Electrochemical driven water oxidation by molecular catalysts in situ polymerized on the surface of graphite carbon electrode

2015 ◽  
Vol 51 (37) ◽  
pp. 7883-7886 ◽  
Author(s):  
Lei Wang ◽  
Ke Fan ◽  
Quentin Daniel ◽  
Lele Duan ◽  
Fusheng Li ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Graphite Electrode ◽  
Oxidation Catalyst ◽  
Molecular Water ◽  
Carbon Electrode ◽  
Turnover Frequency ◽  
Turnover Number ◽  
High Turnover ◽  
Molecular Catalysts

A molecular water-oxidation catalyst polymerized on a graphite electrode has shown a high initial turnover frequency (TOF) of 10.47 s−1 at ∼700 mV overpotential, and a high turnover number (TON) of 31 600 in 1 h electrolysis.

scholarly journals Stabilization of a molecular water oxidation catalyst on a dye−sensitized photoanode by a pyridyl anchor

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Yong Zhu ◽  
Degao Wang ◽  
Qing Huang ◽  
Jian Du ◽  
Licheng Sun ◽  
...  
Keyword(s):  
Water Splitting ◽  
Phosphonic Acid ◽  
Water Oxidation ◽  
Oxidation Catalyst ◽  
Molecular Water ◽  
Applied Bias ◽  
Surface Loading ◽  
Dye Sensitized ◽  
Monomeric Structure ◽  
Molecular Catalysts

Abstract Understanding and controlling the properties of water-splitting assemblies in dye-sensitized photoelectrosynthesis cells is a key to the exploitation of their properties. We demonstrate here that, following surface loading of a [Ru(bpy)3]2+ (bpy = 2,2′-bipyridine) chromophore on nanoparticle electrodes, addition of the molecular catalysts, Ru(bda)(L)2 (bda  =  2,2′-bipyridine-6,6′-dicarboxylate) with phosphonate or pyridyl sites for water oxidation, gives surfaces with a 5:1 chromophore to catalyst ratio. Addition of the surface-bound phosphonate derivatives with L = 4-pyridyl phosphonic acid or diethyl 3-(pyridin-4-yloxy)decyl-phosphonic acid, leads to well-defined surfaces but, following oxidation to Ru(III), they undergo facile, on-surface dimerization to give surface-bound, oxo-bridged dimers. The dimers have a diminished reactivity toward water oxidation compared to related monomers in solution. By contrast, immobilization of the Ru-bda catalyst on TiO2 with the 4,4′-dipyridyl anchoring ligand can maintain the monomeric structure of catalyst and gives relatively stable photoanodes with photocurrents that reach to 1.7 mA cm−2 with an optimized, applied bias photon-to-current efficiency of 1.5%.

Highly efficient and robust molecular water oxidation catalysts based on ruthenium complexes

2014 ◽  
Vol 50 (85) ◽  
pp. 12947-12950 ◽  
Author(s):  
Lei Wang ◽  
Lele Duan ◽  
Ying Wang ◽  
Mårten S. G. Ahlquist ◽  
Licheng Sun
Keyword(s):  
Catalytic Activity ◽  
Dicarboxylic Acid ◽  
Water Oxidation ◽  
Ruthenium Complexes ◽  
Molecular Water ◽  
Oxidation Catalysts ◽  
Turnover Number ◽  
High Turnover ◽  
Molecular Catalyst ◽  
Highly Efficient

The molecular catalyst Ru(bda)L2 (H2bda = 2,2′-bipyridine-6,6′-dicarboxylic acid, L = 6-bromophthalazine) shows excellent catalytic activity for water oxidation. By using Ce(NH4)2(NO3)6 as an oxidant, the catalyst reached a high turnover number TON = 100 000 in 3 hours.

Light-induced water oxidation catalyzed by an oxido-bridged triruthenium complex with a Ru–O–Ru–O–Ru motif

2016 ◽  
Vol 52 (51) ◽  
pp. 8018-8021 ◽  
Author(s):  
Yuta Tsubonouchi ◽  
Shu Lin ◽  
Alexander R. Parent ◽  
Gary W. Brudvig ◽  
Ken Sakai
Keyword(s):  
Water Oxidation ◽  
Oxidation Catalyst ◽  
Turnover Frequency ◽  
Air Oxidation ◽  
Turnover Number

A μ-oxido-bridged triruthenium complex (RuT2+), formed by air oxidation of a previously reported monoruthenium water-oxidation catalyst (WOC), serves as an efficient photochemical WOC with the turnover frequency (TOF) and turnover number (TON) 0.90 s−1 and 610, respectively.

