Engineering the Structural Defects of Spinel Oxide Nanoneedles by Doping of V for a Highly Efficient Oxygen Evolution Reaction

Abstract

Rational design of multi-structural defects in the transition-metal oxides is a very alluring and challenging strategy to significantly improve its oxygen evolution reaction (OER) performance. Herein, a simple and promising element doping approach is demonstrated to fabricate a poor-crystalline V-doping CuCo2O4 (V–CuCo2O4) nanoneedle with rich oxygen vacancies (Vo), partially amorphous phase, and Co2+ defects on the carbon fiber (CF) (V–CuCo2O4/CF). The results indicate that the V doping could further weaken the crystallinity of V–CuCo2O4, providing the thoroughfares for the convenience of electrolyte penetration and the exposure of active sites. Meanwhile, [CoO6] octahedron in the V–CuCo2O4 lattice is gravely distorted due to a strong electronic interaction between the doped V and Co atoms, creating more Co2+ active species. With the merits of these multiple structural defects, V–CuCo2O4/CF exhibits rich active sites, and its intrinsically electrocatalytic activity is significantly enhanced. The optimized V–CuCo2O4/CF electrocatalyst has a significantly enhanced OER activity with a required low overpotential of ∼204 and ∼246 mV at a current density of 100 and 300 mA cm–2, respectively, a small Tafel slope of 40.7 mV dec–1, and excellent stability in an alkaline medium. Furthermore, the results from the projected partial density of states calculation not only demonstrate that the 3-fol-coordinated Co near Vo bonded with Cu and V sites (Cu–Co(surf–Vo)–V) exhibits an enhanced electronic transfer activity but also reveal that the doped V could protect the Co sites from the deactivation by intermediates overbinding on the V sites. This work provides new insights into structure engineering of spinel phase copper cobaltite, resulting in significantly boosting electrocatalytic OER activity.

One-step fabrication of vanadium-doped CoFe PBA nanosheets for efficient oxygen evolution reaction

“…S5c and S5d†) indicates that the surface of the catalyst is oxidized. 43,44 The above evidence indicates that some oxide may be formed on the surface of the catalyst during the OER process.…”

Magnetic Field-Enhanced Oxygen Evolution Reaction via the Tuneability of Spin Polarization in a Half-Metal Catalyst

“…Transition-metal oxides (TMOs) have been widely adopted in the oxygen evolution reaction (OER) as their promising electrochemical properties such as stability, low cost, designability of electronic configuration, etc. − To achieve a moderate binding strength between transition metal and oxygen species (the ability of the oxygen intermediate absorption/desorption), the engineering strategy of e g electron occupancy has been established, − which is optimal at its slightly larger than unit. − Then, it is highly expected to develop the magnetic field tuneability of the OER performance by the TMO catalyst since d electrons usually offer a feature of spin polarization. − Garcia-Melchor et al reported that theoretically photosystem II can serve as a spin-control valve to regulate the charge and spin transport in the OER procedure, − and provides a favorable thermodynamic path for OER. Besides, it has been pointed out by Galán-Mascarós et al that an extra magnetic field applied on a permanent magnet can enhance the OER activity of magnetic oxide. − Most recently, the spin pinning effect-enhanced water oxidation has been discovered by Wu et al via a reconstructed oxyhydroxide layer on ferromagnetic oxides .…”

Enhanced oxygen evolution reactionviathe tunability of spin polarization and electronic states in a flexible van der Waals membranous catalyst

“…19–23 It is highly anticipated that TMO catalysts will exhibit both magnetic field and strain tunable OER performance, as d electrons typically possess spin polarization characteristics. 24–30…”

“…[19][20][21][22][23] It is highly anticipated that TMO catalysts will exhibit both magnetic field and strain tunable OER performance, as d electrons typically possess spin polarization characteristics. [24][25][26][27][28][29][30] Traditionally, the embellishment of the 3d electronic structure can be achieved through A-site chemical doping, [31][32][33] oxygen vacancy tunability, [34][35][36] strain, [37][38][39] and other methods. Strain is considered a promising approach to modulate catalytic performance due to the strong correlation between the itinerant charge and crystal field.…”