scholarly journals Spin pinning effect to reconstructed oxyhydroxide layer on ferromagnetic oxides for enhanced water oxidation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Tianze Wu ◽  
Xiao Ren ◽  
Yuanmiao Sun ◽  
Shengnan Sun ◽  
Guoyu Xian ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Water Electrolysis ◽  
Spin Effect ◽  
Spin Alignment ◽  
Spin Ordering ◽  
Pinning Effect ◽  
Overall Efficiency ◽  
Ferromagnetic Oxides ◽  
Rate Limiting ◽  
Kinetic Barriers

AbstractProducing hydrogen by water electrolysis suffers from the kinetic barriers in the oxygen evolution reaction (OER) that limits the overall efficiency. With spin-dependent kinetics in OER, to manipulate the spin ordering of ferromagnetic OER catalysts (e.g., by magnetization) can reduce the kinetic barrier. However, most active OER catalysts are not ferromagnetic, which makes the spin manipulation challenging. In this work, we report a strategy with spin pinning effect to make the spins in paramagnetic oxyhydroxides more aligned for higher intrinsic OER activity. The spin pinning effect is established in oxideFM/oxyhydroxide interface which is realized by a controlled surface reconstruction of ferromagnetic oxides. Under spin pinning, simple magnetization further increases the spin alignment and thus the OER activity, which validates the spin effect in rate-limiting OER step. The spin polarization in OER highly relies on oxyl radicals (O∙) created by 1st dehydrogenation to reduce the barrier for subsequent O-O coupling.

scholarly journals Controlled Surface Reconstruction on Ferromagnetic Oxides: Spin Pinning Effect to the Oxyhydroxide Layer and Its Enhanced Oxygen Evolution Activity

2021 ◽  
Author(s):  
Tianze Wu ◽  
Xiao Ren ◽  
Yuanmiao Sun ◽  
Shengnan Sun ◽  
Guoyu Xian ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Long Range ◽  
Spin Polarization ◽  
Water Electrolysis ◽  
Intrinsic Activity ◽  
Spin Alignment ◽  
Pinning Effect ◽  
Production Of Hydrogen ◽  
Ferromagnetic Oxides ◽  
Kinetic Barriers

The production of hydrogen by water electrolysis suffers from the kinetic barriers in the oxygen evolution reaction (OER) that limits the overall efficiency. As spin-dependent kinetics exist in OER, the spin alignment in active OER catalysts is critical for reducing the kinetic barriers in OER. It is effective to facilitate the spin polarization in ferromagnetic catalysts by applying external magnetic field, which increases the OER efficiency. However, more active OER catalysts tend to have dynamic open-shell orbital configurations with disordered magnetic moments, without showing an apparent long-range interatomic ferromagnetism; thus controlling the spin alignment of these active catalysts is challenging. In this work, we report a strategy with spin pinning effect to make the spins in active oxyhydroxides more aligned for higher intrinsic OER activity. Such strategy bases on a controllable reconstruction: ferromagnetic oxides with controlled sulfurization can evolve into stable oxide<sub>FM</sub>/oxyhydroxide configurations with a thin oxyhydroxide layer under operando condition. The spin pinning effect is found at the interface of oxide<sub>FM</sub>/oxyhydroxide. The spin pinning effect can promote spin selective electron transfer on OER intermediates to generate oxygens with parallel spin alignment, which facilitates the production of triplet oxygen and increases the intrinsic activity of oxyhydroxide by ~ 1 order of magnitude. Under spin pinning, the spins in oxyhydroxide can become more aligned after magnetization as long-range ferromagnetic ordering is established on the magnetic domains in oxide<sub>FM</sub>. The OER kinetics are facilitated accordingly after magnetization, implying that the spin pinning effect is involved in the rate-determining step and this step is spin dependent. The spin polarization process in OER under spin pinning is also believed to be sensitive to the existence of active oxygen ligand (O(-)) in oxyhydroxide. When the O(-) is created in 1<sup>st</sup> deprotonation step under high pH, the spin polarization of ligand oxygens will be facilitated, which reduces the barrier for subsequent O-O coupling and promotes the O<sub>2</sub> turnover.

scholarly journals Controlled Surface Reconstruction on Ferromagnetic Oxides: Spin Pinning Effect to the Oxyhydroxide Layer and Its Enhanced Oxygen Evolution Activity

2021 ◽  
Author(s):  
Tianze Wu ◽  
Xiao Ren ◽  
Yuanmiao Sun ◽  
Shengnan Sun ◽  
Guoyu Xian ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Long Range ◽  
Spin Polarization ◽  
Water Electrolysis ◽  
Intrinsic Activity ◽  
Spin Alignment ◽  
Pinning Effect ◽  
Production Of Hydrogen ◽  
Ferromagnetic Oxides ◽  
Kinetic Barriers

