In electrocatalysis, layered double hydroxide (LDH) materials have attracted considerable interest in promoting the oxygen evolution reaction (OER). For the hydrogen evolution reaction (HER), these materials show a poor electrocatalytic activity. In this work, we take CoFe LDH grown on nickel foam as a model system, and for the first time we treat CoFe LDH under plasma etching conditions, which results in a highly active HER electrocatalyst in alkaline media. Massive defects and amorphous phase formation occur during plasma etching. More importantly, phase transformation of CoFe LDH into CoFe₂O₄ takes place. Additional introduction of Ce leads to more active sites and improved electrical conductivity, which provide an overpotential of 73 mV at a current density of 10 mA cm⁻² for V-Ce/CoFe LDH. The experimental results match well with DFT calculations, proving that defect engineering, phase transformation, and electronic structure tailoring can result in a high efficiency of HER activity. Moreover, a cell constructed of CoFe LDH‖V-Ce/CoFe LDH is capable of overall water splitting with a cell voltage as low as 1.65 V at 10 mA cm⁻² and a remarkable long-term stability of 60 h. The plasma etching strategy can also be effective for other LDH-based electrocatalysts (e.g. NiFe LDH and NiCo LDH), which demonstrates the universality of the strategy for improving HER performance. This work provides a simple but feasible pathway for designing alkaline HER electrocatalysts based on advanced LDH materials.

中文翻译：

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通过氧空位和相变工程促进层状双氢氧化物纳米片上的氢分解反应†

在电催化中，层状双氢氧化物（LDH）材料在促进氧释放反应（OER）方面引起了相当大的兴趣。对于氢气放出反应（HER），这些材料显示出较差的电催化活性。在这项工作中，我们将镍泡沫上生长的CoFe LDH作为模型系统，并且首次在等离子蚀刻条件下处理CoFe LDH，这在碱性介质中产生了高活性的HER电催化剂。在等离子体蚀刻过程中会发生大量缺陷和非晶相的形成。更重要的是，发生了CoFe LDH到CoFe ₂ O _4的相变。额外引入Ce会导致更多的活性位点并改善电导率，在10 mA cm的电流密度下可提供73 mV的过电势对于V-Ce / CoFe LDH为^-2。实验结果与DFT计算非常吻合，证明缺陷工程，相变和电子结构定制可以导致HER活动的高效率。而且，由CoFe LDH′V-Ce / CoFe LDH构成的电池能够在10 mA cm ^-2的电池电压低至1.65 V的情况下进行整体水分解，并具有60 h的长期稳定性。等离子体蚀刻策略对于其他基于LDH的电催化剂（例如NiFe LDH和NiCo LDH）也可能有效，这证明了提高HER性能的策略的普遍性。这项工作为基于先进的LDH材料设计碱性HER电催化剂提供了一个简单而可行的途径。