scholarly journals Pentanuclear iron catalysts for water oxidation: substituents provide two routes to control onset potentials

2019 ◽  
Vol 10 (17) ◽  
pp. 4628-4639 ◽  
Author(s):  
Vijayendran K. K. Praneeth ◽  
Mio Kondo ◽  
Masaya Okamura ◽  
Takuya Akai ◽  
Hitoshi Izu ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Water Oxidation ◽  
Iron Catalysts ◽  
Redox Potentials ◽  
Onset Potential ◽  
Novel Strategy

Two distinct routes to decrease the onset potential for water oxidation were provided by either control of redox potentials of the complex or change of the reaction mechanism in the pentairon catalysts. The results offer a novel strategy to design efficient molecule-based catalysts for water oxidation.

scholarly journals Aromaticity Driven Electrocatalytic Water Oxidation by a Phosphorus-Nitrogen PN3-Pincer Cobalt Complex

2019 ◽  
Author(s):  
Pradip K. Das ◽  
Sarmistha Bhunia ◽  
Priyanka Chakraborty ◽  
Atanu Rana ◽  
Abhishek Dey ◽  
...  
Keyword(s):  
Water Oxidation ◽  
High Efficiency ◽  
Cobalt Complex ◽  
Potential Jump ◽  
Onset Potential ◽  
New Strategy ◽  
Earth Abundant ◽  
High Valent ◽  
Lower Overpotential ◽  
Cobalt Species

Water oxidation is the primary step in both natural and artificial photosynthesis to convert solar energy in into chemical fuels. Herein, we report the first cobalt-based pincer catalyst for electrolytic water oxidation at neutral pH with high efficiency under electrochemical conditions. Most importantly, ligand (pseudo)aromaticity is identified to play an important role in the electrocatalysis. A significant potential jump (~300 mV) was achieved towards a lower positive value when the aromatized cobalt complex was transformed to a (pseudo)dearomatized cobalt species. This complex catalyzes the water oxidation in its high valent oxidation state at a much lower overpotential (~ 340 mV vs. NHE) based on the onset potential (0.5 mA/cm<sup>2</sup>) of catalysis at pH 10.5, outperforming all the other literature systems. These observations may provide a new strategy for the design of earth-abundant transition metal-based water oxidation catalysts.

Cathodic shift of onset potential for water oxidation on a Ti4+doped Fe2O3photoanode by suppressing the back reaction

2014 ◽  
Vol 7 (2) ◽  
pp. 752-759 ◽  
Author(s):  
Dapeng Cao ◽  
Wenjun Luo ◽  
Jianyong Feng ◽  
Xin Zhao ◽  
Zhaosheng Li ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Back Reaction ◽  
Onset Potential

Co-doped carbon layer to lower the onset potential of hematite for solar water oxidation

2019 ◽  
Vol 258 ◽  
pp. 117962 ◽  
Author(s):  
Huiwen Lan ◽  
Yujian Xia ◽  
Kun Feng ◽  
Aimin Wei ◽  
Zhenhui Kang ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Carbon Layer ◽  
Onset Potential ◽  
Solar Water ◽  
Solar Water Oxidation ◽  
Co Doped

scholarly journals Comparison of two water oxidation electrocatalysts by copper or zinc supermolecule complexes based on porphyrin ligand

RSC Advances ◽  
2018 ◽  
Vol 8 (70) ◽  
pp. 40054-40059 ◽  
Author(s):  
Zhaodi Huang ◽  
Meixi Zhang ◽  
Huan Lin ◽  
Shuo Ding ◽  
Bin Dong ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Water Oxidation ◽  
Porphyrin Ligand

Two supermolecule complexes based on porphyrin ligand have been synthesized. The oxygen evolution reaction properties and proposed reaction mechanism of the complexes were studied.

Magnetic Multifunctional Nanostructures as High-efficiency Catalysts for Oxygen Evolution Reactions

MRS Advances ◽  
2016 ◽  
Vol 1 (34) ◽  
pp. 2401-2407 ◽  
Author(s):  
Umanga De Silva ◽  
W. P. R. Liyanage ◽  
Manashi Nath
Keyword(s):  
Oxygen Evolution ◽  
Water Oxidation ◽  
High Efficiency ◽  
Clean Energy ◽  
Elemental Selenium ◽  
Ferromagnetic Behavior ◽  
High Electron ◽  
Metallic Component ◽  
Onset Potential ◽  
Multifunctional Nanostructures

AbstractThe search for high-efficiency and environmentally benign water splitting catalysts has been on the rise since this process is a source of renewable, clean energy. However the process is inherently slow, especially for the production of O2 from H2O (water oxidation) due to the high electron count and energy intensive bond formation of the reaction. Hence the search for novel catalysts for oxygen evolution reactions (OER) has led researchers to focus on various families of compounds including oxides and recently selenides. Multifunctional nanostructures containing the semiconductor electrocatalyst grafted onto an optically active metallic component might boost the catalytic activity even further due to efficient charge injection. Magnetically active catalysts will also be lucrative since that might induce better adhesion of the oxygenated species at the catalytically active site. In this report we introduce multifunctional, magnetic Au3Pd–CoSe nanostructures as high-efficiency OER electrocatalysts. These multifunctional nanostructures were synthesized by a chemical vapor deposition (CVD) reaction with cobalt acetylacetonate and elemental selenium on Au-Pd sputter coated silica substrate at 800°C. The morphology of these multifunctional nanostructures were mostly bifunctional Janus-like nanoparticles as seen through scanning and transmission electron microscopy. They also showed soft ferromagnetic behavior. These bifunctional nanoparticles were coated on the anodes of a water oxidation cell and it was observed that these nanoparticles showed a higher OER activity with lower onset potential for O2 evolution as compared to the conventional oxide-based OER electrocatalysts.

