Unidirectional current flow of reversible redox couples on a MoO3 film-modified microelectrode

1997 ◽  
Vol 435 (1-2) ◽  
pp. 23-30 ◽  
Author(s):  
Baoxing Wang ◽  
Xiao-yuan Li ◽  
Shaojun Dong
Keyword(s):  
Current Flow ◽  
Redox Couples ◽  
Reversible Redox ◽  
Moo3 Film

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 Voltage fade mitigation in the cationic dominant lithium-rich NCM cathode

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Prem Chandan ◽  
Chung-Chieh Chang ◽  
Kuo-Wei Yeh ◽  
Chui-Chang Chiu ◽  
Dong-Ze Wu ◽  
...  
Keyword(s):  
Metal Ions ◽  
Transition Metal Ions ◽  
Lithium Content ◽  
Capacity Retention ◽  
Capacity Loss ◽  
Redox Couples ◽  
Reversible Redox ◽  
Alternative Approach ◽  
Voltage Fade ◽  
Rich Material

Abstract In the archetypal lithium-rich cathode compound Li1.2Ni0.13Co0.13Mn0.54O2, a major part of the capacity is contributed from the anionic (O2−/−) reversible redox couple and is accompanied by the transition metal ions migration with a detrimental voltage fade. A better understanding of these mutual interactions demands for a new model that helps to unfold the occurrences of voltage fade in lithium-rich system. Here we present an alternative approach, a cationic reaction dominated lithium-rich material Li1.083Ni0.333Co0.083Mn0.5O2, with reduced lithium content to modify the initial band structure, hence ~80% and ~20% of capacity are contributed by cationic and anionic redox couples, individually. A 400 cycle test with 85% capacity retention depicts the capacity loss mainly arises from the metal ions dissolution. The voltage fade usually from Mn4+/Mn3+ and/or On−/O2− reduction at around 2.5/3.0 V seen in the typical lithium-rich materials is completely eliminated in the cationic dominated cathode material.

Non-covalently functionalizing a graphene framework by anthraquinone for high-rate electrochemical energy storage

RSC Advances ◽  
2015 ◽  
Vol 5 (30) ◽  
pp. 23942-23951 ◽  
Author(s):  
Ning An ◽  
Fuhai Zhang ◽  
Zhongai Hu ◽  
Zhimin Li ◽  
Li Li ◽  
...  
Keyword(s):  
Energy Storage ◽  
Rate Capability ◽  
High Specific Capacitance ◽  
Covalent Modification ◽  
High Rate ◽  
Electrochemical Energy Storage ◽  
Long Cycle Life ◽  
Redox Couples ◽  
Reversible Redox ◽  
Good Rate Capability

Anthraquinone (AQ) with electrochemically reversible redox couples is selected to functionalize graphene framework (GF) through non-covalent modification and the composite achieves high specific capacitance, good rate capability and long cycle life.

Electrochemical and Photoelectrochemical Investigation of New Self-Assembled Films Based on Prussian Blue and a Terpyridyl RuII Complex

2015 ◽  
Vol 68 (3) ◽  
pp. 426 ◽  
Author(s):  
Qiu-Ying Huang ◽  
Si-Yuan Kang ◽  
Hao Lin ◽  
Ke-Zhi Wang
Keyword(s):  
Prussian Blue ◽  
Self Assembly ◽  
Multilayer Film ◽  
Saturated Calomel Electrode ◽  
Photocurrent Density ◽  
Layer By Layer ◽  
Redox Couples ◽  
Reversible Redox ◽  
Film Forming ◽  
Photoelectrochemical Studies

A new hybrid multilayer film containing Prussian blue (PB) and a bis-terpyridyl RuII complex of RuII(L)2(ClO4)2 (in which L = 4′-(4-(imidazol-1-yl)phenyl)-2,2′:6′,2″-terpyridine), was fabricated though covalently and electrostatic layer-by-layer self-assembly techniques, and characterised by UV-vis absorption spectroscopy, cyclic voltammetry, and photoelectrochemical techniques. The results demonstrated that the two film-forming components were successfully transferred into the hybrid film, which exhibited three quasi-reversible redox couples centred at 0.06, 0.76, and 1.0 V. The photoelectrochemical studies showed that an 11-layer film exhibited a large cathodic photocurrent density of 7.72 μA cm–2 while irradiated with 100 mW cm–2 polychromatic light (325 < λ < 730 nm) at an applied potential of –0.2 V versus a saturated calomel electrode.

scholarly journals Synthesis of a Ru(II) Complex with a Naphthoquinone-Annelated Imidazole Ligand Exhibiting Proton-Responsive Redox and Luminescent Behavior

Inorganics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 24
Author(s):  
Takuya Shiga ◽  
Minami Tachibana ◽  
Hiroki Oshio ◽  
Masayuki Nihei
Keyword(s):  
Ruthenium Complex ◽  
Blue Shift ◽  
Imidazole Ligand ◽  
Ru Complex ◽  
Redox Couples ◽  
Electronic Delocalization ◽  
Ligand Charge Transfer ◽  
Reversible Redox ◽  
Mlct Band ◽  
Absorption Measurements

