scholarly journals Decoupling Gas Evolution from Water-Splitting Electrodes

2019 ◽  
Author(s):  
Pablo Peñas ◽  
Peter van der Linde ◽  
Wouter Vijselaar ◽  
Devaraj van der Meer ◽  
Detlef Lohse ◽  
...  
Keyword(s):  
Water Splitting ◽  
Water Electrolysis ◽  
Gas Evolution ◽  
Dissolved Gas ◽  
Alkaline Water Electrolysis ◽  
Transport Models ◽  
Cell Potential ◽  
Transient Behaviour ◽  
Mass Transfer Processes ◽  
Novel Method

<div><div><div><p>Bubbles are known to hinder electrochemical processes in water-splitting electrodes. In this study, we present a novel method to promote gas evolution away from the electrode surface. We consider a ring microelectrode encircling a hydrophobic microcavity from which a succession of bubbles grows. The ring microelectrode, tested under alkaline water electrolysis conditions, does not suffer from bubble coverage. Consequently, the chronopotentiometric fluctuations of the cell are weaker than those associated with conventional microelectrodes. Herein, we provide fundamental understanding of the mass transfer processes governing the transient behaviour of the cell potential. With the help of numerical transport models, we demonstrate that bubbles forming at the cavity reduce the concentration overpotential by lowering the surrounding concentration of dissolved gas, but may also aggravate the ohmic overpotential by blocking ion-conduction pathways. The theoretical and experimental insight gained have relevant implications in the design of efficient gas-evolving electrodes.</p></div></div></div>

scholarly journals Decoupling Gas Evolution from Water-Splitting Electrodes

2019 ◽  
Author(s):  
Pablo Peñas ◽  
Peter van der Linde ◽  
Wouter Vijselaar ◽  
Devaraj van der Meer ◽  
Detlef Lohse ◽  
...  
Keyword(s):  
Water Splitting ◽  
Water Electrolysis ◽  
Gas Evolution ◽  
Dissolved Gas ◽  
Alkaline Water Electrolysis ◽  
Transport Models ◽  
Cell Potential ◽  
Transient Behaviour ◽  
Mass Transfer Processes ◽  
Novel Method

<div><div><div><p>Bubbles are known to hinder electrochemical processes in water-splitting electrodes. In this study, we present a novel method to promote gas evolution away from the electrode surface. We consider a ring microelectrode encircling a hydrophobic microcavity from which a succession of bubbles grows. The ring microelectrode, tested under alkaline water electrolysis conditions, does not suffer from bubble coverage. Consequently, the chronopotentiometric fluctuations of the cell are weaker than those associated with conventional microelectrodes. Herein, we provide fundamental understanding of the mass transfer processes governing the transient behaviour of the cell potential. With the help of numerical transport models, we demonstrate that bubbles forming at the cavity reduce the concentration overpotential by lowering the surrounding concentration of dissolved gas, but may also aggravate the ohmic overpotential by blocking ion-conduction pathways. The theoretical and experimental insight gained have relevant implications in the design of efficient gas-evolving electrodes.</p></div></div></div>

Atomic Heterointerface Engineering Breaks Activity Limitation of Electrocatalysts and Promises Highly-Efficient Alkaline Water Splitting

2021 ◽  
Author(s):  
Qiucheng Xu ◽  
Jiahao Zhang ◽  
Haoxuan Zhang ◽  
Liyue Zhang ◽  
Ling Chen ◽  
...  
Keyword(s):  
Water Splitting ◽  
Anion Exchange ◽  
Low Cost ◽  
Water Electrolysis ◽  
Anion Exchange Membrane ◽  
Alkaline Water Electrolysis ◽  
Green Electricity ◽  
Alkaline Water ◽  
Highly Efficient ◽  
Exchange Membrane

Alkaline water splitting, especially the anion-exchange-membrane based water electrolysis, is an attractive way for low-cost and scalable H2 production. Green electricity-driven alkaline water electrolysis is requested to develop highly-efficient electrocatalysts...

