The development of highly efficient, low-cost and stable electrocatalysts for overall water splitting is highly desirable for the storage of intermittent solar energy and wind energy sources. Herein, we show for the first time that nickel can be extracted from NiFe-layered double hydroxide (NiFe-LDH) to generate an Ni₂P@FePO_x heterostructure. The Ni₂P@FePO_x heterostructure was converted to an Ni₂P@NiFe hydroxide heterostructure (P-NiFe) during water splitting, which displays high electrocatalytic performance for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1.0 M KOH solution, with an overpotential of 75 mV at 10 mA cm⁻² for HER, and overpotentials of 205, 230 and 430 mV at 10, 100 and 1000 mA cm⁻² for OER, respectively. Moreover, it could afford a stable current density of 10 mA cm⁻² for overall water splitting at 1.51 V in 1.0 M KOH with long-term durability (100 h). This cell voltage is among the best reported values for bifunctional electrocatalysts. The results of theoretical calculations demonstrate that P-NiFe displays optimized adsorption energies for both HER and OER intermediates at the nickel active sites, thus dramatically enhancing its electrocatalytic activity.

中文翻译：

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将 NiFe-LDH 中的镍萃取成 Ni2P@NiFe 氢氧化物，作为双功能电催化剂，实现高效的整体水分解†

开发用于整体水分解的高效、低成本和稳定的电催化剂对于间歇性太阳能和风能的存储非常有利。在此，我们首次证明可以从NiFe层状双氢氧化物（NiFe-LDH）中提取镍以生成Ni ₂ P@FePO _x异质结构。Ni ₂ P@FePO _x异质结构在水分解过程中转化为 Ni ₂ P@NiFe 氢氧化物异质结构（P-NiFe），其对析氢反应（HER）和析氧反应（OER）均表现出较高的电催化性能。 1.0 M KOH 溶液，对于 HER 在 10 mA cm ^-2下的过电势为 75 mV ，对于 OER 在 10、100 和 1000 mA cm ^-2下的过电势分别为 205、230 和 430 mV。此外，它可以在1.51 V、1.0 M KOH中提供10 mA cm ^-2的稳定电流密度，并具有长期耐久性（100小时）。该电池电压是双功能电催化剂的最佳报告值之一。理论计算结果表明，P-NiFe 在镍活性位点对 HER 和 OER 中间体表现出优化的吸附能，从而显着增强其电催化活性。