A mononuclear ruthenium complex, [RuII(L)(bpy)2](PF6), with a naphthoquinone-annelated imidazole ligand HL (2-(pyridin-2-yl)-1H-naphtho[2,3-d]imidazole-4,9-dione) was synthesized and structurally characterized. Electrochemical study reveals that the Ru complex shows four reversible redox waves at +0.98 V, −1.13 V, −1.53 V, and −1.71 V versus SCE in acetonitrile, which are assigned to Ru(II)/Ru(III), L−/L•2−, and two bpy/bpy•− redox couples, respectively. The redox potential of Ru(II)/Ru(III) was positively shifted upon the addition of trifluoromethanesulfonic acid due to protonation of the L− moiety, leading to stabilization of the Ru 4d orbital. In UV-vis absorption measurements for the Ru complex in acetonitrile, a metal-to-ligand charge transfer (MLCT) band was observed at 476 nm, which was shifted to 450 nm by protonation, which might be due to a decrease in the electron delocalization and stabilization of the π orbitals in L−. The blue shift of the MLCT band by protonation was associated with a shift of an emission band from 774 nm to 620 nm, which could be caused by the decreased electronic delocalization in the MLCT excited state. These electrochemical and spectroscopic changes were reversible for the protonation/deprotonation stimuli.

scholarly journals A Coating Strategy for Coevolving Photocatalysis to Stabilise Visible-Light Absorbing Semiconductors

2020 ◽  
Author(s):  
Tianshuo Zhao ◽  
Rito Yanagi ◽  
Yijie Xu ◽  
Yulian He ◽  
Yuqi Song ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Protective Coating ◽  
General Strategy ◽  
Simulated Sunlight ◽  
Redox Mediators ◽  
High Quantum Efficiency ◽  
Solar Water Splitting ◽  
Redox Couples ◽  
Reversible Redox ◽  
Conformal Coatings

Abstract Semiconductors of narrow bandgaps and high quantum efficiency have not been successfully utilised for coevolving photocatalysis despite the widely demonstrated protective coating schemes. Herein, we showcase a general strategy of using conformal coatings and cocatalysts energetic properties to transform CdS powders and GaInP2 films into stable and efficient photocatalysts for coevolution of H2 and reversible redox couples. A scalable redox-mediated solar water-splitting reactor was constructed, regenerating the redox mediators while evolving O2 in a separate compartment. Distinct from the single direction of charge transfer found with conventional photoelectrode stabilisation, the coating herein allows both photo-excited electrons and holes to spatially separate and inject simultaneously to the respective reductive and oxidative sites. With TiO2 stabilisation, CdS particles produced H2 continuously for 150 hours. Under simulated sunlight, solar-to-hydrogen (STH) efficiency of 5.9% and 9.4% can be achieved for the CdS and GaInP2 panels, respectively, by stacking multiple panels and matching the rate of redox regeneration to that of H2 production.

Structural and electrochemical comparison of trinuclear ruthenium oxo clusters [Ru3(OAc)6O(L)3]+and [Ru3(OAc)6O(L)2(CO)] (L = imidazole, benzimidazole, and 4-phenylpyridine)

2018 ◽  
Vol 74 (11) ◽  
pp. 1487-1494 ◽  
Author(s):  
Brandon Derstine ◽  
Carmen Chamberlain ◽  
Morgan Glover ◽  
Lindsey Porter ◽  
Amanda Eckermann
Keyword(s):  
Cyclic Voltammetry ◽  
Optical Properties ◽  
Single Crystal ◽  
Structure Analysis ◽  
Mixed Valence ◽  
Neutral State ◽  
X Ray ◽  
Redox Couples ◽  
Reversible Redox ◽  
Vis Spectroscopy

The triruthenium oxo clusters [Ru3(OAc)6O(L)3]+ and [Ru3(OAc)6O(L)2(CO)] possess unique electronic characteristics that vary based on the ligands L. Here we report an investigation of the structural, electrochemical, and optical properties of clusters with imidazole, benzimidazole, and 4-phenylpyridine ligands. The complexes [Ru3(OAc)6O(L)3]+ [1+ : L = imidazole (im); 2+ : L = benzimidazole (benzim); 3+ : L = 4-phenylpyridine (4PP)] and [Ru3(OAc)6O(L)2(CO)] (1-CO and 3-CO) were synthesized by reaction of either [Ru3(OAc)6O(MeOH)3]+ or [Ru3(OAc)6O(MeOH)2(CO)], respectively, with the corresponding heterocycle. We further discovered that [3]OAc could be reduced to the mixed-valence neutral state 3 by refluxing the complex under nitrogen in methanol. Single-crystal X-ray structure analysis of hexa-μ2-acetato-μ3-oxido-tris(1H-imidazole)triruthenium hexafluorophosphate acetonitrile hemisolvate, [Ru3(C2H3O2)6O(C3H4N2)3]PF6·0.5CH3CN, [1]PF6 , hexa-μ2-acetato-carbonylbis(1H-imidazole)-μ3-oxido-triruthenium methanol monosolvate, [Ru3(C2H3O2)6O(C3H4N2)(CO)]·CH3OH, 1-CO, hexa-μ2-acetato-μ3-oxido-tris(4-phenylpyridine)triruthenium pentahydrate, [Ru3(C2H3O2)6O(C11H9N)3]·5H2O, 3, and hexa-μ2-acetato-carbonyl-μ3-oxido-bis(4-phenylpyridine)triruthenium methanol monosolvate, [Ru3(C2H3O2)6O(C11H9N)2(CO)]·CH3OH, 3-CO, show the expected triruthenium μ3-oxo core and N-coordination of the ligands. Cyclic voltammetry revealed quasi-reversible and irreversible redox couples in [1]PF6 , 1-CO, and [2]PF6 , while [3]PF6 and 3-CO exhibit reversible redox couples. The optical properties of these richly colored species were investigated using UV–Vis spectroscopy.

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