scholarly journals Nitrogen-Doped Sponge Ni Fibers as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Kaili Zhang ◽  
Xinhui Xia ◽  
Shengjue Deng ◽  
Yu Zhong ◽  
Dong Xie ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
High Performance ◽  
Active Phase ◽  
X Ray ◽  
Highly Active ◽  
N Doping ◽  
Energy Conversion Devices

Abstract Controllable synthesis of highly active micro/nanostructured metal electrocatalysts for oxygen evolution reaction (OER) is a particularly significant and challenging target. Herein, we report a 3D porous sponge-like Ni material, prepared by a facile hydrothermal method and consisting of cross-linked micro/nanofibers, as an integrated binder-free OER electrocatalyst. To further enhance the electrocatalytic performance, an N-doping strategy is applied to obtain N-doped sponge Ni (N-SN) for the first time, via NH3 annealing. Due to the combination of the unique conductive sponge structure and N doping, the as-obtained N-SN material shows improved conductivity and a higher number of active sites, resulting in enhanced OER performance and excellent stability. Remarkably, N-SN exhibits a low overpotential of 365 mV at 100 mA cm−2 and an extremely small Tafel slope of 33 mV dec−1, as well as superior long-term stability, outperforming unmodified sponge Ni. Importantly, the combination of X-ray photoelectron spectroscopy and near-edge X-ray adsorption fine structure analyses shows that γ-NiOOH is the surface-active phase for OER. Therefore, the combination of conductive sponge structure and N-doping modification opens a new avenue for fabricating new types of high-performance electrodes with application in electrochemical energy conversion devices.

scholarly journals Study of oxygen evolution reaction on thermally prepared xPtOy-(100-x)IrO2 electrodes

2020 ◽  
Vol 10 (4) ◽  
pp. 347-360
Author(s):  
Ollo Kambiré ◽  
Lemeyonouin A. G. Pohan ◽  
Konan H. Kondro ◽  
Lassiné Ouattara
Keyword(s):  
Surface Area ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Platinum Oxide ◽  
Basic Medium ◽  
X Ray ◽  
Tafel Slopes ◽  
Ohmic Drop

The mixed coupled xPtOy-(100-x)IrO2 electrodes (x = 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100) were thermally prepared at 450 °C on titanium supports. The prepared electrodes were firstly physically characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Afterwards, electrochemical characteri­zations were performed by voltammetric (cyclic and linear) methods in different electrolyte media (KOH and HClO4). It is shown that the prepared electrodes are composed by both PtOy (platinum and platinum oxide) and IrO2 (iridium dioxide). For xPtOy-(100-x)IrO2 electrodes having higher content of IrO2, more surface cracks and pores are formed, defining a higher surface area with more active sites. Higher surface area due to presence of both PtOy and IrO2, is for xPtOy-(100-x)IrO2 electrodes in 1 M KOH solution confirmed by cyclic voltammetry at potentials of the oxide layer region. For all prepared electrodes, voltammetric charges were found higher than for PtOy, while the highest voltammetric charge is observed for the mixed 40PtOy-60IrO2 (x = 40) electrode. The Tafel slopes for oxygen evolution reaction (OER) in either basic (0.1 M KOH) or acid (0.1 M HClO4) media were determined from measured linear voltammograms corrected for the ohmic drop. The values of Tafel slopes for OER at PtOy, 90PtOy-10IrO2 and IrO2 in basic medium are 122, 55 and 40 mV dec-1, respectively. For other mixed electrodes, Tafel slopes of 40 mV dec-1 were obtained. Although proceeding by different OER mechanism, similar values of Tafel slopes were obtained in acid medium, i.e., Tafel slopes of 120, 60 and 39 mV dec-1 were obtained for PtOy, 90PtOy-10IrO2 and IrO2, and 40 mV dec-1 for other mixed electrodes. The analysis of Tafel slope values showed that OER is more rapid on coupled mixed electrodes than on pure PtOy. For mixed xPtOy-(100-x)IrO2 electrodes, OER is more rapid when the molar percent of PtOy meets the following condition: 0 ˂ x ≤ 80. This study also showed that the mixed coupled electrodes are more electro­cata­lytically active for OER than either PtOy or IrO2 in these two media. 

scholarly journals A Cobalt-Iron Double-Atom Catalyst for the Oxygen Evolution Reaction

2019 ◽  
Author(s):  
Lichen Bai ◽  
Chia-Shuo Hsu ◽  
Duncan Alexander ◽  
Hao Ming Chen ◽  
Xile Hu
Keyword(s):  
Oxygen Evolution ◽  
Active Site ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Single Atom ◽  
X Ray ◽  
Highly Active ◽  
Cobalt Iron ◽  
X Ray Absorption

