Oxygen‐Deficient NiFe₂O₄ Spinel Nanoparticles as an Enhanced Electrocatalyst for the Oxygen Evolution Reaction

Abstract

Herein, mesoporous NiFe2O4 spinel nanoparticles with abundant oxygen vacancies are successfully prepared by a simple hydrothermal method followed by mild H2 reduction and used as catalysts for the oxygen evolution reaction. Compared with the pristine and air‐treated NiFe2O4, the H2‐treated NiFe2O4 shows a much lower overpotential of 389 mV at a current density of 10 mA cm−2. The H2‐treated NiFe2O4 also indicates substantial long‐term stability even after 1000 cyclic tests. This outstanding electrochemical activity and stability can be attributed to the improved physicochemical properties by H2 treatment: small nanoparticles with well‐developed mesoporous structures, a high ratio of Ni2+/Ni3+ cations, and abundant oxygen vacancies. These properties can significantly improve charge transfer kinetics and increase the number of active sites on the catalyst. The results demonstrate that this facile fabrication method is a promising route for developing cost‐effective and high‐performance catalysts to be used in electrochemical applications.

Facile Route of P‐doped Defect‐rich Manganese‐cobalt Oxide Spinel with Enhanced Oxygen Evolution Reaction Performance

“…The O 1s peak of MCO−P shifts positively because the metal atoms leave their initial lattice sites [5b] . Commonly, the above peaks are indexed to lattice oxygen (O latt ), hydroxyl groups (O OH ), defect oxygen (O def ), and adsorbed water (O wat ), respectively [7b,18] . For MCO−P, the integral area of O def apparently increases, and O latt remarkably decreases in comparison with MCO (Table 1).…”

Nitrogen‐doped Binary Spinel CuCo2O4/C Nanocomposite: An Efficient Electrocatalyst for Oxygen Evolution Reaction

“…In Figure 2d, The O 1s spectrum could be deconvoluted into four peaks centered at the binding energies of 529.6, 531, 531.8 and 532.6 eV, which are assigned to lattice oxygen, the oxygen of hydroxideion, oxygen vacancies and oxygen of physically adsorbed H 2 O molecules, respectively [26,29] . The area percentage of O 3 in N−CuCo 2 O 4 @N−C‐2 (9.8%) is larger than that in CuCo 2 O 4 @N−C (8.6%), indicating that N‐doped sample have more oxygen vacancies than pristine sample [35] . For further validating the existence of oxygen vacancies, low temperature electron paramagnetic resonance spectra (EPR) was conducted.…”

Mesoporous NiFe2O4 with Tunable Pore Morphology for Electrocatalytic Water Oxidation

“…Morphological investigations including the hysteresis scanning method can substantially help to fully understand the activity of a nanostructured electrocatalyst. However, the performances of our materials are still limited compared to other NiFe 2 O 4 nanomaterials like -cubes or -particles [56,75,76] and further to other mixed transition metal oxides. [77] However, our materials are of high purity, while materials described in literature often contain α-Fe 2 O 3 [76] or NiO, [78] which prevents complete comparability.…”

“…However, the performances of our materials are still limited compared to other NiFe 2 O 4 nanomaterials like -cubes or -particles [56,75,76] and further to other mixed transition metal oxides. [77] However, our materials are of high purity, while materials described in literature often contain α-Fe 2 O 3 [76] or NiO, [78] which prevents complete comparability. In contrast to, for example faceted NiFe-oxide nanocubes, [75] controlling the exposed facets in the pore channels is not possible, resulting in a weaker activity of mesoporous NiFe 2 O 4 .…”