Cobalt‐Vanadium Hydroxide Nanoneedles with a Free‐Standing Structure as High‐Performance Oxygen Evolution Reaction Electrocatalysts

Abstract

It is a great challenge to develop electrocatalysts with high efficiency and low cost toward oxygen evolution reaction (OER) for the electrolysis of water. Herein, novel CoV-hydroxide nanoneedle arrays with freestanding structure is successfully fabricated as new electrocatalysts for OER. Remarkably, the incorporation of V into Co hydroxide can significantly modulate the nanoneedle morphology, which results in the increase of active surface area, and augment the intrinsic activity by tuning the electronic structure. Particularly, we find that the freestanding Co hydroxide nanoneedles with 25 % Co substituted by V (Co 0.75 V 0.25 -HNNs) show the optimum OER catalytic activity and have a low overpotential (268 mV at 10 mA cm À 2 ), a small Tafel slope (80 mV dec À 1 ) and long-term stability, which are comparable to the other Co-based and V-based electrocatalysts for OER reported in literature.

Well‐Monodispersed Iron‐Doped InOOH Nanoparticles with Enhanced Activity for Oxygen Evolution

“…[37][38][39] Figure 2d is the O 1s high-resolution XPS spectrum, which exhibits three peaks at a BE of 530.0 eV, 531 eV, and 532 eV, corresponding to metal oxygen bond, À OH and adsorbed molecular water, respectively. [40][41][42] The above analysis confirmed the successful synthesis of Fe-InOOH NPs. In 1.0 M KOH solution with a typical three-electrode configuration, we assessed the OER electrocatalytic performance of Fe-InOOH NPs catalysts.…”

“…The Fe 2p spectrum in Figure c exhibits two main peaks for Fe 2p 3/2 and Fe 2p 1/2 at a BE of around 711.6 eV and 725.1 eV, indicating the presence of Fe 3+ . Figure d is the O 1s high‐resolution XPS spectrum, which exhibits three peaks at a BE of 530.0 eV, 531 eV, and 532 eV, corresponding to metal oxygen bond, −OH and adsorbed molecular water, respectively . The above analysis confirmed the successful synthesis of Fe‐InOOH NPs.…”

Synergistic electronic and morphological modulation on ternary Co1−xVxP nanoneedle arrays for hydrogen evolution reaction with large current density

“…The comparative high-resolution Co 2p and P 2p spectra (Fig. 3b, c) show that the surface oxidation is inevitable, when they are exposed to air, leading to the presence of the Co-O and P-O bonds in CoP and Co 1−x V x P. For the NF@CoP electrode, the Co 2p 3/2 (∼778.3 eV) and 2p 1/2 peaks (793.4 eV) indicate the existence of metallic Co in CoP [42,43], while the [37,42]. The strong shakeup satellites (identified as "Sat.")…”

“…The Co 1−x V x hydroxide nanoneedle arrays on NF (NF@Co 1−x V x -HNNs) were prepared by a one-step hydrothermal method as reported in literature ( Fig. 1a) [37]. In a typical process, 0.218 g of Co(NO 3 ) 2 •6H 2 O, 0.0393 g of VCl 3 , 0.6 g of CO(NH 2 ) 2 and 0.16 g of NH 4 F were added into 30 mL of distilled water successively to form a clear solution under continuous stirring for 10 min.…”

“…The NF@Co 1−x V x -HNNs were investigated as highperformance OER electrocatalyst with a low overpotential and long-term stability [37]. Therefore, we combined our 3D ternary NF@Co 1−x V x P with NF@Co 1−x V x -HNNs to build an electrolyzer for overall water splitting in alkaline environment (Fig.…”