Carbazole modification of Ruthenium Bipyridine–dicarboxylate Oxygen Evolution Molecular Catalyst

2021 ◽  
Author(s):  
Hiroki Otsuka ◽  
Atsushi Kobayashi ◽  
Masaki Yoshida ◽  
Masako Kato
Keyword(s):  
Oxygen Evolution ◽  
Pyridyl Ligands ◽  
Molecular Catalyst ◽  
Oxygen Evolving

We newly synthesised oxygen-evolving molecular Ru(II) catalysts with one or two carbazole moieties on the axial pyridyl ligands, namely [Ru(bda)(cbz-py)(py)] and [Ru(bda)(cbz-py)2] [C1 and C2; bdaH2 = 2, 2’-bipyridyl-6, 6’-dicarboxylic...

scholarly journals Atom-by-atom electrodeposition of single isolated cobalt oxide molecules and clusters for studying the oxygen evolution reaction

2020 ◽  
Vol 117 (23) ◽  
pp. 12651-12656 ◽  
Author(s):  
Zhaoyu Jin ◽  
Allen J. Bard
Keyword(s):  
Cobalt Oxide ◽  
Oxygen Evolution ◽  
Single Molecule ◽  
Oxygen Evolution Reaction ◽  
Relative Rate ◽  
Alkaline Media ◽  
Limiting Current ◽  
Equivalent Radius ◽  
Molecular Catalyst ◽  
Oxygen Evolving

We report an electrodeposition protocol for preparing isolated cobalt oxide single molecules (Co1Ox) and clusters (ConOy) on a carbon fiber nanoelectrode. The as-prepared deposits are able to produce well-defined steady-state voltammograms for the oxygen evolution reaction (OER) in alkaline media, where the equivalent radius (rd) is estimated by the limiting current of hydroxide oxidation in accordance with the electrocatalytic amplification model. The size of isolated clusters obtained from the femtomolar Co2+solution through an atom-by-atom technique can reach as small as 0.21 nm (rd) which is approximately the length of Co–O bond in cobalt oxide. Therefore, the deposit was close to that of a Co1Oxsingle molecule with only one cobalt ion, the minimum unit of the cobalt-based oxygen-evolving catalyst. Additionally, the size-dependent catalysis of the OER on ConOydeposits shows a faster relative rate on the smaller cluster in terms of the potential at a given current density, implying the single molecular catalyst shows a superior OER activity.

Effect of Certain Quinones, Diquat, and Diuron on Chlorella pyrenoidosa Chick. (Emerson strain)

Weed Science ◽  
1968 ◽  
Vol 16 (1) ◽  
pp. 69-73 ◽  
Author(s):  
G. Zweig ◽  
J. E. Hitt ◽  
R. McMahon
Keyword(s):  
Chlorophyll Content ◽  
Oxygen Evolution ◽  
Physiological Activity ◽  
Chlorophyll Concentration ◽  
Chlorella Pyrenoidosa ◽  
Inhibitory Effect ◽  
Cell Number ◽  
Drastic Decrease ◽  
Oxygen Evolving

The effect of 1,4-naphthoquinone, 1,4-benzoquinone, and several CI and NH2-substituted quinones has been studied on growth, chlorophyll concentration, and oxygen evolution in Chlorella pyrenoidosa Chick. (Emerson strain). Drastic decrease of the studied parameters usually was noted after 24 to 48 hr treatment at 3×10–5 M concentration. The effect of the quinones was compared with that of 6,7-dihydrodipyrido [l,2-a:2,l-c-]pyrazidinium salt (diquat) and 3-(3,4-dichlorophenyl)-l,l-dimethylurea (diuron). Diuron inhibited oxygen evolution immediately after addition, but could be washed out and the effect was reversible. Diquat had no inhibitory effect on oxygen evolution and chlorophyll content but caused a slight decrease in cell number. Although some quinones have an almost immediate effect on the oxygen-evolving mechanism, it seems more likely that the overall effect of the quinones is on the total physiological activity of the algal cells. Oxygen evolution seems to affected earlier than chlorophyll destruction, and the observed long-term damage is irreversible. Most of the compounds studied could be classified as algicidal, with the exception of diuron, diquat, and 1,4-benzoquinone which may be considered to be algistatic.

Temperature Dependence of the O2-Oscillation Pattern in the Filamentous Cyanobacterium Oscillatoria chalybea and in Chlorella kessleri

1996 ◽  
Vol 51 (11-12) ◽  
pp. 823-832 ◽  
Author(s):  
K Burda ◽  
P He ◽  
K. P Bader ◽  
G. H Schmid
Keyword(s):  
Transition Temperature ◽  
Temperature Dependence ◽  
Oxygen Evolution ◽  
Filamentous Cyanobacterium ◽  
State Distribution ◽  
Oscillation Pattern ◽  
Chlorella Kessleri ◽  
Temperature Range ◽  
Oscillatoria Chalybea ◽  
Oxygen Evolving

Abstract Five characteristic discontinuities of the pattern of oxygen evolution have been detected for the filamentous cyanobacterium Oscillatoria chalybea in the temperature range of 0°C to 30°C. The temperatures at which these discontinuities occur are: ≈ 5°C, ≈ 11°C, ≈ 15°C, ≈ 21°C and ≈ 25°C. The calculated initial 5-S state distribution, the miss parameter and the fraction of the fast transition S3 → S0+ O2 are affected. The discontinuities are observed at the same transition temperature also for Chlorella kessleri hence are not specific for the cyanobacterium. Based on these studies it is concluded that the not vanishing oxygen signal under the first flash of a flash train in Oscillatoria cannot have its origin in interactions between oxygen-evolving complexes. A decrease of temperature should slow down the expected charge exchanges, improve the oscillations, thus reduce or lower the first two oxygen amplitudes of the oscillatoria pattern. Lowering of the temperautres improves the oscillations but does not lower the first O2 signal of the pattern.

