Electrochemical Synergies of Heterostructured Fe2O3-MnO Redox Couple for Oxygen Evolution Reaction in Alkaline Water Splitting

For efficient electrode development in an electrolysis system, Fe2O3, MnO, and heterojunction Fe2O3-MnO materials were synthesized via a simple sol–gel method. These particles were coated on a Ni-foam (NF) electrode, and the resulting material was used as an electrode to be used during an oxygen evolution reaction (OER). A 1000-cycle OER test in a KOH alkaline electrolyte indicated that the heterojunction Fe2O3-MnO/NF electrode exhibited the most stable and highest OER activity: it exhibited a low overvoltage (n) of 370 mV and a small Tafel slope of 66 mV/dec. X-ray photoelectron spectroscopy indicated that the excellent redox performance contributed to the synergy of Mn and Fe, which enhanced the OER performance of the Fe2O3-MnO/NF electrode. Furthermore, the effective redox reaction of Mn and Fe indicated that the structure maintained stability even under 1000 repeated OER cycles.

Download Full-text

MoS2/Ni3S2 nanorod arrays well-aligned on Ni foam: a 3D hierarchical efficient bifunctional catalytic electrode for overall water splitting

RSC Advances ◽

10.1039/c7ra07667c ◽

2017 ◽

Vol 7 (73) ◽

pp. 46286-46296 ◽

Cited By ~ 30

Author(s):

Nan Zhang ◽

Junyu Lei ◽

Jianpeng Xie ◽

Haiyan Huang ◽

Ying Yu

Keyword(s):

Hydrogen Evolution ◽

Water Splitting ◽

Oxygen Evolution ◽

Hydrogen Evolution Reaction ◽

Oxygen Evolution Reaction ◽

Nanorod Arrays ◽

Ni Foam ◽

Overall Water Splitting

A novel 3D hierarchical bifunctional catalytic electrode, MoS2/Ni3S2 nanorod arrays well-aligned on NF exhibited excellent electrocatalytic efficiency for hydrogen evolution reaction, oxygen evolution reaction and overall water splitting.

Download Full-text

Tuning the electronic structure of NiCoVOx nanosheets through S doping for enhanced oxygen evolution

Nanoscale ◽

10.1039/d1nr05060e ◽

2021 ◽

Author(s):

Haibin Ma ◽

ChangNing SUN ◽

Zhili Wang ◽

Qing Jiang

Keyword(s):

Electronic Structure ◽

Water Splitting ◽

Oxygen Evolution ◽

Oxygen Evolution Reaction ◽

Low Cost ◽

Ni Foam ◽

Electrochemical Water Splitting

It is of great importance to develop efficient and low-cost oxygen evolution reaction (OER) electrocatalysts for electrochemical water splitting. Herein, S doped NiCoVOx nanosheets grown on Ni-Foam (S-NiCoVOx/NF) with modified...

Download Full-text

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

Nano-Micro Letters ◽

10.1007/s40820-019-0253-5 ◽

2019 ◽

Vol 11 (1) ◽

Cited By ~ 19

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.

Download Full-text

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

Journal of Electrochemical Science and Engineering ◽

10.5599/jese.806 ◽

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.

Download Full-text

Enhancing hydrogen evolution reaction through modulating electronic structure of self-supported NiFe LDH

Catalysis Science & Technology ◽

10.1039/d0cy00315h ◽

2020 ◽

Vol 10 (13) ◽

pp. 4184-4190 ◽

Cited By ~ 8

Author(s):

Xiao-Peng Li ◽

Wen-Kai Han ◽

Kang Xiao ◽

Ting Ouyang ◽

Nan Li ◽

...

Keyword(s):

Electronic Structure ◽

Hydrogen Evolution ◽

Water Splitting ◽

Oxygen Evolution ◽

Layered Double Hydroxide ◽

Hydrogen Evolution Reaction ◽

Oxygen Evolution Reaction ◽

Alkaline Electrolyte ◽

Overall Water Splitting ◽

Double Hydroxide

NiFe-layered double hydroxide (NiFe LDH), as an efficient oxygen evolution reaction (OER) electrocatalyst, has emerged as a promising electrocatalyst for catalyzing overall water splitting in alkaline electrolyte.

Download Full-text

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

10.26434/chemrxiv.12377879.v1 ◽

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 TiO2, 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.

Download Full-text

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

10.26434/chemrxiv.12377879 ◽

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 TiO2, 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.

Download Full-text