Re-Investigation of Cobalt Porphyrin for Electrochemical Water Oxidation on FTO Surface: Formation of CoOx as Active Species

ACS Catalysis ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 1143-1149 ◽  
Author(s):  
Quentin Daniel ◽  
Ram B. Ambre ◽  
Biaobiao Zhang ◽  
Bertrand Philippe ◽  
Hong Chen ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Active Species ◽  
Surface Formation ◽  
Cobalt Porphyrin

Controllable Synthesis of Cobalt Porphyrin Nanocrystals through Micelle Confinement Self-Assembly

MRS Advances ◽  
2020 ◽  
Vol 5 (42) ◽  
pp. 2147-2155
Author(s):  
Sudi Chen ◽  
Xitong Ren ◽  
Shufang Tian ◽  
Jiajie Sun ◽  
Feng Bai
Keyword(s):  
Self Assembly ◽  
Water Oxidation ◽  
Separation Efficiency ◽  
Noncovalent Interactions ◽  
Building Blocks ◽  
The Self ◽  
Hexagonal Prism ◽  
Assembly Process ◽  
Surfactant Micelles ◽  
Cobalt Porphyrin

AbstractThe self-assembly of optically active building blocks into functional nanocrystals as high-activity photocatalysts is a key in the field of photocatalysis. Cobalt porphyrin with abundant catalytic properties is extensively studied in photocatalytic water oxidation and CO2 reduction. Here, we present the fabrication of cobalt porphyrin nanocrystals through a surfactant-assisted interfacial self-assembly process using Co-tetra(4-pyridyl) porphyrin as building block. The self-assembly process relies on the combined noncovalent interactions such as π-π stacking and axial Co-N coordination between individual porphyrin molecules within surfactant micelles. Tuning different reaction conditions (temperature, the ratio of co-solvent DMF) and types of surfactant, various nanocrystals with well-defined 1D to 3D morphologies such as nanowires, nanorods and nano hexagonal prism were obtained. Due to the ordered accumulation of molecules, the nanocrystals exhibit the properties of the enhanced capability of visible light capture and can conduce to improve the transport and separation efficiency of the photogenerated carriers, which is important for photocatalysis. Further studies of photocatalytic CO2 reduction are being performed to address the relationship between the size and shape of the nanocrystals with the photocatalytic activity.

scholarly journals Morphological and Elemental Investigations on Co–Fe–B–O Thin Films Deposited by Pulsed Laser Deposition for Alkaline Water Oxidation: Charge Exchange Efficiency as the Prevailing Factor in Comparison with the Adsorption Process

2021 ◽  
Author(s):  
Y. Popat ◽  
M. Orlandi ◽  
S. Gupta ◽  
N. Bazzanella ◽  
S. Pillai ◽  
...  
Keyword(s):  
Pulsed Laser Deposition ◽  
Water Oxidation ◽  
Active Sites ◽  
High Surface ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Active Species ◽  
Laser Deposition ◽  
Core Shell ◽  
Adsorption Sites

Abstract Mixed transition-metals oxide electrocatalysts have shown huge potential for electrochemical water oxidation due to their earth abundance, low cost and excellent electrocatalytic activity. Here we present Co–Fe–B–O coatings as oxygen evolution catalyst synthesized by Pulsed Laser Deposition (PLD) which provided flexibility to investigate the effect of morphology and structural transformation on the catalytic activity. As an unusual behaviour, nanomorphology of 3D-urchin-like particles assembled with crystallized CoFe2O4 nanowires, acquiring high surface area, displayed inferior performance as compared to core–shell particles with partially crystalline shell containing boron. The best electrochemical activity towards water oxidation in alkaline medium with an overpotential of 315 mV at 10 mA/cm2 along with a Tafel slope of 31.5 mV/dec was recorded with core–shell particle morphology. Systematic comparison with control samples highlighted the role of all the elements, with Co being the active element, boron prevents the complete oxidation of Co to form Co3+ active species (CoOOH), while Fe assists in reducing Co3+ to Co2+ so that these species are regenerated in the successive cycles. Thorough observation of results also indicates that the activity of the active sites play a dominating role in determining the performance of the electrocatalyst over the number of adsorption sites. The synthesized Co–Fe–B–O coatings displayed good stability and recyclability thereby showcasing potential for industrial applications. Graphic Abstract

Ligand photodissociation in Ru(ii)–1,4,7-triazacyclononane complexes enhances water oxidation and enables electrochemical generation of surface active species

2020 ◽  
Vol 10 (10) ◽  
pp. 3399-3408 ◽  
Author(s):  
Hussein A. Younus ◽  
Nazir Ahmad ◽  
Ibrahim Yildiz ◽  
Serge Zhuiykov ◽  
Shiguo Zhang ◽  
...  
Keyword(s):  
Metal Complexes ◽  
Partial Oxidation ◽  
Water Oxidation ◽  
Active Species ◽  
Electrochemical Generation ◽  
Surface Active ◽  
Complete Dissociation

Ligand transformations involved in metal complexes during water oxidation (WO), such as ligand decomposition, partial oxidation, or complete dissociation have been reported, however, ligand photodissociation has not been reported yet.