Alkaline Electrolysis at Sea for Green Hydrogen Production: A Solution to Electrolyte Deterioration

2018 ◽  
Author(s):  
Rafael d’Amore-Domenech ◽  
Emilio Navarro ◽  
Eleuterio Mora ◽  
Teresa J. Leo
Keyword(s):  
Hydrogen Production ◽  
High Efficiency ◽  
Water Electrolysis ◽  
Alkaline Electrolyte ◽  
Alkaline Water Electrolysis ◽  
Logistic Problem ◽  
Combined Solution ◽  
Electrolysis Method ◽  
Novel Method ◽  
Alkaline Electrolysis

This article illustrates a novel method to produce hydrogen at sea with no carbon footprint, based on alkaline electrolysis, which is the cheapest electrolysis method for in-land hydrogen production, coupled to offshore renewable farms. The novelty of the method presented in this work is the solution to cope with the logistic problem of periodical renewal of the alkaline electrolyte, considered problematic in an offshore context. Such solution consists in the integration of a small chlor-alkali plant to produce new electrolyte in situ. This article describes a proposal to combine alkaline water electrolysis and chlor-alkali processes, first considering both in a separate manner, and then describing and discussing the combined solution, which seeks high efficiency and sustainability.

Modelling and control of an alkaline water electrolysis process

2018 ◽  
Vol 1 (2) ◽  
pp. 9-14
Author(s):  
Marisol Cervantes-Bobadilla ◽  
Ricardo Fabricio Escobar Jiménez ◽  
José Francisco Gómez Aguilar ◽  
Tomas Emmanuel Higareda Pliego ◽  
Alberto Armando Alvares Gallegos
Keyword(s):  
Process Model ◽  
Water Electrolysis ◽  
Alkaline Water Electrolysis ◽  
Alkaline Water ◽  
Electrolysis Process ◽  
Linear Dynamic ◽  
Energy Current ◽  
Identification Technique ◽  
Nonlinear Static ◽  
And Control

In this research, an alkaline water electrolysis process is modelled. The electrochemical electrolysis is carried out in an electrolyzer composed of 12 series-connected steel cells with a solution 30% wt of potassium hydroxide. The electrolysis process model was developed using a nonlinear identification technique based on the Hammerstein structure. This structure consists of a nonlinear static block and a linear dynamic block. In this work, the nonlinear static function is modelled by a polynomial approximation equation, and the linear dynamic is modelled using the ARX structure. To control the current feed to the electrolyzer an unconstraint predictive controller was implemented, once the unconstrained MPC was simulated, some restrictions are proposed to design a constrained MPC (CMPC). The CMPC aim is to reduce the electrolyzer's energy consumption (power supply current). Simulation results showed the advantages of using the CMPC since the energy (current) overshoots are avoided.

Applications of two dimensional material-MXene for proton exchange membrane fuel cells (PEMFCs) and water electrolysis

2020 ◽  
Vol 16 ◽  
Author(s):  
Chanchan Fan ◽  
Peng Zhang ◽  
Ranran Wang ◽  
Yezhu Xu ◽  
Xingrui Sun ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Water Splitting ◽  
Proton Exchange Membrane ◽  
Layer Structure ◽  
Metal Layer ◽  
Water Electrolysis ◽  
Proton Exchange ◽  
Two Dimensional ◽  
Max Phases ◽  
Early Transition Metal

: A new kind of two-dimensional (2D) materials MXene (early transition metal carbides, nitrides and carbonitrides) is obtained by selective etching the A element from the MAX phases. MXene exhibits both the metallic conductivity and the hydrophilic nature due to its metal layer structure and hydroxyl or oxygen terminated surfaces. This review provides an overview of the MXene used in the electrolytes and electrodes for the fuel cells and water splitting. MXene with functional groups termination could construct ion channels that significantly benefits to the ion conductivity through the electrolyte. The metal supported by MXene interaction offers electronic, compositional, and geometric effects that could enhance the catalytic activity and stability. MXene have already shown promising performance for fuel cells and water electrolysis. Herein, the etching and intercalation methods of MXene in recent years are summarized. The applications of MXene for fuel cells electrolyte, catalyst and water splitting catalyst are revealed to provide more brief idea for MXene used as new energy materials.

scholarly journals Boosting alkaline water electrolysis by asymmetric temperature modulation

2021 ◽  
Vol 119 (1) ◽  
pp. 013901
Author(s):  
Qinpeng Zhu ◽  
Peihua Yang ◽  
Tao Zhang ◽  
Zehua Yu ◽  
Kang Liu ◽  
...  
Keyword(s):  
Water Electrolysis ◽  
Temperature Modulation ◽  
Alkaline Water Electrolysis ◽  
Alkaline Water

scholarly journals Hydrogen production from water electrolysis: role of catalysts

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Shan Wang ◽  
Aolin Lu ◽  
Chuan-Jian Zhong
Keyword(s):  
Hydrogen Production ◽  
Water Splitting ◽  
Noble Metal ◽  
Active Sites ◽  
Current Knowledge ◽  
Low Cost ◽  
Critical Role ◽  
Water Electrolysis ◽  
Efficient Production ◽  
Production Of Hydrogen

