A comprehensive review on unitized regenerative fuel cells: Crucial challenges and developments

Thangarasu, Sadhasivam; Dhanabalan, K.; Roh, Sung‐Hee; Kim, Sang Woo; Park, Kyung-Won; Jung, Seunghun; Kurkuri, Mahaveer D.; Jung, Ho‐Young

doi:10.1016/j.ijhydene.2016.10.140

Cited by 122 publications

(56 citation statements)

References 154 publications

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“…A new way to produce and store electrical energy is necessary to address future energy demands and reduce polluting emissions . Rechargeable alkaline metal‐air batteries can be considered one of the most promising next energy systems owing to their extremely high energy densities . These make them particularly interesting for applications in electrical‐energy storage systems for coupling intermittent renewable energy sources into smart energy grids.…”

Section: Introductionmentioning

confidence: 99%

“…[1,2] Rechargeable alkaline metal-air batteries can be considered one of the most promising next energy systems owing to their extremely high energy densities. [3][4][5][6][7] These make them particularly interesting for applications in electrical-energy storage systems for coupling intermittent renewable energy sources into smart energy grids. However, this kind of batteries requires very efficient and durable bifunctional electrocatalysts to accelerate the kinetics of oxygen reduction reaction (ORR), taking place during the discharge, and oxygen evolution reaction (OER), occurring during charging of the battery.…”

Section: Introductionmentioning

confidence: 99%

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Electrocatalysis of Oxygen on Bifunctional Nickel‐Cobaltite Spinel

et al. 2020

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Transition‐metal‐based materials are among the most active and durable catalysts for the effective electrocatalysis of oxygen‐related reactions. Herein, we present a study on bifunctional catalysts as air electrodes aimed at metal‐air batteries based on nickel and cobalt spinel (NiCo2O4) supported on electrospun carbon nanofibers. The physicochemical features of these transition‐metal‐based catalysts are essential for the understanding of their electrochemical activity. Results show that the major presence of oxidized Ni and Co species (Ni3+ and Co3+) produces higher activity for the oxygen evolution reaction (OER), whereas lower oxidation states of the metals (Ni2+, Co2+, Ni0 and Co0) together with the presence of N‐doped carbon lead to enhanced oxygen reduction reaction (ORR) performance. This study highlights the importance of designing catalysts in terms of crystallographic structure and proper oxidation states of the elements for maximizing their performance.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrocatalysis of Oxygen on Bifunctional Nickel‐Cobaltite Spinel

et al. 2020

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“…Unitized regenerative fuel cells (URFCs), which exhibit high energy density, long life span, and no self‐discharge, cannot only implement fuel cell (FC) mode but also electrolysis cell (EC) mode in the same component . The principle of URFC is shown in Figure .…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation on voltage response to operation parameters of a unitized regenerative fuel cell during mode switching from fuel cell to electrolysis cell

Guo

et al. 2018

Int J Energy Res

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Summary In this work, a proton exchange membrane unitized regenerative fuel cell with a 25 cm2 active area and a transparent window was designed to study the influence of mode switching from the fuel cell mode to the electrolysis cell mode on the cell voltage and the gas‐liquid two‐phase flow behaviors in the oxygen flow channels. Results indicate that: the growth rate of electrolysis cell voltage before the water pumped to the oxygen flow channels decreases with the increase of the fuel cell current density; while the growth rate of electrolysis cell voltage before the water pumped to the oxygen flow channels increases with the cell temperature; the voltage of electrolysis cell mode before the water pumped to the oxygen flow channels decreases with the increase of water flow rate; the different voltage reduction speeds are attributed to the different water flow rates. The water temperature has an obscure influence on the cell voltage of electrolysis cell mode before the water pumped to the oxygen flow channels.