Improving Singlet Oxygen Resistance during Photochemical Water Oxidation by Cobalt Porphyrin Catalysts

2015 ◽  
Vol 21 (18) ◽  
pp. 6723-6726 ◽  
Author(s):  
Takashi Nakazono ◽  
Alexander R. Parent ◽  
Ken Sakai
Keyword(s):  
Singlet Oxygen ◽  
Water Oxidation ◽  
Cobalt Porphyrin

Pyrolyzed cobalt porphyrin-modified carbon nanomaterial as an active catalyst for electrocatalytic water oxidation

2015 ◽  
Vol 40 (20) ◽  
pp. 6538-6545 ◽  
Author(s):  
Zijun Sun ◽  
Jingshi Li ◽  
Huafei Zheng ◽  
Xiang Liu ◽  
Sheng Ye ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Active Catalyst ◽  
Carbon Nanomaterial ◽  
Cobalt Porphyrin

Water oxidation catalysis upon evolution of molecular Co(iii) cubanes in aqueous media

2015 ◽  
Vol 185 ◽  
pp. 121-141 ◽  
Author(s):  
Andrea Genoni ◽  
Giuseppina La Ganga ◽  
Andrea Volpe ◽  
Fausto Puntoriero ◽  
Marilena Di Valentin ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Molecular Species ◽  
Water Oxidation ◽  
Energy Demand ◽  
Aqueous Media ◽  
Active Species ◽  
Oxidation Catalysis ◽  
Paramagnetic Resonance ◽  
Catalytic Systems ◽  
Relevant Effect

The increasing global energy demand has stimulated great recent efforts in investigating new solutions for artificial photosynthesis, a potential source of clean and renewable solar fuel. In particular, according to the generally accepted modular approach aimed at optimising separately the different compartments of the entire process, many studies have focused on the development of catalytic systems for water oxidation to oxygen. While in recent years there have been many reports on new catalytic systems, the mechanism and the active intermediates operating the catalysis have been less investigated. Well-defined, molecular catalysts, constituted by transition metals stabilised by a suitable ligand pool, could help in solving this aspect. However, in some cases molecular species have been shown to evolve to active metal oxides that constitute the other side of this catalysis dichotomy. In this paper, we address the evolution of tetracobalt(iii) cubanes, stabilised by a pyridine/acetate ligand pool, to active species that perform water oxidation to oxygen. Primary evolution of the cubane in aqueous solution is likely initiated by removal of an acetate bridge, opening the coordination sphere of the cobalt centres. This cobalt derivative, where the pristine ligands still impact on the reactivity, shows enhanced electron transfer rates to Ru(bpy)33+(hole scavenging) within a photocatalytic cycle with Ru(bpy)32+as the photosensitiser and S2O82−as the electron sink. A more accentuated evolution occurs under continuous irradiation, where Electron Paramagnetic Resonance (EPR) spectroscopy reveals the formation of Co(ii) intermediates, likely contributing to the catalytic process that evolves oxygen. All together, these results confirm the relevant effect of molecular species, in particular in fostering the rate of the electron transfer processes involved in light activated cycles, pivotal in the design of a photoactive device.

Metal Doped TiO2 Photocatalysts for CO2 Photoreduction

2013 ◽  
Vol 757 ◽  
pp. 243-256 ◽  
Author(s):  
Amir Al-Ahmed
Keyword(s):  
Chemical Reactions ◽  
Water Oxidation ◽  
Active Species ◽  
Electron Hole ◽  
Highly Active ◽  
Redox Active ◽  
Recent Developments ◽  
Metal Doped ◽  
Generate Electron ◽  
Hole Recombination

Greenhouse gases such as CO2, CH4 and CFCs are the primary causes of global warming. Worldwide, people are exploring techniques to reduce, capture, store CO2 gas and even convert this gas in to some useful chemicals. CO2 can be transformed into hydrocarbons in a photocatalytic reaction. The advantage of photo reduction of CO2 is to use inexhaustible solar energy. Knowledge of elementary steps in photocatalytic CO2 reduction under UV irradiation is required in order to improve the photo efficiency of the photocatalyst. A semiconductor photocatalyst mediating CO2 reduction and water oxidation needs to absorb light energy, generate electron hole pairs, spatially separate them, transfer them to redox active species across the interface and minimize electron hole recombination. This requires the semiconductor to have its conduction band electrons at higher energy compared to the CO2 reduction potential while the holes in the valence band need to be able to oxidize water to O2. A single semiconductor does not usually satisfy these requirements. Some recent developments in this field have been moves towards rational photocatalyst design, the use of highly active isolated Ti-species in mesoporous and microporous materials, metal-doping of TiO2, development of catalysts active at longer wavelengths than can be achieved with commercially available titania etc. The use of transition-metal loaded titanium dioxide (TiO2) has been extensively studied as a photocatalyst in photoreactions. Unlike traditional catalysts drive chemical reactions by thermal energy, semiconducting photocatalysts can induce chemical reactions by inexhaustible sunlight and convert CO2 in to the useful hydrocarbons. In this review article we will cover different aspects of metal doped nano structured TiO2 photocatalysts, used to convert/reduce CO2 in to useful hydrocarbons.

Temperature-regulated reversible transformation of spinel-to-oxyhydroxide active species for electrocatalytic water oxidation

2020 ◽  
Vol 8 (4) ◽  
pp. 1631-1635 ◽  
Author(s):  
Tingli Zhou ◽  
Changhong Wang ◽  
Yanmei Shi ◽  
Yu Liang ◽  
Yifu Yu ◽  
...  
Keyword(s):  
Reaction Temperature ◽  
Water Oxidation ◽  
Room Temperature ◽  
Active Species ◽  
Reversible Transformation

The active species of NiCo2O4 for OER is found to be NiCo2O4 at room temperature, and Ni(Co) oxyhydroxides at 45 °C. The alternate change of the reaction temperature induce reversible transformation between NiCo2O4 and Ni(Co) oxyhydroxides.

Unravelling the role of polyoxovanadates in electrocatalytic water oxidation reaction: Active species or precursors

2021 ◽  
Vol 540 ◽  
pp. 148306
Author(s):  
Na Hu ◽  
Jing Du ◽  
Yuan-Yuan Ma ◽  
Wen-Jing Cui ◽  
Bo-Rong Yu ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Oxidation Reaction ◽  
Active Species
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