scholarly journals Cerium–quinone redox couples put under scrutiny

2021 ◽  
Author(s):  
Uwe Bayer ◽  
Daniel Werner ◽  
Andreas Berkefeld ◽  
Cäcilia Maichle-Mössmer ◽  
Reiner Anwander
Keyword(s):  
Redox Couples ◽  
Oxidizing Power

Para-quinones reveal distinct reactivity towards homoleptic cerous silylamide and siloxide complexes depending on both their oxidizing power and the supporting ligand L.

scholarly journals Solvent-Dependent Oxidizing Power of LiI Redox Couples for Li-O2 Batteries

Joule ◽  
2019 ◽  
Vol 3 (4) ◽  
pp. 1106-1126 ◽  
Author(s):  
Graham Leverick ◽  
Michał Tułodziecki ◽  
Ryoichi Tatara ◽  
Fanny Bardé ◽  
Yang Shao-Horn
Keyword(s):  
Redox Couples ◽  
Oxidizing Power

scholarly journals Molecular Hydrogen as a Potential Clinically Applicable Radioprotective Agent

2021 ◽  
Vol 22 (9) ◽  
pp. 4566
Author(s):  
Shin-ichi Hirano ◽  
Yusuke Ichikawa ◽  
Bunpei Sato ◽  
Haru Yamamoto ◽  
Yoshiyasu Takefuji ◽  
...  
Keyword(s):  
Radiation Damage ◽  
Molecular Hydrogen ◽  
Regulation Of Gene Expression ◽  
Animal Experiments ◽  
Radiation Energy ◽  
Water Radiolysis ◽  
Low Dose Radiation ◽  
Oxidizing Power ◽  
Radiation Induced ◽  
Radioprotective Agent

Although ionizing radiation (radiation) is commonly used for medical diagnosis and cancer treatment, radiation-induced damages cannot be avoided. Such damages can be classified into direct and indirect damages, caused by the direct absorption of radiation energy into DNA and by free radicals, such as hydroxyl radicals (•OH), generated in the process of water radiolysis. More specifically, radiation damage concerns not only direct damages to DNA, but also secondary damages to non-DNA targets, because low-dose radiation damage is mainly caused by these indirect effects. Molecular hydrogen (H2) has the potential to be a radioprotective agent because it can selectively scavenge •OH, a reactive oxygen species with strong oxidizing power. Animal experiments and clinical trials have reported that H2 exhibits a highly safe radioprotective effect. This paper reviews previously reported radioprotective effects of H2 and discusses the mechanisms of H2, not only as an antioxidant, but also in intracellular responses including anti-inflammation, anti-apoptosis, and the regulation of gene expression. In doing so, we demonstrate the prospects of H2 as a novel and clinically applicable radioprotective agent.

scholarly journals A four-electron Zn-I2 aqueous battery enabled by reversible I−/I2/I+ conversion

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yiping Zou ◽  
Tingting Liu ◽  
Qijun Du ◽  
Yingying Li ◽  
Haibo Yi ◽  
...  
Keyword(s):  
Aqueous Electrolyte ◽  
Chloride Ions ◽  
Experimental Characterization ◽  
Redox Couples ◽  
Free Chloride ◽  
Reversible Redox ◽  
Aqueous Battery ◽  
Storage Batteries ◽  
Aqueous Batteries ◽  
Superior Level

AbstractElectrochemically reversible redox couples that embrace more electron transfer at a higher potential are the eternal target for energy storage batteries. Here, we report a four-electron aqueous zinc-iodine battery by activating the highly reversible I2/I+ couple (1.83 V vs. Zn/Zn2+) in addition to the typical I−/I2 couple (1.29 V). This is achieved by intensive solvation of the aqueous electrolyte to yield ICl inter-halogens and to suspend its hydrolysis. Experimental characterization and modelling reveal that limited water activity and sufficient free chloride ions in the electrolyte are crucial for the four-electron process. The merits of the electrolyte also afford to stabilize Zn anode, leading to a reliable Zn-I2 aqueous battery of 6000 cycles. Owing to high operational voltage and capacity, energy density up to 750 Wh kg−1 based on iodine mass was achieved (15–20 wt% iodine in electrode). It pushes the Zn-I2 battery to a superior level among these available aqueous batteries.

scholarly journals Mixed Lithium and Sodium Ion Aprotic DMSO Electrolytes for Oxygen Reduction on Au and Pt Studied by DEMS and RRDE