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“…[81] Using polydopamine (PDA)-encapsulated Fe 3 [Co(CN) 6 ] 2 nanocubes as the precursor, Xi et al fabricated core-shell (Fe,Co)@nitrogen-doped graphitic carbon ((Fe, Co)@NGC) nanocubes via the approach illustrated in Figure 3a. [81] In detail, Fe 3 6 ] 2 , respectively, it is difficult to comment on the significance of bimetallic cores without considering the role of the NGC shell. In such a study, if Fe@NGC and Co@NGC were synthesized and compared under the same criteria, the role of multiple metals incorporation should be evidently distinguished from that of the single metals.…”

Section: Transition Metal Incorporationmentioning

confidence: 99%

“…These devices appear most promising due to their high energyconversion and storage efficiencies, portability, which can mitigate the intermittent distribution of the aforementioned energy in space and time, and environmental benignancy. [6][7][8][9][10] Fundamentally, these electrochemical systems or devices involve different energy-conversion reactions, such as the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and electrochemical CO 2 reduction (ECR), which provide energy by directly converting chemical energy (e.g., methanol, ethanol, zinc, and hydrogen) into electrical energy, or store energy vice versa. [6][7][8][9][10][11][12] The intrinsically sluggish kinetics of these reactions highlights the critical role of electrocatalysts.…”

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confidence: 99%

Design Strategies toward Advanced MOF‐Derived Electrocatalysts for Energy‐Conversion Reactions

Liu

Zhu

Guo

et al. 2017

Advanced Energy Materials

609

351

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great potential to meet our ever-growing demand for energy. These devices appear most promising due to their high energyconversion and storage efficiencies, portability, which can mitigate the intermittent distribution of the aforementioned energy in space and time, and environmental benignancy. [6][7][8][9][10] Fundamentally, these electrochemical systems or devices involve different energy-conversion reactions, such as the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and electrochemical CO 2 reduction (ECR), which provide energy by directly converting chemical energy (e.g., methanol, ethanol, zinc, and hydrogen) into electrical energy, or store energy vice versa. [6][7][8][9][10][11][12] The intrinsically sluggish kinetics of these reactions highlights the critical role of electrocatalysts. In this regard, the development of advanced electrocatalysts has always been the technological bottleneck that hinders the practical applications of these energy techniques at any appreciable scale. [7][8][9][10][11][12] Currently, noble-metal-based materials (e.g., Pt, IrO 2 , RuO 2 , and Au) are considered to be state-of-the-art catalysts for a variety of energy devices, [13][14][15][16] such as proton exchange membrane fuel cells (PEMFCs). [13] In spite of their outstanding catalytic performance for many electrochemical reactions, the high cost and scarcity of these noble metals severely hamper their large-scale commercialization. [17] Further, precious metal catalysts face issues with poisoning when exposed to a range of chemical compounds like methaol and carbon monoxide, leading to significant activity loss. [18] Therefore, extensive studies have focused on the development of alternative electrocatalysts with high activity, long stability, low cost, widespread availability, and facile synthesis. [8][9][10]19,20] To replace precious-metal-based catalysts, a wide range of non-noble-metal materials, especially transition-metal-based materials and metal-free carbon materials, have been intensively investigated as electrocatalysts for different applications. [21] Most of these electrocatalyst candidates show great promise in energy-conversion reactions. Nevertheless, very few alternative materials have yet to achieve superior electrochemical properties to those of noble-metal-based catalysts. Fortunately, the accumulation of experimental and theoretical studies have significantly advanced our knowledge on the chemical and physical nature of various candidate materials. [10][11][12] For example, our group has shed light on the activity origin of The key challenge to developing renewable and clean energy technologies lies in the rational design and synthesis of efficient and earth-abundant catalysts for a wide variety of electrochemical reactions. This review presents materials design strategies for constructing improved electrocatalysts based on MOF precursors/templates, with special emphasis on component manipulation, morphology control, and structure engineering. G...

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A comprehensive review on unitized regenerative fuel cells: Crucial challenges and developments

Cited by 122 publications

References 154 publications

Electrocatalysis of Oxygen on Bifunctional Nickel‐Cobaltite Spinel

Electrocatalysis of Oxygen on Bifunctional Nickel‐Cobaltite Spinel

Experimental investigation on voltage response to operation parameters of a unitized regenerative fuel cell during mode switching from fuel cell to electrolysis cell

Design Strategies toward Advanced MOF‐Derived Electrocatalysts for Energy‐Conversion Reactions

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