Highly active and durable non-precious-metal catalysts encapsulated in carbon nanotubes for hydrogen evolution reaction

Deng, Jiao; Ren, Pengju; Deng, Dehui; Yu, Liang; Yang, Fan; Bao, Xinhe

doi:10.1039/c4ee00370e

Cited by 879 publications

(616 citation statements)

References 43 publications

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“…While this barrier is in agreement with earlier studies, 17,18,58 analysis of the reaction mechanism reveals it is unlikely that hydrogen atoms bound to adjacent surface sites react through this mechanism, see top panel of Figure 6. The atoms do not react directly on top of the carbon-carbon bond.…”

Section: Tafel Reactionsupporting

confidence: 78%

“…the surface-proton distance in the TS, vary systematically with increasing charge for both electrodes. Additionally, we observe no doping effect, whereas Deng et al 18 note that substitutional nitrogen doping of an iron nanoparticle encapsulated (6, 6) CNT lowers the Volmer reaction activation energy from 1.20 to 0.85 eV at charge neutral conditions (for comparison, the authors report a 2.2 eV barrier for the pristine CNT). These discrepancies are most likely explained by differences in computational setups, e.g., the tube chirality and treatment of water molecules.…”

Section: Volmer Reactionmentioning

confidence: 43%

“…Judging by the maximum activation energies along the Volmer-Heyrovsky path, no improvement due to nitrogen doping was actually observed for Fe encapsulated CNTs (1.26 eV barrier with nitrogen, 1.20 eV without), despite a similar difference in adsorption energies. 18 Naturally, if we associate the calculated adsorption energies with experimental HER activities, the results will match the predictions of the volcano plot; but since 31 the exact, atomic-level structure of experimental NCNTs is unknown and usually contains nitrogen in various bonding configurations, 63 we do not believe this comparison to be fully relevant.…”

Section: Effects Of Hydrogen Coveragementioning

confidence: 93%

“…To our knowledge, with the exception of the pioneering work of Skúlason et al 15 on platinum surfaces and Taylor and co-workers 16 on Ni(111), this is the first time that the electrode potential dependence of HER is determined in a rigorous manner. While previous studies 17,18 of HER on CNTs do include calculations with varying surface charge, we show that it is necessary to correct for changes in the electrode potential during HER to obtain a quantitatively accurate description of the reaction's potential dependence.…”

Section: Introductionmentioning

confidence: 99%

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Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Holmberg

Laasonen

2015

J. Phys. Chem. C

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Density functional theory (DFT) was employed to investigate the hydrogen evolution reaction (HER) on pristine and nitrogen doped carbon nanotubes (CNTs) in acidic solution. As the reaction is an electrocatalytic surface reaction, an accurate description of HER requires performing simulations under constant electrode potential conditions. To this end, we examined HER at several electrode charges allowing us to determine grand canonical activation energies as a continuous function of electrode potential. By studying the elementary steps of HER -the Volmer, Tafel and Heyrovsky reactions -and by considering hydrogen coverage effects, we found that the Volmer-Heyrovsky mechanism is the predominant HER mechanism on CNTs with the Heyrovsky step being rate-determining. Our results indicated that CNTs are electrochemically active towards HER, which seen as a decrease in activation energies with growing electrode potential, but that the activity is lower than on platinum matching experimental data.Substitutional nitrogen doping did not improve HER activity, and further research is required to determine which nitrogen configurations contribute to the enhanced catalytic activity observed for experimental NCNTs.

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Section: Tafel Reactionsupporting

confidence: 78%

Section: Volmer Reactionmentioning

confidence: 43%

Section: Effects Of Hydrogen Coveragementioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

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Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Holmberg

Laasonen

2015

J. Phys. Chem. C

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“…This also confirms retained catalytic activity of Pd when encapsulated inside the CNTs, consistent with previously observations. 36,42,35 In addition, the presence of Pd nanocatalysts in both Pd-filled and Pd-coated CNTs shifts the onset of ORR peak of pristine CNTs from 2.8 V to 2.9 V, showing enhanced cathodic activity. 43 The Pd-filled CNTs also demonstrated 36% increase in first discharge capacity over Pd-coated.…”

Section: Resultsmentioning

confidence: 99%

Palladium-Filled Carbon Nanotubes Cathode for Improved Electrolyte Stability and Cyclability Performance of Li-O₂Batteries