The production of hydrogen by water electrolysis suffers from the kinetic barriers in the oxygen evolution reaction (OER) that limits the overall efficiency. As spin-dependent kinetics exist in OER, the spin alignment in active OER catalysts is critical for reducing the kinetic barriers in OER. It is effective to facilitate the spin polarization in ferromagnetic catalysts by applying external magnetic field, which increases the OER efficiency. However, more active OER catalysts tend to have dynamic open-shell orbital configurations with disordered magnetic moments, without showing an apparent long-range interatomic ferromagnetism; thus controlling the spin alignment of these active catalysts is challenging. In this work, we report a strategy with spin pinning effect to make the spins in active oxyhydroxides more aligned for higher intrinsic OER activity. Such strategy bases on a controllable reconstruction: ferromagnetic oxides with controlled sulfurization can evolve into stable oxide<sub>FM</sub>/oxyhydroxide configurations with a thin oxyhydroxide layer under operando condition. The spin pinning effect is found at the interface of oxide<sub>FM</sub>/oxyhydroxide. The spin pinning effect can promote spin selective electron transfer on OER intermediates to generate oxygens with parallel spin alignment, which facilitates the production of triplet oxygen and increases the intrinsic activity of oxyhydroxide by ~ 1 order of magnitude. Under spin pinning, the spins in oxyhydroxide can become more aligned after magnetization as long-range ferromagnetic ordering is established on the magnetic domains in oxide<sub>FM</sub>. The OER kinetics are facilitated accordingly after magnetization, implying that the spin pinning effect is involved in the rate-determining step and this step is spin dependent. The spin polarization process in OER under spin pinning is also believed to be sensitive to the existence of active oxygen ligand (O(-)) in oxyhydroxide. When the O(-) is created in 1<sup>st</sup> deprotonation step under high pH, the spin polarization of ligand oxygens will be facilitated, which reduces the barrier for subsequent O-O coupling and promotes the O<sub>2</sub> turnover.

Lattice Oxygen Redox Chemistry in Solid-State Electrocatalysts for Water Oxidation

2021 ◽  
Author(s):  
Ning Zhang ◽  
Yang Chai
Keyword(s):  
Solid State ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Water Oxidation ◽  
Water Electrolysis ◽  
Redox Chemistry ◽  
Lattice Oxygen ◽  
Vital Importance ◽  
Production Of Hydrogen ◽  
Overall Efficiency

Fundamental understandings towards oxygen evolution reaction (OER) are of vital importance as it dominates the overall efficiency of water electrolysis – a compelling technique for sustainable production of hydrogen feedstock....

In-situ Ion-Exchange Preparation and Topological Transformation of Trimetal-Organic Frameworks for Efficient Electrocatalytic Water Oxidation

2021 ◽  
Author(s):  
Bao Yu Xia ◽  
Ya Yan ◽  
Xianying Wang ◽  
Yuan Kong ◽  
Jiangwei Zhang ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Ion Exchange ◽  
Anion Exchange ◽  
Water Oxidation ◽  
Water Electrolysis ◽  
Anion Exchange Membrane ◽  
Topological Transformation ◽  
Exchange Membrane ◽  
Kinetics Of

Anion exchange membrane water electrolysis (AEMWE) with non-precious catalysts offers a promising route for industrial hydrogen production. However, the sluggish kinetics of anodic water oxidation hinder its efficiency and cost....

scholarly journals Atomically manipulated proton transfer energizes water oxidation on silicon carbide photoanodes

2018 ◽  
Vol 6 (47) ◽  
pp. 24358-24366 ◽  
Author(s):  
Hao Li ◽  
Huan Shang ◽  
Yuchen Shi ◽  
Rositsa Yakimova ◽  
Mikael Syväjärvi ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Electron Transfer ◽  
Proton Transfer ◽  
Water Oxidation ◽  
Proton Coupled Electron Transfer ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Rate Limiting

Preferential exposure of Si-face of SiC will mechanistically shift the rate limiting step of water oxidation from sluggish proton-coupled electron transfer on C-face to a more energy-favorable electron transfer.

scholarly journals Solution combustion synthesis of highly dispersible and dispersed iridium oxide as an anode catalyst in PEM water electrolysis

2017 ◽  
Vol 5 (10) ◽  
pp. 4774-4778 ◽  
Author(s):  
Muralidhar G. Chourashiya ◽  
Atsushi Urakawa
Keyword(s):  
Combustion Synthesis ◽  
Water Oxidation ◽  
Solution Combustion Synthesis ◽  
Water Electrolysis ◽  
Iridium Oxide ◽  
Anode Catalyst ◽  
Solution Combustion ◽  
Highly Dispersed ◽  
Oxidation Performance

Highly dispersed and dispersible nano-structured IrO2 made by solution combustion synthesis showed excellent water oxidation performance in PEM water electrolysis.

scholarly journals Spectroelectrochemical study of water oxidation on nickel and iron oxyhydroxide electrocatalysts

