Manganese oxide-based heterogeneous electrocatalysts for water oxidation

Park, Sunghak; Lee, Yoon Ho; Choi, Seungwoo; Seo, Hongmin; Lee, Moo Young; Balamurugan, Mani; Nam, Ki Tae

doi:10.1039/d0ee00815j

Cited by 95 publications

(47 citation statements)

References 164 publications

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“…Readers interested in other catalysts can refer to other published studies. [42][43][44] We illustrate plausible OER cycles via H 2 O oxidation in section 2 and review its spectroscopic and computational support, while section 3 deals with those for OH − oxidation. Section 4 discusses the dissolution mechanisms of iridium during the OER mechanism, corroborating the catalytic cycle.…”

Section: Takeshi Nishimotomentioning

confidence: 99%

“…Understanding OER kinetics over iridium oxide under distinct conditions forms a generalized view into its catalysis, which would help rationally design OER catalysts. Secondly, increasing attention has recently been given to the OER at the near-neutral pH levels under buffered conditions, 42,[88][89][90] where the OER can proceed also as the oxidation of OH − . Insights into the OER at alkaline pH thus certainly help advance the electrocatalysis under near-neutral pH conditions.…”

Section: Oer Mechanism Via Oh − Oxidation Over Iridium Oxidementioning

confidence: 99%

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Recent advances in understanding oxygen evolution reaction mechanisms over iridium oxide

Naitô

Shinagawa

Nishimoto

et al. 2021

Inorg. Chem. Front.

103

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Section: Takeshi Nishimotomentioning

confidence: 99%

Section: Oer Mechanism Via Oh − Oxidation Over Iridium Oxidementioning

confidence: 99%

Recent advances in understanding oxygen evolution reaction mechanisms over iridium oxide

Naitô

Shinagawa

Nishimoto

et al. 2021

Inorg. Chem. Front.

103

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“…Furthermore, the newly developed 4 nm Mn 3 O 4 NPs exhibited superior catalytic activity than did any other Mn‐based electrocatalyst under neutral conditions [11] . Recently, we highlighted the important aspects of highly active Mn‐based heterogeneous electrocatalysts and the current understanding of their reaction mechanism for water oxidation [36] . The Mn IV =O water oxidation intermediates has not yet been directly identified by the vibrational spectroscopy such as Raman or Infrared (IR) spectroscopy on Mn‐based heterogeneous electrocatalysts so far.…”

Section: Introductionmentioning

confidence: 99%

Capturing Manganese Oxide Intermediates in Electrochemical Water Oxidation at Neutral pH by In Situ Raman Spectroscopy

et al. 2021

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Electrochemical water splitting is a promising means to produce eco‐friendly hydrogen fuels. Inspired by the Mn4CaO5 cluster in nature, substantial works have been performed to develop efficient manganese (Mn)‐based heterogeneous catalysts. Despite improvements in catalytic activity, the underlying mechanism of the oxygen evolution reaction (OER) is not completely elucidated owing to the lack of direct spectroscopic evidence for the active Mn‐oxo moieties. We identify water oxidation intermediates on the surface of Mn3O4 nanoparticles (NPs) in the OER at neutral pH by in situ Raman spectroscopy. A potential‐dependent Raman peak was detected at 760 cm−1 and assigned to the active MnIV=O species generated during water oxidation. Isotope‐labeling experiments combined with scavenger experiments confirmed the generation of surface terminal MnIV=O intermediates in the Mn‐oxide NPs. This study provides an insight into the design of systems for the observation of reaction intermediates.

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“…Then, the adsorbed water molecule undergoes multiple protons and electrons transfer with a redox state change of the transition metal site to generate high-valent transition metal-oxo species involved in the O–O bond formation step. Understanding each elementary step and developing catalysts under neutral pH conditions have been recently getting much interest due to the advantage of environmentally friendly, less corrosive electrolyte and the possibility of combining with CO 2 reduction or microbial hybrid electrolysis cell 5 – 7 . While many experimental and computational results imply the existence of a high-valent metal-oxo species on the surface of heterogeneous catalysts that serves as an active reaction intermediate during the water oxidation reaction, very few results offering direct evidence of the chemical identity of intermediates have been reported to date for heterogeneous catalysts.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic capture of a low-spin Mn(IV)-oxo species in Ni–Mn3O4 nanoparticles during water oxidation catalysis

et al. 2020

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High-valent metal-oxo moieties have been implicated as key intermediates preceding various oxidation processes. The critical O–O bond formation step in the Kok cycle that is presumed to generate molecular oxygen occurs through the high-valent Mn-oxo species of the water oxidation complex, i.e., the Mn4Ca cluster in photosystem II. Here, we report the spectroscopic characterization of new intermediates during the water oxidation reaction of manganese-based heterogeneous catalysts and assign them as low-spin Mn(IV)-oxo species. Recently, the effects of the spin state in transition metal catalysts on catalytic reactivity have been intensely studied; however, no detailed characterization of a low-spin Mn(IV)-oxo intermediate species currently exists. We demonstrate that a low-spin configuration of Mn(IV), S = 1/2, is stably present in a heterogeneous electrocatalyst of Ni-doped monodisperse 10-nm Mn3O4 nanoparticles via oxo-ligand field engineering. An unprecedented signal (g = 1.83) is found to evolve in the electron paramagnetic resonance spectrum during the stepwise transition from the Jahn–Teller-distorted Mn(III). In-situ Raman analysis directly provides the evidence for Mn(IV)-oxo species as the active intermediate species. Computational analysis confirmed that the substituted nickel species induces the formation of a z-axis-compressed octahedral C4v crystal field that stabilizes the low-spin Mn(IV)-oxo intermediates.

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Manganese oxide-based heterogeneous electrocatalysts for water oxidation

Abstract: A review on manganese oxide-based electrocatalysts for the water oxidation reaction.

Cited by 95 publications

References 164 publications

Recent advances in understanding oxygen evolution reaction mechanisms over iridium oxide

Recent advances in understanding oxygen evolution reaction mechanisms over iridium oxide

Capturing Manganese Oxide Intermediates in Electrochemical Water Oxidation at Neutral pH by In Situ Raman Spectroscopy

Spectroscopic capture of a low-spin Mn(IV)-oxo species in Ni–Mn3O4 nanoparticles during water oxidation catalysis

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