Surface modulated Fe doping of β‐Ni(OH)₂ nanosheets for highly promoted oxygen evolution electrocatalysis

Abstract

Active yet low‐cost electrocatalysts for water oxidation are crucial for the development of hydrogen energy economy. The Fe doping into Ni(OH)2 dramatically enhances catalytic activity toward oxygen evolution reaction (OER) but fabricating Ni(OH)2 of high Fe loading is still challenging. Herein, we report a one‐pot strategy to prepare disordered β‐Ni(OH)2 nanosheets with a high Fe doping level (9.9 at%, D‐Fe‐Ni(OH)2). By engaging 1,4‐phenylenediphosphonic acid (BDPA), FexBDPAy precursors are in situ generated in a growth solution containing Fe3+ ions, which decrease the reaction kinetics of Ni2+ and Fe3+ ions at the surface of Ni foam. This prevents the deconstructive hydrolysis by Fe3+ ions and enables a high Fe‐doping in D‐Fe‐Ni(OH)2. The as‐prepared D‐Fe‐Ni(OH)2 affords 10 mA cm−2 at an ultralow OER overpotential of 194 mV in alkaline media. This work offers a promising strategy of engaging organic ligands to achieve high‐doping levels for the construction of efficient electrocatalysts.

Electrocatalytic Overall Water Splitting Induced by Surface Reconstruction of an Iron-Modified Ni2P/Ni5P4 Heterojunction Array Encapsulated into a N-Doped Carbon Layer

“…24,25 In contrast, the negative shift of P 2p in Fe-Ni 2 P/Ni 5 P 4 @N-C indicates that the P receives electrons and possesses a partial negative charge (δ − ). 26 The Fe 2p spectrum of Fe-Ni 2 P/Ni 5 P 4 @N-C (Figure 2d) confirms the coexistence of Fe 2+ (707.1 and 720.7 eV) and Fe 3+ (712.8 and 725.5 eV), which further demonstrates the successful incorporation of Fe into Ni 2 P/Ni 5 P 4 @N-C. 27,28 As for the C 1s spectrum, the C−C and C−N bonds are identified by the two major peaks centered at 284.6 and 285.4 eV, respectively (Figure 2e). 29,30 The N 1s region (Figure 2f) can be attributed to the N-graphene (401.6 eV), further implying the formation of the N-doped C layer.…”

“…The binding energies of P 2p 3/2 and P 2p 1/2 for the metal phosphide (Figure c) are located at 129.8 and 130.9 eV, respectively, whereas the peak at 134.0 eV is attributed to the phosphorus oxide. , In contrast, the negative shift of P 2p in Fe-Ni 2 P/Ni 5 P 4 @N-C indicates that the P receives electrons and possesses a partial negative charge (δ – ) . The Fe 2p spectrum of Fe-Ni 2 P/Ni 5 P 4 @N-C (Figure d) confirms the coexistence of Fe 2+ (707.1 and 720.7 eV) and Fe 3+ (712.8 and 725.5 eV), which further demonstrates the successful incorporation of Fe into Ni 2 P/Ni 5 P 4 @N-C. , As for the C 1s spectrum, the C–C and C–N bonds are identified by the two major peaks centered at 284.6 and 285.4 eV, respectively (Figure e). , The N 1s region (Figure f) can be attributed to the N-graphene (401.6 eV), further implying the formation of the N-doped C layer . Moreover, two peaks in the O 1s region (Figure S5) are assigned to the P–O (531.5 eV) and absorbed water (533.1 eV) …”

Sea urchin-like amorphous MgNiCo mixed metal hydroxide nanoarrays for efficient overall water splitting under industrial electrolytic conditions

“…64 The band of 560 cm −1 is attributed to Ni–O vibrations in β-NiOOH, indicating a phase transition from Ni(OH) 2 to β-NiOOH. 65…”

Porous yet densely packed metal–organic frameworks (MOFs) toward ultrastable oxygen evolution at practical current densities

“…S5f (ESI †) shows the high-resolution spectrum of Fe 2p, in which the peaks in Fe 2p spectrum at 709.3, 722.9, and 714.2 eV correspond to Fe 2+ , and Fe 3+ respectively. 28,29 Indicating some Fe 3+ ions are reduced to Fe 2+ species (Fe 3+ + e À -Fe 2+ ), while Ni atoms are oxidized to Ni 2+ species (Ni-2e À -Ni 2+ ) (Fig. S5, ESI †).…”