Ultrafine α-CoOOH Nanorods Activated with Iron for Exceptional Oxygen Evolution Reaction

Abstract

Two-dimensional oxyhydroxide materials are proved to be a potential candidate for oxygen evolution reaction (OER). Robust, efficient, and cost-effective electrocatalysts are critical to overcome the sluggish kinetics and high overpotential of OERs. Herein, a simple co-precipitation method followed by solvothermal treatment is used to synthesize Fe-doped α-CoOOH at higher pH under optimum conditions for OER. The α-Fe 0.24 Co 0.76 OOH/NF illustrates superior OER electrocatalytic performance and requires an overpotential of only 280 mV to produce a current density of 50 mA cm −2 with excellent stability. The detailed analysis reveals that the exceptional OER performance originates from thin nanorods and partially due to the replacement of Fe in α-CoOOH. This work illustrates the presence of interlayer chloride ions through energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.

Boosting Surface Reconstruction for the Oxygen Evolution Reaction: A Combined Effect of Heteroatom Incorporation and Anion Etching in Cobalt Silicate Precatalyst

“…The difference in binding energy of the deconvoluted peaks of the Co 2p XPS spectra is ∼ 16 eV which indicates the presence of Co 3+ . However if Co 2+ is present in the system the difference in binding energy between the 2p 3/2 and 2p 1/2 energy state is closer to ∼15 eV [48] . This is further validated by the appearance of a broad peak at 784.3 eV and 801.0 eV originating from satellite peaks.…”

“…The ratio of Co 2+ /Co 3+ determined from the ratio of the area under the corresponding peaks are found to be ∼0.64 (Table S1). Interestingly, upon Fe incorporation, it is observed that the peaks shifted to a slightly higher binding energy (Figure S6b) [48,49] . Also, the ratio of Co 2+ /Co 3+ decreased to ∼0.37 which indicates the facile oxidation of Co 2+ to Co 3+ in presence of Fe.…”

“…However if Co 2 + is present in the system the difference in binding energy between the 2p 3/2 and 2p 1/2 energy state is closer to ~15 eV. [48] This is further validated by the appearance of a broad peak at 784.3 eV and 801.0 eV originating from satellite peaks. The ratio of Co 2 + /Co 3 + determined from the ratio of the area under the corresponding peaks are found to be ~0.64 (Table S1).…”

“…Interestingly, upon Fe incorporation, it is observed that the peaks shifted to a slightly higher binding energy (Figure S6b). [48,49] Also, the ratio of Co 2 + / Co 3 + decreased to ~0.37 which indicates the facile oxidation of Co 2 + to Co 3 + in presence of Fe. However, upon S incorporation, the binding energy of Co 2p shifted to slightly lower value due to the formation of CoÀ S which has smaller binding energy than CoÀ O as depicted in Figure S6c.…”

First-Principles Study on Chromium-Substituted α-Cobalt Oxyhydroxides for Efficient Oxygen Evolution Reaction

“…Among the leading OER catalysts, transition-metal-based oxyhydroxides and layered double hydroxides (LDHs) have gained considerable attention due to their excellent catalytic activity and abundant availability in the earth’s crust. − It is known that incorporation of Fe (III) in oxyhydroxides has outperformed the OER kinetics, although the key factor in improvement is still under consideration. , Besides Fe (III), cobalt is introduced into nickel hydroxides to boost the OER kinetics in water oxidation via constructing NiCo-LDHs. , However, the performance was not as good as that of NiFe-LDHs. Meanwhile, the substitution of Fe in cobalt hydroxides is well documented. , Likewise, before employing LDHs as electrode materials, improved conductivity and the specific surface area need considerable attention to advance OER kinetics. , The size of the hydroxides reported so far is too large to improve the OER kinetics intensely due to the limited accessibility of edges and corner sites . Typically, metal hydroxide nanosheets with dimensions less than 200 nm are being synthesized by microemulsion, plasma etching, layer growth inhibitors, and solvent exfoliations …”