2021 ◽  
Author(s):  
M. Hegemann ◽  
P. P. Bawol ◽  
A. Köllisch-Mirbach ◽  
H. Baltruschat
Keyword(s):  
Oxygen Reduction ◽  
Product Distribution ◽  
Reduction Reaction ◽  
Mixed Electrolytes ◽  
Peroxide Formation ◽  
Pt Electrode ◽  
Rate Determining Step ◽  
Differential Electrochemical Mass Spectrometry ◽  
Redox Couples ◽  
Pt Electrodes

AbstractIn order to advance the development of metal-air batteries and solve possible problems, it is necessary to gain a fundamental understanding of the underlying reaction mechanisms. In this study we investigate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER, from species formed during ORR) in Na+ containing dimethyl sulfoxide (DMSO) on poly and single crystalline Pt and Au electrodes. Using a rotating ring disk electrode (RRDE) generator collector setup and additional differential electrochemical mass spectrometry (DEMS), we investigate the ORR mechanism and product distribution. We found that the formation of adsorbed Na2O2, which inhibits further oxygen reduction, is kinetically favored on Pt overadsorption on Au. Peroxide formation occurs to a smaller extent on the single crystal electrodes of Pt than on the polycrystalline surface. Utilizing two different approaches, we were able to calculate the heterogeneous rate constants of the O2/O2− redox couple on Pt and Au and found a higher rate for Pt electrodes compared to Au. We will show that on both electrodes the first electron transfer (formation of superoxide) is the rate-determining step in the reaction mechanism. Small amounts of added Li+ in the electrolyte reduce the reversibility of the O2/O2− redox couples due to faster and more efficient blocking of the electrode by peroxide. Another effect is the positive potential shift of the peroxide formation on both electrodes. The reaction rate of the peroxide formation on the Au electrode increases when increasing the Li+ content in the electrolyte, whereas it remains unaffected on the Pt electrode. However, we can show that the mixed electrolytes promote the activity of peroxide oxidation on the Pt electrode compared to a pure Li+ electrolyte. Overall, we found that the addition of Li+ leads to a Li+-dominated mechanism (ORR onset and product distribution) as soon as the Li+ concentration exceeds the oxygen concentration. Graphical abstract

Synthesis, characterisation and activity in catalytic epoxidation of olefins of new dinuclear nickel(ll) complexes

2009 ◽  
Vol 2009 (8) ◽  
pp. 527-532
Author(s):  
Manindranath Bera
Keyword(s):  
Visible Region ◽  
Chemical Oxidation ◽  
Cyclic Voltammetric ◽  
Catalytic Epoxidation ◽  
Redox Couples ◽  
Square Planar ◽  
Catalytically Active ◽  
Mecn Solution ◽  
Voltammetric Measurements ◽  
Epoxidation Of Olefins

Two new dinuclear nickel(ll) compounds of formula [Nill2(μ-L1)2](CIO4)2·MeCN (1·MeCN) and [NiII2(μ-L2)2](CIO4)2 (2) where HL1 and HL2 stand for 3-(2-(dimethylamino)ethylimino)butan-2-one oxime and 1-(2-(dimethylamino)ethyl-imino)-1-phenylpropan-2-one oxime respectively, have been synthesised. Single crystal X-ray analyses of the complexes reveal that the nickel(ll) ions are in square-planar N3O environments and form six-membered (NiNO)2 metallacycles. Cyclic voltammetric measurements of 1·MeCN and 2 in MeCN solution show quasirreversible one-electron oxidations at E1/2 = 0.566 V and 0.603 V ( vs Fc+/Fc), respectively, attributed to NiIIINiII/NiII2 redox couples. Additional reversible NiIII2/NiIIINiII redox responses were observed at relatively higher potential near E1/2 = 0.832 V and 0.850 V ( vs Fc+/Fc), respectively, for 1·MeCN and 2. Complexes 1·MeCN and 2 display intense charge-transfer bands at ∼390 and ∼345 nm in the visible region. Chemical oxidation of complex 1·MeCN by sodium hexachloroiridate(IV) hexahydrate generates red Ni2III species with characteristic new bands at ∼520 and 427 nm in the visible region as well as the characteristic EPR signals at 77 K with g⊥ > gII. Similar phenomena were observed for complex 2 upon chemical oxidation. The dinickel(ll) complexes are catalytically active for epoxidation of olefins using iodosylbenzene as the terminal oxidant.

Sign in / Sign up

Export Citation Format

Share Document