NiFe Oxalate Nanomesh Array with Homogenous Doping of Fe for Electrocatalytic Water Oxidation

Abstract

NiFe‐based materials have shown impressive electrocatalytic activity for the oxygen evolution reaction (OER). The mutual effect between proximate Ni and Fe atoms is essential in regulating the electronic structure of the active site to boost the OER kinetics. Detailed studies confirm that the separated monometal phases in NiFe‐based materials are detrimental to OER. Thus, the high‐level blending of Ni and Fe in NiFe‐based OER electrocatalysts is critical. Herein, an NiFe oxalate nanomesh array based on solid solutions between nickel (II) oxalate and iron (II) oxalate is prepared through a facile surfactant‐free approach in the presence of the reductive oxalate anions. The integrated electrode can efficiently catalyze water oxidation to reach a current density of 50 mA cm−2 with a small overpotential of 203 mV in a 1.0 m KOH aqueous solution. The high efficiency can be attributed to the atomic level mix of Ni and Fe in the solid solutions and the hierarchical porous structure of the nanomesh array. These two aspects bring about fast kinetics, efficient mass diffusion, and quick charge transfer, which are the three major positive factors for a high‐performance heterogenous electrocatalyst.

Novel FeNi‐Based Nanowires Network Catalyst Involving Hydrophilic Channel for Oxygen Evolution Reaction

“…[31] High-resolution Fe 2p spectrum (Figure 2g) shows that the energy separation between the peaks located at 711.8 and 718.2 eV of Fe 2p3/2 was 6.4 eV, suggesting a high spin Fe II state, which originated from the reduction of Fe III by oxalate anions. [16] However, the multistate peaks of Fe 2p3/2 in ENWs-FeNi-C 2 O 4 located at 713.9-709.6 eV show an obvious shift toward higher binding energy compared to the OC-FeNi-C 2 O 4 , which can be assigned to the stronger electronegativity of the ethoxy than that of the hydroxyl in OC-FeNi-C 2 O 4 catalyst [32] In conclusion, the novel 3D ethoxy substituted FeNi-based oxalate catalyst with nanowires network can been obtained.…”

“…[13][14][15] In addition, the synthesis of NiFe-based catalyst can realize Fe doping with an atomic-level, avoiding the separated mono-metal phases and thus promoting the OER performance. [16] Thus, it is highly desirable to seek a novel inexpensive FeNi-based oxalate OER catalyst to further increase the intrinsic activity and the total electrode activity. Besides, since the OER reaction proceeds at the catalyst-electrolyte interface, constructing a suitable three-dimensional structure [17][18][19] with designed surface hydrophilic property is an effective strategy to boost the contact area between catalysts and electrolyte, [20][21][22] which is conducive to improve the reaction kinetics and the charge exchange capacity at the electrode/electrolyte interface.…”

Rapid and Scalable Synthesis of Prussian Blue Analogue Nanocubes for Electrocatalytic Water Oxidation†

“…[ 10‐18 ] As a half reaction of water electrolysis, the oxygen evolution reaction (OER) is deemed to be the rate‐limiting step, which significantly hampers the improvement of the overall efficiency of electrochemical hydrogen production. [ 19‐33 ] During the past decade, the earth‐abundant OER catalysts with comparable performance to the state‐of‐the‐art noble metal‐based catalysts have attracted substantial research interests. [ 34‐40 ] Previous investigations indicate that most transition metal‐based catalysts, especially the ones based on Co, Ni, and Fe, undergo a pre‐oxidation reaction prior to OER.…”

Constructing a Rod‐like CoFeP@Ru Heterostructure with Additive Active Sites for Water Splitting

“…The two peaks located at 778.5 eV and 793.3 eV are separately assigned to the binding energies of 2p 3/2 and 2p 1/2 of CoÀ P species (Figure 2b), which is consistent with the reported results. [21,22] Similarly, for the Fe 2p region of CoFeP@Ru (Figure 2c), [22,23] the peaks related to the Fe 2P 3/2 and Fe 2p 1/2 are centered at 709.9 and 724.4 eV, respectively, confirming the formation of FeÀ P bond. The binding energies of 711.6 eV can correspond to oxidized Fe from superficial oxidation of CoFeP@Ru.…”