AbstractAs a promising substitute for fossil fuels, hydrogen has emerged as a clean and renewable energy. A key challenge is the efficient production of hydrogen to meet the commercial-scale demand of hydrogen. Water splitting electrolysis is a promising pathway to achieve the efficient hydrogen production in terms of energy conversion and storage in which catalysis or electrocatalysis plays a critical role. The development of active, stable, and low-cost catalysts or electrocatalysts is an essential prerequisite for achieving the desired electrocatalytic hydrogen production from water splitting for practical use, which constitutes the central focus of this review. It will start with an introduction of the water splitting performance evaluation of various electrocatalysts in terms of activity, stability, and efficiency. This will be followed by outlining current knowledge on the two half-cell reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in terms of reaction mechanisms in alkaline and acidic media. Recent advances in the design and preparation of nanostructured noble-metal and non-noble metal-based electrocatalysts will be discussed. New strategies and insights in exploring the synergistic structure, morphology, composition, and active sites of the nanostructured electrocatalysts for increasing the electrocatalytic activity and stability in HER and OER will be highlighted. Finally, future challenges and perspectives in the design of active and robust electrocatalysts for HER and OER towards efficient production of hydrogen from water splitting electrolysis will also be outlined.

scholarly journals Graphene/MoS2/FeCoNi(OH)x and Graphene/MoS2/FeCoNiPx multilayer-stacked vertical nanosheets on carbon fibers for highly efficient overall water splitting

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xixi Ji ◽  
Yanhong Lin ◽  
Jie Zeng ◽  
Zhonghua Ren ◽  
Zijia Lin ◽  
...  
Keyword(s):  
Water Splitting ◽  
Carbon Fibers ◽  
Graphene Nanosheets ◽  
Water Electrolysis ◽  
Hybrid Structure ◽  
Hydrogen Energy ◽  
Highly Efficient ◽  
Overall Water Splitting ◽  
Stable Oxygen ◽  
Excellent Stability

AbstractDevelopment of excellent and cheap electrocatalysts for water electrolysis is of great significance for application of hydrogen energy. Here, we show a highly efficient and stable oxygen evolution reaction (OER) catalyst with multilayer-stacked hybrid structure, in which vertical graphene nanosheets (VGSs), MoS2 nanosheets, and layered FeCoNi hydroxides (FeCoNi(OH)x) are successively grown on carbon fibers (CF/VGSs/MoS2/FeCoNi(OH)x). The catalyst exhibits excellent OER performance with a low overpotential of 225 and 241 mV to attain 500 and 1000 mA cm−2 and small Tafel slope of 29.2 mV dec−1. Theoretical calculation indicates that compositing of FeCoNi(OH)x with MoS2 could generate favorable electronic structure and decrease the OER overpotential, promoting the electrocatalytic activity. An alkaline water electrolyzer is established using CF/VGSs/MoS2/FeCoNi(OH)x anode for overall water splitting, which generates a current density of 100 mA cm−2 at 1.59 V with excellent stability over 100 h. Our highly efficient catalysts have great prospect for water electrolysis.

scholarly journals Towards the Hydrogen Economy—A Review of the Parameters That Influence the Efficiency of Alkaline Water Electrolyzers

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3193
Author(s):  
Ana L. Santos ◽  
Maria-João Cebola ◽  
Diogo M. F. Santos
Keyword(s):  
Energy Content ◽  
Water Electrolysis ◽  
High Energy ◽  
Operating Conditions ◽  
Energy Sources ◽  
Alkaline Water Electrolysis ◽  
Alkaline Water ◽  
New Energy ◽  
Recent Developments ◽  
Cell Components

Environmental issues make the quest for better and cleaner energy sources a priority. Worldwide, researchers and companies are continuously working on this matter, taking one of two approaches: either finding new energy sources or improving the efficiency of existing ones. Hydrogen is a well-known energy carrier due to its high energy content, but a somewhat elusive one for being a gas with low molecular weight. This review examines the current electrolysis processes for obtaining hydrogen, with an emphasis on alkaline water electrolysis. This process is far from being new, but research shows that there is still plenty of room for improvement. The efficiency of an electrolyzer mainly relates to the overpotential and resistances in the cell. This work shows that the path to better electrolyzer efficiency is through the optimization of the cell components and operating conditions. Following a brief introduction to the thermodynamics and kinetics of water electrolysis, the most recent developments on several parameters (e.g., electrocatalysts, electrolyte composition, separator, interelectrode distance) are highlighted.

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