Electrochemically Aged Ni Electrodes Supporting NiFe₂O₄Nanoparticles for the Oxygen Evolution Reaction

Abstract

The preparation and screening of nanoparticle (NP) electrocatalysts for improved electrocatalytic oxygen evolution reactions (OER) will require a better understanding and optimization of the interactions between NPs and their support. First-row transition metals are used extensively as electrocatalysts in electrochemical energy storage and conversion systems. These electrocatalysts undergo transformations in their phase and surface morphology, which are induced by oxidizing potentials in the alkaline medium. A template-assisted approach to prepare electrodes with regular surface morphologies was used to monitor interactions between the NPs and their support both before and after prolonged electrochemical aging. A template-assisted method was used to prepare uniform surface inclusions of nickel ferrite (NiFe2O4) NPs on conductive nickel (Ni) supports for evaluation toward the OER. Electron microscopy-based methods were used to assess the resulting transformations of the embedded NPs within the Ni support matrix. Electrochemical aging of these textured electrodes was conducted by cyclic voltammetry (CV) techniques, which resulted in the growth of a 200 nm thick Ni oxy­(hydroxide) film on the surfaces of the Ni supports. The growth of the active surface layer led to the encapsulation of the NiFe2O4 NPs as determined by correlative energy dispersive X-ray spectroscopy (EDS) techniques. The NP-modified electrodes exhibited reduced overpotentials and higher sustained current densities for the OER when compared to pure Ni supports. The well-defined morphologies and NP surface inclusions prepared by the template-assisted approach could serve as a platform for investigating additional NP–support interactions for electrocatalytic systems.

Arrays of Microscale Linear Ridges with Self-Cleaning Functionality for the Oxygen Evolution Reaction

“…The three-electrode setup consisted of a Hg/HgO reference electrode, and a graphite rod (same as previously mentioned) as the counter electrode. A reversible hydrogen electrode (RHE) was used to calibrate the Hg/HgO reference electrode, which indicated a potential offset of 0.923 V. 30 The working electrode was held in a vertical orientation. A PTFE holder protected the sides of the working electrode such that only the microstructured surfaces were exposed to the electrolyte.…”

Magnetic NiFe2O4 Nanoparticles Prepared via Non‐Aqueous Microwave‐Assisted Synthesis for Application in Electrocatalytic Water Oxidation

“…The increased number of active sites and shortened charge carrier pathways make them attractive for surface-depending processes like the electrocatalytic water splitting. [26,27] NiFe 2 O 4 nanoparticles with different morphological characteristics can be prepared by manifold preparation techniques: for example, Zhou et al prepared NiFe 2 O 4 nanoparticles with tuneable sizes of 10-120 nm via a low temperature hydrothermal method, [28] whereas Wang et al chose a solvothermal approach in ethylene glycol producing NiFe 2 O 4 nanoparticles with adjustable sizes of 7-200 nm. [29] NiFe 2 O 4 nanoparticles with sizes of 8-28 nm are further available using co-precipitation methods, which is shown by Maaz et al [30] Among the various preparation techniques, the applied microwave-assisted method offers an efficient and controlled heating, shortened reaction times, reproducibility, and improved yields.…”

“…Further, preparation of nanoparticular materials enables high surface‐to‐volume ratios. The increased number of active sites and shortened charge carrier pathways make them attractive for surface‐depending processes like the electrocatalytic water splitting [26,27] …”

Hexacyanoferrate-Complex-Derived NiFe2O4/CoFe2O4 Heterostructure–MWCNTs for an Efficient Oxygen Evolution Reaction

“…Fossil fuel depletion and its detrimental global impact on the environment are the greatest concerns these days. To solve these issues, numerous research groups have carried out comprehensive research on renewable energy sources. − As renewable energy, hydrogen is the most appropriable and clean energy source to deliver high energy density and zero environmental emissions. − The best option to generate hydrogen is by electrochemical water splitting where a lot of research has been pursued in recent years. Nevertheless, due to the slow kinetics, the oxygen evolution reaction (OER) at the electrode surface is not very effective and as a result acquires high overpotential. , Works have been devoted to carry out OER at low overpotential by tuning its electronic and morphological properties .…”

“…The first doublet peak located at 710.7 and 724.2 eV and the second doublet peak located at 713.8 and 726.9 eV (Figure5d) are attributed to the binding energies of Fe 2p 3/2 and Fe 2p 1/2 of Fe 2+ and Fe 3+ , respectively. The coexistence of Fe 2+ and Fe 3+ and the presumed Fe 3+ satellite peak located at 718.7 eV indicate the binding energy of Fe with Ni and Co 5. Further, the O 1s spectrum (Figure5e) shows peaks at 529.4, 530.4 531.3, and 533.0 eV corresponding to the lattice oxygen in the spinel system of Ni/Co−Fe−O 14.…”