Oxygen Reduction in Alkaline Media: From Mechanisms to Recent Advances of Catalysts

Ge, Xiaoming; Sumboja, Afriyanti; Wuu, Delvin; An, Tao; Li, Bing; Goh, F. W. Thomas; Hor, T. S. Andy; Zong, Yun; Liu, Zhaolin

doi:10.1021/acscatal.5b00524

Cited by 1,147 publications

(913 citation statements)

References 288 publications

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“…It is generally considered that ORR can proceed via a four electron transfer to produce water (pathway 1), or via a two electron transfer to produce H 2 O 2 (pathway 2) [5,6].…”

Section: Introductionmentioning

confidence: 99%

AMnO3 (A = Sr, La, Ca, Y) Perovskite Oxides as Oxygen Reduction Electrocatalysts

et al. 2018

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A series of perovskite-type manganites AMnO 3 (A = Sr, La, Ca and Y) particles were investigated as electrocatalysts for the oxygen reduction reaction. AMnO 3 materials were synthesized by means of an ionic-liquid method, yielding phase pure particles at different temperatures. Depending on the calcination temperature, particles with mean diameter between 20 and 150 nm were obtained. Bulk versus surface composition and structure are probed by X-ray photoelectron spectroscopy and extended X-ray absorption fine structure. Electrochemical studies were performed on composite carbon-oxide electrodes in alkaline environment. The electrocatalytic activity is discussed in terms of the effective Mn oxidation state, A:Mn particle surface ratio and the Mn-O distances.

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“…It is generally considered that ORR can proceed via a four electron transfer to produce water (pathway 1), or via a two electron transfer to produce H 2 O 2 (pathway 2) [5,6].…”

Section: Introductionmentioning

confidence: 99%

AMnO3 (A = Sr, La, Ca, Y) Perovskite Oxides as Oxygen Reduction Electrocatalysts

et al. 2018

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“…Their advantage is mainly the possibility of using non-noble catalysts due to faster oxygenreduction-reaction (ORR) kinetics in alkaline media than in acidic media [1][2][3][4] as well as perhaps the use of less expensive hydrocarbon membranes. Disadvantages of AEMFCs include lower hydrogenoxidation-reaction (HOR) kinetics, more complicated water management, and lower intrinsic conductivity for hydroxide compared to proton transport.…”

mentioning

confidence: 99%

“…Anode : H 2 + 2OH − → 2H 2 O + 2e − U 0 = −0.8 V vs. SHE [1] Cathode : 1/2O 2 + H 2 O + 2e − → 2OH − U 0 = 0.4 V vs. SHE [2] Net : H 2 + 1/2O 2 → H 2 O U 0 = 1.2 V [3] Hydrogen combines with hydroxide ions to produce water in the anode. Oxygen reacts with water to generate hydroxide ions in the cathode.…”

mentioning

confidence: 99%

Elucidating Performance Limitations in Alkaline-Exchange- Membrane Fuel Cells

Shiau

Zenyuk

Weber

2017

J. Electrochem. Soc.

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Water management is a serious concern for alkaline-exchange-membrane fuel cells (AEMFCs) because water is a reactant in the alkaline oxygen-reduction reaction and hydroxide conduction in alkaline-exchange membranes is highly hydration dependent. In this paper, we develop and use a multiphysics, multiphase model to explore water management in AEMFCs. We demonstrate that the low performance is mostly caused by extremely non-uniform distribution of water in the ionomer phase. A sensitivity analysis of design parameters including humidification strategies, membrane properties, and water transport resistance was undertaken to explore possible optimization strategies. Furthermore, the strategy and issues of reducing bicarbonate/carbonate buildup in the membrane-electrode assembly with CO 2 from air is demonstrated based on the model prediction. Overall, mathematical modeling is used to explore trends and strategies to overcome performance bottlenecks and help enable AEMFC commercialization. Among existing fuel-cell types, alkaline-exchange-membrane fuel cells (AEMFCs) or hydroxide-exchange-membrane fuel cells (HEMFCs) have intriguing features as compared to proton-exchangemembrane fuel cells (PEMFCs). Their advantage is mainly the possibility of using non-noble catalysts due to faster oxygenreduction-reaction (ORR) kinetics in alkaline media than in acidic media 1-4 as well as perhaps the use of less expensive hydrocarbon membranes. Disadvantages of AEMFCs include lower hydrogenoxidation-reaction (HOR) kinetics, more complicated water management, and lower intrinsic conductivity for hydroxide compared to proton transport. [5][6][7][8][9][10][11][12][13] In addition, CO 2 in the air reacts with hydroxide ions to form bicarbonate and carbonate ions, possibly hindering the terrestrial development of AEMFCs by removing hydroxide available for HOR and further limiting hydroxide conductivity. 14,15 Compared to conventional alkaline fuel cells (i.e., using a liquid electrolyte of potassium hydroxide), AEMFCs use a polymeric membrane and should have better tolerance for CO 2 because the precipitate K 2 CO 3 is absent in the AEMFC due to the lack of mobile cations in the membrane. 16 However, AEMFCs still suffer a decline in performance due to bicarbonate/carbonate formation in the membrane and catalyst layers (CLs) leading to additional ohmic and kinetic losses. [13][14][15] In an AEMFC, the following electrochemical reactions occur in the CLs as follows:Net :Hydrogen combines with hydroxide ions to produce water in the anode. Oxygen reacts with water to generate hydroxide ions in the cathode. Along with the transport of ions from cathode to anode, electro-osmosis moves water from cathode to anode. As shown in the reactions, AEMFCs are expected to have more complicated water management. Water production by the HOR and electro-osmosis may cause flooding in the anode. Since water is a stoichiometric reactant at the cathode, dehydration may occur and limit ORR kinetics as well as ionic conduction in the membrane and cathode CL, ...

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“…Therefore, the mechanism of oxygen reduction is necessarily different in the two different types of fuel cells [3,4].…”

Section: Introductionmentioning

confidence: 99%

One step synthesis of chlorine-free Pt/Nitrogen-doped graphene composite for oxygen reduction reaction

Varga

Ballai

et al. 2018

Carbon

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Oxygen Reduction in Alkaline Media: From Mechanisms to Recent Advances of Catalysts

Cited by 1,147 publications

References 288 publications

AMnO3 (A = Sr, La, Ca, Y) Perovskite Oxides as Oxygen Reduction Electrocatalysts

AMnO3 (A = Sr, La, Ca, Y) Perovskite Oxides as Oxygen Reduction Electrocatalysts

Elucidating Performance Limitations in Alkaline-Exchange- Membrane Fuel Cells

One step synthesis of chlorine-free Pt/Nitrogen-doped graphene composite for oxygen reduction reaction

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