Zhengping Hao _{1,

2}

Affiliation

Here, a strategy is reported to prepare Ni-Fe layered double hydroxide (NiFe-LDH) with abundant exposed edge planes for enhanced oxygen evolution reaction (OER). The edge-to-edge assembly of ultrafine NiFe-LDH directed by graphite-like carbon is performed through a one-step hydrothermal process to form self-supporting nanosheet arrays (named NiFe-LDH/C), in which ascorbic acid is employed as the carbon precursor to control both the platelet size and the assembly mode of NiFe-LDH. Benefiting from the unique structural engineering, NiFe-LDH/C can not only achieve a fast surface reconstruction into the highly active γ-phase structure, but also exposes abundant active edge sites, thus leading to a superior OER performance with the overpotential as low as 234 mV at a current density of 50 mA cm⁻². Furthermore, density functional theory (DFT) calculations reveal that the unsaturated Fe-sites and the bridge-sites connecting Ni and Fe atoms, which only exist on the edge planes of NiFe-LDH, are the main active centers responsible for promoting the intrinsic OER activity. This work provides a specific and valuable reference for the rational design of high-quality electrocatalysts through structural engineering for renewable energy applications.

中文翻译：

将超细 NiFe-LDH 设计成自支撑纳米片：分离和团聚策略以暴露额外的氧气释放边缘位点

在这里，报道了一种制备具有大量暴露边缘平面的 Ni-Fe 层状双氢氧化物 (NiFe-LDH) 以增强析氧反应 (OER) 的策略。由类石墨碳引导的超细 NiFe-LDH 的边缘到边缘组装通过一步水热工艺形成自支撑纳米片阵列（命名为 NiFe-LDH/C），其中抗坏血酸用作控制NiFe-LDH的片晶尺寸和组装模式的碳前体。受益于独特的结构工程，NiFe-LDH/C 不仅可以实现快速的表面重建为高活性的 γ 相结构，而且还暴露出丰富的活性边缘位点，从而获得了优异的 OER 性能，过电位低至234 mV，电流密度为 50 mA cm ^-2. 此外，密度泛函理论 (DFT) 计算表明，仅存在于 NiFe-LDH 边缘平面上的不饱和 Fe 位点和连接 Ni 和 Fe 原子的桥位是促进本征 OER 的主要活性中心活动。这项工作为通过可再生能源应用的结构工程合理设计高质量电催化剂提供了具体而有价值的参考。

更新日期：2021-11-25

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