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 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.

Ruthenium Complex Hydride Catalysts as a Platform for Ammonia Synthesis

2021 ◽  
Author(s):  
Qianru Wang ◽  
Jianping Guo ◽  
Ping Chen
Keyword(s):  
Alkaline Earth ◽  
Ammonia Synthesis ◽  
Ruthenium Complex ◽  
Earth Metal ◽  
Metal Catalyst ◽  
Alkaline Earth Metal ◽  
Dissociative Mechanism ◽  
Complex Hydride ◽  
Ru Complex ◽  
Scientific Goal

Mild-condition ammonia synthesis from N2 and H2 is a long-sought-after scientific goal and a practical need, especially for the intensively pursued “Green Ammonia” production using renewable H2. Under this context, there have been growing interests in the development of new catalysts for effectively catalyzing N2+H2 to NH3. Particular attention has been given to Ru-based catalysts because they are well known to be more active at lower temperatures and pressures than non-noble-metal based catalysts. Here, we demonstrate that a series of Ru complex hydrides An[RuHm], where A is alkali or alkaline earth metal, n= 2, 3 or 4 and m = 6 or 7, exhibit universal and high catalytic activities that far exceed the benchmark Ru metal catalysts under mild conditions. Detailed investigations on the ternary Ru complex hydride catalytic system disclose that the kinetic behaviors depend strongly on the identity of alkali or alkaline earth metal cations. In clear contrast to the closed packed Ru metal catalyst, the unique configuration and synergized scenario of the Ru complex hydride center prefer a non-dissociative mechanism for N2 activation and hydrogenation, which provides a new platform for the design and development of efficient NH3 synthesis catalysts.

Ruthenium Complex Hydride Catalysts as a Platform for Ammonia Synthesis

2021 ◽  
Author(s):  
Qianru Wang ◽  
Jianping Guo ◽  
Ping Chen
Keyword(s):  
Alkaline Earth ◽  
Ammonia Synthesis ◽  
Ruthenium Complex ◽  
Earth Metal ◽  
Metal Catalyst ◽  
Alkaline Earth Metal ◽  
Dissociative Mechanism ◽  
Complex Hydride ◽  
Ru Complex ◽  
Scientific Goal

Mild-condition ammonia synthesis from N2 and H2 is a long-sought-after scientific goal and a practical need, especially for the intensively pursued “Green Ammonia” production using renewable H2. Under this context, there have been growing interests in the development of new catalysts for effectively catalyzing N2+H2 to NH3. Particular attention has been given to Ru-based catalysts because they are well known to be more active at lower temperatures and pressures than non-noble-metal based catalysts. Here, we demonstrate that a series of Ru complex hydrides An[RuHm], where A is alkali or alkaline earth metal, n= 2, 3 or 4 and m = 6 or 7, exhibit universal and high catalytic activities that far exceed the benchmark Ru metal catalysts under mild conditions. Detailed investigations on the ternary Ru complex hydride catalytic system disclose that the kinetic behaviors depend strongly on the identity of alkali or alkaline earth metal cations. In clear contrast to the closed packed Ru metal catalyst, the unique configuration and synergized scenario of the Ru complex hydride center prefer a non-dissociative mechanism for N2 activation and hydrogenation, which provides a new platform for the design and development of efficient NH3 synthesis catalysts.

scholarly journals The Effect of UV-Irradiation (under Short-Circuit Condition) on Dye-Sensitized Solar Cells Sensitized with a Ru-Complex Dye Functionalized with a (diphenylamino)Styryl-Thiophen Group

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Kazuteru Nonomura ◽  
Yunhua Xu ◽  
Tannia Marinado ◽  
Daniel P. Hagberg ◽  
Rong Zhang ◽  
...  
Keyword(s):  
Solar Cells ◽  
Uv Irradiation ◽  
Ruthenium Complex ◽  
Short Circuit ◽  
Dye Sensitized Solar Cells ◽  
Dye Sensitized ◽  
Ru Complex ◽  
Redox Electrolyte ◽  
Sensitized Solar Cells ◽  
Short Circuit Condition

A new ruthenium complex, cis-di(thiocyanato)(2,2′-bipyridine-4,4′-dicarboxylic acid)(4,4′-bis(2-(5-(2-(4-diphenylaminophenyl)ethenyl)-thiophen-2-yl)ethenyl)-2,2′-bipyridine)ruthenium(II) (named E322) has been synthesized for use in dye-sensitized solar cells (DSCs). Higher extinction coefficient and a broader absorption compared to the standard Ru-dye, N719, were aimed. DSCs were fabricated with E322, and the efficiency was 0.12% initially. (4.06% for N719, as reference). The efficiency was enhanced to 1.83% by exposing the cell under simulated sunlight containing UV-irradiation at short-circuit condition. The reasons of this enhancement are (1) enhanceing electron injection from sensitizer toTiO2following a shift toward positive potentials of the conduction band ofTiO2by the adsorption of protons or cations from the sensitizer, or from the redox electrolyte and (2) improving the regeneration reaction of the oxidized dye by the redox electrolyte by the dissolution of aggregated dye from the surface ofTiO2following the treatment.

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.

scholarly journals Efficient photochemical water oxidation by a dinuclear molecular ruthenium complex

2015 ◽  
Vol 51 (10) ◽  
pp. 1862-1865 ◽  
Author(s):  
Tanja M. Laine ◽  
Markus D. Kärkäs ◽  
Rong-Zhen Liao ◽  
Torbjörn Åkermark ◽  
Bao-Lin Lee ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Ruthenium Complex ◽  
Photochemical Oxidation ◽  
Anionic Ligand ◽  
Ru Complex ◽  
Complex Housing

A dinuclear Ru complex housing an anionic ligand scaffold has been developed. The designed Ru complex was found to efficiently mediate the photochemical oxidation of H2O when using [Ru(bpy)3]2+-type photosensitizers.

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