Generalized approximate spin projection calculations of effective exchange integrals of the CaMn4O5 cluster in the S1 and S3 states of the oxygen evolving complex of photosystem II

2014 ◽  
Vol 16 (24) ◽  
pp. 11911-11923 ◽  
Author(s):  
H. Isobe ◽  
M. Shoji ◽  
S. Yamanaka ◽  
H. Mino ◽  
Y. Umena ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Symmetry Breaking ◽  
Oxygen Evolution ◽  
Broken Symmetry ◽  
Spin Projection ◽  
Oxygen Evolving Complex ◽  
Structural Symmetry ◽  
Effective Exchange ◽  
The Right ◽  
Oxygen Evolving

Broken-symmetry UB3LYP calculations have elucidated structural symmetry-breaking in the S1 and S3 states of the oxygen evolution complex (OEC) of photosystem II (PSII), providing the right (RO)- and left (LO)-opened structures.

In situ formation of highly active Ni–Fe based oxygen-evolving electrocatalysts via simple reactive dip-coating

2017 ◽  
Vol 5 (22) ◽  
pp. 11009-11015 ◽  
Author(s):  
Guofa Dong ◽  
Ming Fang ◽  
Jianshuo Zhang ◽  
Renjie Wei ◽  
Lei Shu ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
State Of The Art ◽  
Catalytic Performance ◽  
Dip Coating ◽  
Highly Active ◽  
Coating Method ◽  
In Situ Formation ◽  
Dip Coating Method ◽  
Oxygen Evolving

An extremely simple in situ reactive dip-coating method is developed to prepare Ni–Fe based electrocatalysts with good catalytic performance on oxygen evolution comparable to those of state-of-the art precious catalysts.

Synthesis of CaMn2O4-related electrocatalyst for oxygen evolution electrode of water-splitting

2014 ◽  
Vol 1640 ◽  
Author(s):  
Yuya Taki ◽  
Zhenquan Tan ◽  
Satoshi Ohara ◽  
Takashi Itoh ◽  
Yoshiaki Nakano ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electric Power ◽  
Water Splitting ◽  
Oxygen Evolution ◽  
Electrocatalytic Activity ◽  
Fossil Fuels ◽  
Weight Ratio ◽  
Synthesis Condition ◽  
Carbon Paste ◽  
Oxygen Evolving

ABSTRACTWater-splitting by using electric power produced by solar cells is promising system to produce hydrogen without fossil fuels. Oxygen evolving catalyst is, however, major problem to prevent using this system widely because precious materials are used in the catalyst. Considering from the photosynthesis II of plants, the compound of Ca-Mn-O is one of the candidates for the oxygen evolving catalyst. In this study, the synthesis condition and the oxygen evolving electrocatalytic activity of CaMn2O4•xH2O are investigated. The overpotential at 0.1 mA/cm2 was 0.28 V when using the electrode of carbon paste and CaMn2O4•H2O with the weight ratio of 3:1.

Different sensitivities of photosystem II in green algae and cyanobacteria to phenylurea and phenol-type herbicides: effect on electron donor side

2017 ◽  
Vol 72 (7-8) ◽  
pp. 315-324 ◽  
Author(s):  
Ekaterina K. Yotsova ◽  
Martin A. Stefanov ◽  
Anelia G. Dobrikova ◽  
Emilia L. Apostolova
Keyword(s):  
Photosystem Ii ◽  
Kinetic Parameters ◽  
Oxygen Evolution ◽  
Oxygen Evolving Complex ◽  
Photosynthetic Oxygen Evolution ◽  
Donor Side ◽  
Short Term Treatment ◽  
Psii Photochemistry ◽  
Photosynthetic Oxygen ◽  
Oxygen Evolving

AbstractThe effects of short-term treatment with phenylurea (DCMU, isoproturon) and phenol-type (ioxynil) herbicides on the green algaChlorella kessleriand the cyanobacteriumSynechocystis salinawith different organizations of photosystem II (PSII) were investigated using pulse amplitude modulated (PAM) chlorophyll fluorescence and photosynthetic oxygen evolution measured by polarographic oxygen electrodes (Clark-type and Joliot-type). The photosynthetic oxygen evolution showed stronger inhibition than the PSII photochemistry. The effects of the studied herbicides on both algal and cyanobacterial cells decreased in the following order: DCMU>isoproturon>ioxynil. Furthermore, we observed that the number of blocked PSII centers increased significantly after DCMU treatment (204–250 times) and slightly after ioxynil treatment (19–35 times) in comparison with the control cells. This study suggests that the herbicides affect not only the acceptor side but also the donor side of PSII by modifications of the Mn cluster of the oxygen-evolving complex. We propose that one of the reasons for the different PSII inhibitions caused by herbicides is their influence, in different extents, on the kinetic parameters of the oxygen-evolving reactions (the initial S0−S1state distribution, the number of blocked centers SB, the turnover time of Sistates, misses and double hits). The relationship between the herbicide-induced inhibition and the changes in the kinetic parameters is discussed.

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