PGM‐Free Cathode Catalysts for PEM Fuel Cells: A Mini‐Review on Stability Challenges

Shao, Yuyan; Dodelet, Jean‐Pol; Wu, Gang; Zelenay, Piotr

doi:10.1002/adma.201807615

Cited by 486 publications

(372 citation statements)

References 75 publications

(171 reference statements)

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“…In addition, advanced in situ characterization and more accurate DFT calculations are needed to study the nature of active sites and the catalytic mechanisms from both a thermodynamic and kinetics point of view. It should be noted that we primarily focused on modification of local coordination environments of SACs in terms of their intrinsic activity and selectivity instead of the more crucial issue of stability . We admitted that most carbon‐based catalysts discussed here would not be suitable for oxidative OER reactions that cause serious carbon corrosion and catalyst degradation.…”

Section: Discussionmentioning

confidence: 99%

Engineering Local Coordination Environments of Atomically Dispersed and Heteroatom‐Coordinated Single Metal Site Electrocatalysts for Clean Energy‐Conversion

Zhu

Sokolowski

Song

et al. 2019

Advanced Energy Materials

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280

240

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Carbon‐based heteroatom‐coordinated single‐atom catalysts (SACs) are promising candidates for energy‐related electrocatalysts because of their low‐cost, tunable catalytic activity/selectivity, and relatively homogeneous morphologies. Unique interactions between single metal sites and their surrounding coordination environments play a significant role in modulating the electronic structure of the metal centers, leading to unusual scaling relationships, new reaction mechanisms, and improved catalytic performance. This review summarizes recent advancements in engineering of the local coordination environment of SACs for improved electrocatalytic performance for several crucial energy‐convention electrochemical reactions: oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, CO2 reduction reaction, and nitrogen reduction reaction. Various engineering strategies including heteroatom‐doping, changing the location of SACs on their support, introducing external ligands, and constructing dual metal sites are comprehensively discussed. The controllable synthetic methods and the activity enhancement mechanism of state‐of‐the‐art SACs are also highlighted. Recent achievements in the electronic modification of SACs will provide an understanding of the structure–activity relationship for the rational design of advanced electrocatalysts.

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Section: Discussionmentioning

confidence: 99%

Engineering Local Coordination Environments of Atomically Dispersed and Heteroatom‐Coordinated Single Metal Site Electrocatalysts for Clean Energy‐Conversion

Zhu

Sokolowski

Song

et al. 2019

Advanced Energy Materials

Self Cite

280

240

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“…Therefore, for cost and stability reasons, new catalysts for the ORR are highly sought after. Attention in recent years has focused on transition metal active centers in carbon matrices, especially where the carbon is doped with heteroatoms such as nitrogen, though the presence of metal in these materials leads to significant durability challenges, again, particularly in acidic media, and so a new class of entirely metal‐free ORR catalysts has emerged in recent years as cost effective, durable, and electrochemically selective alternatives to traditional materials …”

Section: D Carbons For the Orrmentioning

confidence: 99%

“…[187] Therefore, for cost and stability reasons, new catalysts for the ORR are highly sought after. Attention in recent years has focused on transition metal active centers in carbon matrices, especially where the carbon is doped with heteroatoms such as nitrogen, [188] though the presence of metal in these materials leads to significant durability challenges, again, particularly in acidic media, [189] and so a new class of entirely metal-free ORR catalysts has emerged in recent years as cost effective, durable, and electrochemically selective alternatives to traditional materials. [90,190] In 2009, Dai's group demonstrated for the first time a superior activity of metal-free ORR catalysis in alkaline media compared to Pt/C, using vertically aligned nitrogen-doped CNT arrays and highlighting the role of nitrogen in greatly enhancing the activity over pure CNTs.…”

Section: D Carbons For the Orrmentioning

confidence: 99%

3D Carbon Materials for Efficient Oxygen and Hydrogen Electrocatalysis

Sobrido

Jervis

Periasamy

et al. 2019

Advanced Energy Materials

114

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Sustainable energy production at an acceptable cost is key for its widespread application. At present, noble metals and metal oxides are the most widely used for electrocatalysis, but they suffer from low selectivity, poor durability, and scarcity. Because of this, metal‐free carbons have become the subject of great interest as promising alternative electrocatalysts for energy conversion and storage devices, and remarkable progress has been accomplished in the advance of metal‐free carbons as electrocatalysts for renewable energy technologies. Particularly interesting are 3D porous carbon architectures, which exhibit outstanding features for electrocatalysis applications, including broad range of active sites, interconnected porosity, high conductivity, and mechanical stability. This review summarizes the latest advances in 3D porous carbon structures for oxygen and hydrogen electrocatalysis. The structure–performance relationship of these materials is consequently rationalized and perspectives on creating more efficient 3D carbon electrocatalysts are suggested.

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“…OH) and hydroperoxo radical ( . OOH) species via Fenton's reactions in acidic electrolyte . The possible role of H 2 O 2 and ROS species was originally underlined by Lefevre et al .…”

Section: Introductionmentioning

confidence: 99%

On the Influence of Oxygen on the Degradation of Fe‐N‐C Catalysts

Kumar,

Dubau,

Mermoux

et al. 2020

Angew Chem Int Ed

179

170

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Fe‐N‐C catalysts containing atomic FeNx sites are promising candidates as precious‐metal‐free catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. The durability of Fe‐N‐C catalysts in fuel cells has been extensively studied using accelerated stress tests (AST). Herein we reveal stronger degradation of the Fe‐N‐C structure and four‐times higher ORR activity loss when performing load cycling AST in O2‐ vs. Ar‐saturated pH 1 electrolyte. Raman spectroscopy results show carbon corrosion after AST in O2, even when cycling at low potentials, while no corrosion occurred after any load cycling AST in Ar. The load‐cycling AST in O2 leads to loss of a significant fraction of FeNx sites, as shown by energy dispersive X‐ray spectroscopy analyses, and to the formation of Fe oxides. The results support that the unexpected carbon corrosion occurring at such low potential in the presence of O2 is due to reactive oxygen species produced between H2O2 and Fe sites via Fenton reactions.

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PGM‐Free Cathode Catalysts for PEM Fuel Cells: A Mini‐Review on Stability Challenges

Cited by 486 publications

References 75 publications

Engineering Local Coordination Environments of Atomically Dispersed and Heteroatom‐Coordinated Single Metal Site Electrocatalysts for Clean Energy‐Conversion

Engineering Local Coordination Environments of Atomically Dispersed and Heteroatom‐Coordinated Single Metal Site Electrocatalysts for Clean Energy‐Conversion

3D Carbon Materials for Efficient Oxygen and Hydrogen Electrocatalysis

On the Influence of Oxygen on the Degradation of Fe‐N‐C Catalysts

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