Hydrogenation Facilitates Proton Transfer through Two-Dimensional Honeycomb Crystals

Feng, Yexin; Chen, Ji; Fang, Wei; Wang, Enge; Michaelides, Angelos; Li, Xinzheng

doi:10.1021/acs.jpclett.7b02820

Cited by 66 publications

(113 citation statements)

References 53 publications

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“…These discoveries were absolutely unexpected since graphene was believed to be completely impermeable to all atoms and molecules under ambient conditions [3,4]. A number of works have subsequently appeared -both experimental [5][6][7][8][9][10] and theoretical [11][12][13][14][15][16]-not only stimulated by the promise of important applications in hydrogen technology but also with the aim to uncover the microscopic mechanisms underlying these observations.…”

Section: Introductionmentioning

confidence: 99%

Graphene multi-protonation: A cooperative mechanism for proton permeation

Bartolomei

Hernández

Campos‐Martínez

et al. 2019

Carbon

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The interaction between protons and graphene is attracting a large interest dueto recent experiments showing that these charged species permeate through the 2D material following a low barrier (∼ 0.8 eV) activated process. A possible explanation involves the flipping of a chemisorbed proton (rotation of the C-H + bond from one to the other side of the carbon layer) and previous studies have found so far that the energy barriers (around 3.5 eV) are too high to explain the experimental findings. Contrarily to the previously adopted model assuming an isolated proton, in this work we consider protonated graphene at high local coverage and explore the role played by nearby chemisorbed protons in the permeation process. By means of density functional theory calculations exploiting large molecular prototypes for graphene it is found that, when various protons are adsorbed on the same carbon hexagonal ring, the permeation barrier can be reduced down to 1.0 eV. The related mechanism is described in detail and could shed a new light on the interpretation of the experimental observations for proton permeation through graphene.

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Section: Introductionmentioning

confidence: 99%

Graphene multi-protonation: A cooperative mechanism for proton permeation

Bartolomei

Hernández

Campos‐Martínez

et al. 2019

Carbon

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“…Further measurements involving hydrogen's isotope deuterium have shown that this barrier is in fact 0.2 eV higher than the measured activation energy because the initial state of incoming protons is lifted by zero-point oscillations at oxygen bonds within the proton-conducting media used in the experiments 2 . The resulting value of 1.0 eV for the graphene barrier is somewhat lower (by at least 30%) than the values obtained theoretically for ideal graphene 1,[8][9][10][11] , which triggered a debate about the exact microscopic mechanism behind the proton permeation [8][9][10][11][12][13] . For example, it was recently suggested that graphene's hydrogenation could be an additional ingredient involved in the process 11 .…”

mentioning

confidence: 71%

“…The resulting value of 1.0 eV for the graphene barrier is somewhat lower (by at least 30%) than the values obtained theoretically for ideal graphene 1,[8][9][10][11] , which triggered a debate about the exact microscopic mechanism behind the proton permeation [8][9][10][11][12][13] . For example, it was recently suggested that graphene's hydrogenation could be an additional ingredient involved in the process 11 . Furthermore, it was shown experimentally that graphene's barrier for protons could be lowered quite substantially by decorating graphene with nanoparticles of catalytically-active metals such as Pt and Pd 1 .…”

mentioning

confidence: 71%

“…Indeed, the observed dependence I  P 1/4 is similar to that of the temperature of hot electrons in graphene, which displays a similar power law 23 . Another possible effect to consider is that the increased electron temperature can promote hydrogenation of graphene, which should also lower the proton barrier 11 . More work is needed to explain the photo-proton effect but we have to point out that the exact microscopic mechanism of proton transport through graphene is still under debate and, probably, should be understood first.…”

Section: Figure 1|mentioning

confidence: 99%

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Giant photo-effect in proton transport through graphene

Lozada-Hidalgo¹,

Hu²,

Zhang³

et al. 2017

EasyChair Preprints

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Graphene has recently been shown to be permeable to thermal protons, nuclei of hydrogen atoms, which sparked interest in its use as a proton-conducting membrane in relevant technologies. Here we report that proton transport through graphene can be enhanced strongly by iluminating it with visible light. Using electrical measurements and mass spectrometry, we find a photoresponsivity of ∼104 A W-1, which translates into a gain of ∼104 protons per photon, with response times in a microsecond range. These characteristics are competitive with thos of state-of-the-art photodetectors based on electron transport using silicon and novel two-dimensional materials. The photo-proton effect can be important for graphene's envisaged use in fuel cells and hydrogen isotope separation. Our observations can also be of interest for other applications such as light-iduced water splitting, photo-catalysis and novel photodetectors.

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“…Partly because of the fascinating measurements, considerable theoretical effort have gone into understanding the microscopic details of how protons penetrate graphene and h-BN and to understand the role of NQEs in the process [159,[163][164][165]. In work that we were involved in, we used DFT-based PIMD to examine the proton penetration process [165]. With the specific DFT functional used and model system employed we found that the classical H + penetration barrier was approximately 3.5 eV, in line with earlier studies.…”

Section: Proton Penetration Of 2d Materialsmentioning

confidence: 99%

The quantum nature of hydrogen

Fang

Chen

Feng

et al. 2019

International Reviews in Physical Chemistry

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Hydrogen is the most abundant element. It is also the most quantum, in the sense that quantum tunnelling, quantum delocalisation, and zero-point motion can be important. For practical reasons most computer simulations of materials have not taken such effects into account, rather they have treated nuclei as classical particles. However, thanks to methodological developments over the last few decades, nuclear quantum effects can now be treated in complex materials. Here we discuss our studies on the role nuclear quantum effects play in hydrogen containing systems. We give examples of how the quantum nature of the nuclei has a significant impact on the location of the boundaries between phases in high pressure condensed hydrogen. We show how nuclear quantum effects facilitate the dissociative adsorption of molecular hydrogen on solid surfaces and the diffusion of atomic hydrogen across surfaces. Finally, we discuss how nuclear quantum effects alter the strength and structure of hydrogen bonds, including those in DNA. Overall these studies demonstrate that nuclear quantum effects can manifest in different, interesting, and non-intuitive ways. Whilst historically it has been difficult to know in advance what influence nuclear quantum effects will have, some of the important conceptual foundations have now started to emerge.

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Hydrogenation Facilitates Proton Transfer through Two-Dimensional Honeycomb Crystals

Cited by 66 publications

References 53 publications

Graphene multi-protonation: A cooperative mechanism for proton permeation

Graphene multi-protonation: A cooperative mechanism for proton permeation

Giant photo-effect in proton transport through graphene

The quantum nature of hydrogen

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