Highly efficient mixed-metal spinel cobaltite electrocatalysts for the oxygen evolution reaction

Abstract

Cation substitution in spinel cobaltites (e.g., ACo2O4, in which A = Mn, Fe, Co, Ni, Cu, or Zn) is a promising strategy to precisely modulate their electronic structure/properties and thus improve the corresponding electrochemical performance for water splitting. However, the fundamental principles and mechanisms are not fully understood. This research aims to systematically investigate the effects of cation substitution in spinel cobaltites derived from mixed-metal-organic frameworks on the oxygen evolution reaction (OER). Among the obtained ACo2O4 catalysts, FeCo2O4 showed excellent OER performance with a current density of 10 mAcm -2 at an overpotential of 164 mV in alkaline media. Both theoretical calculations and experimental results demonstrate that the Fe substitution in the crystal lattice of ACo2O4 can significantly accelerate charge transfer, thereby achieving enhanced electrochemical properties. The crystal field of spinel ACo2O4, which determines the valence states of cations A, is identified as the key factor to dictate the OER performance of these spinel cobaltites.

Heteroatomic Interface Engineering of MOF-Derived Metal-Embedded P- and N-Codoped Zn Node Porous Polyhedral Carbon with Enhanced Sodium-Ion Storage

“…50 As shown in Figure 3c, the C 1s spectrum contains the peaks of sp 2 carbon C-C at 284.6 eV, sp 3 C-N/C-P bond at 285.7 eV, and C=O bond at 287.8 eV. 41,[51][52] The defect level is reflected by the sp 3 content. The value of sp 2 /sp 3 for the P-N-Zn-C composite decreased from 1.35 to 0.92 compared with the N-Zn-C composite.…”

In situ evolution of surface Co2CrO4 to CoOOH/CrOOH by electrochemical method: Toward boosting electrocatalytic water oxidation

“…The oxidative process of water splitting, that is, the oxygen evolution reaction (OER), is a multielectron transfer process and a bottleneck in hydrogen generation. The OER involves the breakage of O-H bonds and the reconstruction of O=O bonds [7][8][9][10]. Accordingly, it requires highly efficient OER catalysts to obtain a large geometrical current density as low as the overpotential.…”

Advances in Electrochemical and Catalytic Performance of Nanostructured FeCo2O4 and Its Composites

“…Varun Rai and co-workers [92] carried out the OER studies using a series of MCo [20] stated that FeCo 2 O 4 nanoplate executed better OER performance (10 mA cm À 2 of current density at an overpotential of 164 mV in alkaline media) amongst all the mixed-metal-organic framework-based catalysts as is clear from the linear sweep voltammetry (LSV) plot in Figure 11-b. Kundu et al [93] further studied the water splitting reaction using the novel FeCo 2 O 4 @N-Doped Carbon Dots (CD) nanoflowers, which performed better as binder-free electrode than FeCo 2 O 4 in alkaline medium for reduction (HER) and oxidation of water (OER).…”

“…The synergistic effect between Co and M atoms along with the multiple valence states of MTMOs and the partially filled 3d orbitals of transition metals is anticipated to display excellent electrochemical and catalytic activities owing to the better electron transfer rate and greater number of surface-active sites. [14,19,20] The spinel structure (A x B 3-x O 4 ) of MTMOs is also equally responsible for their better redox potentials and electrical conductivities in comparison to the STMOs. [21] Moreover, as will be illustrated further in the subsequent sections, among the MTMOs, Fe and Co based spinel oxides are widely being researched due to the presence of multiple oxidation states (Fe 2 + /Fe 3 + ; Co 2 + /Co 3 + ), very high conductivity of Fe metal along with its greater abundance, its ease of substitution, and its non-toxic nature in comparison to other metal ion candidates.…”