Introducing Fe²⁺ into Nickel–Iron Layered Double Hydroxide: Local Structure Modulated Water Oxidation Activity

Abstract

Exploring materials with regulated local structures and understanding how the atomic motifs govern the reactivity and durability of catalysts are a critical challenge for designing advanced catalysts. Herein we report the tuning of the local atomic structure of nickel-iron layered double hydroxides (NiFe-LDHs) by partially substituting Ni with Fe to introduce Fe-O-Fe moieties. These Fe -containing NiFe-LDHs exhibit enhanced oxygen evolution reaction (OER) activity with an ultralow overpotential of 195 mV at the current density of 10 mA cm , which is among the best OER catalytic performance to date. In-situ X-ray absorption, Raman, and electrochemical analysis jointly reveal that the Fe-O-Fe motifs could stabilize high-valent metal sites at low overpotentials, thereby enhancing the OER activity. These results reveal the importance of tuning the local atomic structure for designing high efficiency electrocatalysts.

Engineering Active Fe Sites on Nickel–Iron Layered Double Hydroxide through Component Segregation for Oxygen Evolution Reaction

“…Next, we engineered the active Fe sites through a facile acid treatment. First, following a well‐developed co‐precipitation synthetic approach, NiFe LDH catalyst was obtained through the hydrolysis of iron nitrates and nickel nitrates in water. Then, the obtained dried catalyst was subjected to the same amount of deionized water containing different volumes (25, 50, 100 μL) of 1 m nitric acid at room temperature for 30 min, which gave rise to catalysts NiFe LDH‐A25, NiFe LDH‐A50, and NiFe LDH‐A100, respectively.…”

Nickel Foam‐Supported Amorphous FeCo(Mn)−O Nanoclusters with Abundant Oxygen Vacancies through Selective Dealloying for Efficient Electrocatalytic Oxygen Evolution

“…While the Mn 2p region for the FeCoMn/NF can be fitted into six peaks at 640.6 eV, 642.0 eV and 643.4 eV for Mn 2p 3/2 as well as 652.2 eV, 653.7 eV and 655.6 eV for Mn 2p1/2 (Figure b), implying the co‐existence of Mn 2+ , Mn 3+ and Mn 4+ . The binding energies (BEs) of Fe 3+ are probed at 711.2 eV and 724.7 eV in the FeCo(Mn)−O/NF (Figure c) . Co 2p spectra of FeCo(Mn)−O/NF are deconvoluted into three groups of characteristic signals at 780.8 eV, 782.7 eV and 786.7 eV (satellite peak) for 2p3/2 as well as 796.8 eV, 798.1 eV and 803.0 eV (satellite peak) for 2p1/2 (Figure d), suggesting the coexistence of Co 3+ and Co 2+ .…”

“…[32,33] The binding energies (BEs) of Fe 3 + are probed at 711.2 eV and 724.7 eV in the FeCo(Mn)À O/NF (Figure 3c). [34,35] Co 2p spectra of FeCo(Mn)À O/NF are deconvoluted into three groups of characteristic signals at 780.8 eV, 782.7 eV and 786.7 eV (satellite peak) for 2p3/2 as well as 796.8 eV, 798.1 eV and 803.0 eV (satellite peak) for 2p1/2 (Figure 3d), suggesting the coexistence of Co 3 + and Co 2 + . [36,37] The O 1s region of FeCo (Mn)À O/NF exhibits four BEs at 529.9 eV, 530.9 eV, 531.5 eV and 532.0 eV (Figure 3e), which can be assigned respectively to lattice oxygen (O lat ), defective oxygen (O def ), metal hydroxide and absorbed water.…”

NiFe Hydroxide Lattice Tensile Strain: Enhancement of Adsorption of Oxygenated Intermediates for Efficient Water Oxidation Catalysis

“…[5] Previous dedications in designing efficient OER catalysts include noble-metal oxides, [6] perovskites, [7] transition-metal oxides, [8] sulfides [9] and (oxy)hydroxides. [10] Among the various OER catalysts developed so far, NiFeh ydroxide (NiFe-LDH) is apotential species with promising activity, [11] yet its catalytic activity is still badly limited by the weak oxygenated intermediates adsorption. Recent theoretical studies by Nørskov [12] reported the vital role of Fe in (Ni,Fe)OOH and Goddard [13] stated that Fe in NiFe-LDH can benefit the OC radical formation and Ni facilitates the OÀOcoupling, but the weak adsorption of NiFe-LDH to the oxygenated intermediates (specially *OH) is potentially the highest energyconsuming step.T ofurther improve the catalytic performance of NiFe-LDH in OER, the binding of oxygenated intermediates has to be strengthened.…”