scholarly journals Generation and Reactivity of a NiIII2(μ-1,2-peroxo) Complex

2020 ◽  
Author(s):  
Norman Zhao ◽  
Alexander S. Filatov ◽  
Jiaze Xie ◽  
Ethan A. Hill ◽  
John Anderson
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Oxidation States ◽  
Peroxo Complex ◽  
Intermediate Species ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tetrabutylammonium Chloride ◽  
High Valent ◽  
X Ray Absorption

Ni-based oxide materials are promising candidates for catalyzing the oxygen evolution reaction. The detailed mechanism of water splitting in these systems has been of interest with a goal of understanding the intermediate species vital for catalytic activity. A potential intermediate species prior to release of oxygen is a bridging Ni<sup>III</sup><sub>2</sub>(<i>μ</i>-1,2-peroxo) complex. However, Ni<sub>2</sub>(<i>μ</i>-1,2-peroxo) complexes are rare in general and are unknown with oxidation states higher than Ni<sup>II</sup>. Herein, we report the isolation of such an unusual high-valent species in a Ni<sup>III</sup><sub>2</sub>(<i>μ</i>-1,2-peroxo) complex, which has been characterized using single-crystal X-ray diffraction and X-ray absorption, NMR, and UV-vis spectroscopies. In addition, treatment with excess tetrabutylammonium chloride results in regeneration of the precursor Ni–Cl species, implicating the reversible release of oxygen or a reactive oxygen species. Taken together, this suggests that Ni<sup>III</sup><sub>2</sub>(<i>μ</i>-1,2-peroxo) species are accessible and may be viable intermediates during the oxygen evolution reaction.

scholarly journals Generation and Reactivity of a NiIII2(μ-1,2-peroxo) Complex

2020 ◽  
Author(s):  
Norman Zhao ◽  
Alexander S. Filatov ◽  
Jiaze Xie ◽  
Ethan A. Hill ◽  
John Anderson
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Oxidation States ◽  
Peroxo Complex ◽  
Intermediate Species ◽  
X Ray Diffraction ◽  
X Ray ◽  
Tetrabutylammonium Chloride ◽  
High Valent ◽  
X Ray Absorption

Ni-based oxide materials are promising candidates for catalyzing the oxygen evolution reaction. The detailed mechanism of water splitting in these systems has been of interest with a goal of understanding the intermediate species vital for catalytic activity. A potential intermediate species prior to release of oxygen is a bridging Ni<sup>III</sup><sub>2</sub>(<i>μ</i>-1,2-peroxo) complex. However, Ni<sub>2</sub>(<i>μ</i>-1,2-peroxo) complexes are rare in general and are unknown with oxidation states higher than Ni<sup>II</sup>. Herein, we report the isolation of such an unusual high-valent species in a Ni<sup>III</sup><sub>2</sub>(<i>μ</i>-1,2-peroxo) complex, which has been characterized using single-crystal X-ray diffraction and X-ray absorption, NMR, and UV-vis spectroscopies. In addition, treatment with excess tetrabutylammonium chloride results in regeneration of the precursor Ni–Cl species, implicating the reversible release of oxygen or a reactive oxygen species. Taken together, this suggests that Ni<sup>III</sup><sub>2</sub>(<i>μ</i>-1,2-peroxo) species are accessible and may be viable intermediates during the oxygen evolution reaction.

scholarly journals Detection of high-valent iron species in alloyed oxidic cobaltates for catalysing the oxygen evolution reaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nancy Li ◽  
Ryan G. Hadt ◽  
Dugan Hayes ◽  
Lin X. Chen ◽  
Daniel G. Nocera
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Redox State ◽  
Ligand Field ◽  
Zero Field ◽  
X Ray ◽  
Fe Oxides ◽  
High Valent ◽  
X Ray Absorption ◽  
Alloying Compositions

AbstractIron alloying of oxidic cobaltate catalysts results in catalytic activity for oxygen evolution on par with Ni-Fe oxides in base but at much higher alloying compositions. Zero-field 57Fe Mössbauer spectroscopy and X-ray absorption spectroscopy (XAS) are able to clearly identify Fe4+ in mixed-metal Co-Fe oxides. The highest Fe4+ population is obtained in the 40–60% Fe alloying range, and XAS identifies the ion residing in an octahedral oxide ligand field. The oxygen evolution reaction (OER) activity, as reflected in Tafel analysis of CoFeOx films in 1 M KOH, tracks the absolute concentration of Fe4+. The results reported herein suggest an important role for the formation of the Fe4+ redox state in activating cobaltate OER catalysts at high iron loadings.

Revealing the structural transformation of rutile RuO2via in situ X-ray absorption spectroscopy during the oxygen evolution reaction

2019 ◽  
Vol 48 (21) ◽  
pp. 7122-7129 ◽  
Author(s):  
Chia-Jui Chang ◽  
You-Chiuan Chu ◽  
Hao-Yu Yan ◽  
Yen-Fa Liao ◽  
Hao Ming Chen
Keyword(s):  
Oxygen Evolution ◽  
Structural Transformation ◽  
Absorption Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
The State ◽  
X Ray ◽  
Alkaline Conditions ◽  
X Ray Absorption ◽  
State Of Art

The state-of-art RuO2 catalyst for the oxygen evolution reaction (OER) is measured by using in situ X-ray absorption spectroscopy (XAS) to elucidate the structural transformation during catalyzing the reaction in acidic and alkaline conditions.

scholarly journals A Cobalt-Iron Double-Atom Catalyst for the Oxygen Evolution Reaction

