Fluoridated Iron–Nickel Layered Double Hydroxide for Enhanced Performance in the Oxygen Evolution Reaction

Abstract

Layered double hydroxides (LDHs) are very promising but still far from satisfactory for catalyzing the electrochemical oxygen evolution reaction (OER) in water electrolysis. Herein, it was found that the catalytic performance of iron–nickel LDHs for OER can be largely boosted by a facile and controllable fluoridation approach at low temperatures. Temperature dependence of the crystal structure and surface chemical state was observed for the simple fluoridation of the iron–nickel LDH. However, no significant surface roughness and electrochemical active surface area increases were found, which was probably owing to the structure change from nanosheets to nanorods. Significant improvements in the performance, including the catalytic activity, stability, efficiency, and kinetics, were found compared with the pristine iron–nickel LDH. Specifically, iron–nickel fluoride obtained at 250 °C afforded the lowest overpotential of 225 mV (no iR correction) to drive 10 mA cm−2 loaded on an inert glassy carbon electrode with a small Tafel slope of 79 mV dec−1, outperforming the noble‐metal IrO2 catalyst and most of the similar Fe–Ni based catalysts. The performance improvement could be mainly attributed to the phase‐structure transfer from metal−O bonding in the FeNi‐LDHs to metal−F bonding after fluoridation, which means it is easier to form the real active sites of Fe‐doped high‐valence Ni‐(oxy)hydroxide over the iron–nickel fluoride surface.

In Situ Activation of Anodized Ni–Fe Alloys for the Oxygen Evolution Reaction in Alkaline Media

“…% fluorine. Pei et al reported that fluoridated Fe–Ni LDH exhibits greatly enhanced OER performance compared with that of pristine Fe–Ni LDH; further, they attributed the enhanced performance to the formation of a core–shell structure of Fe-doped high-valence Ni-oxyhydroxide over Fe–Ni fluoride …”

“…Pei et al reported that fluoridated Fe− Ni LDH exhibits greatly enhanced OER performance compared with that of pristine Fe−Ni LDH; further, they attributed the enhanced performance to the formation of a core−shell structure of Fe-doped high-valence Ni-oxyhydroxide over Fe− Ni fluoride. 51 Prolonged oxygen evolution was conducted at a constant current density of 50 mA cm −2 to elucidate the role of the inner fluoride-containing layer in the OER performance. The constant potential of ∼1.55 V versus RHE maintained for 24 h during galvanostatic polarization (Figure 11a) demonstrates the high stability of anodized Ni-11.8 at.…”

An Efficient RuTe2/Graphene Catalyst for Electrochemical Hydrogen Evolution Reaction in Acid Electrolyte

“…Turnover frequency (TOF) versus potential plots was also plotted based on a previously reported method (Figure 3f). [24] The TOF value of RuTe 2 /Gr was 0.087 s À 1 at an overpotential of 100 mV, which is 7.25 and 217.5 times higher than that of Ru/C (0.012 s À 1 ) and Te (0.0004 s À 1 ), respectively. This value was also much higher than some highperformance catalysts reported in the literature like Ru/NC (0.036 s À 1 ) [25] and Ni 2 P (0.015 s À 1 ).…”

Fluorine-Doped LiNi0.8Mn0.1Co0.1O2 Cathode for High-Performance Lithium-Ion Batteries

“…To investigate the replacement of oxygen with Fions at the oxygen sites, XPS analysis was performed ( Figure 3 and Figure S1). In the O1s spectra, the characteristic peaks at 528-530 and 531-533 eV correspond to bonds between the transition metal (M) and oxygen and oxygen vacancies, respectively (Figure 3a (Table S2) [32][33][34][35]. Furthermore, the Ni2p spectrum of NCMF consisted of characteristic peaks at 854-856 and 858-859 eV, which corresponded to Ni−O and M−F bonds, respectively ( Figure 3b).…”