Nanoporous NiAl-LDH nanosheet arrays with optimized Ni active sites for efficient electrocatalytic alkaline water splitting,Sustainable Energy & Fuels

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Nanoporous NiAl-LDH nanosheet arrays with optimized Ni active sites for efficient electrocatalytic alkaline water splitting
Sustainable Energy & Fuels ( IF 5.0 ) Pub Date : 2020-03-30 , DOI: 10.1039/d0se00050g
Liangliang Feng _{1,

2,

3,

4,

5} , Yingying Du _{1,

2,

3,

4,

5} , Jianfeng Huang _{1,

2,

3,

4,

5} , Liyun Cao _{1,

2,

3,

4,

5} , Li Feng _{1,

2,

3,

4,

5} , Yongqiang Feng _{1,

2,

3,

4,

5} , Qianqian Liu _{1,

2,

3,

4,

5} , Dan Yang _{1,

2,

3,

4,

5} , Koji Kajiyoshi _{6,

7,

8,

9,

10}

Affiliation

The rational design and development of cost-effective and high-efficiency bifunctional electrocatalysts for overall water splitting is of prime significance for advancing large-scale commercial hydrogen production. Herein, a novel nanoporous NiAl layered double hydroxide nanosheet array with optimized Ni active sites on nickel foam (np-NiAl-LDH/NF) is prepared by a facile and simple metal-defect engineering strategy. We demonstrate that the partial leaking of catalytically inactive Al sites in NiAl-LDH nanosheets during anodic electrochemical etching can not only trigger the generation of a nanoporous structure and electron-rich Ni²⁺ sites, but can also increase the content of Ni³⁺ active sites accompanied by abundant oxygen defects, resulting in the synchronously increased density and intrinsic activity of Ni active sites and also enhanced mass and electron transport, thus greatly promoting the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics. As expected, the as-obtained np-NiAl-LDH/NF electrode needs extremely small overpotentials of 90 and 180 mV to deliver the 10 mA cm⁻² current density for the HER and OER in alkaline media, respectively. Moreover, an alkaline electrolyzer assembled with np-NiAl-LDH/NF functioning as both the anode and cathode can yield 10 and 100 mA cm⁻² at quite low voltages of ∼1.5 and 1.7 V, respectively, far outperforming the Pt/C/NF–IrO₂/NF-coupled electrolyzer, and can give durable stability for at least 60 h. This work provides new insights for creating highly efficient Ni-based electrocatalysts toward overall water splitting via engineering on catalytically active Ni sites.

中文翻译：

具有优化的Ni活性位的纳米多孔NiAl-LDH纳米片阵列，可实现有效的电催化碱性水分解

合理设计和开发用于整体水分解的经济高效的双功能电催化剂，对于推进大规模商业制氢至关重要。在此，通过一种简便而简单的金属缺陷工程策略，制备了一种新型的纳米多孔NiAl层状双氢氧化物纳米片阵列，其在泡沫镍上具有优化的Ni活性位（np-NiAl-LDH / NF）。我们证明，在阳极电化学蚀刻过程中，NiAl-LDH纳米片中的无催化活性的Al部位的部分泄漏不仅可以触发纳米孔结构和富电子的Ni ²⁺部位的产生，而且可以增加Ni ³⁺的含量活性位点伴随着大量的氧缺陷，导致镍活性位点的密度和内在活性同步增加，并且质量和电子传输增强，从而极大地促进了析氢反应（HER）和析氧反应（OER）动力学。如预期的那样，如此获得的np-NiAl-LDH / NF电极需要极小的90和180 mV的过电势，才能分别在碱性介质中为HER和OER提供10 mA cm ^-2的电流密度。此外，组装有np-NiAl-LDH / NF的阳极和阴极功能的碱性电解槽在约1.5和1.7 V的极低电压下可分别产生10和100 mA cm ^-2，远胜过Pt / C / NF–IrO ₂/ NF耦合电解槽，可提供至少60小时的持久稳定性。这项工作为通过在活性镍位点上进行工程设计来创建高效的镍基电催化剂，实现总水分解提供了新的见解。

更新日期：2020-03-30

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