Composition‐Dependent Morphology, Structure, and Catalytical Performance of Nickel–Iron Layered Double Hydroxide as Highly‐Efficient and Stable Anode Catalyst in Anion Exchange Membrane Water Electrolysis

Abstract

Water splitting is an environmentally friendly strategy to produce hydrogen but is limited by the oxygen evolution reaction (OER). Therefore, there is an urgent need to develop highly efficient electrocatalysts. Here, NiFe layered double hydroxides (NiFe LDH) with tunable Ni/Fe composition exhibit corresponding dependent morphology, layered structure, and chemical states, leading to higher activity and better stability than that of conventional NiFe LDH-based catalysts. The characterization data show that the low overpotentials (249 mV at 10 mA cm -2 ), ultrasmall Tafel slopes (24 mV dec -1 ), and high current densities of Ni 3 Fe LDH result from the larger fraction of trivalent Fe 3+ and the optimized local chemical environment with more oxygen coordination and ordered atomic structure for the metal site. Owing to the active intermediate species, Ni(Fe)OOH, under OER conditions and a reversible dynamic phase transition during the cycling process, the Ni 3 Fe LDH achieves a high current density of over 2 A cm -2 at 2.0 V, and durability of 400 h at 1 A cm -2 in a single cell test. This work provides insights into the relationship between the composition, electronic structure of the layer, and electrocatalytic performance, and offers a scalable and efficient strategy for developing promising catalysts to support the development of the future hydrogen economy.

Key components and design strategy of the membrane electrode assembly for alkaline water electrolysis

“…8c, Jiang and co-workers effectively regulated the composition and morphology of NiFe LDH for OER. 58 The obtained single layer NiFe 3 LDH showed a low overpotential of 249 mV at 10 mA cm À2 and an ultrasmall Tafel slope of 24 mV dec À1 . In AEMWE, the Ni 3 Fe LDH achieved a high current density of 2 A cm À2 at 2.0 V, and maintained long-term stability for 400 h at 1 A cm À2 (Fig.…”

“…The OER process in alkaline electrolytes involves the consumption of OH À in multiple steps. The widely recognized OER mechanisms can be summarized as the , 27 3, 28 4, 29 5, 30 6, 31 7, 32 8, 33 9, 34 10, 35 11, 36 12, 37 13, 38 14, 39 15, 40 16, 41 17, 42 18, 43 19, 44 20, 45 21, 46 22, 47 23, 48 24, 49 25, 50 26, 51 27, 52 28, 53 29, 54 30, 55 31, 56 32, 57 33, 58 34, 59 35, 60 36, 61 37, 62 38, 63 39, 64 40, 65 41. 66 (b): 1, 67 2, 32 3, 33 4, 35 5, 48 6, 68 7, 69 8, 70 9, 39 10, 62 11, 71 12, 41 13, 72 14, 53 15,…”

“…(c) Degradation rates during continuous long-term durability testing of the reported alkaline water electrolysis employing PGM-free electrocatalysts. References for data points for (a): 1,26 2, 27 3, 28 4,29 5,30 6,31 7,32 8,33 9,34 10,35 11,36 12,37 13,38 14,39 15,40 16,41 17,42 18,43 19,44 20,45 21,46 22,47 23,48 24,49 25,50 26,51 27,52 28,53 29,54 30,55 31,56 32,57 33,58 34,59 35,60 36,61 37,62 38,63 39,64 40,65 41. 66 (b): 1, 67 2,32 3, 33 4,35 5,48 6,68 7,69 8,70 9,39 10,62 11,71 12,41 13,72 14,53<...…”

High-performing catalysts for energy-efficient commercial alkaline water electrolysis

“…During the drafting of this publication, Jiang et al 194 reported Ni 3 Fe LDH synthesized by a co-precipitation method from Ni(NO 3 ) 2 and Fe(NO 3 ) 3 in alkaline solution, which exhibited a low overpotential of 249 mV at 10 mA cm −2 in 1 M KOH electrolyte, room temperature, with an ultra-small Tafel slope of 24 mV dec −1 . To evaluate stability, Ni 3 Fe LDH with a 0.2 mg cm −2 loading on Ni foam was tested at a fixed voltage of 1.6 V for 400 h in 1 M KOH.…”

The Influence of Loadings and Substrates on the Performance of Nickel‐Based Catalysts for the Oxygen Evolution Reaction

“…The NiFe LDH catalyst was synthesized by the precipitation method described in our previous work. [33] 3 mmol Ni(NO 3 ) 2 (nickel(II) nitrate hexahydrate) and 0.75 mmol Fe(NO 3 ) 3 (iron(II) nitrate hexahydrate) were added to an aqueous NaOH solution (0.15 mol/L) and stirred at 1000 rpm for 10 minutes at room temperature. Then the precipitate was washed with water and centrifuged, followed by ultrasonication for half an hour to achieve exfoliation.…”