scholarly journals X-ray Spectroscopic Characterization of Co(IV) and Metal–Metal Interactions in Co4O4: Electronic Structure Contributions to the Formation of High-Valent States Relevant to the Oxygen Evolution Reaction

2016 ◽  
Vol 138 (34) ◽  
pp. 11017-11030 ◽  
Author(s):  
Ryan G. Hadt ◽  
Dugan Hayes ◽  
Casey N. Brodsky ◽  
Andrew M. Ullman ◽  
Diego M. Casa ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Spectroscopic Characterization ◽  
X Ray ◽  
Metal Interactions ◽  
Metal Metal ◽  
High Valent

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.

Spectroscopic Characterization of Mixed Fe–Ni Oxide Electrocatalysts for the Oxygen Evolution Reaction in Alkaline Electrolytes

ACS Catalysis ◽  
2012 ◽  
Vol 2 (8) ◽  
pp. 1793-1801 ◽  
Author(s):  
James Landon ◽  
Ethan Demeter ◽  
Nilay İnoğlu ◽  
Chris Keturakis ◽  
Israel E. Wachs ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Spectroscopic Characterization ◽  
Alkaline Electrolytes ◽  
Ni Oxide

scholarly journals Pt-Co3O4 Superstructures by One-Pot Reduction/Precipitation in Bicontinuous Microemulsion for Electrocatalytic Oxygen Evolution Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1311
Author(s):  
Elijah T. Adesuji ◽  
Esther Guardado-Villegas ◽  
Keyla M. Fuentes ◽  
Margarita Sánchez-Domínguez ◽  
Marcelo Videa
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Linear Sweep Voltammetry ◽  
One Pot ◽  
Metal Metal ◽  
Bicontinuous Microemulsion ◽  
Initial Ph ◽  
And Performance ◽  
Reaction Media

Bicontinuous microemulsions (BCME) were used to synthesize hierarchical superstructures (HSs) of Pt-Co3O4 by reduction/precipitation. BCMEs possess water and oil nanochannels, and therefore, both hydrophilic and lipophilic precursors can be used. Thus, PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi were prepared (where Aq and Oi stand for the precursor present in aqueous or oily phase, respectively). The characterization of the Pt-Co3O4-HS confirmed the formation of metallic Pt and Co3O4 whose composition and morphology are controlled by the initial pH and precursor combination, determining the presence of the reducing/precipitant species in the reaction media. The electrocatalytic activity of the Pt-Co3O4-HSs for oxygen evolution reaction (OER) was investigated using linear sweep voltammetry in 0.1 M KOH and compared with Pt-HS. The lowest onset overpotentials for Pt-Co3O4-Hs were achieved with PtOi-CoOi (1.46 V vs. RHE), while the lowest overpotential at a current density of 10 mA cm−2 (η10) was obtained for the PtAq-CoAq (381 mV). Tafel slopes were 102, 89, 157 and 92 mV dec−1, for PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi, respectively. The Pt-Co3O4-HSs showed a better performance than Pt-HS. Our work shows that the properties and performance of metal–metal oxide HSs obtained in BCMEs depend on the phases in which the precursors are present.

Structural and spectroscopic characterization of an Fe(VI) bis(imido) complex

Science ◽  
2020 ◽  
Vol 370 (6514) ◽  
pp. 356-359 ◽  
Author(s):  
Jorge L. Martinez ◽  
Sean A. Lutz ◽  
Hao Yang ◽  
Jiaze Xie ◽  
Joshua Telser ◽  
...  
Keyword(s):  
Double Resonance ◽  
Spectroscopic Characterization ◽  
Biological Processes ◽  
X Ray Diffraction ◽  
Electron Nuclear Double Resonance ◽  
X Ray ◽  
High Valent ◽  
X Ray Absorption ◽  
Structure Calculations

High-valent iron species are key intermediates in oxidative biological processes, but hexavalent complexes apart from the ferrate ion are exceedingly rare. Here, we report the synthesis and structural and spectroscopic characterization of a stable Fe(VI) complex (3) prepared by facile one-electron oxidation of an Fe(V) bis(imido) (2). Single-crystal x-ray diffraction of 2 and 3 revealed four-coordinate Fe centers with an unusual “seesaw” geometry. 57Fe Mössbauer, x-ray photoelectron, x-ray absorption, and electron-nuclear double resonance (ENDOR) spectroscopies, supported by electronic structure calculations, support a low-spin (S = 1/2) d3 Fe(V) configuration in 2 and a diamagnetic (S = 0) d2 Fe(VI) configuration in 3. Their shared seesaw geometry is electronically dictated by a balance of Fe-imido σ- and π-bonding interactions.

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.

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 Operando X-ray characterization of high surface area iridium oxides to decouple their activity losses for the oxygen evolution reaction

2019 ◽  
Vol 12 (10) ◽  
pp. 3038-3052 ◽  
Author(s):  
Mauro Povia ◽  
Daniel F. Abbott ◽  
Juan Herranz ◽  
Adrian Heinritz ◽  
Dmitry Lebedev ◽  
...  
Keyword(s):  
Surface Area ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
High Surface ◽  
High Surface Area ◽  
Oxide Catalysts ◽  
X Ray ◽  
Iridium Oxides ◽  
Evolution Of Oxygen

Operando X-ray techniques allow an unprecedented, quantitative discrimination of the instability mechanisms affecting Ir-oxide catalysts for the evolution of oxygen.

scholarly journals 4-[(2,4-Dichlorophenyl)carbamoyl]butanoic Acid

Molbank ◽  
10.3390/m1227 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1227
Author(s):  
Bibi Hanifa ◽  
Muhammad Sirajuddin ◽  
Zafran Ullah ◽  
Sumera Mahboob ◽  
See Mun Lee ◽  
...  
Keyword(s):  
Torsion Angle ◽  
Acid Amide ◽  
Spectroscopic Characterization ◽  
Amide Bond ◽  
Amide Hydrogen ◽  
Butanoic Acid ◽  
X Ray ◽  
Amide Derivative

The synthesis and spectroscopic characterization of the glutaric acid-amide derivative, 2,4-Cl2C6H3N(H)C(=O)(CH2)3C(=O)OH (1), are described. The X-ray crystal structure determination of (1) shows the backbone of the molecule to be kinked about the methylene-C–N(amide) bond as seen in the C(p)–N–C(m)–C(m) torsion angle of −157.0(2)°; m = methylene and p = phenyl. An additional twist in the molecule is noted between the amide and phenyl groups as reflected in the C(m)–N–C(p)–C(p) torsion angle of 138.2(2)°. The most prominent feature of the molecular packing is the formation of supramolecular tapes assembled through carboxylic acid-O–H…O(carbonyl) and amide-N–H…O(amide) hydrogen bonding.

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