Chawla

Chamaani

Safa

et al. 2016

J. Electrochem. Soc.

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Li-oxygen (Li-O 2 ) cathodes using palladium-coated and palladium-filled carbon nanotubes (CNTs) were investigated for their battery performance. The full discharge of batteries in the 2-4.5 V range showed 6-fold increase in the first discharge cycle of the Pd-filled over the pristine CNTs and 35% increase over their Pd-coated counterparts. The Pd-filled also exhibited improved cyclability with 58 full cycles of 500 mAh · g −1 at current density of 250 mA · g −1 versus 35 and 43 cycles for pristine and Pd-coated CNTs, respectively. In this work, the effect of encapsulating the Pd catalysts inside the CNTs proved to increase the stability of the electrolyte during both discharging and charging. Voltammetry, Raman spectroscopy, FTIR, XRD, UV/Vis spectroscopy and visual inspection of the discharge products using scanning electron microscopy confirmed the improved stability of the electrolyte due to this encapsulation and suggest that this approach could lead increasing the Li-O 2 battery capacity and cyclability performance. High energy density batteries have garnered much attention in recent years due to their demand in electric vehicles. Lithium oxygen (Li-O 2 ) batteries have nearly 10 times the theoretical specific energy of common lithium-ion batteries and in that respect have been regarded as the batteries of the future. and other forms of carbons 13,14 have been commonly used as cathode materials in Li-O 2 batteries. Among carbon-based materials, carbon nanotubes (CNTs) have been widely used in Li-O 2 cathodes due to their high specific surface area, good chemical stability, high electrical conductivity, and large accessibility of active sites. 15,16 Zhang et al. reported one of the early uses of CNT (single-walled) as cathode materials in Li-O 2 batteries in which discharge specific capacities as high as 2540 mAh · g −1 were obtained at 0.1 mA · cm −2 discharge current density.8 Although many research studies have been done to improve the performance metrics of Li-O 2 batteries, they are still in their early stages and many technical challenges have to be addressed before their practical applications. 17,18 The most common problems impeding the development of Li-O 2 batteries have been low rate capability, poor recyclability and low round-trip efficiency.19,3 All of these issues are originally stemmed from sluggish kinetics and irreversible characteristic of the OER and ORR reactions which causes high overpotentials in discharging/charging process. Hence, increasing the efficiency of OER/ORR reactions and minimizing the overpotentials during the = These authors contributed equally to this work. 21 Alternatively, the use of different noble metals and metal oxide catalysts has also been integrated in the cathodes of Li-O 2 batteries. [22][23][24][25] The catalyst may influence the performance of Li-O 2 batteries by destabilizing the oxidizing species which decreases the charging overpotential.26,27 They may also increase the surface active sites and facilitate charge transport from oxidized reactants to the e...

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Nanocarbon Materials in Catalysis

Zhang

Liang

2017

Nanotechnology Commercialization

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Highly active and durable non-precious-metal catalysts encapsulated in carbon nanotubes for hydrogen evolution reaction

Abstract: Novel non-precious-metal catalysts encapsulated in N-doped carbon nanotubes exhibit high activity and remarkable stability towards hydrogen evolution reaction (HER) in acidic medium.

Cited by 879 publications

References 43 publications

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Palladium-Filled Carbon Nanotubes Cathode for Improved Electrolyte Stability and Cyclability Performance of Li-O₂Batteries

Nanocarbon Materials in Catalysis

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Highly active and durable non-precious-metal catalysts encapsulated in carbon nanotubes for hydrogen evolution reaction

Abstract: Novel non-precious-metal catalysts encapsulated in N-doped carbon nanotubes exhibit high activity and remarkable stability towards hydrogen evolution reaction (HER) in acidic medium.

Cited by 879 publications

References 43 publications

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Ab Initio Electrochemistry: Exploring the Hydrogen Evolution Reaction on Carbon Nanotubes

Palladium-Filled Carbon Nanotubes Cathode for Improved Electrolyte Stability and Cyclability Performance of Li-O2Batteries

Nanocarbon Materials in Catalysis

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Product

Resources

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Palladium-Filled Carbon Nanotubes Cathode for Improved Electrolyte Stability and Cyclability Performance of Li-O₂Batteries