2019 ◽  
Author(s):  
Lichen Bai ◽  
Chia-Shuo Hsu ◽  
Duncan Alexander ◽  
Hao Ming Chen ◽  
Xile Hu
Keyword(s):  
Oxygen Evolution ◽  
Active Site ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Single Atom ◽  
X Ray ◽  
Highly Active ◽  
Cobalt Iron ◽  
X Ray Absorption

Single atom catalysts exhibit well-defined active sites and potentially maximum atomic efficiency. However, they are unsuitable for reactions that benefit from bimetallic promotion such as the oxygen evolution reaction (OER) in alkaline medium. Here we show that a single atom Co precatalyst can be in-situ transformed into a Co-Fe double atom catalyst for OER. This catalyst exhibits one of the highest turnover frequencies among metal oxides. Electrochemical, microscopic, and spectroscopic data including those from operando X-ray absorption spectroscopy, reveal a dimeric Co-Fe moiety as the active site of the catalyst. This work demonstrates double-atom catalysis as a promising approach for the developed of defined and highly active OER catalysts.

Electronic structure of (MePh3P)2[NiII(bdtCl2)2]·2(CH3)2SO and (MePh3P)[NiIII(bdtCl2)2] (bdtCl2 = 3,6-dichlorobenzene-1,2-dithiolate)

2021 ◽  
Vol 77 (6) ◽  
Author(s):  
Julia Adamko Koziskova ◽  
Yu-Sheng Chen ◽  
Su-Yin Grass ◽  
Yu-Chun Chuang ◽  
I-Jui Hsu ◽  
...  
Keyword(s):  
Electronic Structure ◽  
High Resolution ◽  
Theoretical Calculations ◽  
Nickel Complexes ◽  
Oxidation States ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption ◽  
Bond Character ◽  
Density Modeling

High-resolution X-ray diffraction experiments, theoretical calculations and atom-specific X-ray absorption experiments were used to investigate two nickel complexes, (MePh3P)2[NiII(bdtCl2)2]·2(CH3)2SO [complex (1)] and (MePh3P)[NiIII(bdtCl2)2] [complex (2)]. Combining the techniques of nickel K- and sulfur K-edge X-ray absorption spectroscopy with high-resolution X-ray charge density modeling, together with theoretical calculations, the actual oxidation states of the central Ni atoms in these two complexes are investigated. Ni ions in two complexes are clearly in different oxidation states: the Ni ion of complex (1) is formally NiII; that of complex (2) should be formally NiIII, yet it is best described as a combination of Ni2+ and Ni3+, due to the involvement of the non-innocent ligand in the Ni—L bond. A detailed description of Ni—S bond character (σ,π) is presented.

Valence- and element-dependent water oxidation behaviors: in situ X-ray diffraction, absorption and electrochemical impedance spectroscopies

2017 ◽  
Vol 19 (13) ◽  
pp. 8681-8693 ◽  
Author(s):  
Chia-Shuo Hsu ◽  
Nian-Tzu Suen ◽  
Ying-Ya Hsu ◽  
Hsuan-Yu Lin ◽  
Ching-Wei Tung ◽  
...  
Keyword(s):  
Metal Oxides ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Water Oxidation ◽  
Electrochemical Impedance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxidation Behaviors

Various metal oxides of the spinel family have shown great potential towards the oxygen evolution reaction, but this behavior only works in specific cases.

scholarly journals A Cobalt-Iron Double-Atom Catalyst for the Oxygen Evolution Reaction

2019 ◽  
Author(s):  
Lichen Bai ◽  
Chia-Shuo Hsu ◽  
Duncan Alexander ◽  
Hao Ming Chen ◽  
Xile Hu
Keyword(s):  
Oxygen Evolution ◽  
Active Site ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Single Atom ◽  
X Ray ◽  
Highly Active ◽  
Cobalt Iron ◽  
X Ray Absorption

Single atom catalysts exhibit well-defined active sites and potentially maximum atomic efficiency. However, they are unsuitable for reactions that benefit from bimetallic promotion such as the oxygen evolution reaction (OER) in alkaline medium. Here we show that a single atom Co precatalyst can be in-situ transformed into a Co-Fe double atom catalyst for OER. This catalyst exhibits one of the highest turnover frequencies among metal oxides. Electrochemical, microscopic, and spectroscopic data including those from operando X-ray absorption spectroscopy, reveal a dimeric Co-Fe moiety as the active site of the catalyst. This work demonstrates double-atom catalysis as a promising approach for the developed of defined and highly active OER catalysts.

Molecular and electronic structure of AnIVFeII(CN)6·xH2O (An = Th, U, Np) compounds: an X-ray absorption spectroscopy investigation

2000 ◽  
Vol 78 (10) ◽  
pp. 1305-1317
Author(s):  
Isabelle Bonhoure ◽  
Christophe Den Auwer ◽  
Christophe Cartier dit Moulin ◽  
Philippe Moisy ◽  
Jean-Claude Berthet ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Molecular Structures ◽  
Oxidation States ◽  
X Ray Diffraction ◽  
Acidic Media ◽  
X Ray ◽  
X Ray Absorption ◽  
Molecular Compounds ◽  
Molecular And Electronic Structure ◽  
Chemical Formulas

AnIVFeII(CN)6·xH2O (An = Th, U, Np) molecular compounds have been prepared by precipitation from acidic media. These microcrystalline compounds have been characterized by infrared spectroscopy, X-ray diffraction, and X-ray absorption spectroscopy. They have been found to be isostructural with the LnIIIKFeII(CN)6·4H2O compounds. The molecular structures of these compounds are presented and their chemical formulas are given: in all compounds, the Fe(CN)6 octahedra is conserved and the An ion is linked to the N atoms of the CN ligands. The formal oxidation states are also discussed.Key words: hexacyanoferrate, actinide, EXAFS, XANES, X-ray absorption spectroscopy.

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