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.

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

Methane Partial Oxidation over [Cu2(μ-O)]2+ and [Cu3(μ-O)3]2+ Active Species in Large-Pore Zeolites

ACS Catalysis ◽  
2018 ◽  
Vol 8 (2) ◽  
pp. 1500-1509 ◽  
Author(s):  
M. Haris Mahyuddin ◽  
Takahiro Tanaka ◽  
Yoshihito Shiota ◽  
Aleksandar Staykov ◽  
Kazunari Yoshizawa
Keyword(s):  
Partial Oxidation ◽  
Active Species ◽  
Methane Partial Oxidation ◽  
Large Pore ◽  
Large Pore Zeolites

scholarly journals Understanding the formation of bulk- and surface-active layered (oxy)hydroxides for water oxidation starting from a cobalt selenite precursor

2020 ◽  
Vol 13 (10) ◽  
pp. 3607-3619
Author(s):  
Jan Niklas Hausmann ◽  
Stefan Mebs ◽  
Konstantin Laun ◽  
Ingo Zebger ◽  
Holger Dau ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Structural Properties ◽  
Oxygen Evolution ◽  
Water Oxidation ◽  
Active Oxygen ◽  
Near Surface ◽  
Surface Active

Starting from a cobalt selenite precatalyst, we obtained a bulk and a near-surface active oxygen evolution catalyst and connected their structural properties to the precatalyst structure, the transformation conditions, and the catalytic activity.

The Need for Microstructural Measurement Techniques in the Study of Cosmetic Product Properties

MRS Bulletin ◽  
2007 ◽  
Vol 32 (10) ◽  
pp. 793-800
Author(s):  
P. G. Cummins ◽  
C. Fthenakis
Keyword(s):  
Small Molecules ◽  
Measurement Techniques ◽  
Active Species ◽  
Clear Understanding ◽  
Interfacial Interactions ◽  
Product Property ◽  
Chemical Systems ◽  
Cosmetic Product ◽  
Cosmetic Industry ◽  
Surface Active

AbstractA cosmetic product is often a complex non-homogeneous mixture of physicochemical units including polymers, small molecules, surface-active species, and particles. In use, it is applied to an equally heterogeneous substrate, skin. Consequently, materials structure as well as composition and the nature of the surfaces are relevant to a clear understanding of any technologically important product property or process. No longer is it sufficient to answer the classical questions of analysis—what and how much?—for many applications; we must now ask the additional questions of where, how organized, and how is it manifest to the customer? Although analytical sciences have, for many years, been applied to the problem of characterizing what is in chemical systems, the need to understand spatial and interfacial interactions has received much less attention. The explosive growth, however, in electronics, computing, biology, mathematical methodologies, microscopy, and optics now present the cosmetic industry with a new set of tools that can be utilized to address this issue. It is the objective of this article to highlight some of these measurement advances and how they might have relevance in the cosmetics industry in the coming years.

Earth-abundant metal complexes as catalysts for water oxidation; is it homogeneous or heterogeneous?

2015 ◽  
Vol 5 (11) ◽  
pp. 4901-4925 ◽  
Author(s):  
Md. Ali Asraf ◽  
Hussein A. Younus ◽  
Mekhman Yusubov ◽  
Francis Verpoort
Keyword(s):  
Metal Complexes ◽  
Water Oxidation ◽  
Earth Abundant

This minireview focuses on the aspects that determine whether particular catalysts for the oxidation of water are homogeneous or heterogeneous.

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.

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