Electrochemical water oxidation by a copper complex with N4-donor ligand at neutral condition

2021 ◽  
Author(s):  
Junqi Lin ◽  
Xin Chen ◽  
Nini Wang ◽  
Shanshan Liu ◽  
Zhijun Ruan ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Copper Complex ◽  
Water Oxidation ◽  
Neutral Condition ◽  
Turnover Frequency ◽  
High Turnover ◽  
Donor Ligand ◽  
Redox Active

Herein, electrochemical water oxidation catalyzed by a copper(II) complex [CuII(H2L)](NO3)2 with redox-active salophen-like N4-donor ligand N,N′-bis-(1H-imidazol-4-yl)methylidene-o-phenylenediamine is demonstrated. Oxygen evolution with high turnover frequency of 11.09 s-1 and low onset...

scholarly journals In Situ EPR Characterization of a Cobalt Oxide Water Oxidation Catalyst at Neutral pH

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 926 ◽  
Author(s):  
Yury Kutin ◽  
Nicholas Cox ◽  
Wolfgang Lubitz ◽  
Alexander Schnegg ◽  
Olaf Rüdiger
Keyword(s):  
Cobalt Oxide ◽  
Water Oxidation ◽  
Large Scale ◽  
Low Cost ◽  
Operating Conditions ◽  
Oxidation Catalyst ◽  
O2 Evolution ◽  
Ligand Field ◽  
Neutral Ph

Here we report an in situ electron paramagnetic resonance (EPR) study of a low-cost, high-stability cobalt oxide electrodeposited material (Co-Pi) that oxidizes water at neutral pH and low over-potential, representing a promising system for future large-scale water splitting applications. Using CW X-band EPR we can follow the film formation from a Co(NO3)2 solution in phosphate buffer and quantify Co uptake into the catalytic film. As deposited, the film shows predominantly a Co(II) EPR signal, which converts into a Co(IV) signal as the electrode potential is increased. A purpose-built spectroelectrochemical cell allowed us to quantify the extent of Co(II) to Co(IV) conversion as a function of potential bias under operating conditions. Consistent with its role as an intermediate, Co(IV) is formed at potentials commensurate with electrocatalytic O2 evolution (+1.2 V, vs. SHE). The EPR resonance position of the Co(IV) species shifts to higher fields as the potential is increased above 1.2 V. Such a shift of the Co(IV) signal may be assigned to changes in the local Co structure, displaying a more distorted ligand field or more ligand radical character, suggesting it is this subset of sites that represents the catalytically ‘active’ component. The described spectroelectrochemical approach provides new information on catalyst function and reaction pathways of water oxidation.

Catalytic water oxidation by an in-situ generated ruthenium nitrosyl complex bearing a bipyridine-bis(alkoxide) ligand

2021 ◽  
Author(s):  
Yingying Liu ◽  
Siu-Mui Ng ◽  
Shek-Man Yiu ◽  
Tai-Chu Lau
Keyword(s):  
Water Oxidation ◽  
Oxidative Degradation ◽  
Nitrosyl Complex ◽  
Ruthenium Nitrosyl ◽  
Molecular Catalysts

Oxidative degradation and transformation of catalysts are commonly observed in water oxidation by molecular catalysts, especially when highly oxidizing reagent such as (NH4)2[Ce(NO3)6] [Ce(IV)] is used. We report herein the...

scholarly journals From Ru-bda to Ru-bds: a step forward to highly efficient molecular water oxidation electrocatalysts under acidic and neutral conditions

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jing Yang ◽  
Lei Wang ◽  
Shaoqi Zhan ◽  
Haiyuan Zou ◽  
Hong Chen ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Density Functional ◽  
Bond Formation ◽  
Density Functional Theory Calculations ◽  
Oxidation Catalyst ◽  
Nucleophilic Attack ◽  
Molecular Water ◽  
Formation Mechanisms ◽  
Equatorial Position ◽  
Neutral Conditions

AbstractSignificant advances during the past decades in the design and studies of Ru complexes with polypyridine ligands have led to the great development of molecular water oxidation catalysts and understanding on the O−O bond formation mechanisms. Here we report a Ru-based molecular water oxidation catalyst [Ru(bds)(pic)2] (Ru-bds; bds2− = 2,2′-bipyridine-6,6′-disulfonate) containing a tetradentate, dianionic sulfonate ligand at the equatorial position and two 4-picoline ligands at the axial positions. This Ru-bds catalyst electrochemically catalyzes water oxidation with turnover frequencies (TOF) of 160 and 12,900 s−1 under acidic and neutral conditions respectively, showing much better performance than the state-of-art Ru-bda catalyst. Density functional theory calculations reveal that (i) under acidic conditions, the high valent Ru intermediate RuV=O featuring the 7-coordination configuration is involved in the O−O bond formation step; (ii) under neutral conditions, the seven-coordinate RuIV=O triggers the O−O bond formation; (iii) in both cases, the I2M (interaction of two M−O units) pathway is dominant over the WNA (water nucleophilic attack) pathway.

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