In Situ L-Edge XAS Study of a Manganese Oxide Water Oxidation Catalyst

2017 ◽  
Vol 121 (22) ◽  
pp. 12003-12009 ◽  
Author(s):  
Lifei Xi ◽  
Christoph Schwanke ◽  
Jie Xiao ◽  
Fatwa F. Abdi ◽  
Ivelina Zaharieva ◽  
...  
Keyword(s):  
Manganese Oxide ◽  
Water Oxidation ◽  
Oxidation Catalyst

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.

scholarly journals Synthesis of an amorphous Geobacter-manganese oxide biohybrid as an efficient water oxidation catalyst

2020 ◽  
Vol 22 (17) ◽  
pp. 5610-5618
Author(s):  
Shafeer Kalathil ◽  
Krishna P. Katuri ◽  
Pascal E. Saikaly
Keyword(s):  
Manganese Oxide ◽  
Water Oxidation ◽  
Geobacter Sulfurreducens ◽  
Oxidation Catalyst ◽  
Oxidation Catalysts

Self-decorated Mn2O3 nanocrystals on Geobacter sulfurreducens were synthesized as sustainable and efficient water oxidation catalysts.

Structure and Valency of a Cobalt−Phosphate Water Oxidation Catalyst Determined by in Situ X-ray Spectroscopy

2010 ◽  
Vol 132 (39) ◽  
pp. 13692-13701 ◽  
Author(s):  
Matthew W. Kanan ◽  
Junko Yano ◽  
Yogesh Surendranath ◽  
Mircea Dincă ◽  
Vittal K. Yachandra ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Oxidation Catalyst ◽  
X Ray ◽  
Cobalt Phosphate

scholarly journals Decoration of the layered manganese oxide birnessite with Mn(ii/iii) gives a new water oxidation catalyst with fifty-fold turnover number enhancement

2015 ◽  
Vol 44 (29) ◽  
pp. 12981-12984 ◽  
Author(s):  
Ian G. McKendry ◽  
Sandeep K. Kondaveeti ◽  
Samantha L. Shumlas ◽  
Daniel R. Strongin ◽  
Michael J. Zdilla
Keyword(s):  
Manganese Oxide ◽  
Oxidation State ◽  
Water Oxidation ◽  
Oxidation Catalysis ◽  
Oxidation Catalyst ◽  
Turnover Number ◽  
Average Oxidation State ◽  
Water Oxidation Catalysis ◽  
Layered Manganese Oxide

The role of the manganese average oxidation state (AOS) in water oxidation catalysis by birnessite was investigated.

In-situ surface selective removal: An efficient way to prepare water oxidation catalyst

2019 ◽  
Vol 44 (29) ◽  
pp. 14955-14967 ◽  
Author(s):  
Pan Wang ◽  
Ji Qi ◽  
Chuang Li ◽  
Xiao Chen ◽  
Jingjie Luo ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Selective Removal ◽  
Oxidation Catalyst

In Situ ATR Infrared Study of Cobalt-Borate Water Oxidation Catalysts

2020 ◽  
Vol 998 ◽  
pp. 123-133
Author(s):  
Li Fei Xi ◽  
Christoph Schwanke ◽  
Kathrin M. Lange ◽  
Marcel Risch
Keyword(s):  
Water Oxidation ◽  
Attenuated Total Reflection ◽  
Oxidation Catalysis ◽  
Oxidation Catalyst ◽  
Sodium Borate ◽  
Intermediate Species ◽  
Infrared Study ◽  
Electrode Surfaces ◽  
Water Oxidation Catalysis

Understanding the process of water oxidation, especially intermediate species, represents an important step toward gaining a mechanistic understanding of new emerging catalysts. The aim of this study is exploring the process of water oxidation and electrolyte orientation under external potential when using an emerging water oxidation catalyst, CoBi, in sodium borate (NaBi) buffer using in situ attenuated–total-reflection Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopy. CoBi is generated via electrodeposition from aqueous solutions containing borate and Co2+. IR spectra were obtained for CoBi films under applied potentials supporting water oxidation catalysis. The spectra of water and CoBi on ZnSe/Cr/Au electrode surfaces change in intensity and their slope depends on the potential, which is rarely reported. The appearance of new bands at certain potentials is interpreted in terms of the potential-dependent re-alignment of water and borate molecules both from the film and electrolyte. A superoxide surface intermediate at 1027 cm-1 was observed in both thin and thick films. It is proposed to be Co (III)OO*H bridging and relates to a fast water oxidation process. The chemical structure of the intermediate species is proposed finally.

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