Kinetically Controlled, Scalable Synthesis of γ‐FeOOH Nanosheet Arrays on Nickel Foam toward Efficient Oxygen Evolution: The Key Role of In‐Situ‐Generated γ‐NiOOH

Abstract

Layered γ‐type iron oxyhydroxide (γ‐FeOOH) is a promising material for various applications; however, its sheet‐shaped structure often suffers from instability that results in aggregation and leads to inferior performance. Herein, a kinetically controlled hydrolysis strategy is proposed for the scalable synthesis of γ‐FeOOH nanosheets arrays (NAs) with enhanced structural stability on diverse substrates at ambient conditions. The underlying mechanisms for the growth of γ‐FeOOH NAs associated with their structural evolution are systematically elucidated by alkalinity‐controlled synthesis and time‐dependent experiments. As a proof‐of‐concept application, γ‐FeOOH NAs are developed as electrocatalysts for the oxygen evolution reaction (OER), where the sample grown on nickel foam (NF) exhibits superior performance of high catalytic current density, small Tafel slope, and exceptional durability, which is among the top level of FeOOH‐based electrocatalysts. Density functional theory calculations suggest that γ‐NiOOH in situ generated from the electrooxidation of NF would induce charge accumulation on the Fe sites of γ‐FeOOH NAs, leading to enhanced OER intermediates adsorption for water splitting. This work affords a new technique to rationally design and synthesize γ‐FeOOH NAs for various applications.

Corrosive-coordinate engineering to construct 2D-3D nanostructure with trace Pt as efficient bifunctional electrocatalyst for overall water splitting

“…As illustrated in Fig. 2c, Fe 3+ (725.1 eV) was detected in the prepared nanomaterial [48,49]. As for the high-resolution XPS spectrum of Pt (Fig.…”

Magnetic field assisted electrocatalytic oxygen evolution reaction of nickel-based materials

“…S14d-f †). [41][42][43][44] These results indicate that the magnetic eld will not change the active species of the OER, and the crystal structure of internal species is basically unchanged except for the active substances on the surface. Here, the features of overpotential and EIS under the magnetic eld are amazingly consistent with that of MR, a strong indication that the origin of the observed electrochemical phenomena should be highly dependent on the magnetophysical properties.…”

Bioinspired NiFe–gallate metal–organic frameworks for highly efficient oxygen evolution electrocatalysis

“…This shi could be attributed to the formation of FeOOH owing to the structural evolution during the stability test. 24 Obvious electronic structural changes of O are observed as shown in Fig. S17(c).…”