Single atom catalysts exhibit well-defined active sites and potentially maximum atomic efficiency. However, they are unsuitable for reactions that benefit from bimetallic promotion such as the oxygen evolution reaction (OER) in alkaline medium. Here we show that a single atom Co precatalyst can be in-situ transformed into a Co-Fe double atom catalyst for OER. This catalyst exhibits one of the highest turnover frequencies among metal oxides. Electrochemical, microscopic, and spectroscopic data including those from operando X-ray absorption spectroscopy, reveal a dimeric Co-Fe moiety as the active site of the catalyst. This work demonstrates double-atom catalysis as a promising approach for the developed of defined and highly active OER catalysts.

scholarly journals Nanotubular Titanium Oxynitride with an Ultra-Low Iridium Loading as a High-Performance Oxygen-Evolution-Reaction Thin-Film Electrode

2020 ◽  
Author(s):  
Marjan Bele ◽  
Primož Jovanovič ◽  
Živa Marinko ◽  
Sandra Drev ◽  
Vid Simon Šelih ◽  
...  
Keyword(s):  
Thin Film ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
High Surface ◽  
High Surface Area ◽  
Additional Contribution ◽  
X Ray ◽  
Metal Support Interaction

The present study targets one of the grand challenges of electrochemical hydrogen production: a durable and cost-effective oxygen-evolution catalyst. We present a thin-film composite electrode with a unique morphology and an ultra-low loading of iridium that has extraordinary electrocatalytic properties. This is accomplished by the electrochemical growth of a defined, high-surface-area titanium oxide nanotubular film followed by the nitridation and effective immobilization of iridium nanoparticles. The applicative relevance of this production process is justified by a remarkable oxygen-evolution reaction (OER) activity and high stability. Due to the confinement inside the pores and the strong metal-support interaction (SMSI) effects, the OER exhibited a higher turnover. The high durability is achieved by self-passivation of the titanium oxynitride (TiON) surface layer with TiO<sub>2</sub>, which in addition also effectively embeds the Ir nanoparticles, while still keeping them electrically wired. An additional contribution to the enhanced durability comes from the nitrogen atoms, which according to our DFT calculations reduce the tendency of the Ir nanoparticles to grow. We also introduce an advanced electrochemical characterization platform for the in-depth study of thin-film electrodes. Namely, the entire process of the TiON-Ir electrode’s preparation and the electrochemical evaluation can be tracked with scanning electron microscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) at identical locations. In general, the novel experimental approach allows for the unique morphological, structural and compositional insights into the preparation and electrocatalytic performance of thin films, making it useful also outside electrocatalysis applications.

scholarly journals A Cobalt-Iron Double-Atom Catalyst for the Oxygen Evolution Reaction

2019 ◽  
Author(s):  
Lichen Bai ◽  
Chia-Shuo Hsu ◽  
Duncan Alexander ◽  
Hao Ming Chen ◽  
Xile Hu
Keyword(s):  
Oxygen Evolution ◽  
Active Site ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Single Atom ◽  
X Ray ◽  
Highly Active ◽  
Cobalt Iron ◽  
X Ray Absorption

Single atom catalysts exhibit well-defined active sites and potentially maximum atomic efficiency. However, they are unsuitable for reactions that benefit from bimetallic promotion such as the oxygen evolution reaction (OER) in alkaline medium. Here we show that a single atom Co precatalyst can be in-situ transformed into a Co-Fe double atom catalyst for OER. This catalyst exhibits one of the highest turnover frequencies among metal oxides. Electrochemical, microscopic, and spectroscopic data including those from operando X-ray absorption spectroscopy, reveal a dimeric Co-Fe moiety as the active site of the catalyst. This work demonstrates double-atom catalysis as a promising approach for the developed of defined and highly active OER catalysts.

Nanotubular Titanium Oxynitride with an Ultra-Low Iridium Loading as a High-Performance Oxygen-Evolution-Reaction Thin-Film Electrode

2020 ◽  
Author(s):  
Marjan Bele ◽  
Primož Jovanovič ◽  
Živa Marinko ◽  
Sandra Drev ◽  
Vid Simon Šelih ◽  
...  
Keyword(s):  
Thin Film ◽  
Oxygen Evolution ◽  
Photoelectron Spectroscopy ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
High Surface ◽  
High Surface Area ◽  
Additional Contribution ◽  
X Ray ◽  
Metal Support Interaction

The present study targets one of the grand challenges of electrochemical hydrogen production: a durable and cost-effective oxygen-evolution catalyst. We present a thin-film composite electrode with a unique morphology and an ultra-low loading of iridium that has extraordinary electrocatalytic properties. This is accomplished by the electrochemical growth of a defined, high-surface-area titanium oxide nanotubular film followed by the nitridation and effective immobilization of iridium nanoparticles. The applicative relevance of this production process is justified by a remarkable oxygen-evolution reaction (OER) activity and high stability. Due to the confinement inside the pores and the strong metal-support interaction (SMSI) effects, the OER exhibited a higher turnover. The high durability is achieved by self-passivation of the titanium oxynitride (TiON) surface layer with TiO<sub>2</sub>, which in addition also effectively embeds the Ir nanoparticles, while still keeping them electrically wired. An additional contribution to the enhanced durability comes from the nitrogen atoms, which according to our DFT calculations reduce the tendency of the Ir nanoparticles to grow. We also introduce an advanced electrochemical characterization platform for the in-depth study of thin-film electrodes. Namely, the entire process of the TiON-Ir electrode’s preparation and the electrochemical evaluation can be tracked with scanning electron microscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) at identical locations. In general, the novel experimental approach allows for the unique morphological, structural and compositional insights into the preparation and electrocatalytic performance of thin films, making it useful also outside electrocatalysis applications.