Oriented Growth of Sc-Doped Ta3N5 Nanorod Photoanode Achieving Low-Onset-Potential for Photoelectrochemical Water Oxidation

2018 ◽  
Vol 1 (8) ◽  
pp. 4150-4157 ◽  
Author(s):  
Lang Pei ◽  
Bihu Lv ◽  
Shuangbao Wang ◽  
Zhentao Yu ◽  
Shicheng Yan ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Oriented Growth ◽  
Onset Potential ◽  
Photoelectrochemical Water Oxidation

Polymerization and oxidation of phenols in supercritical water

2019 ◽  
Vol 80 (4) ◽  
pp. 620-633 ◽  
Author(s):  
Huiwen Zhang ◽  
Xiaoman Zhang ◽  
Lei Ding ◽  
Miao Gong ◽  
Ying Su ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Phenolic Compounds ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Reaction Pathway ◽  
Radical Reaction ◽  
Dominant Factor ◽  
Supercritical Water Oxidation ◽  
Free Radical Reaction ◽  
Reaction Conditions

Abstract The treatment of toxic and difficult-to-degrade phenolic compounds has become a key issue in the coking, pharmaceutical, and chemical industries. Considering the polymerization and oxidation of phenolic compounds in supercritical water partial oxidation/supercritical water oxidation (SCWPO/SCWO), the present study reviewed the removal efficiency and reaction pathway of phenolic compounds and phenolic waste/wastewater under different reaction conditions. Temperature is the dominant factor affecting the SCWO reaction. When the oxidizing ability is insufficient, the organics polymerize to form phenolic compounds. The gradual increase of oxidant equivalent causes the intermediate product to gradually oxidize to CO2 and H2O completely. Finally, the free radical reaction mechanism is considered to be a typical SCWO reaction mechanism.

A novel strategy for surface treatment on hematite photoanode for efficient water oxidation

2013 ◽  
Vol 4 (1) ◽  
pp. 164-169 ◽  
Author(s):  
Lifei Xi ◽  
Sing Yang Chiam ◽  
Wai Fatt Mak ◽  
Phong D. Tran ◽  
James Barber ◽  
...  
Keyword(s):  
Surface Treatment ◽  
Water Oxidation ◽  
Novel Strategy

scholarly journals Comparison of photoelectrochemical water oxidation activity of a synthetic photocatalyst system with photosystem II

2014 ◽  
Vol 176 ◽  
pp. 199-211 ◽  
Author(s):  
Yi-Hsuan Lai ◽  
Masaru Kato ◽  
Dirk Mersch ◽  
Erwin Reisner
Keyword(s):  
Photosystem Ii ◽  
Indium Tin Oxide ◽  
Water Oxidation ◽  
Charge Separation ◽  
High Energy ◽  
Oxidation Catalysis ◽  
Hydrogen Electrode ◽  
Oxidation Activity ◽  
Indium Tin Oxide Electrode ◽  
Onset Potential

This discussion describes a direct comparison of photoelectrochemical (PEC) water oxidation activity between a photosystem II (PSII)-functionalised photoanode and a synthetic nanocomposite photoanode. The semi-biological photoanode is composed of PSII from the thermophilic cyanobacterium Thermosynechococcus elongatus on a mesoporous indium tin oxide electrode (mesoITO|PSII). PSII embeds all of the required functionalities for light absorption, charge separation and water oxidation and ITO serves solely as the electron collector. The synthetic photoanode consists of a TiO2 and NiOx coated nanosheet-structured WO3 electrode (nanoWO3|TiO2|NiOx). The composite structure of the synthetic electrode allows mimicry of the functional key features in PSII: visible light is absorbed by WO3, TiO2 serves as a protection and charge separation layer and NiOx serves as the water oxidation electrocatalyst. MesoITO|PSII uses low energy red light, whereas nanoWO3|TiO2|NiOx requires high energy photons of blue-end visible and UV regions to oxidise water. The electrodes have a comparable onset potential at approximately 0.6 V vs. reversible hydrogen electrode (RHE). MesoITO|PSII reaches its saturation photocurrent at 0.84 V vs. RHE, whereas nanoWO3|TiO2|NiOx requires more than 1.34 V vs. RHE. This suggests that mesoITO|PSII suffers from fewer limitations from charge recombination and slow water oxidation catalysis than the synthetic electrode. MesoITO|PSII displays a higher ‘per active’ site activity, but is less photostable and displays a much lower photocurrent per geometrical surface area and incident photon to current conversion efficiency (IPCE) than nanoWO3|TiO2|NiOx.

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