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Laia Francàs ◽  
Sacha Corby ◽  
Shababa Selim ◽  
Dongho Lee ◽  
Camilo A. Mesa ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Reactive Intermediates ◽  
Reaction Rates ◽  
Iron Oxyhydroxide ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Earth Abundant ◽  
Fe Oxyhydroxides ◽  
Rate Limiting ◽  
Kinetics Of

AbstractNi/Fe oxyhydroxides are the best performing Earth-abundant electrocatalysts for water oxidation. However, the origin of their remarkable performance is not well understood. Herein, we employ spectroelectrochemical techniques to analyse the kinetics of water oxidation on a series of Ni/Fe oxyhydroxide films: FeOOH, FeOOHNiOOH, and Ni(Fe)OOH (5% Fe). The concentrations and reaction rates of the oxidised states accumulated during catalysis are determined. Ni(Fe)OOH is found to exhibit the fastest reaction kinetics but accumulates fewer states, resulting in a similar performance to FeOOHNiOOH. The later catalytic onset in FeOOH is attributed to an anodic shift in the accumulation of oxidised states. Rate law analyses reveal that the rate limiting step for each catalyst involves the accumulation of four oxidised states, Ni-centred for Ni(Fe)OOH but Fe-centred for FeOOH and FeOOHNiOOH. We conclude by highlighting the importance of equilibria between these accumulated species and reactive intermediates in determining the activity of these materials.

Defects tailoring IrO2@TiN1+x nano-heterojunction for superior water oxidation activity and stability

2021 ◽  
Author(s):  
Sen Wang ◽  
Hong Lv ◽  
Songhu Bi ◽  
Tianqi Li ◽  
Yongwen Sun ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Proton Exchange Membrane ◽  
Water Electrolysis ◽  
Cost Effective ◽  
Proton Exchange ◽  
Pragmatic Approach ◽  
Oxidation Activity ◽  
Anode Catalysts ◽  
Exchange Membrane

Developing cost-effective Ir-based anode catalysts for proton exchange membrane (PEM) water electrolysis has been recognized as an efficient and pragmatic approach, however, many challenges remain to lower Ir content while...

Reduced overpotentials for electrocatalytic water splitting over Fe- and Ni-modified BaTiO3

2016 ◽  
Vol 18 (42) ◽  
pp. 29561-29570 ◽  
Author(s):  
Nongnuch Artrith ◽  
Wutthigrai Sailuam ◽  
Sukit Limpijumnong ◽  
Alexie M. Kolpak
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Water Splitting ◽  
Water Oxidation ◽  
Water Electrolysis ◽  
Transition Metal Doping ◽  
Metal Doping ◽  
Earth Abundant ◽  
Promising Avenue

Transition-metal doping can significantly improve the catalytic activity of BaTiO3 for water oxidation. Modification of earth-abundant perovskites can be a promising avenue towards inexpensive catalysts for water electrolysis.

scholarly journals Electrochemical characterization of manganese oxides as a water oxidation catalyst in proton exchange membrane electrolysers

2019 ◽  
Vol 6 (5) ◽  
pp. 190122 ◽  
Author(s):  
Toru Hayashi ◽  
Nadège Bonnet-Mercier ◽  
Akira Yamaguchi ◽  
Kazumasa Suetsugu ◽  
Ryuhei Nakamura
Keyword(s):  
Water Oxidation ◽  
Manganese Oxides ◽  
Proton Exchange Membrane ◽  
Water Electrolysis ◽  
Electrode System ◽  
Proton Exchange ◽  
Oxidation Catalyst ◽  
Carbon Supports ◽  
Exchange Membrane ◽  
Mn Oxides

The performance of four polymorphs of manganese (Mn) dioxides as the catalyst for the oxygen evolution reaction (OER) in proton exchange membrane (PEM) electrolysers was examined. The comparison of the activity between Mn oxides/carbon (Mn/C), iridium oxide/carbon (Ir/C) and platinum/carbon (Pt/C) under the same condition in PEM electrolysers showed that the γ-MnO 2 /C exhibited a voltage efficiency for water electrolysis comparable to the case with Pt/C, while lower than the case with the benchmark Ir/C OER catalyst. The rapid decrease in the voltage efficiency was observed for a PEM electrolyser with the Mn/C, as indicated by the voltage shift from 1.7 to 1.9 V under the galvanostatic condition. The rapid deactivation was also observed when Pt/C was used, indicating that the instability of PEM electrolysis with Mn/C is probably due to the oxidative decomposition of carbon supports. The OER activity of the four types of Mn oxides was also evaluated at acidic pH in a three-electrode system. It was found that the OER activity trends of the Mn oxides evaluated in an acidic aqueous electrolyte were distinct from those in PEM electrolysers, demonstrating the importance of the evaluation of OER catalysts in a real device condition for future development of noble-metal-free PEM electrolysers.

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