Controllable growth of graphdiyne layered nanosheets for high-performance water oxidation

2021 ◽  
Author(s):  
Shuya Zhao ◽  
Yurui Xue ◽  
Zhongqiang Wang ◽  
Zhiqiang Zheng ◽  
Xiaoyu Luan ◽  
...  
Keyword(s):  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Water Oxidation ◽  
High Performance ◽  
Low Cost ◽  
Highly Active ◽  
Controllable Growth

Developing highly active, stable and low-cost electrocatalysts capable of an efficient oxygen evolution reaction (OER) is urgent and challenging.

High-performance anion exchange membrane alkaline seawater electrolysis

2021 ◽  
Author(s):  
Yoo Sei Park ◽  
Jooyoung Lee ◽  
Myeong-Je Jang ◽  
Juchan Yang ◽  
Jae Hoon Jeong ◽  
...  
Keyword(s):  
Anion Exchange ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
Anion Exchange Membrane ◽  
Hydrogen Energy ◽  
Highly Active ◽  
Production Of Hydrogen ◽  
Exchange Membrane ◽  
Seawater Electrolysis

Seawater electrolysis is a promising technology for the production of hydrogen energy and seawater desalination. To produce hydrogen energy through seawater electrolysis, highly active electrocatalysts for the oxygen evolution reaction...

Cathodic Corrosion Activated Fe-based Nanoglass as Highly-Active and -Stable Oxygen Evolution Catalyst for Water Splitting

2021 ◽  
Author(s):  
Kaiyao Wu ◽  
Fei Chu ◽  
Yuying Meng ◽  
Kaveh Edalati ◽  
Qingsheng Gao ◽  
...  
Keyword(s):  
Water Splitting ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Amorphous Alloys ◽  
Precious Metal ◽  
Active Sites ◽  
Metal Free ◽  
Highly Active ◽  
Stable Oxygen ◽  
Surface Active

Transition metal-based amorphous alloys have attracted increasing attention as precious-metal-free electrocatalysts for oxygen evolution reaction (OER) of water splitting due to their high macro-conductivity and abundant surface active sites. However,...

Tunable mesoporous manganese oxide for high performance oxygen reduction and evolution reactions

2016 ◽  
Vol 4 (2) ◽  
pp. 620-631 ◽  
Author(s):  
Islam M. Mosa ◽  
Sourav Biswas ◽  
Abdelhamid M. El-Sawy ◽  
Venkatesh Botu ◽  
Curtis Guild ◽  
...  
Keyword(s):  
Oxygen Reduction Reaction ◽  
Manganese Oxide ◽  
Oxygen Reduction ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
High Performance ◽  
Reduction Reaction ◽  
Noble Metal Catalysts ◽  
Highly Active ◽  
State Of Art

Understanding the origin of manganese oxide activity for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a key step towards rationally designing of highly active catalysts capable of competing with the widely used, state-of-art noble metal catalysts.

scholarly journals Spin-sate reconfiguration induced by alternating magnetic field for efficient oxygen evolution reaction

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Gang Zhou ◽  
Peifang Wang ◽  
Hao Li ◽  
Bin Hu ◽  
Yan Sun ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Active Sites ◽  
Reaction Pathway ◽  
Low Cost ◽  
Orbital Interaction ◽  
New Paradigm ◽  
Metal Organic ◽  
Energy Conversion Devices

AbstractOxygen evolution reaction (OER) plays a determining role in electrochemical energy conversion devices, but challenges remain due to the lack of effective low-cost electrocatalysts and insufficient understanding about sluggish reaction kinetics. Distinguish from complex nano-structuring, this work focuses on the spin-related charge transfer and orbital interaction between catalysts and intermediates to accelerate catalytic reaction kinetics. Herein, we propose a simple magnetic-stimulation approach to rearrange spin electron occupation in noble-metal-free metal-organic frameworks (MOFs) with a feature of thermal-differentiated superlattice, in which the localized magnetic heating in periodic spatial distribution makes the spin flip occur at particular active sites, demonstrating a spin-dependent reaction pathway. As a result, the spin-rearranged Co0.8Mn0.2 MOF displays mass activities of 3514.7 A gmetal−1 with an overpotential of ~0.27 V, which is 21.1 times that of pristine MOF. Our findings provide a new paradigm for designing spin electrocatalysis and steering reaction kinetics.

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